Haptics: Generating and Perceiving Tangible Sensations

The paper studies two methods of haptic. One is an attraction force display that can induce attraction force by a cyclic movement of a weight with asymmetric acceleration. Another is a texture display that induces a sensation of texture by giving off vibration while a subject traces a finger over a flat surface. In this paper, we propose a novel design that can induce both attraction force and texture feeling. The prototype consists of four vibration motors, which are controlled to generate asymmetric acceleration and vibration. The device is evaluated by experiments.

Tactile roughness magnitude estimates increase with contact force. However, it is not known whether discrimination thresholds are affected by contact force and other parameters, such as duration and tangential movement. The effects of these factors on roughness discrimination thresholds were determined using an adaptive staircase procedure for coarse and fine texture discrimination during active touch. The presence of tangential movement (dynamic touch) significantly reduced thresholds in coarse and fine texture discrimination compared to static touch, with effects more marked with fine textures. Contact force did not affect discrimination except in static touch of coarse texture when the threshold was significantly higher with low force. Within the perspective that texture discrimination involves distinct vibratory and spatial mechanisms, the results suggest that spatial-dependent texture discrimination deteriorates when contact force is reduced whereas vibration-dependent texture discrimination is unaffected by contact force. Texture discrimination was independent of contact duration in the range 1.36s to 3.46s, suggesting that tactile integration processes are completed relatively quickly.

When a finger scans a non-smooth surface, a sensation of roughness is experienced. A similar sensation is felt when a finger is in contact with a mobile surface vibrating in the tangential direction. Since an actual finger-surface interaction results in a varying friction force, how can a measured friction force can be converted into skin relative displacement. With a bidirectional apparatus that can measure this force and transform it into displacement with unambiguous causality, such mapping could be experimentally established. A pilot study showed that a subjectively equivalent sensation of roughness can be achieved betweem a fixed real surface and a vibrated mobile surface.

Raised line patterns are used extensively in the design of tactile graphics for persons with visual impairments. A tactile stroke pattern was therefore developed to enable the rendering of vector graphics by lateral skin deformation. The stroke pattern defines a transversal profile and a longitudinal texture which provide tactile feedback while respectively crossing over the stroke and tracing its length. The stroke pattern is demonstrated with the rendering of lines, circles and polygons, and is extensible to other vector graphics primitives such as curves. The parametric nature of the stroke allows the representation of distinctive line types and the online adjustment of line thickness and other parameters according to user preferences and capabilities. The stroke pattern was informally evaluated with four visually impaired volunteers.

In this study we present a comparative research between the discrimination capabilities of two populations: Professionals in manual skills and non-professionals, in a task that was not related to their field of expertise. The task was, in a psychophysical test, to discriminate between surfaces of different roughness by indirect touch, using a 3D hapto-visual virtual reality (VR) device. In a texture-difference recognition test subjects glided a pen-like stylus on a virtual surface. The surface was divided into five areas: one central, and four surrounding areas. The roughness of the central area was kept constant throughout the experiment. In each run, three of the four surrounding areas were kept at the same roughness as the central surface, and one, randomly, was different. From run to run, surface roughness was changed following a binary search paradigm. If a subject recognized the portion of the surface with a different roughness, then the roughness was reduced by half; if not, the roughness increased, and so on, until the desired degree of accuracy was achieved. Five professionals from different haptic expertise fields and five non professionals participated in the experiment. The results of the study showed that laymen were significantly more sensitive than experts on roughness discrimination (p < 0.01). These results may suggest that intensive manual activity that demands particular haptic expertise may have a negative impact on manual tasks that are irrelevant to their daily professional activity.

The present study investigated low-oscillatory (theta band, 3-7 Hz) modulations induced by tactile roughness stimulations under two attention-demanding conditions. Four levels of roughness were presented under low-demanding and high-demanding conditions. In both conditions, an oddball paradigm was used to present three target surfaces varying in roughness (low, mid, and high levels of roughness), and a nontarget flat surface. The results showed that centro-parietal theta oscillations are involved in allocating attentional resources when participants have to update new information induced by incoming haptic stimuli. Theta power was higher in the high-demanding task compared to the low-demanding. Furthermore, theta power varied depending on tactile roughness but not in a linear manner. This was interpreted as that theta oscillations were sensitive not only to task difficulty but also to physical properties.

This paper describes design improvements of a friction reduction based tactile device, which yields to reduction of the supply power. We first evaluated the power consumption of four different plates. We found that a convenient design could cut the power losses down by 90%. To explain these changes we propose a modelling of the dielectric losses in the piezoelectric actuators and of the vibration amplitude.

