Haptics: Perception, Devices and Scenarios

The performance of haptic application is highly sensitive to communication delays and losses of data. It implies several constraints in developing networked haptic applications. This paper describes a new internet protocol called Efficient Transport Protocol (ETP), which aims at developing distributed interactive applications. TCP and UDP are transport protocols commonly used in any kind of networked communication, but they are not focused on real time application. This new protocol is focused on reducing roundtrip time (RTT) and interpacket gap (IPG). ETP is, therefore, optimized for interactive applications which are based on processes that are continuously exchanging data. ETP protocol is based on a state machine that decides the best strategies for optimizing RTT and IPG. Experiments have been carried out in order to compare this new protocol and UDP.

This paper presents a bilateral control architecture for teleoperation systems where the environment must not be identified to design the control gains. In this control scheme, the interaction force of the slave with the environment is an external input. This force is not modeled by gains inside the control architecture. In the paper, the state convergence methodology is used to design the control gains of the teleoperation system. The control system allows that the slave state follows the master state and to establish the desired dynamics of the teleoperation system. Several simulation results are shown to verify the performance of the control scheme.

We investigated the detection of vibrotactile targets against a background of concurrent non-targets, presented by eight tactors equally distributed in a horizontal band around the torso. Stimuli consisted of temporal activation patterns. Single targets (T) were presented among two to seven non-targets (N). The similarity between targets and non-targets was varied between low and high. For target-present trials the response times increased with set size, indicating a serial discrimination process. For target-absent trials the response times did not vary with the number of stimulus items, indicating a parallel discrimination process. The results showed no effect of T-N similarity. The results suggest that tactile search is not comparable to visual search.

Wristalyzer is a portable robotic device combining haptic technology with electromyographic assessment. It allows to assess wrist motion in physiological and pathological conditions by applying loads and mechanical oscillations, taking into account the ergonomy and the angular positioning of the joints. The wristalyzer works in a free or loaded mode for assessment of metrics of motion and tremor, analyzes the behavior of the wrist joints and the associated muscle activities during delivery of mechanical oscillations, estimates the maximal voluntary contraction, assesses automatically the impedance of the wrist for assessment of rigidity or spasticity. Position, torques and electromyographic activities are analyzed in real time. The device characterizes the effects of damping on voluntary motion. A personal computer implements control loops and user application. This is the first standardized tool to assess wrist motion with high accuracy and reliability using the haptic technology with concomitant investigation of muscle activity.

The apparent mass of haptic device end-effector depends on its position inside the workspace. This paper presents a recursive algorithm to detect effective direction of gravity force, and to automatically estimate the apparent mass of the end-effector when placed at the vertices of a cubic grid contained into the device workspace. Then an on-line technique is proposed to actively compensate gravity, exploiting trilinear interpolation to compute an estimate of end-effector apparent mass in any position of the workspace. Experiments have been performed with three different haptic devices, and results shown that the apparent mass of the end-effector is compensated almost homogeneously with respect to its position in the workspace.

Physically dissipative damping can increase the range of passive stiffness that can be rendered by a haptic device. Unlike simulated damping it does not introduce noise into the haptic control system. A DC motor can generate such damping if it’s terminals are shorted. We employ a configuration of the H-bridge which can cause this damping to impart stability to our haptic device. This results in an increase in passive wall stiffness of about 33.3% at a sampling rate of 100Hz and 16.6% at 1kHz over the performance of an undamped DC motor. We have also attempted to implement the system on the hybrid haptic control system [1], it was seen that a perceivable change in the performance of this system was not observed by the use of DC motor damping.

The slave robot in this research is a 1-DOF piezo actuatorwhich includes hysteresis nonlinearity. Nonlinear hysteresis behavior makes robot control a complex task. In this research, the nonlinear and uncertain dynamics of the slave robot has been considered through the teleoperation control loop. LuGre friction model is used as the estimator of the hysteresis loop. An impedance controller for the master side and a sliding-mode-based impedance controller for the slave side have been proposed. The latter is a sliding mode controller, because the plant is nonlinear and uncertain. Also, it is an impedance controller providing both high performances during contact and excellent tracking in free space motion. These controllers make teleoperator robustly stable against uncertainties and bounded constant time delay. Meanwhile, scaling factors, known as sources of instability, have no disturbing effect. After canceling the nonlinear term out of the teleoperator by the controllers, stability of the entire system will be guaranteed by Llewellyn’s absolute stability criterion. Performance of the proposed controllers is investigated through simulation.

At present, surgical master-slave systems lack any kind of force feedback. Typically, controllers giving good stiffness transparency for soft environments cannot guarantee stability during hard contact. This paper presents a pragmatic method to avoid instability of a master-slave system during hard contacts, which does not affect the stiffness reflection for soft environments. The time derivative of the interaction force with the environment is used to detect a hard contact. Upon detection of a hard contact the force feedback is switched off and a virtual wall is activated at the master side in order to guarantee the perception of hard contact by the operator. The experiments demonstrate good stiffness transparency for soft environments, while the system remains stable for both soft and hard environments.

The slave robot of the macro-micro teleoperation system presented in this paper is a 1-DOF piezo actuator including hysteresis nonlinearity. This nonlinear behavior makes robot control a complex task. In this research the nonlinear and uncertain dynamics of the slave robot has been entered directly into the teleoperation control loop. The LuGre friction model is used as the estimator of the hysteresis loop to cancel out this undesirable term. A 2-DOF master-slave system is decomposed into two 1-DOF systems: a shape system representing the master-slave position coordination, and a locked system representing the dynamics of the coordinated system. For making the closed-loop teleoperation system passive against dynamic parameter uncertainty and force measurement inaccuracy, four virtual flywheels are designed. In this way, the energy generated by troublesome terms inside controllers (i.e. the terms which may endanger passivity of the controller) would be taken from the bounded kinetic energy deposited on these flywheels. Simulations are performed to show effectiveness of the proposed controllers.

This paper describes a preliminary work devoted to the design of a control architecture for a defective haptic interface, i.e. an underactuated haptic interface not able to apply forces along arbitrary directions. This interface is intended to be used for grasping tasks, where unilateral constraints are usually present. The main control problems considered in this paper concern the study of friction compensation techniques by means of a force feedback loop and a feedforward controller. This has been implemented with three different methods: two are based on a model of the friction present in the actuation system, while the latter on a Momentum Observer. These schemes have been experimentally tested on a simplified setup of the haptic interface, composed by a linear motor, a force sensor, and a Kevlar wire. Two sets of experiments have been considered, i.e. free space motions and interaction with a virtual wall.

In this paper we describe a system that combines human input and automatic grasp planning for controlling an artificial hand, with applications in the area of hand neuroprosthetics. We consider the case where a user attempts to grasp an object using a robotic hand, but has no direct control over the hand posture. An automated grasp planner searches for stable grasps of the target object and shapes the hand accordingly, allowing the user to successfully complete the task. We rely on two methods for achieving the computational rates required for effective user interaction: first, grasp planning is performed in a hand posture subspace of highly reduced dimensionality; second, our system uses real-time input provided by the human user, further simplifying the search for stable grasps to the point where solutions can be found at interactive rates. We demonstrate our approach on a number of different hand models and target objects, in both real and virtual environments.

In this paper we focus our research on user identification rather than user verification by analyzing handwritten signature and haptic information such as pressure. For analysis, a multilayer perception (MLP) neural network is adopted. In order to verify the proposed method, 16 users’ signatures were measured with haptic information. We successfully identified users at an average success rate of 81%.

This paper shows a new methodology for bilateral controller design based on transparency using a modified state convergence control scheme. This methodology offers some advantages upon designing bilateral systems. The design is based on modelling the behaviour of the master and the slave by applying state space equations, and considering perfect transparency cannot be reached. Therefore, the objective of the controllers is to guarantee the convergence of the master and slave status. This paper describes the criteria to achieve transparency on steady state.

Multimedia systems and applications have recently started to integrate the sense of touch and force feedback in the human-computer interaction. Surprisingly, measuring the quality of experience (QoE) when haptic modality is incorporated in a virtual user interface has received limited attention from the research community. In this paper, we propose a taxonomy for measuring the quality of experience of Virtual Reality (VR) applications. Furthermore, the taxonomy is modeled using a Fuzzy Logic Inference System (FIS) to quantitatively measure the QoE of a haptic virtual environment. Finally, the proposed model is tested using the Mamdani system. The simulation and usability analysis demonstrated that the proposed model reflects the user estimation for the applications more accurately and thus is capable of measuring the overall QoE of a haptic application.

