Force and Touch Feedback for Virtual Reality

Rating:
Summary: Feeling Virtual Worlds
Review: One of the most common complaints about virtual world experiences is that the lack of physical sensations in the environment. Visual simulation is nearing photographic quality, and 3D sound is very convincing. But as soon as one touches a virtual object, or picks up a virtual car and tosses it into the next simulation, one has a great sense of incompleteness. "Why", the question is often asked, "can't I feel anything in this great virtual reality?"

There is no easy answer to that question, despite the millions of
dollars and thousands of hours spent trying to understand and
duplicate our incredibly subtle and complex haptic senses. However, at last, we can at least understand the magnitude of the problem, and the state of the art. Grigore Burdea, an Associate Professor at the CAIP Center of Rutgers University, spent most of last year engaged in research and writing about this missing dimension of VR. His new book, Force and Touch Feedback for Virtual Reality, is the result of that effort. As far as I know, there is no more complete or erudite book on the subject.

Burdea careful lays the groundwork for his survey of force feedback (resistive impulses, FFB) and tactile feedback (sensations of texture, temperature, etc., TFB) devices and concepts by providing a thorough background in human proprioception. He shares with the reader the fruits of his research: how the various receptors in the skin, muscles, bones and joints interact, how the nervous system perceives and conveys haptic data, reaction times and bandwidths of human response, and much more. He describes studies on the resolution of feeling, the average strength of various parts of the body, and time to fatigue. All in all, one is left with the impression that
Burdea is a man with a good feel for the subject.

Interestingly, reading this book made me all the more pessimistic
regarding our likelihood of ever having good FFB devices for general use. The problem is manifold. As Burdea points out, the range of forces that human beings are capable of feeling and reacting to is great. It spans several orders of magnitude, from the gentle caress of a lover brushing away a strand of hair, to the rough effort required to push a recalcitrant automobile.

Designing one device, even a hybrid device, to duplicate this range of force is a daunting concept. Furthermore, FFB devices must be grounded. That is, they must have something to push against. A portable FFB device would necessarily be of limited scope.

The outlook for TFB devices is much better. Because these devices are not resistive in nature, they can (indeed, should be) small and portable. A glove with an inner surface made of nano-mechanical effectors is conceivable, and could possibly provide realisticsensations of friction, slippage, texture, and other sensations. However, the likelihood of such a device being built in the next few years is slim.

Lacking any ideal solution, many experimenters and manufacturers,
Burdea among them, have developed limited force and tactile feedback devices. Many such devices, such as the (award-winning) Phantom, and the Impulse Engine, are commercially available and are finding acceptance in specialty applications. Most people in the VR business are familiar with the GROPE experiment carried out at UNC chapel Hill, in which a large FFB arm, designed for working with radioactive materiel, has been used to evaluate the value of FFB in molecular docking research. Medical simulation is an important use of FFB, and gamers are starting to see low-cost devices built into joysticks and other controllers. All of this, and a great deal more, is carefully covered in this book.

Were I giving a course in haptic simulation, this would be my text of choice. I recommend it without reservation to anyone considering adding haptic feedback to a simulation. If you haven't covered this material, you would need a lot of time to catch up. Luckily, Burdea has done it for us.

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This review first appeared in CyberEdge Journal, October 1996.

© CyberEdge Information Services, Inc. 1996

Rating:
Summary: Terse & uninsightful, but lots pictures & a few good links
Review: There are two main good points to this book: 1) there are many citations (references), not only to articles but to companies mentioned; 2) tons of photos, though many I found insufficiently captioned (ie, only a person who's seen the device would understand it from the picture and text). Good explanation of basic haptic & VR concepts.

The main bad points are: either too terse or too superficial, no real insight, pedantic.

The two halves of the book were quite different. The second half of the book is more interesting, but first things first:

Basically, the first half of the book is a compilation of technical information on existing haptic devices and haptic software for VR applications. It's basically regurgitation of data, very terse, factual, and boring. No analysis or insight. More a reference. Loaded with truisms like (paraphrasing) "This device requires more force to activate, so it's found to increase fatigue quicker and potential for injury". Duh!

Second half of the book deals with applications: physical modelling (surface deformation, ...), human factors (how haptics affect tasks, ...), medical, etc. Short chapter on future trends, which again I found unenlightening. But there were a few good discussions here and there, about collision detection and the like, but I found they were few and far between.

In conclusion, what I mostly got out of this book were a few references to look up for further reading, an idea of the vaste array of technologies used in haptics, some pictures of real haptic devices, and an indigestion of technical facts. I got some insight into certain issues in collision detection, and some feeling for how limited and simplistic the field of VR haptics still is.

I would have liked to see more of a debate on whether certain applications were even sensible, how much computing power is required for certain tasks, etc. Not easy questions to answer, but why bother write a book with only stuff most people could figure out on their own?

Rating:
Summary: A reference book for VR haptic technology
Review: This a great textbook on this new human-computer interface technology. The book is destined to become a classic of this field due to its in-depth, comprehensive treatment of the haptic technology. It was no suprise to me to see it is cited in many technical articles.

The book present not only technical data (actuators, force and touch feedback devices) but also the basic information related to human haptic sensing. In addition, the book complete its review of haptic systems with a chapter on human factors, which contains a collection of interesting experiments attesting the potential of this new technology. Unfortunately haptics is still in its infancy which makes it difficult to speculate on its future (as concluded in the last chapter).

In short the book will give you a good understanding of this new technology, being also a very good reference compendium.