HAPTIC TECHNOLOGY

by Weicheng Hwang

Introduction

With the technology advances in the past few years, computer technology is making its way to the general public at an affordable price.Such as a faster CPU, a larger hard drive, better graphic card, better multimedia system, and better computer tools.One of these computer technologies that are finding it’s way to the home and business PC market is the haptic technology.Haptics is "one of the growing areas in human computer interaction or new types of sensory interaction with computers besides keyboards and mice".

A haptic technology is a force or tactile feedback technology, which allows a user to touch, feel, manipulate, create, and/or alter simulated three-dimensional objects in a virtual environment. Such an interface could be used to train physical skills such as those jobs requiring specialized hand-held tools, for instance, surgeons, astronauts, and mechanics.Or to enable modeling of three dimensional objects without a physical medium such as automobile body designers working with clay models, to mock-up developmental prototypes directly from CAD databases rather than in a machine shop using virtual reality modeling language in conjunction with haptic technology.In addition, haptic help doctors to locate any change in temperature, or tumor in certain part of body without physically being there.

Literature Review

The paper will explore the background and examination of haptic, experiences of other universities in developing haptic, advantage and shortcoming of haptic, possibilities for the future, and commercial applications of haptic.

The sources of data were gathered from the Internet and ProQuest online database.Information is mainly the published research of universities that have worked with or researching on haptic technology.

Background and Examination of Haptic

According to Salisbury, haptics is "the newest technology to arrive in the world of computer interface devices."After many years of over-emphasis on the visual elements of computing, for example, in PCs and videogame consoles, the other senses are beginning to become important. As processor speed and memory size increases dramatically in PCs especially, the "gap between capability and usability".Haptic technologies are making an appearance in high-end workstations for computer-aided design (CAD) as well as at the lower end, on home PCs and consoles, to increase the human-computer interface.

This means adding a "new mechanical channel," or a further strand, to human-computer communication so that data can be accessed and literally manipulated not just through visual means.For example if the keyboard is a passive mechanical channel between the computer and user, haptics then enables a more active exploration, is programmable according to the type of data or object to be manipulated, and allows the user not just to see three dimensional shapes on the screen visually but also to feel them and mould them through the haptic interface.

The term "haptics" refers to sensing and manipulation through the sense of touch. Although the word haptics may be new to many users, chances are that they are already using haptic interfaces (for example, keyboard and mouse).The haptic sensory system is usually regarded as having two components: tactile sensing, and kinesthetic sensing. Tactile sensing refers to an awareness of stimulation to the outer surface of the body (the softness of a blanket). Kinesthetic sensing refers to an awareness of limb position and movement (for example, an ability to touch your nose with your eyes closed), as well as muscle tension (for example, estimation of object weights) (Buffs, 1986).Unlike vision and audition that are mainly input systems for the human observer, the haptic system is bi-directional. Many activities, such as the reading of Braille text by the blind, require the use of both the sensing and manipulation aspects of the haptic system.

Of the five major human visions, audition, touch, smell, and taste, only the first three have been engaged in most human-machine interface research. Of these three, a disproportional majority of work has been conducted on visual and auditory systems. Historically, work on haptic display has been motivated by the desire to develop sensory-substitution systems for the visually or hearing impaired. Examples include the Optacon (Telesensory Corp., Mountain View, Calif.,), a reading aid for the blind; and TactaidVII (Audiological Engineering Corp., Somerville, Mass.,), a hearing aid for the deaf.

The human haptic system is made up of two sub-systems, the motor sub-system and the sensory sub-system. There is a strong link between the two systems. Unlike the visual system, it is not only important what the sensory system detects, but what motions were used to gain that information.Humans use two different forms of haptic exploration: active and passive. Active haptic exploration is when the user controls his actions. Passive haptic exploration is when another person guides the hand or finger of the user (Brewster 2000). When the users are in control they often makes mistakes. In the case of two-dimensional exploration, the most common mistake is that of wandering off of a contour and the user must spend a large amount of effort to stay on the contour. However, when the subject is being guided, user’s entire attention can be devoted to identifying the object represented.Many features can be identified more readily with passive haptic exploration (Young, 1999).

Experiments comparing the accuracy of active versus passive tactile stimulations show that passive haptics are more accurate at identifying features as a whole. When a subject's finger was guided around a two-dimensional object, such as the profile of a swan, they were more likely to be able identify the object. Some studies point out that active observers make more distracting 'errors', and may have difficulty differentiating between the erroneous paths and the correct paths of exploration.When faced with a multi-dimensional task, such as moving an object in three-dimensional space.