At the present, it is impossible to identify a defined set of quantified parameters which describe the haptic sensation felt when interacting with physical objects. Literature describes haptic properties like shape, texture or the passivity of an interaction, however quantitative values being used in independent experiments do hardly exist. This fact gives the central reason why in haptic science – in contrast to scientific research for the visual sense or the sense of hearing – no measurement technology has yet been established to compare the haptic properties of different objects and devices among each other. The purpose of this paper is to make a suggestion for a model offering both: a quantification of haptic interaction and an approach to measure haptic sensation.The document starts with a discussion about the properties of haptic sensations from a technical viewpoint. A model of haptic interaction is given as established as a working hypothesis at the authors’ institution. The components of the model are explained and the mathematical background is formulated. A method to quantify haptic impression derived from the usage of the model is presented. An example of the application of the model is shown and a forecast on the chances of this approach is given. The paper closes with a look at the ongoing work on the model and the method.

This paper describes a technical solution that has been devised to embed the SensAble PHANTOM

®

6dof force feedback device with a light-weight 6dof force sensor from ATI: the Nano43. The design has been made in a way such that original performances are kept in terms of force feedback and sensing.

The force vector information is essential while collision avoidance planning through tactile feedback in autonomous or teleoperation mode. In this paper, we concentrate on the approach to calculation of the applied force vector at any point of the robot arm and its technical realization. Based on the presented force vector calculation flow, we obtained the experimental results validating the ability of the proposed method to trace the contact point position and to estimate force vector robustly and accurately.

This paper proposes a nonlinear controller to extend the Z-width of a haptic device. A time-domain passivity analysis of the Z-width diagram leads to the new haptic controller, which employs acceleration feedback. The passivity condition for one degree of freedom (1DOF) haptic interaction with a virtual wall via the proposed controller is derived using passivity theory in the frequency domain. The perfomance of the proposed controller is validated experimentally on a PHANTOM Omni haptic device. The experiments illustrate that the new controller considerably extends the Z-witdh of the haptic interface.

We present some results regarding utilizing Graphics Processing Unit (GPU) for computing the deformation of two experimental objects. A suture simulation model with GPU and a 2D deformable cloth model with nVidia CUDA techniques are also proposed. We conducted experimental studies to compare the GPU-based suture models and with the CPU implementation. We also experimented with the implicit model of the 2D mesh which offer similar computational challenges associated with any Finite-Element modeling approaches. A method for computing the inverse of a matrix with truncated Neumann series is also introduced.

This paper expresses the ”Wave variable” and the Lawrence/Salcudean ”4-Channel” architectures in a unified MIMO framework in the frequency domain. This illustrates how these popular control architectures are related, and in which way they are equivalent. Furthermore, it is shown that the information communicated between master and slave is very similar in both cases. It is suggested to use the term ”control effort” instead of ”wave-variable”, to clarifiy the mechanism of the controllers.

For both, the analysis of haptic interaction and the quantification of haptic perception a profound knowledge of the mechanical impedance of human touch are needed. Several models for a user’s impedance have been suggested in literature and some guidelines and quantitative values from independent models for different contact situations are available. However for the analysis of haptic interaction and the quantification of perception it is necessary to allow comparison between different grasps. Therefore a reduced set of models which covers many types of touch in an acceptable quality would be ideal. Additionally the influence of the change of touch – the pretension of fingers – on the impedance is seldom referred to and even more seldom quantified.

In 2005 the authors defined a method to quantify the impedance of a three finger precision grasp. In continuation of this approach and with the aim to collect a catalogue of impedance measures, this document presents results from set of 192 measurements regarding the impedance of the index finger from eight subjects. The resulting models and their dependencies are given as approximated plots of the impedance in dependency of frequency, direction of touch and size of the contact area. The resulting curves are discussed and put into context of the influence of impedance.

This paper presents a bilateral control method by state convergence for teleoperation systems where the master and slave robots do not necessarily have homothetic kinematics. This method uses a virtual robot to relate the kinematics of the master and slave robots. An application of this type of control is also presented in which a robot of three degrees of freedom is teleoperated by using a commercial haptic device with six degrees of freedom.

This study is concerned with the overshoot effect in a task of surface differentiation when both surface stiffness and impact velocity are varied. Psychophysical experiments are conducted using virtual surfaces rendered with a force-feedback device with velocity as visual constraint. We test the force constancy hypothesis formulated by Walker and Tan [12][1] which states that users maintain constant penetration force while exploring haptic virtual surfaces. Data collected during stroking surfaces of varying stiffness partially support this hypothesis and allow to consider the relevance of the impact velocity factor. Our results clearly show that changes in impact velocity affects surface penetration. Our findings underscore the importance of better understanding the interplay of the human perceptual parameters in a haptic framework. Future work will focus on the development of compensation rules for ensuring perceptual accuracy of anatomic haptic virtual environments. This will ensure accurate simulation of the haptic interaction between surgical tools and body organs.

Haptic icons (brief tangible stimuli with associated meanings) are a new way to convey information, but are difficult to design in large quantities due to technological and perceptual constraints. Here, we employ

rhythm

in combination with frequency and amplitude to systematically produce 84 distinguishable tactile stimuli for use as icons. The set’s large size is made possible by an analysis of how users perceptually organize tactile rhythm. Through our evaluation, we find that the two primary characteristics by which users distinguish its tactile rhythms are

note length

and

unevenness

.

The present study examined our ability to identify the location of a single vibration delivered to the dorsal and/or volar side of the forearm near the wrist. Three participants took part in three absolute identification experiments. In Exps. I and II, a 3-by-3 tactor array was placed on the dorsal and volar side of the wrist, respectively. In Exp. III, two 3-by-3 tactor arrays were placed on both sides of the wrist. Prior to each experiment, the intensities of the tactors were adjusted to be equally loud. Each participant completed a total of 405, 405 and 810 trials for Exps. I, II and III, respectively. The results indicate that on average, only 2 tactor locations can be correctly identified on either the dorsal or the volar side of the wrist, and 4 locations on both sides. The implications of our results for the design of mobile devices are discussed.

The active control of exploratory movements is an integral part of active touch. In two experiments we investigated (and manipulated) the relationship between the haptic discrimination of small bumps and the direction of exploratory movements relative to the body. Shape discrimination performance systematically varied with the direction of stimulus exploration. Further, if they were rewarded for good perceptual performance and had the choice, participants displayed clear strategic preferences for certain exploratory directions. Chosen directions, at least on average, were accompanied by low discrimination thresholds. Overall, the findings emphasize the necessity to focus at the explorator’s active contribution to haptic perception, and provide the first hints that exploratory behavior might be exploited to optimize haptic perception.

We describe a new tactile illusion of surface geometry that can be easily produced with simple materials. When the fingertip skin is strained by loading it in traction along a narrow band surrounded by two fixed traction surfaces, the sensation of a raised surface is typically experienced. This and other analogous cases are discussed in terms of tissue deformation created at a short distance inside the skin where the target mechanoreceptors are presumably located. A finite element analysis allowed us to propose that the basis of this illusion is connected with the observation that normal loading and tangential loading can create similar strain distribution, thereby creating an instance of an ambiguous stimulus. In the discussion we relate this stimulus to several other ambiguous tactile stimuli.

The existence and intermanual transfer of curvature aftereffects was studied for static and dynamic touch, whereby only the index fingers were used. A curvature aftereffect is the phenomenon that a flat surface is judged concave if the preceding touched stimulus was convex and vice versa. Substantial aftereffects were demonstrated when the subsequently presented adaptation and test stimulus were touched by the same index finger. When one index finger was used to touch the adaptation stimulus and the opposite index finger was employed to touch the test stimulus, only a partial transfer of the aftereffect was found for static touch, but a complete transfer was obtained in the dynamic case. These findings suggest that the representation of curvature information depends on the exploration mode.

In order to realize artificial tactile sensation, we are researching the natural nerve activity timing of mechanoreceptors. Considering the energy conversion system of the Meissner corpuscle, we insist that the corpuscles encode the normal strain, particularly detecting horizontal normal strain. We observed a clear difference in the thresholds between the pushing and pulling cases. This finding suggests that horizontal stretch preferentially induces nerve activity in the Meissner corpuscle.