This work evaluates the haptic rendering capabilities of a low density and portable tactile device displaying small-scale surface features, such as ridge patterns and sinusoidal gratings. Psychophysical experiments were conducted to investigate and compare JND’s for distance, angle and wavelength perception of virtual and real surface features. Velocity was monitored during the active exploration of ridges and controlled during the passive-guided exploration of gratings. JND’s found for the virtual surfaces are 22%, 12.6% and 13.3% of the standard stimuli (4.2mm, 45° and 5.09mm). JND’s for real surfaces indicate that subjects’ discrimination ability using the tactile device decreases roughly 65%. Results provide insight of the sensory resolution associated with the tactile device which can guide the development of an improved device, suitable applications and effective tactile rendering methods.

We investigated the tactile perception of a liquid surface that can be clearly felt as a thin line by a hand moving in the liquid. Although this phenomenon was first reported by Meissner in 1859 and is quite well known, the underlying mechanism is poorly understood. This study aimed to clarify how we perceive the boundary between the atmosphere and water as a cutaneous sensation. We found that skin hair plays a major role in the perception on hairy skin, while surface tension does not significantly contribute to perception of a liquid surface. Furthermore, we found that glabrous skin has a smaller role than hairy skin in this sensation.

The paper describes a haptic device whose aim is to permit the assessment of digital prototypes of industrial products with aesthetic value. The device haptically renders curves belonging to digital surfaces. The device is a haptic strip consisting of a modular servo-controlled mechanism able to deform itself, allowing the user to feel the resulting shape with his free hands. The haptic strip is also equipped with two force sensitive handles placed at the extremities, and a capacitive touch sensor along its length, which are used for applying deformations to the digital shape.

We studied the influence of visual feedback on the tactual perception of both speed and spatial period of a rotating texture. Participants were placed in a situation of perceptual conflict concerning the rotation speed of a cylindrical texture. Participants touched a cylindrical texture of gratings rotating around its axis at a constant speed, while they watched a cylinder without gratings rotating at a different speed on a computer screen. Participants were asked to estimate the speed of the gratings texture under the finger and the spacing (or spatial period) of the gratings. We observed that the tactual estimations of both speed and spacing co-varied with the speed of the visual stimulus, although the cylinder perceived tactually rotated at a constant speed. The first effect (speed effect) could correspond to the resolution of the perceptual conflict in favor of vision. The second effect (spacing effect) is apparently surprising, since no varying information about spacing was provided by vision. However, the physical relation between spacing and speed is well established according to every day experience. Thus, the parameter extraneous to the conflict could be influenced according to previous experience. Such cross-modal effects could be used by designers of virtual reality systems and haptic devices to improve the haptic sensations they can generate using simple (constant) tactile stimulations combined with visual feedback.

Haptics research has seen several recent efforts at understanding and recreating real vibrations to improve the quality of haptic feedback in both virtual environments and teleoperation. To simplify the modeling process and enable the use of single-axis actuators, these previous efforts have used just one axis of a three-dimensional vibration signal, even though the main vibration mechanoreceptors in the hand are know to detect vibrations in all directions. Furthermore, the fact that these mechanoreceptors are largely insensitive to the direction of high-frequency vibrations points to the existence of a transformation that can reduce three-dimensional high-frequency vibration signals to a one-dimensional signal without appreciable perceptual degradation. After formalizing the requirements for this transformation, this paper describes and compares several candidate methods of varying degrees of sophistication, culminating in a novel frequency-domain solution that performs very well on our chosen metrics.

In the domain of haptics, the sensation of touch is normally classed into two types: tactile and kinesthetic. Correspondingly, the haptic display can also be divided into two categories: tactile display and kinesthetic display. The two aspects are commonly addressed separately, but life experience has shown that this is not intuitive and not effective. Therefore, it is a significant work to couple the tactile display and the kinesthetic display. In this paper, we propose a new design of haptic display coupling tactile and kinesthetic feedback for rendering spatial texture (tactile) and haptic shape (kinesthetic).

This study examines to what extent limitations in short-term memory capacity in the haptic modality depends on (1) the narrowness of the effective field of view combined with a sequential processing of information, and/or (2) the format in which spatial configurations are represented internally. A total of 64 participants carried out memory span tasks in four different conditions: haptic, visual, visual with a limited field of view, and haptic with visual cues. Results provide support for both hypotheses. Differences in haptic and visual short-term memory disappeared when the visual processing of information occurred within a limited field and when the haptic processing of information was aided by visual cues.

