Showing papers on "Haptic technology published in 2000"

An experimental study on the role of touch in shared virtual environments

Abstract: Investigating virtual environments has become an increasingly interesting research topic for engineers, computer and cognitive scientists, and psychologists. Although there have been several recent studies focused on the development of multimodal virtual environments (VEs) to study human-machine interactions, less attention has been paid to human-human and human-machine interactions in shared virtual environments (SVEs), and to our knowledge, no attention paid at all to what extent the addition of haptic communication between people would contribute to the shared experience. We have developed a multimodal shared virtual environment and performed a set of experiments with human subjects to study the role of haptic feedback in collaborative tasks and whether haptic communication through force feedback can facilitate a sense of being and collaborating with a remote partner. The study concerns a scenario where two participants at remote sites must cooperate to perform a joint task in an SVE. The goals of the study are (1) to assess the impact of force feedback on task performance, (2) to better understand the role of haptic communication in human-human interactions, (3) to study the impact of touch on the subjective sense of collaborating with a human as reported by the participants based on what they could see and feel, and (4) to investigate if gender, personality, or emotional experiences of users can affect haptic communication in SVEs. The outcomes of this research can have a powerful impact on the development of next-generation human-computer interfaces and network protocols that integrate touch and force feedback technology into the internet, development of protocols and techniques for collaborative teleoperation such as hazardous material removal, space station.

Supporting presence in collaborative environments by haptic force feedback

Abstract: An experimental study of interaction in a collaborative desktop virtual environment is described. The aim of the experiment was to investigate if added haptic force feedback in such an environment affects perceived virtual presence, perceived social presence, perceived task performance, and task performance. A between-group design was employed, where seven pairs of subjects used an interface with graphic representation of the environment, audio connection, and haptic force feedback. Seven other pairs of subjects used an interface without haptic force feedback, but with identical features otherwise. The PHANToM, a one-point haptic device, was used for the haptic force feedback, and a program especially developed for the purpose provided the virtual environment. The program enables for two individuals placed in different locations to simultaneously feel and manipulate dynamic objects in a shared desktop virtual environment. Results show that haptic force feedback significantly improves task performance, perceived task performance, and pereceived virtual presence in the collaborative distributed environment. The results suggest that haptic force feedback increases perceived social presence, but the difference is not significant.

Pseudo-haptic feedback: can isometric input devices simulate force feedback?

Abstract: This paper considers whether a passive isometric input device, such as a Spaceball/sup TM/, used together with visual feedback, could provide the operator with a pseudo-haptic feedback. For this aim, two psychophysical experiments have been conducted. The first experiment consisted of a compliance discrimination, between two virtual springs hand-operated by means of the Spaceball/sup TM/. In this experiment, the stiffness (or compliance) JND turned out to be 6%. The second experiment assessed stiffness discrimination between a virtual spring and the equivalent spring in reality. In this case, the stiffness (or compliance) JND was found to be 13.4%. These results are consistent with previous outcomes on manual discrimination of compliance. Consequently, this consistency reveals that the passive apparatus that was used can, to some extent, simulate haptic information. In addition, a final test indicated that the proprioceptive sense of the subjects was blurred by visual feedback. This gave them the illusion of using a nonisometric device.

Vibrotactile haptic feedback devices

Abstract: Vibrotactile haptic feedback devices are disclosed. For example, in one embodiment, a device includes: a mass, an actuator configured to vibrate the mass, and a coupling disposed between the actuator and the mass or between the mass and a housing, the coupling having a first configuration with a compliance and a second configuration with a compliance, the compliance of the coupling in the first configuration being different from the compliance of the coupling in the second configuration, the actuator being configured to output haptic feedback associated with the first configuration of the coupling and haptic feedback associated with the second configuration of the coupling, the haptic feedback associated with the first configuration of the coupling being different from the haptic feedback associated with the second configuration of the coupling.

