Haptics

haptic

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Haptic technology, or haptics [hap-tiks], is a tactile feedback technology that takes advantage of a user’s sense of touch by applying forces, vibrations, and/or motions. This mechanical stimulation aids in the creation and control of virtual objects, and enhances the remote control of machines and devices by teleoperators, such as remote surgeons and military drone pilots. The word haptic, from the Greek (haptikos), means pertaining to the sense of touch.

One of the earliest forms of haptic devices is used in large modern aircraft where some forces applied to the control surfaces are not perceived at the controls, with the missing normal forces simulated with springs and weights. In earlier, lighter aircraft, as the aircraft approached a stall, buffeting was felt in the pilot’s controls, a useful warning. To replace this missing cue a ‘stick shaker’ (an unbalanced rotating mass) is engaged when larger planes approach a critical stall point, simulating the effects of a simpler control system. This is known as haptic feedback.

Alternatively the external 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.

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.

Some simple haptic devices are common in the form of game controllers, in particular of joysticks and steering wheels. 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. Tactile haptic feedback is becoming common in cellular devices; in most cases this takes the form of vibration response to touch. Researchers from the University of Tokyo have developed an ‘Airborne Ultrasound Tactile Display,’ in which 3D holograms can be ‘touched’ through haptic feedback using acoustic radiation to create a pressure sensation on a user’s hands.

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. Some speculate 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.

Researchers at Stanford are currently developing technology to simulate surgery for training purposes. Simulated operations would let surgeons and surgical students practice and train more. The idea behind the research is that ‘just as commercial pilots train in flight simulators before they’re unleashed on real passengers, surgeons will be able to practice their first incisions without actually cutting anyone.’

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