Studies at the University of North Carolina at Chapel Hill have shown that users usually break the task into a series of one or two-dimensional problems. They would move an object in the x-y plane before moving it into its final position by moving in the z direction (Salisbury Jr., 1999). This dimensional decomposition could be due to the particular experiment, or it could hold a clue as to how people think about multi-dimensional tasks.Another important factor in virtual reality systems is the situation when a visual cue and a haptic cue are in contradiction. The visual cue typically over-powers the haptic cue. This fact could help solve `the stiff wall problem', which is as follows. It is very difficult to create a machine that will correctly simulate the meeting of a virtual object with a hard immovable object. If the user is presented with a visual cue that the virtual effector has reached a hard surface, even though the haptic interface does not give the force of a hard, stiff surface, but rather a linear Hooke's law approximation, the user can be fooled into thinking the virtual wall is rigid.

Humans are very adept in determining if a force is real or simulated. In an experiment conducted by Edin, a device was used to determine how humans reacted when they sensed that an object they were holding began to slip. The device consisted of a solenoid attached to a metal plate that was allowed to slide when the solenoid was turned off. None of the subjects were 'tricked' into believing that the object was actually slipping. They all noted that “something was wrong with the object”', but none commented that the object behaved as if it were slippery.Studies show that there is a strong link between the sensations felt by a human hand, such as an object slipping, and the motions the hand was going through to acquire that knowledge, such as holding an experimental apparatus (Durlach, 1994)

Experiences of other Universities in Developing Haptic Technology

Ever since the haptic interface been introduced to the computer science community.Many universities have begun studies on haptic technology to develop devices that help users at home, business, and science environment.The information will be based on the research done at MIT, Purdue University, and University of Colorado.

MIT

Haptics evolution is examined, focusing primarily on developments derived from research at MIT in the early 1990s.During the spring of 1993, MIT’s work on haptic has introduced a new haptic interface that came to be called PHANTOM.This quickly commercialized due to strong interest from many colleagues and technically progressive corporations.Right now there are more than hundreds of PHANTOM haptic interfaces worldwide, this could represent an emerging market for haptic interface device.The PHANTOM interface is an electromechanical device small enough to sit on the surface of a desk and connects to a computer’s input/output port..

Fig 1. Phantom haptic interface device

The Phantom is a computer peripheral most closely related to the mouse. Its function is to interact with objects in a three dimensional environment. It has a mechanical arm supporting a pen or thimble interface at its tip, through which it can exert forces on users while tracking their motions (see fig. 1).PHANTOM applies forces on users in ways that give them the illusion of touching something.It may be as simple as feeling a wall or as complex as simulating the physical sensation of a surgical procedure.The force to create such physical illusions requires three main components: a model of object geometry and material properties; a haptic interface that can track users’ motion and impose forces on them; and a rendering algorithm that generates forces in response to user movement.

Purdue

At the same time, Purdue is currently working on a haptic perceptive UI call sensing chair.Originally conceived at the MIT Media Lab, the sensing chair project is aimed toward a real time system that tracks the sitting posture of a user through the use of surface mounted contact sensors.The realization of a robust tracking system will lead to many exciting applications such as automatic control of airbag deployment forces, ergonomics of furniture design, and biometric authentication for computer security.

University of Colorado

A high fidelity haptic interface testbed has been developed over the last five years at the University of Colorado at Boulder to enable scientific studies of the limits of interface technology and human sensory perception.The user grasps a stylist, pencil type, grip, which is connected to actuator/sensor modules by hollow steel rods.Optical encoders via linear rod motion sense motion of the user’s hand.Axial forces are transmitted by the rods from motors in each actuator module to one of the two tips of the stylist grip.This is the device that is being developed at University of Colorado at Boulder, although this device is very similar to the MIT developed PHANTOM it has its distinct difference from PHANTOM in some more specific detail.

Advantages and Disadvantages

Even the best technology has its advantages and disadvantages sometimes.This is also true for haptic, for example, a shortcoming of haptic is the technological challenge associated with the device at the home or business environment.At the same time, haptic also has its advantages, for example, helping sensory impaired user to receive information otherwise only available to the impaired sense.

Advantages

Ivan Sutherland, a founding father of virtual reality, suggested that the “human kinesthetic sense is as yet another independent channel to the brain, a channel whose information is assimilated quite subconsciously” This and other statements led researchers to develop haptic interfaces. By adding an independent input channel, the amount of information that is processed by the brain is increased. The increase in information reduces the error and time taken to complete a task. It also reduces the energy consumption and the magnitudes of contact forces used in a tele-operation situation.Humans use their hands in exploring environments that have poor or no visibility.