This paper presents a novel design of a virtual dental training system (hapTEL) using haptic technology. The system allows dental students to learn and practice procedures such as dental drilling, caries removal and cavity preparation for tooth restoration. This paper focuses on the hardware design, development and evaluation aspects in relation to the dental training and educational requirements. Detailed discussions on how the system offers dental students a natural operational position are documented. An innovative design of measuring and connecting the dental tools to the haptic device is also shown. Evaluation of the impact on teaching and learning is discussed.

There are many ways by which we can learn new skills. For sensory motor skills, repeated practice (often under supervision and guidance of an expert mentor) is required in order to progressively understand the consequences of our actions, adapt our behavior and develop optimal perception-action loops needed to intuitively and efficiently perform the task. VR multimodal platforms, if adequately designed, can offer an alternative to real environments therefore. Indeed they present interesting features: controlled environment, measure of the user’s performance, display of quantitative feedback. This paper presents such a platform that was developed for surgery skills training.

This paper presents the MIMICS MMS rehabilitation system with a virtual rehabilitation task that includes several modes of haptic assistance. We observed the influence of these different modes of assistance on task performance and work performed toward the target during the pick-and-place movement. Twenty-three hemiparetic subjects and a control group of twenty-three subjects participated in the study. The haptic assistance resulted in improved task performance and lower work performed during pick-and-place movement.

We describe a system that provides combined auditory and haptic sensations to simulate walking on different grounds. It uses a physical model that drives haptic transducers embedded in sandals and headphones. The model represents walking interactions with solid surfaces that can creak, or be covered with crumpling material. In a preliminary discrimination experiment, 15 participants were asked to recognize four different surfaces in a list of sixteen possibilities and under three different conditions, haptics only, audition only and combined haptic-audition. The results indicate that subjects are able to recognize most of the stimuli in the audition only condition, and some of the material properties such as hardness in the haptics only condition. The combination of auditory and haptic cues did not improve recognition significantly.

A setup for bimanual virtual object manipulation is described in this paper. Index and thumb fingers are inserted in the corresponding thimbles in order to perform virtual object manipulations. A gimble, with 3-rotational degrees of freedom, connects each thimble to the corresponding serial-parallel mechanical structure with 3 actuated DoF. As a result, each finger has 6 DoF, movements and forces can be reflected in any direction without any torque component. Scenarios for virtual manipulation are based on distributed architecture where each finger device has its own real-time controller. A computer receives the status of each finger and runs a simulation with the virtual object manipulation. The information of the Scenario is updated at a rate of 200 Hz. The information from the haptic controller is processed at 1 kHz; it provides a good realism for object manipulation.

The aim of this paper is to validate a virtual reality (VR) environment for the analysis of the sensorimotor processes underlying learning of object grasping and manipulation. This study was inspired by recent grasping studies indicating that subjects learn skilled manipulation by concurrently modulating digit placement and forces as a function of the position of object center of mass (CM) in an anticipatory fashion, i.e. by modulating a compensatory moment before the onset of object manipulation (object lift onset). Data from real and virtual grasping showed a similar learning trend of digit placement and forces, resulting in successful object roll minimization. Therefore, the overall behavioral features associated with learning real object manipulation were successfully replicated by the present VR environment. The validation of our VR experimental approach is an important preliminary step towards studying more complex hand-object interactions.

In this paper we present a point based potential field mechanics model for suture interaction. We study extended models to represent suture behaviors such as bending, stretching, twisting, which can be used in haptic rendering of knotting and unknotting tasks. In this paper, one-dimensional single point-samples and adaptive point-samples are studied and compared. In the adaptive model description, we develop a novel LOD(Level of detail) and re-sampling method using fluid particle flow model. A multi-resolution suture model is constructed based on the proposed LOD. Experimental studies demonstrate the feasibility of our proposed model for knotting and unknotting of the suture and can offer an adaptive and stable modeling environment for both graphic and haptic rendering. In addition, through the tuning of several key parameters, different material behavior such as elasticity can be obtained.

We introduce a new technique of haptic guidance for item selection in 3D menus for VR applications called “haptic walls”. It consists in haptically rendering a solid funnel to guide the pointer towards a target located in the angle. We designed a 3D haptic menu using this approach: a thin polyhedral shape with the items at the corners. The “haptic walls” are experimented with 2 different shapes of polyhedra, and compared to 2 reference conditions. We propose the results of our first empirical evaluation of this technique.

This research improves the position measurement system of a magnetorheological (MR) spherical brake we recently designed. The brake is a multi-DOF actuator. The initial design had a position measurement system with infrared (IR) sensors. Although the IR sensors gave good results, there were some performance degradations in the brake due to the noise in the sensors. In this research we implemented a new position measurement system using accelerometers and gyroscopes from a Nintendo Wii. Much better haptic feedback could be obtained in virtual wall collisions and in a virtual gear shifter simulation that used the brake as a joystick.