Putting the feel in ’look and feel‘

Abstract: Haptic devices are now commercially available and thus touch has become a potentially realistic solution to a variety of interaction design challenges. We report on an investigation of the use of touch as a way of reducing visual overload in the conventional desktop. In a two-phase study, we investigated the use of the PHANToM haptic device as a means of interacting with a conventional graphical user interface. The first experiment compared the effects of four different haptic augmentations on usability in a simple targeting task. The second experiment involved a more ecologically-oriented searching and scrolling task. Results indicated that the haptic effects did not improve users performance in terms of task completion time. However, the number of errors made was significantly reduced. Subjective workload measures showed that participants perceived many aspects of workload as significantly less with haptics. The results are described and the implications for the use of haptics in user interface design are discussed.

A virtual-reality-based telerehabilitation system with force feedback

Abstract: A PC-based orthopedic rehabilitation system was developed for use at home, while allowing remote monitoring from the clinic. The home rehabilitation station has a Pentium II PC with a graphics accelerator, a Polhemus tracker and a multi-purpose haptic control interface. This novel interface is used to sample a patient's hand positions and to provide resistive forces using the Rutgers Master II (RMII) glove. A library of virtual rehabilitation routines was developed using WorldToolKit software. At the present time, it consists of three physical therapy exercises (DigiKey, ball and Power Putty) and two functional rehabilitation exercises (peg board and ball game). These virtual reality exercises allow automatic and transparent patient data collection into an Oracle database. A remote Pentium II PC is connected with the home-based PC over the Internet and an additional video conferencing connection. The remote computer runs an Oracle server to maintain the patient database, monitor progress and change the exercise level of difficulty. This allows for patient progress monitoring and repeat evaluations over time. The telerehabilitation system is undergoing clinical trials at Stanford Medical School, with progress being monitored from Rutgers University. Other haptic interfaces currently under development include devices for elbow and knee rehabilitation connected to the same system.

Tactile mouse device

Abstract: A low-cost tactile feedback mouse device for providing haptic feedback to a user for enhancing interactions and manipulations in a graphical environment provided by a computer. The mouse device includes a sensor device able to detect the movement of the mouse in the planar workspace. An actuator is coupled to the housing of the mouse and applies an inertial force in a particular degree of freedom, preferably along an axis perpendicular to the planar workspace, where the inertial force is transmitted through the housing to the user. The actuator outputs the inertial force preferably by linearly moving an inertial mass along the Z-axis. The output force is correlated with interaction of a controlled graphical object, such as a cursor, with other graphical objects in a graphical environment displayed by the host computer. The inertial force can be a pulse, vibration, texture force, or other type of force.

Closed-Loop Force Control for Haptic Simulation of Virtual Environments

Abstract: Force feedback control is investigated for improving the quality of the haptic feedback in virtual reality applications. Advanced control design can increase the transparency of the haptic device at the haptic interface thereby increasing the realism of the simulation. Force feedback also enables the implementation of admittance control approaches heretofore considered the domain of large robotic platforms. The quality of the haptic interface is "rst quanti"ed, and the standard open-loop impedance approach to haptic control is reviewed. Dual-input control schemes with sensory force feedback are then introduced, and the resulting quality of the haptic interface is derived. A four-bar linkage example is used to illustrate the improvement in "delity realized with the various approaches. The tradeoffs encountered in moving to force feedback controllers for haptic applications are also discussed.

A compliant tactile display for teletaction

Abstract: A teletaction system uses a tactile display to present the user with information about texture, local shape, and/or local compliance. Current tactile displays are flat and rigid, and require precise machining and assembly of many parts. This paper describes the fabrication and performance of a one-piece pneumatically-actuated tactile display molded from silicone rubber. Tactor spacing is 2.5 mm with 1 mm diameter tactor elements. Tactile display compliance ensures contact between the finger and tactile display at all times. Unlike previous pneumatic tactile displays, there is no chamber leakage and no seal friction. A psychophysics experiment showed that a synthetic grating on the tactile display was perceived as well as a low-pass-filtered real contact.