For instance, divers in murky water use their haptic senses in substitution for their visual senses with little loss in performance. Humans are very good at identifying three-dimensional objects placed in their hands, but are not as able to identify two-dimensional objects. Although not as adept at searching across a two-dimensional space, humans have particular ways of exploring such spaces. In two-dimensional exploration, such as exploring raised surfaces on a plane, humans use a set of exploratory procedures as observed by Lederman, Klatzky and Balakrishnan. Their research describes how humans gather information about a two-dimensional surface. This usually happens by first identifying an edge and then following a contour.

Haptic displays alone are nearly useless, but when they are used in conjunction with a visual display, they can become more useful than a stereoscopic display or a display with multiple viewpoints. Batter and Brooks did an experiment to prove that the haptic interfaces actually affected how well a user could learn from the system. They tested several sections of a physics class that were learning electrostatic fields. The experimental part of the class was allowed to use a force feedback device in a laboratory exercise, and the control group was not. The experimental group did better than the control groups because of their access to a haptic display in their lab work.

Disadvantage

Despite the progress made in the past two decades, haptic interfaces have not yet become commonplace.One main reason is the technological challenge associated with the design and production of interfaces that make physical contact with human users.Although there is hardware such as PHANTOM out in the commercial market, it is still very expensive for the home users or business users to purchase the PHANTOM device.At the same time the software compatibility is also another issue why haptic is still not very common yet.

Possibilities for the Future

Haptic interfaces will continue to be centered on the hands because people gather information from their surroundings in a haptic manner with their hands more than any other body part. The search for an inexpensive, portable and useful haptic display will be long and difficult, but it will continue for many years to come. Many researchers look for a 'natural' interface, but since there is a physical barrier between the human sensory-motor capabilities and the electronic world of the computer, there will not be a natural system until they can use direct neural stimulation of the brain. Instead, some suggest the search should be for an intuitive system. Robert Stone emphasized this point by stating:

An intuitive interface between man and machine is one which requires little training and proffers a working style most like that used by the human being to interact with environments and objects in his day-to-day life. In other words, the human interacts with elements of his task by looking, holding, manipulating, speaking, listening, and moving, using as many of his natural skills as are appropriate, or can reasonably be expected to be applied to a task. (Stone, 1995)

When creating a haptic interface, it is important to keep in mind what the device is going to be used for. If it is not going to be used in a way that is intuitive to an operator, it may cause problems even though the user is trained in its use. In times of stress, excitement, or fatigue, people forget much of their training and do what comes intuitively. So if a haptic interface is not being used in an intuitive manner, the operator may misuse the interface by doing something that is natural to them.The study of haptics holds a key to unlocking interface problems with the computer. Haptics enable a fairly intuitive way for the human user to get information into the computer, and for the computer to display information from a virtual world. Research in this area can help enable those who have been unable to use a computer to its fullest extent overcome a physical limitation, and it can enable users to explore objects and places that have been inaccessible under normal circumstances.

Commercial Applications

More recently, there has been a tremendous increase in commercial haptic activities aimed at moving the technology from the laboratories into commercial applications.Seismic modeling, faced with enormous quantities of volumetric data, modern mineral and oil prospectors use haptic technology to help visually and haptically look for important features in their data. Enabling geologists to feel soil density, stratification, and other properties, while seeing the information in 3D, has inspired significant commitment to haptic by a number of major companies, including Shell Oil.

Virtual prototyping (see fig. 2 and fig. 3), designers especially in the aircraft and automobile industries, moving from expensive physical mockups of complex designs to digital designs need effective ways to test the assemble ability and maintainability of virtual prototypes. This need has inspired development of haptically accessible virtual environments in which assembly and disassembly can be used to guide final design.


Fig 2. Boeing LHD with F-18 flight stick	Fig 3. UW LHD with integrated handgrip force sensor (w/o covers)

Shape sculpting. In the design community, the need to expressively and quickly create and modify computer-modeled shapes has inspired SensAble Technology, Cambridge, Mass., to develop "digital clay" technology (see fig. 4). Along with familiar and novel sculpting tools, this technology allows users to carry out expressive, free-form shape generation and modifications. It is reasonable to expect industrial designers and animators to soon use such tools to construct and modify their models.