Compressibility or hardness of objects is an important aspect in haptic perception. Both cutaneous and kinaesthetic information are used for the perception of compressibility. In this paper, the relative role of these contributions is investigated. This is done with psychophysical experiments using a purpose-made silicon rubber stimulus set. The fabrication and characterisation of the stimuli are described, as well as discrimination experiments with and without surface deformation of the stimuli. With the cutaneous cues of surface deformation present, the Weber fraction for hardness discrimination was 0.12. When surface deformation was removed and only kinaesthetic cues were available, the Weber fraction doubled, suggesting that the cutaneous sense contributes almost three quarters to hardness perception, and the kinaesthetic just over one quarter, if the information is integrated in a statistically optimal fashion.

In this study we show that humans are able to form a perceptual space from a complex, three-dimensional shape space that is highly congruent to the physical object space no matter if the participants explore the objects visually or haptically. The physical object space consists of complex, shell-shaped objects which were generated by varying three shape parameters. In several psychophysical experiments participants explored the objects either visually or haptically and performed similarity ratings. Multidimensional scaling (MDS) analyses showed high congruency of the visual and haptic perceptual space to the physical object space. Additionally, visual and haptic exploration resulted in very similar MDS maps providing evidence for one shared perceptual space underlying both modalities.

If you have multiple objects in your pocket, some are easy to find among the other ones, for instance, when they differ much in material properties or shape. Information on which haptic features stand out among others is valuable for research into the haptic system in general, but also for haptic interface design. In this research we focussed on saliency of shape, by letting subjects search for cubes or spheres. Response times were measured as a function of the number of items. We found that search for a cube among spheres is more efficient than search for a sphere among cubes and that the dynamics of the sliding of the shapes along each other play an important role in haptic search.

Accurate encoding of object size is important for the control of grasp aperture and object manipulation. When an object is grasped between index finger and thumb, size perception may be based on kinaesthetic input, indicating digit separation, and tactile input from the digit pads, signalling the moment of contact with the object. We present a case study of stroke patient JB with tactile extinction who underestimated the size of contralesional objects in simultaneous bimanual grasping and, with the passage of time, when objects were held in a contralesional unimanual grasp. We propose that extinction of tactile input from the contralesional finger pads signalling the moment of contact with grasped objects resulted in the contralesional digits being perceived to be closer together than those of the ipsilesional hand. In contrast, when objects were held in a contralesional unimanual grasp, fading tactile afferent input from the finger pads, in combination with a stable motor output and sense of effort resulted in fading perception of object size.

When three pulses mark two open intervals, the length of the second interval is underestimated when it is longer than the first. This phenomenon is called time-shrinking and found in audition and vision. In the present experiment, we investigated time-shrinking for the tactile modality. Eighteen observers adjusted the length of a comparison interval to match a test interval that was presented alone or with a preceding interval. In the range of test intervals (260 – 580 ms), we found a time-shrinking effect of 30 ms that was not dependent on the difference between the test interval and the preceding interval. This result is relevant for the design of tactons that use rhythm or the interval length between pulses to code information.

Haptics research has begun implementing haptic feedback in tasks of great precision and skill, such as robotic surgery. Haptic displays can represent task environments with arbitrary scaling. Fitts’ Law suggests differences in the scale of a workspace rendered on a visual display and in a haptic display should not affect performance of those tasks. However, interactions of great precision and skill may require understanding and verifying the influence of perceiving an environment when the visual and haptic displays represent those environments with differing scales. This experiment measured the influence that mismatched haptic and visual display scalings had on movement times in. Each of five treatments used different scales in the visual and the haptic displays. A Friedman rank test showed a significant difference across all treatments. A

post hoc

pairwise comparison showed a nearly significant difference between two treatments. These findings suggest the need for further study using more participants and parametric statistics to measure the magnitude of the possible influences.

This paper describes an experiment that studies the effect of basic haptic feedback in creating a sense of social interaction within a shared virtual environment (SVE). Although there have been a number of studies investigating the effect of haptic feedback on collaborative task performance, they do not address the effect it has in inducing social presence. The purpose of this experiment is to show that haptic feedback enhances the sense of social presence within a mediated environment. An experiment was carried out using a shared desktop based virtual environment where 20 remotely located couples who did not know one another had to solve a puzzle together. In 10 groups they had shared haptic communication through their hands, and in another group they did not. Hence the haptic feedback was not used for completing the task itself, but rather as a means of social interacting – communicating with the other participant. The results suggest that basic haptic feedback increases the sense of social presence within the shared VE.

Previous research on haptic object recognition has focused mainly on static objects and very little is understood about the role of dynamic information in haptic object recognition. In this study we examined if motion, particularly dynamic object parts, is combined with shape information in the representation of an object in haptic memory. In our behavioural studies we found that target objects previously learned as moving objects were more easily recognized when presented dynamically than when presented as static objects, even though, shape information alone was sufficient to recognize each object. Moreover, cross-modal, visuo-tactile object recognition was better for dynamic than static objects.

This study investigates the influence of stimulus properties on explorative movement parameters in active touch. Using a PHANToM force-feedback device we generated virtual stimuli with different stiffness values. Participants freely explored pair-wise presented stimuli and were asked to select the softer one. Afterwards we analyzed their explorative movements considering the parameters velocity, pressure and the indentation depth. We found a systematic influence of stimulus’ stiffness on pressure/indentation depth and velocity. We conclude that observers adapted the movement parameters depending on stiffness variations.

Being able to readily discriminate between natural things and synthetic mimics in our environment is an important ability for many species. Making these judgements relies on the acuity of our different senses. Here, we investigated the relative contribution of visual and tactile cues, alone or in combination, to the categorisation of wood and fabric stimuli as natural or unnatural. For both wood and fabric stimuli we found that natural and unnatural stimuli could be discriminated, although performance varied as a function of modality. Specifically, for the wood stimuli, performance was better when vision and touch were combined, whereas for the fabric stimuli, performance was least accurate when using touch alone, compared to the visual or bimodal conditions, which were quantitatively similar. We concluded that both vision and touch contribute, albeit in qualitatively different ways, to the perception of “naturalness”, and that a combination of these modalities facilitates this perception.

Despite the advantages of minimally invasive surgery the applicability of (robot assisted) minimally invasive techniques is limited to simple operations due to the lack of tactile feedback. Tactile feedback is essential in many operations such as border detection during tumor resections and localization of nerves and veins embedded in soft tissue. This work compares the performance of existing tactile stimulation methods using psychophysical techniques in an edge detection test. Several mechanical and psychophysical design considerations for lateral skin stretch and perpendicular indentation displays are given. Considering the list of disadvantages, related to lateral skin stretch, we conclude that perpendicular indentation is the preferred stimulation method for tactile feedback systems to be used in minimally invasive surgery.

A lateral motion touchscreen display can produce satisfying tactile feedback reminiscent of high quality mechanical switches. This study examines the perception of lateral motion acceleration for touchpanel displays for a variety of activation thresholds. A user study directly comparing short, high magnitude normal and lateral accelerations shows that for low accelerations, lateral motion is perceived as slightly weaker than normal, but for high accelerations, lateral acceleration is perceived as stronger than normal acceleration by as much as 40%. The results indicate that for high acceleration, high activation threshold mechanical switches, such as are found in automotive dashboards, lateral motion touchpanels can provide equivalent strength to normal motion displays with significantly less fingertip acceleration.

The aim of this study was to identify the tactile dimensions in the discrimination of light-weight wool fabrics. The participants judged the overall similarity between 21 light-weight wool fabrics using free sorting tasks. The fabrics were evaluated using active touch with limited exploratory procedure. Multidimensional scaling (MDS) was used to generate the perceptual space, revealing one dimension of tactile perception. Finally, through regression analysis we were able to interpret this dimension, using verbal attributes and physical properties of the fabrics. We discuss the relevance of the stimuli properties and the associations between verbal attributes and between physical properties, on the evaluation of the fabrics, considering its theoretical implications.

Among the challenges of haptic displays is the objective of creating a tactile language. Tactile language is used as a substitute to visual and auditory languages when either of the modalities is overloaded or impaired. Haptic displays have been implemented using a variety of technologies to stimulate different tactile sensations such as pressure, vibration and temperature. In this work, we present a novel implementation of a thermal sensation known as the Thermal Grill Illusion as the basis of a tactile language. A designated system, the Thermoelectric Tactile Display, was developed to generate Thermal Grill Illusion based stimuli. The usability of this type of display is being evaluated.

Realistic haptic rendering is one of the most challenging issues in the field of virtual reality. The intent is for the user to experience the same kinesthetic sensations in the virtual realm as they would in the real world. Therefore, we need to know the capabilities of the human haptic system. The issue investigated in this study was the adaptation to force feedbacks in a haptic-enabled virtual environment (VE). Psychophysical experiments are conducted to study how adaptation is influenced by changes in the force intensity and direction. The results indicate that the users definitely adapt to forces in a VE. However, the force direction and force increment/decrement do not affect adaptation. This information can be used to create haptic models with much less detail.

