Haptic technology
Haptic technology, or haptics, is a tactile feedback technology which takes advantage of a user's sense of touch by applying forces, vibrations, and/or motions upon the user. This mechanical stimulation may be used to assist in the creation of virtual objects (objects existing only in a computer simalation), for control of such virtual objects, and for the enhancement of the remote control of machines and devices (teleoperators). It has been described as "(doing) for the sense of touch what computer graphics does for vision". Although haptic devices are capable of measuring bulk or reactive forces that are applied by the user, it should not be confused with touch or tactile sensors that measure the pressure or force exerted by the user to the interface.
Haptic technology has made it possible to investigate in detail how the human sense of touch works by allowing the creation of carefully controlled haptic virtual objects. These objects are used to systematically probe human haptic capabilities, which would otherwise be difficult to achieve. These new research tools contribute to the understanding of how touch and its underlying brain functions work.
The word haptic, from the Greek ἁπτικός (haptikos), means pertaining to the sense of touch and comes from the Greek verb ἅπτεσθαι haptesthai meaning to “contact” or "touch”.
History
One of the earliest forms of haptic devices is used in large modern aircraft that use servomechanism systems to operate control systems. Such systems tend to be "one-way" in that forces applied aerodynamically to the control surfaces are not perceived at the controls, with the missing normal forces simulated with springs and weights. In earlier, lighter aircraft without servo systems, as the aircraft approached a stall the aerodynamic buffeting was felt in the pilot's controls, a useful warning to the pilot of a dangerous flight condition. This control shake is not felt when servo control systems are used. To replace this missing cue, the angle of attack is measured, and when it approaches the critical stall point a "stick shaker" (an unbalanced rotating mass) is engaged, simulating the effects of a simpler control system. This is known as haptic feedback. Alternatively the servo force may be measured and this signal directed to a servo system on the control. This method is known as force feedback. Force feedback has been implemented experimentally in some excavators. This is useful when excavating mixed materials such as large rocks embedded in silt or clay, as it allows the operator to "feel" and work around unseen obstacles, enabling significant increases in productivity.
Current Applications of Haptic Technology
Teleoperators and Simulators
Teleoperators are remote controlled robotic tools, and when contact forces are reproduced to the operator, it is called "haptic teleoperation". The first electrically actuated teleoperators were built in the 1950s at the Argonne National Laboratory in the United States, by Raymond Goertz, to remotely handle radioactive substances. Since then, the use of "force feedback" has become more widespread in all kinds of teleoperators such as underwater exploration devices controlled from a remote location.
When such devices are simulated using a computer (as they are in operator training devices) it is useful to provide the force feedback that would be felt in actual operations. Since the objects being manipulated do not exist in a physical sense, the forces are generated using haptic (force generating) operator controls. Data representing touch sensations may be saved or played back using such haptic technologies.
Haptic simulators are currently used in medical simulators and flight simulators for pilot training (2004).
Computer and Video Games
Some simple haptic devices are common in the form of game controllers, in particular of joystick and steering wheels. At first, such features and/or devices used to be optional components (like the Nintendo 64 controller's Rumble Pak). Now many of the newer generation console controllers and some joysticks feature built in devices (such as Sony's DualShock technology). An example of this feature is the simulated automobile steering wheels that are programmed to provide a "feel" of the road. As the user makes a turn or accelerates, the steering wheel responds by resisting turns or slipping out of control. Another concept of force feedback is that of the ability to change the temperature of the controlling device. This would prove especially efficient for prolonged usage of the device. However, due to the high cost of such a technology and the power drainage it would cause, the closest many manufacturers have come to realizing this concept has been to install air holes or small fans into the device to provide the user's hands with ventilation while operating the device.
In 2007, Novint released the Falcon, the first consumer 3D touch device with high resolution three-dimensional force feedback, allowing the haptic simulation of objects, textures, recoil, momentum, physical presence of objects in games.
Mobile Consumer Technologies
Tactile haptic feedback is becoming common in cellular devices. Handset manufacturers like LG and Motorola are including different types of haptic technologies in their devices. In most cases this takes the form of vibration response to touch. Alpine Electronics uses a haptic feedback technology named PulseTouch on many of their touch-screen car navigation and stereo units.
Haptics in Virtual Reality
Haptics are gaining widespread acceptance as a key part of virtual reality systems, adding the sense of touch to previously visual-only solutions. Most of these solutions use stylus-based haptic rendering, where the user interfaces to the virtual world via a tool or stylus, giving a form of interaction that is computationally realistic on today's hardware. Systems are also being developed to use haptic interfaces for 3D modeling and design that are intended to give artists a virtual experience of real interactive modeling. Researchers from the University of Tokyo have developed 3D holograms that can be "touched" through haptic feedback using "acoustic radiation" to create a pressure sensation on a user's hands. The researchers, led by Hiroyuki Shinoda, currently have the technology on display at SIGGRAPH 2009 in New Orleans.