We developed a novel haptic interface FlexTorque that enables realistic physical interaction with real (through teleoperation system) and Virtual Environments. The idea behind FlexTorque is to reproduce human muscle structure, which allows us to perform dexterous manipulation and safe interaction with environment in daily life. FlexTorque suggests new possibilities for highly realistic, very natural physical interaction in virtual environments. There are no restrictions on the arm movement, and it is not necessary to hold a physical object during interaction with objects in virtual reality. Because the system can generate strong forces, even though it is light-weight, easily wearable, and intuitive, users experience a new level of realism as they interact with virtual environments.

This paper focuses on the effects of visual and haptic feedback on the experienced plausibility of social interaction in a virtual reality scenario, where participants were asked to perform handshakes with a virtual, visually and haptically rendered partner. A 3D virtual environment was created and integrated with a handshaking robot, enabling the participant to see the virtual partner while shaking hands. To assess the effect of visual and haptic rendering strategies on plausibility, an experiment with human subjects was carried out. The results indicate that adding vision and improving the quality of haptics, both improve plausibility. Similar effect sizes further suggest that vision and haptics are equally important to the perceived plausibility of a virtual handshaking task.

Passing an object between two people is a common event that happens in various forms for example when giving someone a cup of coffee. An experimental study is presented where passing objects between two people in a virtual environment with haptic feedback was compared to passing objects in a nonhaptic virtual environment. The aim of the experiment was to investigate if and how added haptic feedback in such an environment affects perceived virtual presence, perceived social presence and perceived task performance. A within subject design was used, were nine pairs of subjects performed a hand off task with six differently sized cubes without audio communication. Results showed that haptic force feedback significantly improved perceived virtual presence, perceived social presence and perceived performance in this experiment.

The Nine Hole Peg Test (NHPT) is routinely used in clinical environments to evaluate a patient’s fine hand control. A physician measures the total time required to insert nine pegs into nine holes and obtains information on the dexterity of the patient. Even though this method is simple and known to be reliable, using a virtual environment with haptic feedback instead of the classical device could give a more complete diagnosis which would isolate different constituting components of a pathology and objectively assess motor ability. Haptic devices enable extracting a large quantity of information by recording the position and the exerted forces at high frequency (1kHz). In addition to the creation of a realistic virtual counterpart of the NHPT, the present work also includes the implementation of real-time data analysis in order to extract meaningful and objective scores for the physician and the patient. A healthy group of volunteers performed the real and virtual tests which yielded a baseline for the scores of the different measured mobility parameters. Once calibrated, the virtual test successfully discriminates different mobility dysfunctions simulated by a healthy subject.

Body awareness has important implications for the use of virtual reality (VR) and its effectiveness. This involves the senses of agency and body ownership, studied in the past by producing the “Rubber Hand Illusion” (RHI). Recent studies reported the RHI on virtual environments (VE) by giving the participant synchronous 3D visual stimulation and passive tactile stimulation manually on the hidden real hand placed on a static position. In this paper we present a novel study of the RHI within highly dynamic VE sessions with synchronous pure virtual vibrotactile stimulation of the fingers. The hand/arm participant’s movements are realistically reproduced on the VE and tactile stimulations are self-inflicted by the participant through actively touching the virtual objects. The results revealed that the RHI is possible in active, dynamic and fully multisensored VE sessions.

A 3D deformable hand avatar for virtual grasping using multiple single-contact-point haptic devices is introduced. The proposed technique has two main advantages. First, the whole hand motion is reconstructed by measuring only fingertips positions and using a biomechanical model of the hand along with the postural synergies characterizing grasping actions. Secondly, this technique requires only simple algebraic computations.

This paper describes a 3 DoF MR-compatible haptic interface which can be used to investigate human brain mechanisms of voluntary finger movements. The newly developed device is built of non-ferromagnetic materials to avoid safety hazards and uses MR-compatible sensors and actuators to not disturb the image quality. The selected parallel kinematics not only guarantees a stiff construction and reduces inertia of moving parts, but also avoids time-varying motion artifacts originating from moving active components. Geometric parameters of the device are selected to optimize manipulability and to cover the workspace of pointing movements using the index finger up to small reaching movements with the arm. Finally, performance indices like transmission-quality, force, velocity, and acceleration capability are evaluated for the presented device.