A Virtual Environment Testbed for Training Laparoscopic Surgical Skills

Abstract: With the introduction of minimally invasive techniques, surgeons must learn skills and procedures that are radically different from traditional open surgery. Traditional methods of surgical training that were adequate when techniques and instrumentation changed relatively slowly may not be as efficient or effective in training substantially new procedures. Virtual environments are a promising new medium for training. This paper describes a testbed developed at the San Francisco, Berkeley, and Santa Barbara campuses of the University of California for research in understanding, assessing, and training surgical skills. The testbed includes virtual environments for training perceptual motor skills, spatial skills, and critical steps of surgical procedures. Novel technical elements of the testbed include a four-DOF haptic interface, a fast collision detection algorithm for detecting contact between rigid and deformable objects, and parallel processing of physical modeling and rendering. The major technical challenge in surgical simulation to be investigated using the testbed is the development of accurate, real-time methods for modeling deformable tissue behavior. Several simulations have been implemented in the testbed, including environments for assessing performance of basic perceptual motor skills, training the use of an angled laparoscope, and teaching critical steps of the cholecystectomy, a common laparoscopic procedure. The major challenges of extending and integrating these tools for training are discussed.

Haptic discrimination of softness in teleoperation: the role of the contact area spread rate

Abstract: Many applications in teleoperation and virtual reality call for the implementation of effective means of displaying to the human operator information on the softness and other mechanical properties of objects being touched. The ability of humans to detect softness of different objects by tactual exploration is intimately related to both kinesthetic and cutaneous perception, and haptic displays should be designed so as to address such multimodal perceptual channel. In this paper, we investigate the possibility of surrogating detailed tactile information for softness discrimination, with information on the rate of spread of the contact area between the finger and the specimen as the contact force increases. Devices for implementing such a perceptual channel are described, and a practical application to a mini-invasive surgery tool is presented. Psychophysical test results are reported, validating the effectiveness and practicality of the proposed approach.

Tactile Display Device Using Distributed Lateral Skin Stretch

Abstract: In the past, tactile displays were of one of two kinds: they were either shape displays, or relied on distributed vibrotactile stimulation. A tactile display device is described in this paper which is distinguished by the fact that it relies exclusively on lateral skin stretch stimulation. It is constructed from an array of 64 closely packed piezoelectric actuators connected to a membrane. The deformations of this membrane cause an array of 112 skin contactors to create programmable lateral stress fields in the skin of the finger pad. Some preliminary observations are reported with respect to the sensations that this kind of display can produce. INTRODUCTION Tactile displays are devices used to provide subjects with the sensation of touching objects directly with the skin. Previously reported tactile displays portray distributed tactile stimulation as a one of two possibilities [1]. One class of displays, termed “shape displays”, typically consists of devices having a dense array of skin contactors which can move orthogonally to the surface of the skin in an attempt to display the shape of objects via its spatially sampled approximation. There exist numerous examples of such displays, for recent designs see [2; 3; 4; 5]. In the interest of brevity, the distinction between “pressure displays” and shape displays is not made here. However, an important distinction with regard to the focus of this paper must be made between displays intended to cause no slip between the contactors and the skin and those intended for the opposite case.1 Displays which are intended to be used without slip can be mounted on a carrier device [6; 2]. 1Braille displays can be found in this later category. Another class of displays takes advantage of vibrotactile stimulation. With this technique, an array of tactilly active sites stimulates the skin using an array of contactors vibrating at a fixed frequency. This frequency is selected to maximize the loudness of the sensation (200–300 Hz). Tactile images are associated, not to the quasi-static depth of indentation, but the amplitude of the vibration [7].2 Figure 1. Typical Tactile Display. Shape displays control the rising movement of the contactors (resp. the force applied to). In a vibrotactile display, the contactors oscillate at a fixed frequency. Devices intended to be used as general purpose tactile displays cause stimulation by independently and simultaneously activated skin contactors according to patterns that depend both on space and on time. Such patterns may be thought of as “tactile images”, but because of the rapid adaptation of the skin mechanoreceptors, the images should more accurately be described as “tactile movies”. It is also accepted that the separation between these contactors needs to be of the order of one millimeter so that the resulting percept fuse into one single continuous image. In addition, when contactors apply vibratory signals to the skin at a frequency, which may range from a few Hertz to a few kiloHertz, a perception is derived which may be described 2The Optacon device is a well known example [8]. Proceedings of the Haptic Interfaces for Virtual Environment and Teleoperator Systems Symposium, ASME International Mechanical Engineering Congress & Exposition 2000, Orlando, Florida, USA . pp. 1309-1314