Most studies on the haptic perception of force direction have been conducted without hand movements, whereas hand movements are normally required in real-world applications. This paper reports a study on the perception of haptic force direction during hand movement. Discrimination thresholds for force direction were determined for two hand movement speeds, slow and fast, and for five reference force directions. The results show that the perception of force direction is not affected by hand movement speed. We also found that the perception of force direction was not impaired by the hand motion, nor by the direction of the reference force.

In this study we compared human discrimination performance for real and virtual curved shapes. To simulate a curved shape we used a device that could independently orient and elevate a moving surface that was in contact with an exploring finger. Thus, the geometry was preserved up to the first order in the virtual shape. In our experiment we found that this preservation was indeed sufficient: discrimination thresholds were similar for the real and virtual conditions. Our results were also in line with previous curvature studies performed with real stimuli.

The illusion described here is well documented, and known as the rubber hand illusion (RHI). It is used to investigate perceptual processes and multisensory interactions. In the presented study we aimed to achieve the projected sensation using a paradigm designed to achieve a Virtual Hand Illusion (VHI). This allowed the exploration of novel stimuli including passive and active movement of the arm, self stimulus and haptic stimuli other than just brushing. Our results showed similar effects to the original RHI and demonstrated the advantage of active haptic stimulation for enhancement of body ownership.

Frictional properties at the interface finger/object influence forces exerted on the object during dexterous manipulation. Furthermore, the coefficient of friction (CF) of the skin at fingertip is influenced by moisture. In this study, we propose to assess the influence of moisture at fingertip on grip force (GF) during a horizontal pointing task. We developed a specific device to measure the skin hydration (Moisture Evaluator) and we show that the changes in moisture are taken into account by the GF controller.

There is evidence that weight perception with one hand may be based on integrating effort signals resulting from muscular activity to support arm and weight against gravity [1]. When lifting an object with both hands, the magnitude of effort signals due to supporting the arms and weight against gravity may change in opposite ways: posture effort signals may

increase

due to the employment of both hands while weight effort signals may

decrease

due to sharing the weight between the two hands. Here, we report preliminary results of a study in which participants judged the heaviness of weights lifted with one and two hands. It was found that a weight lifted with both hands felt lighter than equal weights lifted with the left or right hand. However, unimanually lifted weights did not feel twice as heavy as bimanually lifted weights. This may suggest that an imperfect integration of both postural and weight signals could be taken into account when judging weight bimanually.

In this paper the humans’ hand movement as response to a vibration signal is presented. The signal thereby is composed of single vibration stimuli. The results of this study are used for signal generation of a tactile display for computer aided surgery. Each of the display’s tactors represents one movement direction of the hand. To present directions between single movement axes it is necessary to combine single vibration signals. Therefore an experiment is presented to examine the fusion of single tactile signals. The experiment is divided into three parts to compare three different ways of merging vibration signals. Best results were achieved with a modulation of the pulse duty factor.

We used transcranial magnetic stimulation (TMS) to explore the stability of the three components of the multi-finger prehension synergy during holding a vertically oriented object vertically in the air. TMS led to close to proportional changes in the mechanical variables produced by the digits. These changes violated synergy components that took different times to restore. Patterns of co-variation of the mechanical variables produced by individual digits corresponding to the equation of statics restored first followed by a change in the magnitude of the performance variables such as grip force, total tangential force, and total moment of force. The results support the principle of superposition as applied to the prehension synergy.

We investigated the effect of different types of interference in visual and haptic working memory using a dual-task paradigm. At encoding, 16 young adults performed both, a haptic and a visual primary task followed by the performance of a secondary interference task during a retention interval. The interference task could be a haptic (spatial), visual (spatial), auditory, or control (visual-static) task. The idea was to study the influence of spatial and verbal interference on working memory for spatial targets encoded visually or haptically. The results indicated that the auditory interference task did not deteriorate performance compared to the control condition in which participants performed the visual-static task. The negative effects of spatial interference increased when both the primary and secondary tasks were performed using the same modality. Spatial interference selectively deteriorated both visual and haptic working memory but more strongly the later.

At present Laparoscopic surgeries are performed regularly. In practice, no augmented feedback on pinch force is currently available. However,research has proven this to be useful. This research explored the location of a visual feedback signal on pinch force. The reaction time and amount of errors of two different positions of a feedback signal was studied. Firstly, the feedback signal was placed next to the endoscopic view and secondly, it was placed near the tips. Each experiment contained a crossed and an uncrossed tool configuration and was performed with and without view of the tips. It was expected that in the crossed tool conditions problems could occurred as a result of the (non) existence of spatial compatibility between feedback stimulus and response goal. Based on reaction time, it can be concluded that the best position for a visual feedback signal on pinch forces is on top of the instrument tip.

This paper introduces the MasterFinger developemt and application, a multi-finger haptic interface for virtual object manipulation. This haptic device, with a modular interface, is specially designed to perform collaborative tasks. Each module is in charge of managing the haptic interaction with a finger. The mechanical structure of the module is based on a serial-parallel structure linked to the finger thimble by a gimble with its own controller. Cooperative applications based on MasterFinger-2 (MF2) are also described in this study. Results from these applications show that multifinger interface is a significant leap in haptic devices since precise object grasping and collaborative manipulation by using two hands are successfully performed.

We present a floor tile designed to provide the impression of walking on different ground materials, such as gravel, carpet, or stone. The device uses affordable and commercially available vibrotactile actuators and force sensors, and as such might one day be cost-effectively used in everyday environments. The control software is based on a lumped model of physical interactions between the foot and the ground surface. We have prototyped a measurement scheme for calibrating the device to match real-world ground materials.

This paper analyzes fingertip behavior on sticky surfaces for synthesizing stickiness sensation. Changes of fingertip contact area were monitored during contacts to sticky surfaces, which were then analyzed with respect to contact force. The analysis revealed that stickiness surfaces cause large hysteresis on the relationship between contact force and area. Based on the analysis, the sticky sensation was simply synthesized by using vacuum pressure. The synthesized sensation elicited a similar feeling as sticky sensation caused by adhesive glue, although the sensation was weaker than the intended one.

This paper presents a highly integrated tactile display which is being conceived using Micro-Electro-Mechanical Systems (MEMS). This device provides great assets in terms of process repeatability and integration of actuation mechanisms. This tactile interface is based on an array of 4x4 vibrating micro-actuators with 2 mm spatial resolution, providing a discrete stimulation of skin mechanoreceptors by vertical vibration. The actuation mechanism is based on the deflection of polymer or metallic membranes of various shapes. The concept we designed is mainly aimed to give back tactile sensations similar to textures, with possible applications for e-commerce and entertainment, or for the medical world. The actuation mechanism of this device is magnetostatic, based on the interaction between Copper coils and small-sized NdFeB magnets. Realization aspects and actual developments are also presented in this article.

In minimally invasive surgery, tactile feedback is lacking. A tactile display, consisting of a matrix of micro-actuators, represents tactile sensations on the fingertip. Miniaturising powerful, dynamic and accurate actuators with a sufficient stroke is a considerable challenge. This paper presents a proof of concept of a tactile display, based on microhydraulic actuators. A prototype with five taxels is designed, built and evaluated. The result is a light and compact display. It is mobile, has a stroke of 2 mm, a spatial resolution of 2 mm and can exert a maximal force of 0.5 N. The actuation principle is innovative in the field of tactile displays and has a great potential.

We propose a wearable haptic display that indicates the pressure and vibration on the palm for bimanual operations in virtual reality environments. This system aims to provide the touch and stroke sensations of virtual objects or virtual creatures. We constructed a prototype device that can reproduce vertical and shearing forces on the palm and evaluate the capability of the proposed method to recognize the existence of a virtual object in one-handed and two-handed operations.

Considering tactile sensors there are two ways to acquire object information. These are spatial sensing with two dimensional devices and fast sensing with simple devices. Because the reflection-type tactile sensor uses a reflection image, both methods can be employed. Though there exist some dynamic characteristics in these two ways.

In this study, we first validate the hysteresis of the reflection-type tactile sensor. The results show the sensor can evaluate displacement less than 2 mm. Then we propose a novel interface called “fibratus tactile sensor.” Secondly we construct a fast sensing device using reflection image and a combination of light emitting diodes (LEDs) and photodiodes (PDs), and validate the sensor’s reactivity. It can distinguish 300 ms interval between two signals. Moreover the correlation between the standard deviations of the acquired outputs from the sensor and the centerline average roughness is 0.90.

