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2005 | Buch

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Multi-point Interaction with Real and Virtual Objects

herausgegeben von: Federico Barbagli, Domenico Prattichizzo, Kenneth Salisbury

Verlag: Springer Berlin Heidelberg

Buchreihe : Springer Tracts in Advanced Robotics

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

The problem of robotic and virtual interaction with physical objects has been the subject of research for many years in both the robotic manipulation and haptics communities. Both communities have focused much attention on human touch-based perception and manipulation, modelling contact between real or virtual hands and objects, or mechanism design. However, as a whole, these problems have not yet been addressed from a unified perspective. This edited book is the outcome of a well-attended workshop which brought together leading scholars from various branches of the robotics, virtual-reality, and human studies communities during the 2004 IEEE International Conference on Robotics and Automation. It covers some of the most challenging problems on the forefront of today’s research on physical interaction with real and virtual objects, with special emphasis on modelling contacts between objects, grasp planning algorithms, haptic perception, and advanced design of hands, devices and interfaces.

Inhaltsverzeichnis

Frontmatter

1 Rapid Collision Dynamics for Multiple Contacts with Friction

Abstract

We examine the interaction of complex two-dimensional rigid bodies with friction. Given their idealized description, many different feasible solutions for frictional contact and collision are possible. The usual assumptions of noninterpenetration and negligible deformation at the global scale constrain contact behaviors, while incomplete descriptions of material properties at the local scale allow for a large amount of latitude in solution methods. Existing techniques for the multiple contact problem with friction either depend upon collision ordering (propagation methods) or apply LCP methods. We propose a method that generalizes Moreau’s impact law to formulate a simple but complete contact law in which both multiple constraints and multiple contacts are possible. Our algorithm finds a simultaneous solution for a system of contacts. Its implementation is simple and obtains real-time speeds.

Danny Kaufman, Dinesh K. Pai

2 Does Torque Minimization Yield a Stable Human Grasp?

Abstract

In this chapter, we present a study of the human grasp conducted with a mathematical formalism that has been developed in robotics during the last two decades. The main objective of this study is to assess the extent to which the structure of the hand is adapted to its grasping function by identify the conditions under which a model minimizing energy expenditure predicts a stable grasp. The idea is that the human hand, as the result of evolutionary pressure, must be designed in such a way that it can grasp objects with minimum effort. To test this hypothesis, we defined a cost function minimizing the weighted norm of the joint torque vector of a simple biomechanical model of the hand. The contact forces predicted by the model are then compared to the ones observed in a experimental study of the human tripod grasp. The results indicate that this cost function can predict a stable grasp when the external force is zero. A possible interpretation of this result is that the external force represents an unknown that cannot be taken into account by an evolutionary process.

“The coordination of a movement is the process of mastering redundant degrees of freedom of the moving organ, in other words it s conversion to a controllable system” (Bernstein, [25], p. 127).

Gabriel Baud-Bovy, Domenico Prattichizzo, Nadia Brogi

3 Dynamic Proxies and Haptic Constraints

Abstract

Haptic simulations strive to provide users with realistic renditions of virtual environments but often struggle to display convincing rigid constraints or impacts. They generally utilize a proxy representation of the physical haptic device inside the virtual world to detect collisions, enforce constraints, and compute feedback forces. Traditional implementations are quasi-static and do not capture the dynamic energy and momentum transfer of impacts nor the associated characteristic impulse forces. To further the development of haptic interactions, we introduce and explore the concept of dynamic proxies. Associating dynamics with a proxy allows greater control over its motion and behavior and enables a general force-based simulation framework. We suggest first-order, massless dynamics to maintain a light feel and low computational update rate, while easily incorporating collisions and constraints as velocity limits. User feedback is improved and may include acceleration terms to replicate any sudden momentum changes. The resulting system shows greater realism and flexibility, allowing extensions to multi-user/multi-proxy applications with dynamic interactions.