Haptic Feedback: A Brief History from Telepresence to Virtual Reality

Abstract: This paper presents a short review of the history surrounding the development of haptic feedback systems, from early manipulators and telerobots, used in the nuclear and subsea industries, to today's impressive desktop devices, used to support real-time interaction with 3D visual simulations, or Virtual Reality. Four examples of recent VR projects are described, illustrating the use of haptic feedback in ceramics, aerospace, surgical and defence applications. These examples serve to illustrate the premise that haptic feedback systems have evolved much faster than their visual display counterparts and are, today, delivering impressive peripheral devices that are truly usable by non-specialist users of computing technology.

Haptic Graphs for Blind Computer Users

Abstract: In this paper we discuss the design of computer-based haptic graphs for blind and visually impaired people with the support of our preliminary experimental results. Since visual impairment makes data visualisation techniques inappropriate for blind people, we are developing a system that can make graphs accessible through haptic and audio media. The disparity between human haptic perception and the sensation simulated by force feedback devices is discussed. Our strategies to tackle technical difficulties posed by the limitations of force feedback devices are explained. Based on the results of experiments conducted on both blind and sighted people, we suggested two techniques: engraving and the use of texture to model curved lines on haptic graphs. Integration of surface property and auditory cues in our system are proposed to assist blind users in exploring haptic graphs.

Rate-hardness: a new performance metric for haptic interfaces

Abstract: Rate-hardness is introduced as a quality metric for hard virtual surfaces, and linked to human perception of hardness via a psychophysical study. A 3 degree-of-freedom haptic interface is used to present pairs of virtual walls to users for side-by-side comparison, 19 subjects are tested in a series of three blocks of trials, where different virtual walls are presented in randomly ordered pairs. Results strongly support the use of rate-hardness, as opposed to mechanical stiffness, as the more relevant metric for haptic interface performance in rendering hard virtual surfaces. It is also shown that common techniques of enhancing stability of the rendered surfaces tend to actually enhance performance as measured by rate-hardness.

Haptic trackball device

Abstract: A low-cost haptic feedback trackball device for providing haptic feedback to a user for enhancing interactions in a graphical environment provided by a computer. The trackball device includes a sensor device that detects the movement of a sphere in two rotary degrees of freedom. An actuator applies a force preferably along a z-axis perpendicular to the plane of the surface supporting the device, where the force is transmitted through the housing to the user. The output force is correlated with interaction of a controlled graphical object, such as a cursor, with other graphical objects in the displayed graphical environment. Preferably, at least one compliant element is provided between a portion of the housing contacted by the user and the support surface, where the compliant element amplifies the force output from the actuator by allowing the contacted portion of the housing to move with respect to the support surface. The force can be an inertial force, contact force, or a combination of forces that provide tactile sensations to the user.

Hybrid control of haptic feedback for host computer and interface device

Abstract: A hybrid haptic feedback system in which a host computer and haptic feedback device share processing loads to various degrees in the output of haptic sensations, and features for efficient output of haptic sensations in such a system. A haptic feedback interface device in communication with a host computer includes a device microcontroller outputting force values to the actuator to control output forces. In various embodiments, the microcontroller can determine force values for one type of force effect while receiving force values computed by the host computer for a different type of force effect. For example, the microcontroller can determine closed loop effect values and receive computed open loop effect values from the host; or the microcontroller can determine high frequency open loop effect values and receive low frequency open loop effect values from the host. Various features allow the host to efficiently stream computed force values to the device.

Haptic interaction with global deformations

Abstract: Force feedback coupled with a real-time physically realistic graphic display provides a human operator with an artificial sense of presence in a virtual environment. Furthermore, it allows a human operator to interact with the virtual environment through "touch". We describe a haptic simulation system that allows a human operator to perform real-time interaction with soft 3D objects that go through large global deformations. We model and simulate such a global deformation using geometrically nonlinear finite element methods (FEM). We also introduce an efficient method that computes the force feedback, in real-time, by simulating the collision between the virtual "proxy" and the deformable object. To perceptually satisfy a human operator, haptics requires a much higher update frequency (at least 1000 Hz) than graphics. We update the graphics using full simulation and interpolate the fully simulated states at a higher frequency to render haptics. The interpolation is made possible by intentionally delaying the display (both graphics and haptics) by one full simulation cycle.