We can haptically extract thermal properties of different material, but we can also sense object temperature. It has been shown that thermal properties of materials are not very salient features. In this study, we investigate saliency of actual temperature differences. To this end we let subjects grasp varying numbers of spheres in the hand. These spheres were warmer (38°C) than the hand temperature, but in half of the trials there was one sphere colder (22°C) than the hand temperature. Subjects had to indicate whether the cold sphere was present and response times were measured as a function of the number of spheres. This yielded a target present slope as small as 32 ms/item. This is comparable to slopes found earlier for search for a tetrahedron among spheres and indicates that there is pop-out effect for a cold sphere among warm spheres.

Gender differences in spatial abilities are widely acknowledged and scientifically proved. In this paper, we explore the feasibility of implementing a behavioral biometrics system capable of distinguishing between men and women, based on a 3D trajectory following test that examines abilities in a spatial context. Haptics were used in order to capture and record various behavioral biometric characteristics such as exerted force, distance from the target trajectory etc. A 83.11% accuracy was observed, suggesting that this novel use of haptics is suitable for this purpose.

This study measured the minimum amount of force necessary to identify its direction. The force was produced by a robot and transmitted to a small spherical handle held between the thumb and index finger. We also examined whether this threshold changed during movement. We found that the force threshold was lower when it was possible to move the arm (5 g) than when it was immobile (10 g).

This paper presents a new planar Spring & Cable driven Force feedback Device (SCAFD). The new device uses fewer cables to realize multi-finger grasp and manipulation feedback. The principle and cable tension calculation of the planar SCAFD are explained. The result of an example of virtual grasp task shows that the device can realize 1-DOF grasp and 3-DOF manipulation force feedback on a plane with only four cables and a spring.

During laparoscopic grasping, excessive grasp forces and tissue slippage may well lead to tissue damage. Because surgeons have difficulty gauging the force exerted on the grasped tissue, it is desirable to train them in applying the right degree of force in order to prevent tissue damage. Previously it was demonstrated that grasp force control can be learned when augmented tactile feedback is provided in a training task. The present paper discusses the design of a new laparoscopic grasper with augmented tactile feedback. Two grasper handles were developed and tested. Each of them contained augmented tactile feedback actuators.

To present three-directional force at ten fingertips of both human hands, we previously developed a multi-fingered bimanual haptic interface consisting of two five-fingered haptic hands and two interface arms. However, there is a risk that haptic hands and interface arms will collide while a user is manipulating the haptic interface. To alleviate this risk, we propose a collision avoidance control for the multi-fingered bimanual haptic interface. In particular, by constructing the collision avoidance using a penalty method, we hope to reduce the user’s feeling of collision insecurity. Through an experiment, we investigated the validity of the proposed control law.

Which criteria determine the formation of rest-to-rest arm movements when interacting with virtual mass-damper dynamics? A novel bilevel optimization approach is used to find the optimal linear combination of common optimization criteria for human trajectory formation such that the resulting trajectory comes closest to the human-performed one. The goal is to utilize this optimal combination to predict human motions in robot control. Experimental results show that subject-dependent criteria combinations can be found for different dynamics.

The brain localizes body parts in their perceived visual locations. The brain can, however, be easily fooled. By making use of the Rubber Hand Illusion (RHI), a feeling of ownership of the rubber hand can be evoked. The influence of this illusion on grasp force has not yet been researched, but it might well prove promising for grasp control during tool usage. This study explores whether the RHI can be used to give a person better control over grasp force when manipulating an instrument that makes use of the RHI than when using an instrument that does not. Ten participants performed grasp and pull tasks under three different conditions. They were required to grasp an object with their bare hands, with a rubber-hand, and with an instrument. After analyzing grasp forces during maximal pulling loads (4.95 N barehanded, 6.45 N rubber-handed and 7.9 N using an instrument), it may be concluded that the RHI can contribute to improved grasp control.

In a recent study, Cardinali et al. (2009) showed that training the use of a tool affected kinematic characteristics of subsequent free movements (i.e., movement were slower, for instance), which they interpreted as that the use of a tool affects the body schema. The current study examined whether these results can also be explained in terms of motor learning where movement characteristics during tool use persist in the free movements. Using a different tool we replicated parts of the study of Cardinali et al: As did Cardinali et al. we found that tool use after-effects can be found in subsequent free movements. Importantly, we showed that the tooling movement was very slow compared to the free hand movement. We concluded that it can not be ruled out yet that after-effects of tool use originate from a general slowing down of movement speed that persists in free hand movements.