Günter Niemeyer, Probal Mitra

4 Modelling and Controlling the Compliance of a Robotic Hand with Soft Finger-pads

Abstract

Compliant pads greatly contribute to increase the robustness and the stability of grasps of robot hands, because of their conformability to the objects’ surfaces, the capability to damp dynamic effects and to dissipate repetitive strains, the enlarged contact areas they allow. On the other hand, besides the difficulty to obtain a precise model of soft pads, they appears not suitable to achieve stiff and accurate grasps in those tasks that require high stiffness and precision. In this chapter, the normal and tangential stiffnesses of soft materials have been experimentally investigated in order to demonstrate their suitability with the development of compliant pads for robotic hands. Since these stiffnesses strongly depends on the applied load, a control approach , exploiting such relation, is proposed in order to “arbitrarily” change the overall stiffness of the hand. In this sense, the perspective of this control strategy, differently from the traditional one that “makes more compliant a stiff system” , is to use the internal forces of the grasp to “make stiffer a compliant system”.

L. Biagiotti, P. Tiezzi, G. Vassura, C. Melchiorri

5 Grasp Synthesis from Example: Tuning the Example to a Task or Object

Abstract

Many approaches to grasp synthesis do not scale well as the desired number of contacts is increased. In previous work [223], we have presented a technique that makes use of an example grasp to make synthesis tractable for grasps having larger numbers of contacts. However, an interesting side effect of this approach is that results can pick up quirks that are present in the example, some of which may be undesirable. We are beginning to explore techniques to tune an example grasp for a specific collection of task wrenches and to a given object geometry. This chapter presents preliminary results.

Nancy S. Pollard, Alon Wolf

6 Efficient and Precise Grasp Planning for Real World Objects

Abstract

With the development of .exible and highly integrated dexterous gripping devices (e.g. fig.6.1) the research results on grasp and manipulation planning can be applied to realize systems with autonomous grasping capabilities. The need for efficient methods to perform grasp analysis and planning for real world applications, therefore increases.

The so far proposed grasp planning and grasp evaluation methods made big contributions on the understanding of the structure of the grasping problem. However, not too many grasp planning systems are known that are able to cope with the constraints of planning grasps in reality, like short planning times, complex and incomplete object models and physical relevance of the planning results.

In this chapter we summarize different grasp qualification methods and out line a physically well motivated grasp quality measure using wrench spaces. We present an algorithm, based on a physically well motivated grasp quality measure to qualify a given grasp with negligible approximation errors. Justified by statistic evaluations for some real world objects based on this grasp quality measure, we suggest a very effective generate and test grasp planner architecture. The proposed planner allows for planning high quality grasps for realistic object models extremely fast a nd thus can be used for online autonomous grasping systems.

Christoph Borst, Max Fischer, Gerd Hirzinger

7 Toward Sensorless Acquisition of Multiple Contact Points Between Planar Parts

Abstract

A fixture is a device which immobilizes a part through a maximal set of linearly independent contacts. While many techniques exist to determine an appropriate arrangement of contacts, little research has been done on how to acquire those contacts (i.e., move the part such that it makes contact with the fixture at all intended points). In previous work, it was assumed that the gaps between the part and the fixture were infinitesimal. This allowed the use of a continuous-time model (formulated as a linear complementarity problem) to determine a set of contact wrenches, any one of which could be applied to the part to acquire all contacts simultaneously. This set was mapped to the boundary of the part to identify a pushing region on the part; the portion of it boundary where one could push with a single finger to acquire the contacts.

The work presented here provides two primary improvements. First, it is based on a discrete-time rigid body dynamics model that takes into account the finite motion of a part needed to close finite initial gaps between the part and the fixture. This model also allows one to determine a convex set of applicable wrenches. Second, a technique is developed whereby finite regions of the part’s boundary can be tested for membership in the pushing region, thus eliminating the need for point-wise testing.