Fig 4. Modeling haptic device

Molecular docking, simulating the forces of interaction-through haptic feedback-between a legend and a protein allows chemists to directly manipulate the complex structure. Mapping the natural phenomena of molecular forces into a perceptually accessible domain helps reveal the underlying mechanisms leading to or preventing successful docking in a way not possible before.Examples include investigating static and electrostatic forces acting on a complex model, testing of conformational flexibility, and assessing the quality of fit. This information can be factored into the design process to help maximize the bioactivity of new compounds. This work, with origins in the molecular docking research at the University of North Carolina, is now being commercialized, most notably by Interactive Simulations, San Diego (Tan, 2000).

Surgical simulation and training (see fig. 5). Surgery was one of the earliest research topics in" computer haptic based training. But the complexity of rendering compliant biomaterials makes virtual surgery a particularly challenging undertaking. The potential benefits of simulation-based training and preoperative planning have attracted significant research interest and commercial investment. Systems under development are moving toward use in training and certification in several surgical specialties. For example, in machine haptic, surgical tele-robots already help humans perform cardiac and abdominal surgery. And it is easy to imagine the convergence of bio-simulation and tele-surgery in the near future.

Fig 5. Developing device for medical uses.

Simple versions of the devices, such as "force-feedback mice," are already on the market and soon may become standard on personal computers, some researchers predict (see fig. 6). With them, the computer desktop becomes a virtual landscape where links feel like embossed text, scroll bars feel like gutters, and the borders of windows feel like picture frames.Computer users may decide, however, that they don't need to know how their cluttered computer screens feel to the touch.The idea for such devices has been around for decades, but researchers say useful haptic interfaces have been developed only in the last few years."It is growing rapidly-I think that's beyond doubt," says Robert D. Howe, a professor of engineering and applied sciences at Harvard University who is working on haptic devices. "People are finding all sorts of interesting applications for these things. 'Haptic' will soon become a household word."

Fig 6. iFeel mouse developed by Logitech

Ed Colgate, an associate professor of mechanical engineering at Northwestern University, says the "killer application" for haptic devices will be in design.He says that if haptic features could be added to standard computer-aided design (CAD) software, manufacturers could get a better sense of how their designs would fit together before building them. He says the software would give industrial designers "more than just geometry," but would let them feel "how much things weigh and how stiff they are." McGill's Mr. Hayward, however, says that haptic devices may be more useful to niche fields, such as robotics, than for the average industrial designer.

At least three companies now sell haptic interfaces designed for researchers-Haptic Technologies, Immersion Corporation, and SensAble Technologies.One such device is called the Phantom. It looks something like the jointed, swing arm lamps used by architects. A user puts a finger in a thimble-like object at the end of the arm. The device can then sense the user's motions in three dimensions and send the corresponding data to a computer. Powered by motors and cables, the device can also keep the user from moving his finger in one direction or another-to simulate, for instance, the user's having hit an object on the computer screen.

Conclusion

With the increase of the computation power of office and home PC one-day haptic mouse and interface device will be a common item in the house.The haptic development helps the sense impaired people to experience a new way of operating computers in a way they never do.From the examples mentioned in the commercial applications we can see that the use of haptic is actually infinite.Haptic could be used in medical, training, e-commerce, or even games.These are just some rough uses for haptic, the possibility is so much more and right now haptic is helping NASA to explore planets in the Solar system by controlling the robots.Though the technology is still quite unfamiliar to the general public but once haptic is introduced I believe it will grow like the Internet back in the late 1980’s early 1990’s.Haptic is the future for online computing and e-commerce it will enhance the shopper experience and help online shopper to feel the merchandise without leave their home.Thus I believe Internet is the way of the future and haptic will make Internet be the future.

References

Buff, KR. Kaufman, L., and Thomas, J.P. (Eds).Handbook of Perception and

Human Performance Sensory Processes and Perception.Vols. 1 and 2.Wiley,

New York, N.Y., 1986.

Cole, J. Pride and a Daily Marathon.MIT Press, Cambridge, MA, 1995.

Durlach N. and Mavor A. S.. Virtual Reality: Scientific and Technological Challenges. National Academy Press, Washington, D.C, 1994

Brewster, S.A.(1999). Sound in the interface to a mobile computer. In Proceedings of HCI International'99 (Munich, Germany), Lawrence Erlbaum Associates, NJ, pp 43-47.

Brewster, S.A. and Walker, V.A. (2000). Non-Visual Interfaces for Wearable Computers. IEE Workshop on wearable Computing (00/145). IEE Press.

Brewster, S.A. Overcoming the Lack of Screen Space on Mobile Computers. Department of Computing Science Technical Report TR-2001-87, April. Glasgow University.

Srinivasan, M., Cutkosky, M., Howe, R., and Salisbury, J. Human and Machine Haptics. MIT Press, Cambridge, Mass., 1999.