This paper deals with a motion-based handheld haptic interface. A 6 DOF motion sensor and hybrid vibrators are embedded into the device. With wrist motion, a user controls the position of the pointer on the screen. Haptic feedback is provided in response to the manipulation of a GUI element. Gyroscope-based motion sensing and the rapid response of a hybrid actuator improve the usability of a remote control for a GUI.

We present a novel rehabilitation device for forearm/wrist and grasp therapy of a neurologically injured human arm and hand. Emphasizing the importance of coordinated movements of the wrist and hand while performing activities of daily living (ADL) tasks, the device is designed to assist abduction/adduction and palmar/dorsal flexion of the wrist and pronation/supination of the forearm, concurrently with grasping and releasing movements of hand. Thanks to its modular, interchangeable end-effectors, the device supports ADL exercises, such as door opening. It can also be used as a measurement device, to characterize the range of motion and the isometric strength of the injured forearm/wrist and hand. Usability studies have been conducted and accuracy of the measurements provided with the device has been characterized.

In haptically enabled virtual reality, most existing devices render kinesthetic feedback via one 3DoF single-contact-point, thus they cannot stimulate tactily teh fingertip skin. This lack of information prevents the perception of contact surface orientation in absence of vision and of free exploratory movements. In this work we experimentally investigate the rendering performance of a contact model which exploits anisotropic contact stiffness to convey such information.

Tactile feedback has the potential to provide rich communication in a range of embedded applications, but this requires a finger restraint that is effective and practical for integration into a handheld device. This paper investigates an aperture-based restraint, a simple conical hole, used to prevent unwanted motion of the finger and to provide access to the tactile device. A range of aperture sizes were tested with both the index finger and thumb using a tactile display that applies tangential skin displacement. The aperture restraint was found to be effective, comparable to a traditional thimble-type restraint, with larger apertures performing better. There was no significant interaction between finger size and aperture size, meaning that the same aperture could be used for a wide range of fingers sizes.

This paper presents an on-going research project undertaken by an artist-researcher who uses both investigation into haptic theory and the creation of ceramic objects to increase our understanding of the experience of touch. It asks the question, “How and in what way can an artist contribute to understanding haptics?” The artistic journey began with an interest in the textured surface of ceramics. Physiological, anthropological, and philosophical perspectives were interwoven with studio practice, resulting in the creation of ‘cast hugs’, ceramic sculptures made through the use of the artist’s body. The physical qualities of the ceramic objects positively engaged participants’ haptic abilities to distinguish shape, to discriminate texture, temperature, and weight, and to engage their sense of proprioception. It was found that when these senses were fully stimulated, emotions, memories, and associations were strongly evoked.

In recent times, dimensions of consumer products have decreased, with components sizes ranging down to micrometers/nanometers. In case of microproducts that are produced in low-medium quantities with many variants, the automation of their assembly process may not be economically profitable. On the other hand, the purely manual approach is not sufficient to fulfill the task with high efficiency since a human operator has limitations for the force and precision requirements. In order to overcome these difficulties, tele-haptic micro-assembly systems are a promising approach. One of the bottlenecks on the development of such a system is the micro-gripper, which should be able to perform pick-and-place of micro-objects with diverse sizes and sense the grasping force. In this work, a developmental effort to build a mechanical micro-gripper capable of sensing grasping force and transferring these forces to the human operator using a 1-DOF master device is presented. Experimental results concerning pick-and-place of micro-objects are demonstrated.

This paper presents a two degrees–of–freedom haptic interface that uses force control to reproduce the behavior of a customary lever and gearshift in automotive applications. The haptic simulation of the gear selector lever has been done by the appropriated design of virtual artificial potential functions. These functions contain parameters that have intuitive physical meaning and that can be easily adjusted to change the force sensations fed to the user. To validate our approach, experiments have been carried out.

Participants completed a series of seven tasks to assess proprioceptive acuity of each hand. Proprioceptive localization was fairly accurate and precise. Constant error and precision differences were found as a function of the task, movement of the hand target, the hand being localized, and localization from memory.

We measured the minimum transient change of length of a bimanually hand-held bar that could be detected. A bimanual haptic interface was used to haptically render the bar in a static condition and two dynamic conditions involving discrete movements. The detection thresholds were much lower in the static (< 2 mm) than in the dynamic conditions (> 10 mm). This finding suggests that our proprioceptive acuity markedly decreases during movement.

Haptic feedback for micro- and nanomanipulation is a research area of growing importance with many potential applications in micro- and biotechnology. Past research often involves the coupling of atomic force microscopes to haptic devices, but the results are not satisfactory. We propose to adopt a different approach, which consists of contactless manipulation, in particular by using optical tweezers, coupled with a haptic feedback device. In this article, we describe the potential of such a tool and show with some first experiments of stable interactions between micro-particles.