Kevin Egan, Stephen Berard, Jeffrey C. Trinkle

8 Semi-Autonomous Human-Robot Interaction for People with Disability

Abstract

This chapter presents an innovative semi-autonomous human-robot interaction concept for people with disability and discusses a proof-of-concept prototype system. The communication between the user and the robot is performed by electromyographic (EMG) signals. However, unlike most EMG controlled robotic operations, in this framework the user can issue high-level commands to the robot through a novel EMG based approach. The robot controller is designed such that it is capable of decomposing these high-level commands into primitive subtasks using task grammar. It then develops a dynamic plan that links these primitives with knowledge about the world view to accomplish the high-level task commands. In this manner, a user can achieve semi-autonomous human-robot interaction. This proposed concept eliminates the need for continuous control of the robot and as a result, makes the system easier to use, less tiring and less error-prone. This system provides a platform for the people with disability to supervise a robot through high-level qualitative commands, rather than through low-level robotic teleoperation directives. Such a system would permit a person with disability and a robot to communicate task-relevant information in a convenient, robust, and reliable manner.

Pramila Rani, Medha Sarkar, Robert Brackin, Nilanjan Sarkar

9 On Observing Contact States in Overconstrained Manipulation

Abstract

Estimation of contact state is important to any multi-point interaction that involves frictional stick/slip phenomena. In particular, when there are more kinematic constraints than there are degrees of freedom, some contact interfaces must slip, leading to the need for contact state estimation. Fortunately, supervisory control techniques from adaptive control can be applied to this problem with relatively little modification. We discuss this approach in terms of a distributed manipulation experiment developed to explore overconstrained manipulation. In this context, we show in a simulated model that on-line contact state estimation dramatically improves performance over methods that estimate contact states off-line.

Todd D. Murphey

10 Tactile Flow and Haptic Discrimination of Softness

Abstract

Haptic perception involves both cutaneous perception, through mechanoreceptors lying on the skin, and kinaesthetic perception mediated by the position of the fingers. Analogously, artificial devices should replicate both these perceptual channels, as well. While kinesthetic information is satisfactorily replicated by current technology, cutaneous information is still a challenging task to be provided. In order to comply with this goal, a computational model of perceptual flow, inspired to established models for vision, has been recently extended to the tactile domain. It has been shown that tactile flow encodes important information on relative motion and segmentation of tactual scenes. In this chapter we illustrate how previous results on the ”contact area spread rate” with softness detection can be conveniently explained in terms of integral of tactile flow over the contact area.

Antonio Bicchi, Enzo P. Scilingo, Davide Dente, Nicola Sgambelluri

11 Evaluation of Multipoint Contact Interfaces in Haptic Perception of Shapes

Abstract

This chapter presents the evaluation of a multicontact point interface for the shape recognition of objects. A set-up constituted of an Haptic Interface system with several contact points, from one up to three, was used to present to four different subjects a set of 6 basic shapes. The experimental results suggest that the number of contact points do not produce an improvement of the ability to identify shapes, and this is strongly in contrast with what happens in touch with bare fingers. These findings confirmed results already found in other works, where experiments were conducted with fingers covered by sheaths, and provide indications for the design of more effective multipoint haptic interfaces.

Antonio Frisoli, Massimo Bergamasco, Sue L. Wu, Emanuele Ruffaldi

12 Contact Location Trajectory on the Fingertip as a Sufficient Requisite for Illusory Perception of Haptic Shape and Effect of Multiple Contacts

Abstract

This chapter seeks to demonstrate that haptic curvature perception can result solely from the trajectory of the deformed region of the fingertip due to contact with an object during tactile exploration. To test this hypothesis, we built a servo controlled 2-degree-of-freedom spherical mechanism called a Morpheotron. This device operates by rolling a flat plate on the fingertip during the exploration of a virtual surface while eliminating all other cues that are normally present, including kinesthetic cues. In carrying out the experimental protocols described herein, we found that subjects were able to perform curvature discrimination at levels comparable to those achieved when using direct manual contact with real objects, and that the highly simplified stimulus provided was able to give the illusion of touching three dimensional surfaces.