Cable robots or wire driven robots possess many advantages that make them well suited to be used as haptic interfaces. They present very low inertia and very low friction because of their very light mechanical structure. However, a bulky structure is needed to carry the motor units all around the handle. To avoid this problem, we previously proposed to replace one of the pulling cables with a pushing cylinder. Nevertheless, the actuation lines tend to be less regularly distributed in space, resulting in anisotropic and inhomogeneous static and dynamic performances. In this paper, we introduce a new architecture allowing better performances all over the workspace. This upgrade is validated with a precise cartography of the robot’s most important haptic characteristics.

We have proposed a new type of audio-tactile interface called the Straw-like User Interface (SUI) that allowed users to virtually experience the sensations of drinking with straw. The sensations were created based on data of pressure, vibration and sound recorded during drinking with a straw. The device enabled us to develop many unique interfaces, facilitating extension of research fields related to tactile displays, from medical care to entertainment. However, with the previous system, the recorded data were replayed at the same speed without reference to the suction power, and so the sensation became unnatural. In this paper we propose a simple technique to preserve naturalness. We dynamically change the play list in accordance with the user’s behavior. We believe that the proposed method provides a simple approach to record-and-replay of audio-tactile information without needing a physical model.

This paper presents an investigation into the workspace constraints observed through the use of multiple single point haptic interfaces, which lead to the design of a novel grasping device that improves upon current commercial haptic interfaces. The presented device is desktop based, and has been designed to maximise the haptic workspace while offering the ability to grasp and manipulate virtual objects, which is a function that current commercial interfaces are limited in providing. The performance of the commercial haptic interface in producing sustained effective operation and increased workspace with the attached haptic gripper is evaluated, and the improvement of both has been determined.

This paper describes a new tactile device which produces stress fields in 3D space. Combined with 3D stereoscopic displays, this device is expected to provide high-fidelity tactile feedback for the interaction with 3D visual objects. The principle is based on a non-linear phenomenon of ultrasound, acoustic radiation pressure. We fabricated a prototype device to confirm the feasibility as a tactile display. The prototype consists of 91 airborne ultrasound transducers packed in the hexagonal arrangement, a 12 channel driving circuit, and a PC. The transducers which were in the same distance from the center of the transducer array were connected to form a 12 channel annular array. The measured total output force within the focal region was 0.8 gf. The spatial resolution was 20 mm. The prototype could produce sufficient vibrations up to 1 kHz.

We describe a prototype mobile force-only feedback system called ‘Limbot’ constructed by placing a six degree-of-freedom force feedback system onto a two degree-of-freedom motorised platform. Existing mobile force-feedback platforms are typically designed to expand the virtual haptic workspace and support exploration of large haptic objects in the style of traditional Virtual Reality (VR) interfaces. Systems which focus on the VR paradigm typically preclude navigation of real environments because attention is primarily directed at the graphical display. In contrast, our device is unconstrained and designed for force-only explorations of real wide-area environments, for example as part of a location-based pervasive game. In order to achieve such wide-area exploration and navigation, our platform allows the user to couple and decouple the force feedback encoders to control the platform’s wheels. The device’s encoders switch between ’traditional’ virtual exploration of a haptic object and as a real navigation controller for the base platform motors. Initial testing of our prototype highlights (i) that our positioning and mobility approaches require that we consider haptic perspective more closely; (ii) that the necessary speed and control of repositioning requires easily backdrivable base motors; and (iii) that our mobile force feedback experience is an unavoidably social experience in the real world, inspiring quick movements between haptic and robotic modes of operation.

One aim of haptic interfaces is to enhance the user’s immersion in a virtual environment through the stimulation of the haptic sense. Some applications demand a large-volume workspace to allow human-scale interaction. Different design approaches aimed at addressing this issue, such as specific non redundant devices, redundant robots, mobile or wearable haptic interfaces and tensed cable architectures are reviewed and compared in this paper, concluding with some guidelines for their applicability.

This paper presents multi-criteria design optimization of a 3RPS-R parallel mechanism to be employed as a dual purpose haptic exoskeleton for human forearm and wrist. The primary use for the optimized device is aimed as a high fidelity haptic interface, while the exoskeleton can also be employed as a rehabilitation device. Multiple design objectives are discussed and classified for both application scenarios, and optimization problems to study the trade-offs between these criteria are formulated. A general framework for optimization of haptic interfaces is applied to efficiently obtain the Pareto-front hyper-surfaces between conflicting criteria. Optimal dimensional synthesis of the dual purpose haptic exoskeleton is demonstrated.

We have developed the five-fingered Haptic Interface Robot: HIRO II

 + 

that can present the force at the human five fingertips. Since the number of the wiring cables for motors and sensors increases by making the robot multi-DOF, it is a big obstruction of the miniaturization and the smooth movement of the robot. So, we developed the wire-saving interface board which is based on FPGA, and we considered the control system of HIRO II

 + 

. This paper presents the concept of FPGA-based control system for the wire-saving of HIRO II

 + 

and presents the experimental result to show high potential of the interface.

Nails are not just an instrument to protect fingers and scratch an object. They improve our tactile sensitivity. In this paper, a novel tactile device considering nail function, which we call a “tactile nail chip,” is proposed. This device is mounted on the nail and deforms the nail to change the capability of tactile perception. The effectiveness of the tactile nail chip is supported by results through psychophysical experiments. Then, the effect is discussed through photoelasticity experiment and analysis using a simple nail model. In addition, the tactile nail chip with adjustable function is presented.

Although haptic interaction which provides direct touch sensation is the most natural way of interacting with VR environment, existing haptic solutions are not yet fully satisfying due to the interaction problems such as the hand penetration, frictionlessness, lack of visual feedback, and so on. Among these problems, the hand penetration problem which is an effect sinking into a virtual object is the most visually distracting artifact in grasping, and it is mainly caused by the incomplete physical capabilities of haptic devices and poor grasping manipulation. To address this problem, we have developed a realistic haptic interaction system, which consists of the new 6DOF whole-hand hardware combined with a glove-type device, and propose a hybrid grasping method which intelligently uses both heuristic and physics-based approach.

The aim of this study is to put forward potential advantages of redundant haptic devices. The use of redundancy in haptic devices basically provides a larger workspace without changing kinematics parameters such as joint variables, joint offsets, effective link lengths and twist angles. Besides an increase in the workspace, redundant manipulators allow appropriate posture selection for different purposes, such as singularity avoidance, obstacle avoidance, inertia minimization, power minimization. These purposes can be considered either together or separately in order to determine optimal posture. The study in this paper is focused on optimal posture control of a 7 DOF haptic device based on power minimization. The designed haptic device has 4 DOF for positioning stage and 3 DOF for orientation stage.

We are developing a minute tactile sensor having four cantilevers for sensing pressure and shear forces simultaneously and for distributing over a small area to recognize a certain area’s conditions. Toward our goal, another important task is to establish, in parallel with the sensor’s fabrication, a computing method that converts measured signals to applied forces. In this paper, we first investigate our sensing mechanism using a centimeter scale mockup of the actual sensor. Then, we formulate the relationship between the applied forces and the sensor outputs by a numerical analysis using a sufficient number of pairings of the forces and outputs. Finally, we examine the potential of the method.

By shaking a box, we can estimate content inside. Relationship between force that is applied to the box and resulting motion of the box is considered to be a clue to the estimation. In this paper, an approach to implementing a device that virtually represents the force-motion relationship is discussed.

In minimally invasive surgery, tactile feedback is lacking. An elastoresistive tactile sensor is designed to feel inside the body of the patient. The sensor is thin, flexible, robust, cheap, and has a simple structure. It has 16×16 elements, a spatial resolution of 1 mm and a bandwidth of 78 Hz. Despite a large hysteresis and non-linear behaviour, the sensor is very well suited for a qualitative measurement of the pressure distribution, with a high resolution in position, force and time.

We have proposed a force perception method based on asymmetric oscillation that exploits the characteristics of human perception. Our previous findings indicate that the pulse frequency determines the effective generation of the kinesthetic illusion of being pulled. However, whether pulse frequency or pulse width for force perception has not been clarified. If the pulse width is more dominant, the force sensation induced by sequential pulses will be more continuous. This is important because many of those who have experienced the asymmetric oscillation pointed out that the force sensation induced by the stimuli was not felt smoothly compared to physical force. This paper describes the design and development of a new multicylinder-like mechanism for generating sequential pulses, which should enable us to determine which is dominant for force perception.