Designing with haptic feedback

Abstract: Haptic feedback is a design element for human-computer interfaces, and this paper discusses when and how it can be used to best effect in interactive applications. It begins with consideration of the unique attributes of the touch sense in physiological and psychological terms, and the nature of information and control that touching provides. It reviews where active touching helps, by setting forth the forms it may take and important parameters that describe it; and evaluates the specific benefits it offers to contemporary interface problems. It ends with a proposal for a simple interaction model that emphasizes holistic design principles, and highlights issues that arise in the process of creating specific haptic interfaces.

Guaranteed stability of haptic systems with nonlinear virtual environments

Abstract: Design of haptic systems that guarantee stable interaction is a challenging task. Virtual environments are typically highly nonlinear-resulting in a nonpassive discrete-time model. This paper will investigate how nonlinear mass/spring/damper virtual environments can be designed to guarantee the absence of oscillations and other chaotic behavior in the signal presented to the human operator. In particular, delayed and nondelayed implementation of the mass/spring/damper virtual environment is considered, revealing a nonintuitive result with regard to the allowable local stiffness.

Haptics issues in virtual environments

Abstract: Haptics is a recent enhancement to virtual environments, allowing users to "touch" and feel the simulated objects they interact with. Current commercial products allow tactile feedback through desktop interfaces (such as the FEELIt/sup TM/ mouse or the PHANToM/sup TM/ arm) and dextrous tactile and force feedback at the fingertips through haptic gloves (such as the CyberTouch/sup TM/ and the CyberGrasp/sup TM/). Virtual reality haptic programming requires good physical modeling of user interactions, primarily through collision detection, and of object responses, such as surface deformation, hard-contact simulation, slippage, etc. It is at present difficult to simulate complex virtual environments that have a realistic behavior. This task is added to by the recent introduction of haptic toolkits (such as Ghost/sup TM/ or VPS). Current technology suffers from a number of limitations, which go beyond the higher production cost of haptic interfaces. These technical drawbacks include the limited workspace of desktop interfaces, the large weight of force-feedback gloves, the lack of force feedback to the body, safety concerns, etc. Not to be neglected is the high bandwidth requirement of haptics, which is not met by current Internet technology. As a result, it is not possible at present to have a large number of remote participants interacting haptically in a shared virtual space.

Six degree-of-freedom haptic display of polygonal models

Abstract: We present an algorithm for haptic display of moderately complex polygonal models with a six degree of freedom (DOF) force feedback device. We make use of incremental algorithms for contact determination between convex primitives. The resulting contact information is used for calculating the restoring forces and torques and thereby used to generate a sense of virtual touch. To speed up the computation, our approach exploits a combination of geometric locality, temporal coherence, and predictive methods to compute object-object contacts at kHz rates. The algorithm has been implemented and interfaced with a 6-DOF PHANToM Premium 1.5. We demonstrate its performance on force display of the mechanical interaction between moderately complex geometric structures that can be decomposed into convex primitives.

Multirate simulation for high fidelity haptic interaction with deformable objects in virtual environments

Abstract: Haptic interaction is an increasingly common form of interaction in virtual environment simulations. This medium introduces some new challenges. In this paper we study the problem arising from the difference between the sampling rate requirements of haptic interfaces and the significantly lower update rates of the physical models being manipulated. We propose a multirate simulation approach which uses a local linear approximation. The treatment includes a detailed analysis and experimental verification of the approach. The proposed method is also shown to improve the stability of the haptic interaction.

Artificial tactile feel display using soft gel actuators

Abstract: It is difficult for the conventional tactile displays to express fine touch as a surface of cloth. A mechanical device appropriate for minute distributed stimuli on human skin does not exist. This paper proposes a ciliary device using soft high polymer gel actuators (ICPF) as a solution to this problem. This new device can generate various distributed stimuli to human sense receptors. It was experimentally confirmed that, combinations of vibratory stimuli of high frequency and low frequency produced complex tactile feels. Comparison of the artificial tactile feels and cloth material samples demonstrated that this device developed could display subtle distinction in the touch of cloth.