While force output is discussed as the predominant controlled output of the motor program for object manipulation, various studies have demonstrated that local pressure distribution at the fingerpad and coefficient of friction at the finger-object interface are also important for grasp control. We investigated the role of local pressure as a possible controlled output during a lift-hold-replace task. Participants lifted one of two masses with either normal or slippery contact surfaces using one of two grip postures that varied contact area. Grip force data was collected by a force/torque transducer while pressure and contact area data were collected using a Tekscan flexible sensor. Grip force and pressure both increased with increased mass or reduced friction while contact area increased with reduced friction and use of the flat grip posture. Additionally, grip force was significantly affected by a friction-grip posture interaction, whereas pressure was significantly affected by a mass-grip posture interaction.

Participants attempted to create squares of four different sizes in two orientations in one of three modality conditions - physically adjusting a tangible template while blindfolded (haptic condition), directing the experimenter to adjust the template (vision condition), or adjusting the template themselves without the blindfold (mixed-mode condition). The side of square was robustly overestimated, resulting in a rectangle elongated in the horizontal direction - evidence for the horizontal-vertical illusion. There was no difference in the illusion’s strength as a function of modality conditions or orientation.

Tactile and haptic interaction is becoming increasingly important and ergonomic standards can ensure that systems are designed with sufficient concerns for ergonomics and interoperability. 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 work in progress and the recently published International Standard on tactile/haptic interactions. Active involvement of experts is sought for work on terms and definitions and measures to characterize devices and operator capabilities.

This multiple phase research examines the utility of the thigh as a placement for a vibrotactile display in the cockpit. The initial phase of this research is presented hereby. Vibrotactile displays designed to convey horizontal directional waypoints or warnings are commonly situated on the torso of the pilot. Here, an eight-tactors belt prototype fixed around the thigh of a seated operator was used to convey vertical directional waypoints. Localization accuracy was examined. Analysis revealed that vibrotactile cues embracing the thigh are discriminated in a similar manner to the torso, providing initial evidence that vibrotactile signaling on the thigh can provide directional cues in the vertical plane.

In this study a haptic object matching task is used to examine the accuracy of identification of the object dimensions: texture, weight, volume and exact shape in four different participant groups: congenitally blind adults, sighted adults, congenitally blind children, and sighted children. The results show that age is more influential for the accuracy to identify object dimensions by touch than the visual status.

A new approach to teaching the skills used by health professionals during hands-on (palpation-based) examinations and procedures is reported, where students practice individual ‘core’ skills by playing haptic computer games. These core palpatory skills were identified through interviews and a survey of clinicians and include determining size, firmness, shape and moving and thinking in 3D. A learning environment using haptic force-feedback technology (The Core Skills Trainer) was created that consisted of a set of eight computer games, one game for each core skill. Concepts from computer gaming were used to help engage students in the learning process including acquiring points, losing lives, different levels of difficulty and high scores tables. Each game has three levels of difficulty to support progressive improvement and the player’s ultimate task is to become proficient in all the core skills.

In the context of training for industrial maintenance the capturing and modeling of interaction forces are important elements that allow to characterize the skills of users. This paper describes a device that can be used for acquiring such forces for later use in the context of a training system. The device has been designed for managing the force ranges and the precision required by typical maintenance operations and it can be easily adapted to different type of tools. The paper discusses also the calibration of the device and presents a case study in which actions from different users are being captured.

Tactile display devices must fulfill various technical requirements for tactile stimulation, and present a good compactness for handheld applications; control strategies must also be defined in order to optimize their efficiency. This paper focuses on the control strategies of a 4x4 tactile highly integrated magnetic micro-actuator array offering a resolution of 2 mm. This device is dedicated to provide both static and dynamic tactile sensations, from DC to a 350 Hz.

Preliminary perception tests were led on this device and confirm the effectiveness of the device and its ability to deliver meaningful tactile sensations. Two matters were investigated. The first one concerned spatial localization of tactile stimuli, while the second one was related to the evaluation of the device capacity to create easily detectable temporal stimuli. The considered control strategy also aimed at decreasing power consumption while increasing actuation forces.

In haptic length perception biases occur that have previously been shown to depend on stimulus orientation and stimulus length. We propose that these biases arise from the muscular torque needed to counteract the gravitational forces acting on the arm. In a model study, we founded this hypothesis by showing that differences in muscular torque can indeed explain the pattern of biases obtained in several experimental studies.