While standard closed haptic control loop used in haptic simulation of rigid bodies are bounded to low frequency force restitution, event-based or open-loop haptic, by superimposing a high-frequency transient force pattern, can provide a realistic feeling of the impact. This high-frequency transient can provide the user with rich information about the contact such as the material properties of the object. Similarly, an impact on different locations of an object produces different vibration patterns that can be used to determine the impact location.

This paper investigates the use of such high-frequency vibration patterns to provide impact position information on a simulated long rod held by the edge. We propose in this paper different vibration pattern models to convey the position information: a realistic model based on a numerical simulation of a beam and three empirical simplified models based on exponentially decaying sinusoids. A preliminary evaluation has been conducted with 15 participants. Taken together, our results showed that the users are able to associate vibration information with impact position efficiently.

We present a mechanics-based haptic simulation of an arbitrary suturing task for a simple skin or a soft tissue wound closure. The pre-wound suturing target, the skin or the deformable tissue, is modeled as a modified mass-spring system. The suturing material is modeled based on the linear finite-element model with some novel extensions for enhancing the computation of the constrained mechanics models. Novel extensions to typical suturing models are defined. For example, if the needle incision points are too close to each other or from the edge of the wound and if the user pulls on the suture with a force which is beyond a predefined threshold, the suture will tear the soft tissue instead of suturing the incision. Experiment results show that our simulator can run on a standard desk-top computing environment and allow the user to perform different suturing patterns with smooth haptic feedback.

In haptic augmented reality, a user can enjoy the sensations of real objects augmented with synthetic haptic stimuli created by a haptic interface. For example, a haptic augmented reality system may allow the user to feel a soft sponge as a stiffer rubber. In this paper, we present a framework in which the stiffness of a real object can be modulated with additional virtual haptic feedback. For this, a commercial haptic interface is extended with a force sensor. Efficient and effective algorithms for contact detection and stiffness modulation are proposed for the closed-loop framework. Performance evaluation with real samples showed that the stiffness modulation is quite capable except for very rigid objects (e.g., a wood plate) where unstable oscillations dominate the response. This work serves as an initial building block towards a general haptic augmented reality system.

A new display method of friction sensation based on tactile stimulation is proposed. In this method, no tangential force on the fingertip is required to represent friction sensation. We focus on the activities of tactile receptors in response to stick-slip contact phenomena with the fingertip. The proposed method controls the activities of FA II type receptors using very high frequency vibrations (at 600 Hz) in corresponding to the phase of stick-slip transition. The stick-slip transition was expressed by a single DOF model with Coulomb’s friction, which represents the effects of coefficients of dynamic/static friction and hand movements. The sensory magnitudes of the perceived friction by the proposed method were evaluated in contrast with a force display. The experimental results showed that the perceived friction proposed had high correlation with that of the force display in regard to the increase tendency toward static friction coefficients. The sensory magnitudes of the tactile perceived friction were about one-seventh smaller than that of the force display.

In this paper we present an interactive dynamic simulator for virtual avatars. It allows creation and manipulation of objects in a collaborative way by virtual avatars or between virtual avatars and users. The users interact with the simulation environment using a haptic probe which provides force feedback. This dynamic simulator uses fast dynamics computation and constraint-based methods with friction. It is part of a general framework that is being devised for studies of collaborative scenarios with haptic feedback.

This paper presents Depth Image-Based Haptic Rendering (DIBHR), a haptic rendering algorithm that enables users to haptically explore 3D video media based on depth image-based representation (DIBR). The algorithm computes the shortest proxy (god-object) path along which the proxy goes into the local distance minimum to the goal (haptic interaction point) constrained on surface in order to obtain correct friction force when the friction cone algorithm is applied. This algorithm is based on the god-object [3] concept and adopted the neighborhood search algorithm [5][6]. The experiments compare DIBHR with two previous algorithms [5][6] as per computation time and smoothness of resultant force rendering. The results show slower computation time yet within 1 millisecond and smoother force with friction.

This paper models force of machining a piece of bone by a spherical rotating tool for haptic simulation of bone surgery. The cutting edges of the spherical tool are modeled as a set of infinitesimal cutting elements. Each cutting element in contact with the bone piece undergoes an orthogonal cutting process. The force of cutting is obtained by summing up the forces of each element of the engaged cutting element. The force of each cutting element is related to the size of the chip formed at the bone piece due to a fracture process. The coefficients that relate the chip thickness to the cutting forces are derived from the experimental results. A voxel-based method is developed to simulate chip formation and the force of bone machining. The simulation results show a close force correlation between the voxel-based method and an analytical force model at certain loading conditions. This voxel-based method offers a physics-based continuous force model for bone machining.

This paper focuses on developing a haptic rendering technique for cellular manipulation using image processing techniques and physically based models. The interaction forces between a micropipette and cellular tissues are predicted based on biomechanical models of cells, which consist of a boundary element model and a prior knowledge of the cell’s mechanical properties. These models are used to allow users to feel amplified reaction forces during cell injection tasks through a haptic device in real time. The experimental system, equipped with a micro-injection system and a commercial haptic display, was developed and tested using zebrafish embryos. The proposed haptic rendering algorithm could be used to improve success rates of cellular manipulation tasks.

This paper presents an efficient modeling system of virtual pottery in which the user can deform a body of virtual clay with a haptic tool. The clay body is represented with a set of circular sector elements based on the cylindrical symmetry of pottery. The circular sector element method allows much finer spatial resolution for modeling than previous techniques. Also described are efficient algorithms for collision detection and response where the viscosity of virtual clay is simulated along with the friction due to the rotating potter’s wheel. Empirical evaluation showed that the modeling system is computationally efficient, is intuitive to use, and provides convincing model deformation and force feedback.

In our previous study, a method that allows dynamic interaction with an elastic object, which is called impulse response deformation model, has been proposed. An advantage of the method is that the order of complexity is lower than other approaches that solve equations of deformation models in real time; hence the method enables haptic interaction with more complex object. In this paper, an extension of the model that enables efficient computation of elastic deformation in interaction with surfaces, such as floor and wall, is discussed; unlike point-based interaction in our previous studies, pre-recorded response to impulse force that is applied by surface rather than point is used for the computation.

We propose a multimodal interface on the abdomen to realize the experience of ”being cut by a sword”, for gaming applications. Tactile and auditory sensations were simultaneously presented on the abdomen by using sparsely located tactors and densely located speakers. We compared motion of the two modalities, and compared tactile apparent movement with auditory motion, focusing on the position and speed. Subjectively equivalent position and velocity of the two modalities matched well.

Our work proposes a haptic interaction technique for the rendering of isosurfaces. A virtual contact point is computed corresponding to the most suitable isovalue position in a 3D data grid. With this method we can freely explore and understand complex data fields without explicitly computing the geometry of the isosurface, nor having any intermediate representation. Thus, a very fast haptic rendering loop is easily obtainable. Moreover, our approach is flexible because the contact detection and force feedback computation are automatically adapted to take into account regions presenting high spatial frequency data as in the CFD case.

Volume haptics has become an increasingly popular way of adding guidance and improving information bandwidth in scientific visualization. State-of-the-art methods, however, use linear equations, which allows for a precision that can be insufficient in some circumstances. This paper describes how step-length subdivision can be used to improve precision even though these methods do not use integration steps in its usual meaning.

In this paper we propose a strategy for modelling a human hand for Haptics interaction.The strategy consists in a parallel computing architecture that calculates the dynamics of a hand, this is accomplished by computing the dynamics of each finger in a parallel manner. In this approach multiple threads (e.g. haptics thread, graphics thread, collision detection thread, etc.) run concurrently and therefore we developed a synchronization mechanism for data exchange. We describe in detail the elements of the developed software.

In general, an input/output (I/O) relation from a command sent to a haptic interface to a resulting percept forms a complicated function, due to the complexity of the haptic interface dynamics and the associated perception process. However, if such I/O relation can be found, using its inverse will allow haptic effects designed in terms of a target percept to be autonomously converted to corresponding device commands, so that the desired haptic effects can be exactly perceived by the user. We call this rendering framework as

perceptually transparent rendering

. Previously, we showed that perceptually transparent rendering is feasible for vibration rendering in a mobile device with perceived magnitude as a target percept. As a follow-up study, this paper investigates its benefits through a psychophysical experiment. In the experiment, we designed a set of vibration stimuli the intensities of which were evenly spaced either in the device command (applied voltage; the current practice) and the target percept (perceived magnitude; perceptually transparent rendering), and measured the pairwise discriminability of each stimulus set. The results showed that the average discrimination scores of perceptually transparent rendering were always higher, indicating its superior performance to the current practice of mobile device vibration rendering.