Eye-hand co-ordination with force feedback

Abstract: The term Eye-hand co-ordination refers to hand movements controlled with visual feedback and reinforced by hand contact with objects. A correct perspective view of a virtual environment enables normal eye-hand co-ordination skills to be applied. But is it necessary for rapid interaction with 3D objects? A study of rapid hand movements is reported using an apparatus designed so that the user can touch a virtual object in the same place where he or she sees it. A Fitts tapping task is used to assess the effect of both contact with virtual objects and real-time update of the centre of perspective based on the user's actual eye position. A Polhemus tracker is used to measure the user's head position and from this estimate their eye position. In half of the conditions, head tracked perspective is employed so that visual feedback is accurate while in the other half a fixed eye-position is assumed. A Phantom force feedback device is used to make it possible to touch the targets in selected conditions. Subjects were required to change their viewing position periodically to assess the importance of correct perspective and of touching the targets in maintaining eye-hand co-ordination, The results show that accurate perspective improves performance by an average of 9% and contact improves it a further 12%. A more detailed analysis shows the advantages of head tracking to be greater for whole arm movements in comparison with movements from the elbow.

inTouch: interactive multiresolution modeling and 3D painting with a haptic interface

Abstract: We present an intuitive 3D interface for interactively editing and painting a polygonal mesh using a force feedback device. An artist or a designer can use the system to create and refine a three-dimensional multiresolution polygonal mesh. Its appearance can be further enhanced by directly painting onto its surface. The system allows users to naturally create complex forms and patterns not only aided by visual feedback, but also by their sense of touch.

Tactile Navigation Display

Abstract: The use of the tactile modality is not common in Human Computer Interaction. However, there may be good reasons to do so. For example in situations in which the visual sense is restricted (e.g., in virtual environments lacking a wide field of view, or for the visually handicapped persons), or overloaded (e.g., flying an airplane or driving in an unknown city). The lack of a wide visual field of view excludes the use of peripheral vision and may therefore degrade navigation, orientation, motion perception, and object detection. Tactile actuators applied to the torso, however, have a 360° horizontal 'field of touch', and may therefore be suited to compensate for the degraded visual information.

A haptic interface for a virtual exam of the human thigh

Abstract: This paper proposes a method for interfacing a force-feedback device of type PHANToM to a spring-damper model of the human thigh. The model was defined from experimental data and it is simulated using implicit integration. The main difficulty encountered is that while the PHANToM needs to receive the force values at a rate of 1 KHz, the physical model runs at a maximum speed of 100 Hz. Supplying forces at this frequency leads to unrealistic vibration in the force feedback. The novelty of our approach is the use of a local model supplying reliable force values at a high frequency. The purpose of this work is to contribute for the implementation of an echographic simulator with force-feedback.

Physically-based manipulation on the Responsive Workbench

Abstract: Describes how a physical simulation can be integrated with our Responsive Workbench system to support complex assembly tasks involving multiple hands and users. Our system uses the CORIOLIS physical simulation package extended to meet the real-time requirements for our highly interactive virtual environment. We develop a new set of interface tools that exploit the natural properties of physical simulation (i.e. the superposition of forces). Our tools are based on sets of springs connecting the user's hand to a virtual object. Visualizing these springs provides "visual force feedback" of the applied forces and facilitates the prediction of the objects' behavior. Our force-based interaction concept allows multiple hands and users to manipulate a single object without the need for locking the object.

Realistic force feedback for virtual reality based diagnostic surgery simulators

Abstract: Virtual reality surgery simulators are almost certainly the future of endoscopic surgery trainers. While many aspects of such systems, such as the visualization of the operating scene, have been brought to satisfactory levels of resemblance to real endoscopic surgery, the haptic feedback simulation is one of the major obstacles remaining. The aim of this work is to describe the main components necessary for a realistic haptic feedback in surgery, concentrating on the modelling of soft organic tissue, necessary for the simulation of soft tissue deformation. We also present a method to measure in-vivo the material parameters figuring in the developed elastomechanical models of living tissues.