The effect of Coulomb friction in a haptic interface was investigated for a simple positioning task. A custom 1-DOF interface was used, for which the Coulomb friction was varied from virtually zero to .70 N. The interface was operated using the wrist and fingers. Results based on the numbers of errors, completion times and subjective ratings show that, for this type of interface and task, Coulomb friction between .15 and .42 N is optimum.

When the presentation of a single flash is paired with that of 2 taps, a second, illusory, flash is sometimes perceived. We presented participants with 1 or 2 flashes paired with 1 or 2 taps and asked them to report the number of flashes. In experiment 1, we used the response categories 1, 2, 3 and analyzed the responses to 2 consecutive illusory flash trials (1 flash, 2 taps). The chance to report 2 flashes was 70% when their preceding answer was 2 and only 10% when it was 1 (p < .001). This effect can occur when participants’ percept neither fits the 1 or 2 response category. In experiment 2, we introduced a new response category, viz. ‘something different from 1 or 2 flashes’ and found that observers used this category in 50.0% of the illusory flash trials, while 2 real flashes were reported as 2 in 87.3% of the trials (

χ

2 = 116.62; p < .001). We conclude that the percept of an illusory flash differs from that of a real flash.

The present study tests whether age at onset of total blindness and the proportion of life-time without visual experience affect the haptic processing and recognition of tactile pictures in a sample of 20 totally blind adults. We also examine the type of mental strategy (visual, non-visual) used to perform the haptic recognition task. The results indicate that haptic processing of non-figurative tactile pictures may be efficiently achieved with different levels of visual experience and different strategies in totally blind adults. Interestingly, they also reveal interplays between strategy and the proportion of life-time without visual experience.

This paper shows a preliminary experimental evaluation of a novel haptic aiding for Remotely Piloted Vehicles. The aerodynamically-inspired haptic feedback law was named Conventional Aircraft Artificial Feel, and was implemented as a variable stiffness spring. The experimental set-up comprises a fully nonlinear mathematical model of the aircraft, a visual display and a haptic device (a 3 DoF Omega Device). The tests, performed using a set of 18 naïve subjects, show the validity of the proposed approach.

Haptic curvature discrimination experiments have typically been done with relatively small stimuli (at most hand-sized) placed on a table. In daily life, however, we often handle large curved objects (think of basket balls), which we usually hold with two hands. Here, I focus on the question how well shape information from the two hands is integrated. I investigated subjects’ ability to adjust the distance between two large cylindrical shells in such a way that the two shells together would perceptually form a circular cylinder. All subjects were able to perform this task in a consistent way, but adjustments were often far from veridical. As deviations were often larger than discrimination thresholds, I hypothesize that they are either due to systematic biases in curvature perception or to misestimations of the distance between the hands. These results contribute to our understanding of haptic shape perception.

Ten operators had to complete a complex visuo-motor task in two extreme presentation conditions, 2D dislocated display and 3D collocated display. Using 3D collocated display operators had better total time performance as well as improved error time performance. In all conditions learning occurred. Error-time improvement following training in the 3D collocated condition carried over to a following 2D dislocated condition but there was no carry over following a block of 2D dislocated display.

If participants simultaneously feel an object and see it through an anamorphic lens, adults judge object size to be in-between seen and felt size [1]. Young children’s judgments were, however, dominated by vision [2]. We investigated whether this age difference depends on the magnitude of the intersensory discrepancy. 6-year old children and adults judged the length of objects that were presented to vision, haptics or both senses. Lenses reduced or magnified seen length. With large intersensory discrepancies, children’s visuo-haptic judgments were dominated by vision (~90% visual weight), whereas adults weighted vision just by ~40%. With smaller discrepancies, the children’s visual weight (~50%) approximated that of the adults (~35%)–and a model of multisensory integration predicted discrimination performance in both age groups. We conclude that children focus on a single sense, when information in different senses is in conflict, but can combine seemingly corresponding multisensory information in similar ways as adults do.

In this study, we investigated the “heat phantom sensation” induced by thermal stimulation of two points. Phantom sensations are tactile illusions induced at a point between two or more stimuli, and have been demonstrated to occur in the event of vibration stimulation. However, their induction by thermal stimuli has not been fully investigated. We confirmed the existence of a heat phantom sensation using two heat stimulators, and succeeded in presenting the heat source image at an arbitrary position by changing the temperature ratio.

In this paper the performance of a haptic playback system with two different control algorithms was experimentally investigated. Accuracy of tracking the reference position and force trajectories of each system during training was examined, and their effectiveness in teaching a hybrid sensorimotor skill with significant position and force components was compared. It was determined that superior tracking performance during training does not necessarily indicate superior effectiveness in motor skill acquisition.