Virtual Prototyping with haptic feedback offers great benefits in the development process of actuated systems. We present a generic control scheme for the haptic rendering of actuated mechanisms, introducing the

active admittance

. It extends the conventional admittance control by modeling the actuation and the movable parts of the mechanism separately. This allows for an efficient iterative design and evaluation of an actuated mechanism and its single elements. The practicability of active admittance control is demonstrated by haptically rendering a car door with two actuated degrees-of-freedom.

We describe experiments that compared the perceived relative roughness of textured virtual walls synthesized with an accurately controlled haptic interface. Texture was modeled as a spatially modulated sinusoidal friction grating. The results indicate that both the modulation depth of the grating (

A

), and the coefficient of friction (

μ

) are strongly associated with the perceived roughness when increasing either

A

or

μ

. Changing the spatial period of the grating (

l

), however, did not yield consistent relative roughness judgement results, indicating that there is a weaker association.

The shape recognition of an object is important for dexterous manipulation by humans. Therefore, we have developed a haptic display that integrates both electrotactile and kinesthetic sensations to present shape information. However, the electrotactile display only presents the contact field between the object and the fingertip. Therefore, we propose a method of electrotactile stimulation using the strain energy density model at the fingertip to generate the tactile sensation of the fingertip deformation. The result of the shape recognition experiment verifies the efficiency of the proposed method.

This work is focused on obtaining realistic human hand models that are suitable for manipulation tasks. Firstly, a 24 DOF kinematic model of the human hand is defined. This model is based on the human skeleton. Intra-finger and inter-finger constraints have been included in order to improve the movement realism. Secondly, two simplified hand descriptions (9 and 6 DOF) have been developed according to the constraints predefined. These simplified models involve some errors in reconstructing the hand posture. These errors are calculated with respect to the 24 DOF model and evaluated according to the hand gestures. Finally, some criteria are defined by which to select the hand description best suited to the features of the manipulation task.

CAD systems are powerful software tools used to manage numerical edition and simulation of products. Edition of CAD objects is a fundamental step in the lifecycle of these products. Although CAD benefits from improvements in functionalities, user interaction on these systems does not evolve anymore. Our goal is to propose novel haptic techniques to enhance user interaction with such applications. An important issue in CAD systems is the modification of the Boundary Representation (B-Rep) of 3D objects. Our general goal is to determine suitable haptic methods to increase accuracy of 3D interaction with CAD objects. This paper focuses on CAD edition processes based on parameterization of extrusion operators.

A new computer assistance concept for bilateral telepresence is introduced which increases telepresent task performance without being explicitly perceived by the operator. Therefore, no training related to the assistance functions is needed, and intuitive telepresence is maintained. In the presented study, we analyze how an intelligent teleoperator can correct the inputs of the operator most efficiently without degrading the feeling of presence. It is expected that there is a tradeoff between maximizing task performance and maintaining feeling of presence. However, our experiments show that appropriate computer assistance methods can increase task performance and feeling of presence at the same time.

In a telemanipulation system a human operator controls a remotely located teleoperator by a human system interface. In this work the effects of varied human movement control on task performance and feeling of telepresence by using such systems are analyzed. While it is well known that humans are able to coordinate and integrate multiple degrees of freedom the focus of this work is on how humans utilize rotational degrees of freedom provided by a human system interface. For the analysis a telemanipulation experiment with varying freed degrees of freedom has been conducted. The results indicate that rotational movements are performed intuitively by the human operator without considering the efficiency of task performance.

After Stability, transparency is a major goal when designing haptic telepresence schemes. Ideal transparency, where the user feels direct haptic interaction with the remote environment, becomes affected by each of the components of the teleoperation system. In an ideal scenario, the energy observed at the master side is straightforwardly conveyed to the slave side. Conversely, realistic scenarios include sources of energy leaks, such as time delays and discretization blocs, which, if stability is to be preserved, they will normally have a lossy passive nature, which therefore lowers transparency. Only a few studies on how to evaluate transparency quantitatively are reported in the literature. This work investigates and extends two methods which aim at outputting a transparency coefficient: an analytical model-based method which uses Yokokohji’s Indexes of Transparency [1], and an empirical approach based on the

Z

width

concept [2], which allows to measure transparency without the need of precise knowledge of the system. The methods are validated using a velocity-force haptic telepresence system testing for different control parameters and different time delays in channel.

This paper presents a paradigm of augmented reality haptic through an application enabling the interaction on real objects with a virtual tool. In order to interact within the real world, a real haptic probe is used so that the user feels the interaction. Furthermore, through the use of a visual partial reality removal process and a camera placed on the real scene, the real tool is visually hidden in the visual feedback and replaced by the virtual tool. Since, the real and virtual probes do not necessarily match, a model of the virtual tool is used to adjust and tune the haptic feedback, while at the same time the virtual tool is visually rendered according to the real measured forces by the haptic probe. Eventually, proposing a mixed painting application, the painting, applied on the real object, i.e. when the user comes in contact with this latter, is visually displayed such that its form is computed from the virtual tool geometry while its size and intensity from the real measured forces.

The ability to recognize and classify human gestures bears a huge potential of improving haptic feedback in virtual environments: when it is possible to predict how a user wants to explore or manipulate his environment both the visual and the auditive feedback may be adapted in order to enhance the immersiveness of haptic displays. Within this work a software approach is suggested that allows for such a real-time classification of gestures in a continuous data stream. A visually based tracking system is used to record the hand movements, while Hidden Markov models are applied to analyze the data. After presenting the methodological background and the software implementation, the outcome of an evaluation study is discussed. It reveals satisfying results of gesture classification and, what is particularly important, the recognition is fast enough to enable multi-modal haptic feedback.

In this paper, a study on the role of force feedback for teleoperation of industrial overhead crane is presented. Teleoperation of industrial crane was described and analyzed. We proposed several types of force feedback signals which can reduce sway motion in industrial crane. First, force feedback signal was selected and designed based on dynamic model of the system. Then, we simplified force feedback calculation method, and proposed velocity and sway angle based force feedback signals. Series of simulations and experiments for studying the role of force feedback for crane teleoperation were performed. User study showed importance of force feedback in crane teleoperation for reducing load sway. Experimental results for load anti-sway control without and with force feedback were compared and analyzed. Force feedback in teleoperation of overhead crane helped human-operator to reduce load sway two times faster than in conventional system without force feedback. Research illuminated a large role of force feedback compare to vision in industrial crane teleoperation.

Research has highlighted difficulties that individuals encounter in identifying haptic-only objects, i.e. objects with three dimensional surfaces which are only represented to users in the haptic modality. This paper investigates whether and how collaboration between distributed users supports identification processes. We present a qualitative study in which pairs of participants collaboratively identify haptic objects. Our study uses conversation analysis to reveal benefits and problems in communication between participants. We highlight shared exploration strategies, techniques for mutual correction, and issues around understanding haptic device use in the remote space. This leads us to suggest that haptic devices should be actuated to match a remote device’s movements, synchronising perspectives on haptic features and allowing mutual orientation to be established while retaining a user’s spatial understanding of the haptic workspace.

We propose a new method for thermal rendering in telepresence systems which allows an operator to feel most transparently the thermal behavior of the remote object. It is based on learning and thermal heat flux generation. Two databases are constructed from real measurements recorded during direct contact between operator’s finger and different materials. One database is used in order to identify the material in the slave side, the other database is used to generate desired heat flux for the thermal display loop. The identification bloc is based on Principal Component Analysis and Neural Network. Experimental results validating the proposed method are discussed.

Over the last few years, a growing number of IT devices have started to incorporate touch-screen technology in order to create more effective multimodal user interfaces. The use of such technology has opened up the possibility of presenting different kinds of tactile feedback (i.e., active vs. passive) to users. Here, we report 2 experiments designed to investigate the spatiotemporal constraints on the multisensory interaction between vision and touch as they relate to a user’s active vs. passive interaction with a touch screen device. Our results demonstrate that when touch is active, tactile perception is less influenced by irrelevant visual stimulation than when passively touching the screen. Our results also show that vision has to lead touch by approximately 40ms in order for optimal simultaneity to be perceived, no matter whether touch is active or passive. These findings provide constraints for the future design of enhanced multimodal interfaces.