Hanifa Dostmohamed, Vincent Hayward

13 Haptic Interfaces: Collocation and Coherence Issues

Abstract

Multi-modality, collocation and immersive VE nowadays represents the break-trough barrier of human computer interaction. Typical VE systems synthesize the information to be presented to the user by means of different algorithms and present them using different interfaces. On the other hand the human perceptive system is strongly integrated and “fatigues” to interpret these stimuli as belonging to a unique information source. Collocation and coherence issues may be noticed in any kind of multimodal integration: “visual and audio”, “visual and vestibular”, “audio and haptic”, “visual and haptic”, ...

The present chapter deals with two specific kinds of multimodal integration: “visual and haptic” and “haptic and haptic”. The coherence problem of synchronizing several haptic devices is analyzed and an optimized solution is proposed. The proposed solution has been tested on a dual point HI, behaving a wide workspace realized at PERCRO. More specifically the present chapter will present a novel algorithm to achieve the absolute coordination of multiple HI working in the same VE. The system performances have been assessed and compared to those of existing solutions. The achieved results have been exploited for the EU project GRAB. The GRAB project investigates to which extent a purely haptic environment can be employed from sightless users.

Carlo Alberto Avizzano, Simone Marcheschi, Massimo Bergamasco

14 Intrinsically Passive Control using Sampled Data System Passivity

Abstract

In this chapter, which is a distilled version of [271], we present a novel way to approach the interconnection of a continuous and a discrete time physical system firstly presented in [270, 268, 257]. This is done in a way which preserves passivity of the coupled system independently of the sampling time T. This strategy can be used both in the field of telemanipulation, for the implementation of a passive master-slave system on a digital transmission line with varying time delays and possible loss of packets (e.g. the Internet), and in the field of haptics, where the virtual environment should ‘feel’ like a physical equivalent system.

Stefano Stramigioli

15 Effects of Gripping and Translational Forces on Teleoperation

Abstract

For minimally invasive surgical teleoperation systems, it is often impractical to provide the same number of degrees of freedom (dof) for position control at the slave and force feedback to the master. Sensor/actuator asymmetries are created when the user receives partial force feedback. This chapter presents an experimental study of the performance of telemanipulation with different combinations of grip and 3-dof translational force feedback. Users performed standardized tasks with varying force feedback conditions on a pair of 3-dof haptic interfaces configured for telemanipulation and augmented with 1-dof grippers. The system has four degrees of freedom of position tracking and allows modified force feedback conditions. Forcing conditions sent back to the master include (1) no forces, (2) grip forces only, (3) translational forces only, or (4) grip and translationa l forces (sensor/actuator symmetry). A position exchange controller is used to apply force feedback to the operator. We hypothesized that performance, measured by applied force, completion time and error rate, will be maximized for a system with sensor/actuator symmetry.

Lawton N. Verner, Kristin A. Jeung, Allison M. Okamura

16 Design of 100G Capturing Robot

Abstract

How much acceleration can a robot produce? Pursuing a robot with an extremely high response is a challenging matter. We have designed and developed the 100G (gravitational acceleration) capturing robot that can catch an object dropping in air. This robot keeps the world record in maximum acceleration. Since the capturing time is so short, roughly 30ms, we can not see what is actually happening through our eyes. Only a high speed camera can chase the actual motion of the robot. The basic design of the robot is precisely explained. The arm/gripper coupling mechanism is introduced for successfully transmitting the energy from the arm to the gripper. We also discuss the sliding distance after the object is captured within the gripper, and reflect the result to the design of gripper so that the gripper can completely stop the object in it.

Makoto Kaneko, Mitsuru Higashimori

Backmatter

Titel: Multi-point Interaction with Real and Virtual Objects
herausgegeben von: Federico Barbagli
Domenico Prattichizzo
Kenneth Salisbury
Verlag: Springer Berlin Heidelberg
Electronic ISBN: 978-3-540-31503-2
Print ISBN: 978-3-540-26036-3
DOI: https://doi.org/10.1007/b136620