Research
Some research has been done into simulating the different kinds of tactition by means of high-speed vibrations or other stimuli. One device of this type uses a pad array of pins, where the pins vibrate to simulate a surface being touched. While this does not have a realistic feel, it does provide useful feedback, allowing discrimination between various shapes, textures, and resiliencies.
Several haptics APIs have been developed for research applications, such as Chai3D, OpenHaptics and H3DAPI (Open Source).
Medicine
Various haptic interfaces for medical simulation may prove especially useful for training of minimally invasive procedures (laparoscopy/interventional radiology)and remote surgery using teleoperators. A particular advantage of this type of work is that the surgeon can perform many more operations of a similar type, and with less fatigue. It is well documented that a surgeon who performs more procedures of a given kind will have statistically better outcomes for his patients. Haptic interfaces are also used in Rehabilitation robotics.
In ophthalmology, "haptic" refers to a supporting spring, two of which hold an artificial lens within the lens capsule (after surgical removal of cataracts).
A 'Virtual Haptic Back' (VHB) is being successfully integrated in the curriculum of students at the Ohio University College of Osteopathic Medicine. Research indicates that VHB is a significant teaching aid in palpatory diagnosis (detection of medical problems via touch). The VHB simulates the contour and compliance (reciprocal of stiffness) properties of human backs, which are palpated with two haptic interfaces (SensAble Technologies, PHANToM 3.0).
Robotics
The Shadow Dextrous Robot Hand uses the sense of touch, pressure, and position to reproduce the human grip in all its strength, delicacy, and complexity. The SDRH was first developed by Richard Greenhill and his team of engineers in Islington, London,as part of The Shadow Project, (now known as the Shadow Robot Company) an ongoing research and development program whose goal is to complete the first convincing humanoid. An early prototype can be seen in NASA's collection of humanoid robots, or robonauts. The Dextrous Hand has haptic sensors embedded in every joint and in every finger pad which relay information to a central computer for processing and analysis. Carnegie Mellon University in Pennsylvania and Bielefeld University in Germany in particular have found The Dextrous Hand is an invaluable tool in progressing our understanding of haptic awareness and are currently involved (2006) in research with wide ranging implications. The first PHANTOM, which allows one in the human world to interact with objects in virtual reality through touch, was developed by Thomas Massie, while a student of Ken Salisbury at M.I.T.
Arts and Design
Touching is not limited to a feeling, but it allows interactivity in real-time with virtual objects. Thus, haptics are commonly used in virtual arts, such as sound synthesis or graphic design/animation. The haptic device allows the artist to have direct contact with a virtual instrument which is able to produce real-time sound or images. For instance, the simulation of a violin string produces real-time vibrations of this string under the pressure and expressivity of the bow (haptic device) held by the artist. This can be done with physical modelling synthesis.
Designers and modellers may use high-degree of freedom input devices which give touch feedback relating to the "surface" they are sculpting or creating, allowing faster and more natural workflow than with traditional methods.
Actuators
Haptics is enabled by actuators that apply the forces to the skin for touch feedback. The actuator provides mechanical motion in response to an electrical stimulus. Most early designs of haptic feedback use electromagnetic technologies such as vibratory motors with an offset mass, such as the pager motor, that is in most cell phones or voice coils where a central mass or output is moved by a magnetic field. The electromagnetic motors typically operate at resonance and provide strong feedback, but have limited range of sensations. Next-generation actuator technologies are beginning to emerge, offering a wider range of effects thanks to more rapid response times. Next generation haptic actuator technologies include Electroactive Polymers, Piezoelectric, and Electrostatic surface actuation.
Future Applications of Haptic Technology
Future applications of haptic technology cover a wide spectrum of human interaction with technology. Some of the current research is focusing on the mastery of tactile interaction with holograms and distant objects, which if successful will result in applications and advancements in industries such as the gaming, movie, manufacturing, and medical industry. The medical industry will also gain from virtual and telepresence surgeries, raising the overall standard of medical care. There is even talk that the clothing retail industry could gain from haptic technology in ways such as being able to "feel" the texture of clothes for sale on the internet. Future advancements in haptic technology may even create new industries that were not feasible or realistic before the advancements happening right now.
Holographic Interaction
Researchers at the University of Tokyo are currently working on adding haptic feedback to holographic projections. The feedback allows the user to interact with a hologram and actually receive tactile response, as if the holographic object were physically real. The research uses ultrasound waves to create a phenomenon referred to as "acoustic radiation pressure" which provides tactile feedback to the user as they interact with the holographic object. The haptic technology does not affect the hologram, or the interaction with it, only the tactile response that the user perceives. The researchers posted a video displaying what they call the "Airborne Ultrasound Tactile Display." The technology is not yet ready for mass production or mainstream application in industries, but it is quickly progressing, and "industrial companies" are already showing a positive response to the technology. It is important to note that this example of possible future application is the first in which the user does not have to be outfitted with a special glove or use a special control, they can "just walk up and use [it] " which paints a promising picture for future applications.