The elicited sense of presence in a virtual environment (VE) is affected by the sensory cues provided during the interaction. Moreover multimodal integration may also be a contributing effect in this factor. The experiment presented analyzes the extent in which the addition of haptic, auditory and visual cues, as well as the integration that may take place between them, affects presence. We also analyze the effects of co-location between visual and haptic sensory modalities. Thus the experiment has a between subject design, where 16 subjects interact in a co-located condition (C)using the Reachin display and the other 16 in a non co-located condition (NC). The system used is a virtual version of the ”Simon” game and subjects are requested to complete a memory task which consists in reproducing sequences, via selecting buttons. Results of this experiment have shown how firstly haptic cues are the principal modality for eliciting sense of presence and secondly the existence of differences in the benefits of multimodality between the two conditions.

In this work, we analyze whether oscillatory motion between two extreme positions could be used to create a robotic dancing partner that provides natural haptic feedback. To this end, we compared the pattern of hand movements performed following a pacing signal while participants were instructed to either move rhythmically or to dance. Furthermore, we analyzed the influence of the frequency and type of pacing signal on the two kinds of movements. Trajectories were analyzed in terms of: frequency of movement, spatial and temporal synchronization, and jerk.

Results indicate that it is easier to perform synchronized movements while dancing, even though these movements partially deviate from the pacing frequency. Dance movements are in fact more complex than the ones produced to keep the rhythm and for this reason they should be modeled accordingly in order to provide realistic haptic feedback.

This paper introduces a new pedagogical tool using haptic feedback and visual analogy, to improve perception and learning of nanoscale phenomena, for people without prior knowledge of nanophysics. This tool is a haptic and virtual-reality simulator of a foremost one-dimensional nanophysical phenomenon: the approach-retract cycle of an Atomic Force Microcope (AFM) probe, with a force-feedback device and two graphic representations. One representation is a virtual AFM cantilever and the other one is a virtual magnet-spring system, whose haptic behavior is analog. Preliminary results from an experiment conducted with forty-five students seem to show a better efficiency with the combination of both haptic feedback and visual analogy.

Haptic applications have received enormous attention in the last decade. Nonetheless, the diversity of haptic interfaces, virtual environment modeling, and rendering algorithms have made the development of hapto-visual applications a tedious and time consuming task that requires significant programming skills. To tackle this problem, we present a HAML-based Authoring Tool (HAMLAT), an authoring tool based on the HAML description language that allows users to render the graphics and haptics of a virtual environment with no programming skills. The modeler is able to export the developed application in a standard HAML description format. The proposed system comprises three components: the authoring tool (HAMLAT), the HAML engine, and the HAML player. The tool is implemented by extending the 3D Blender modeling platform to support haptic interaction. The demonstrated tool proves the simplicity and efficiency of prototyping haptic applications for non-programmer developers or artists.

Helicopter landings are more challenging in ‘brownout’ conditions, in which sand and dust is stirred up by the rotary wing aircraft, obscuring visibility. Safe brownout landings require new sensor and display technologies to provide the pilot with information on helicopter motion. In this respect tactile displays are promising: The pilot can maintain visual references as much as possible while ‘feeling’ the crucial helicopter speed and altitude information. The Royal Netherlands Air Force and TNO developed a tactile display to provide the helicopter pilot with information on groundspeed and altitude during landings in degraded visual environments like brownouts. The tactile display was tested in flight trials with a Cougar helicopter. The test pilot performed brownout-like landing manoeuvres faster, more accurate, better controlled, and with less mental effort when altitude and/or groundspeed information was presented on the tactile display.

In this paper, we propose a networked shared 6-DOF haptic cooperation system, based on several distributed physical simulations dedicated to CAD objects simulation. The simulations are linked together with a spring-damper coupling scheme. This system achieves good local responsiveness and enables remote users to perform complex virtual prototyping tasks.

A preliminary test was conducted on this system using a complex industrial virtual prototyping scenario. This test required a good coordination between participants. These first experimentations give promising results to carry on prototyping task over large delayed networks.

The well known property of haptic interaction is the high refresh rate of the haptic loop that is necessary for the stability of the interaction. Therefore, only simple computations can be done within the loop. On the other hand, physically-based deformation modeling requires heavy computations. Moreover, if realistic behavior is desired, the models are non-linear and iterative solution is necessary.

In this paper, the technique for haptic interaction with non-linear complex model is presented. Our approach, based on approximations of configuration space, is described and the accuracy of the approximation is experimentally determined.

Potential applications of online virtual worlds are attracting the interest of many researchers around the world. One and perhaps the most famous example of such systems is Linden Lab’s

Second Life

. Last year, sources for its client application have been released under the GPL license, allowing anyone to extend it building a modified client. This work presents an effort to explore the possibilities that haptic technologies can offer to multiuser online virtual worlds, to provide users with an easier, more interactive and immersive experience. A haptic-enabled version of the Second Life Client, supporting major haptic devices, is proposed. Two haptic-based input modes have been added which help visually impaired people to navigate and explore the simulated 3D environment by exploiting force feedback capabilities of these devices.

Design, ergonomics and haptic feedback are features critical to the development of an eye-catching automobile gearshift. Manufacturers have to design and test a large number of prototypes, with different transmissions, dynamics, etc., before an appealing and marketable solution can be found. This paper introduces a haptic interface for automobile gearshift design and benchmark. It allows automobile gearshift developers to test new models quickly and change most critical design features on the fly in order to find the best possible solution. As a result, traditional trial-and-error methods can be avoided, significantly reducing design costs and time. The system is also a powerful test-bed to perform large-scale studies to analyse key selling features and preferences among customers.

Many clinical examinations involve palpation and part of the diagnostic process depends on the application of pressure. Teaching and learning such skills is difficult especially for internal examinations. A modification to a veterinary virtual reality (VR) simulator, the Haptic Cow, was planned to teach safe and effective use of pressure for bovine pregnancy diagnosis. Expert technique was captured when veterinarians performed pregnancy diagnosis in a simulated environment. The information is being used to calibrate a pressure indicator, the ‘Ouch-o-meter’ that together with palpation profiles will provide guidance for students.

This paper presents a real-time physically based platform for multi-sensory interactive simulation. It is centred on high quality dynamic requirements driven by the concept of instrumental interaction and is able to render a wide variety of physical phenomena : from very rigid interactions to large and complex phenomena such pastes or plastic soils. The platform consists in a precisely synchronized multiprocessor architecture extended with a DSP board used for the simulation of very reactive models. It aims for obtain simulation rate necessary for rigid object (1KHz and more) in the context of 6 Degree of Freedom.

Touch is acknowledged as an important and often underutilized sense in human-computer interaction. In this study a method to present time with vibrotactile pulse sequences was developed and tested. The study answers two questions, namely how to communicate the time with vibrotactile signals only, and how can people understand the signals with and without training? Two experiments were conducted to reveal how accurately people can read time from simple sequences of vibration, and how training affects the recognition rate. It was found that the average recognition rate for untrained participants was 80% while a short training increased it to 88%. Generally, minute part in the vibrotactile sequence caused most errors both with and without practice compared to hour part.

Surgical simulation trains medical residents and surgeons in specific interventions and therefore improves the surgical outcome and reduces operation time. This work focuses on the development of a surgical simulator emulating a tumor resection, whereby 3D tissue mesh resection is implemented. Collision detection algorithms in surgical simulation are not developed to model a changing form of the operating instrument during the operation, which is why tool-centered collision detection is created. One important objective in simulation is clinical realism, and the recruitment of the IOMaster7D, capable of seven degrees of freedom for the dominant hand and six degrees of freedom for the other, allows to synthesize the effect of the Blakesley forceps and the endoscope respectively, as well as provide force feedback.

Tactile and haptic interaction is becoming increasingly important and is no longer restricted to assistive technologies and special purpose computing environments. The technology has gone through numerous breakthroughs and replications and is now entering a period of developing empiricism, the phase in which the first benefits of this new development are becoming available. While considerable research exists, the current lack of ergonomic standards results in systems without sufficient concerns for either ergonomics or interoperability, leading to difficulties for users of multiple, incompatible or conflicting applications. ISO (through working group TC159/SC4/WG9) is working toward international standards, which are being dual-tracked as both ISO and CEN standards. This paper gives an update on the status of the Draft International Standard on tactile/haptic interactions and the recently initiated work on a framework for tactile/haptic interactions.

This paper addresses the design and characterization of a single-disk magnetorheological fluid brake developed for haptic rendering. An analytical method was used for dimensioning. Brake is tested under constant current and velocity inputs. We observe that torque has a low dependence on velocity and that it has a hysteretic evolution with current as a result of magnetization properties of steel used for parts.