Haptic technology, also known as kinaesthetic communication or 3D touch, refers to any technology that can create an experience of touch by applying forces, vibrations, or motions to the user. These technologies can be used to create virtual objects in a computer simulation, to control virtual objects, and to enhance remote control of machines and devices (telerobotics). Haptic devices may incorporate tactile sensors that measure forces exerted by the user on the interface. The word haptic, from the Greek: ἁπτικός (haptikos), means "tactile, pertaining to the sense of touch". Simple haptic devices are common in the form of game controllers, joysticks, and steering wheels.
Haptic technology facilitates investigation of how the human sense of touch works by allowing the creation of controlled haptic virtual objects. Most researchers distinguish three sensory systems related to sense of touch in humans: cutaneous, kinaesthetic and haptic. All perceptions mediated by cutaneous and kinaesthetic sensibility are referred to as tactual perception. The sense of touch may be classified as passive and active, and the term "haptic" is often associated with active touch to communicate or recognize objects.
One of the earliest applications of haptic technology was in large aircraft that use servomechanism systems to operate control surfaces. In lighter aircraft without servo systems, as the aircraft approached a stall, the aerodynamic buffeting (vibrations) was felt in the pilot's controls. This was a useful warning of a dangerous flight condition. Servo systems tend to be "one-way," meaning external forces applied aerodynamically to the control surfaces are not perceived at the controls, resulting in the lack of this important sensory cue. To address this, the missing normal forces are simulated with springs and weights. The angle of attack is measured, and as the critical stall point approaches a stick shaker is engaged which simulates the response of a simpler control system. Alternatively, the servo force may be measured and the signal directed to a servo system on the control, also known as force feedback. Force feedback has been implemented experimentally in some excavators and is useful when excavating mixed material such as large rocks embedded in silt or clay. It allows the operator to "feel" and work around unseen obstacles.
In the 1960s, Paul Bach-y-Rita developed a vision substitution system using a 20x20 array of metal rods that could be raised and lowered, producing tactile "dots" analogous to the pixels of a screen. People sitting in a chair equipped with this device could identify pictures from the pattern of dots poked into their backs.
The first US patent for a tactile telephone was granted to Thomas D. Shannon in 1973. An early tactile man-machine communication system was constructed by A. Michael Noll at Bell Telephone Laboratories, Inc. in the early 1970s and a patent was issued for his invention in 1975.
In 1994, the Aura Interactor vest was developed. The vest is a wearable force-feedback device that monitors an audio signal and uses electromagnetic actuator technology to convert bass sound waves into vibrations that can represent such actions as a punch or kick. The vest plugs into the audio output of a stereo, TV, or VCR and the audio signal is reproduced through a speaker embedded in the vest.
In 1995, Thomas Massie developed the PHANToM (Personal HAptic iNTerface Mechanism) system. It used thimble-like receptacles at the end of computerized arms into which a person's fingers could be inserted, allowing them to "feel" an object on a computer screen.
In 1995, Norwegian Geir Jensen described a wristwatch haptic device with a skin tap mechanism, termed Tap-in. The wristwatch would connect to a mobile phone via Bluetooth, and tapping-frequency patterns would enable the wearer to respond to callers with selected short messages.
In 2015, the Apple Watch was launched. It uses skin tap sensing to deliver notifications and alerts from the mobile phone of the watch wearer.
The majority of electronics offering haptic feedback use vibrations, and most use a type of eccentric rotating mass (ERM) actuator, consisting of an unbalanced weight attached to a motor shaft. As the shaft rotates, the spinning of this irregular mass causes the actuator and the attached device to shake. Some newer devices, such as Apple's MacBooks and iPhones featuring the "Taptic Engine", accomplish their vibrations with a linear resonant actuator (LRA), which moves a mass in a reciprocal manner by means of a magnetic voice coil, similar to how AC electrical signals are translated into motion in the cone of a loudspeaker. LRAs are capable of quicker response times than ERMs, and thus can transmit more accurate haptic imagery.
Piezoelectric actuators are also employed to produce vibrations, and offer even more precise motion than LRAs, with less noise and in a smaller platform, but require higher voltages than do ERMs and LRAs.
Some devices use motors to manipulate the movement of an item held by the user. A common use is in automobile driving video games and simulators, which turn the steering wheel to simulate forces experienced when cornering a real vehicle. In 2007, Novint released the Falcon, the first consumer 3D touch device with high resolution three-dimensional force feedback. This allowed the haptic simulation of objects, textures, recoil, momentum, and the physical presence of objects in games.
Air vortex rings
Air vortex rings are donut-shaped air pockets made up of concentrated gusts of air. Focused air vortices can have the force to blow out a candle or disturb papers from a few yards away. Both Microsoft Research (AirWave) and Disney Research (AIREAL) have used air vortices to deliver non-contact haptic feedback.
Focused ultrasound beams can be used to create a localized sense of pressure on a finger without touching any physical object. The focal point that creates the sensation of pressure is generated by individually controlling the phase and intensity of each transducer in an array of ultrasound transducers. These beams can also be used to deliver sensations of vibration, and to give users the ability to feel virtual 3D objects.
Tactile electronic displays
A tactile electronic display is a display device that delivers text and graphical information using the sense of touch. Devices of this kind have been developed to assist blind or deaf users by providing an alternative to visual or auditory sensation.
Haptic feedback is commonly used in arcade games, especially racing video games. In 1976, Sega's motorbike game Moto-Cross, also known as Fonz, was the first game to use haptic feedback, causing the handlebars to vibrate during a collision with another vehicle. Tatsumi's TX-1 introduced force feedback to car driving games in 1983. The game Earthshaker! added haptic feedback to a pinball machine in 1989.
Simple haptic devices are common in the form of game controllers, joysticks, and steering wheels. Early implementations were provided through optional components, such as the Nintendo 64 controller's Rumble Pak in 1997. In the same year, the Microsoft SideWinder Force Feedback Pro with built-in feedback was released by Immersion Corporation. Many console controllers and joysticks feature built-in feedback devices, including Sony's DualShock technology and Microsoft's Impulse Trigger technology. Some automobile steering wheel controllers, for example, 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.
Notable introductions include:
- 2013: Steam Machines microconsoles by Valve, including a new Steam Controller unit that uses weighted electromagnets capable of delivering a wide range of haptic feedback via the unit's trackpads. These controllers' feedback systems are user-configurable.
- 2015: The Steam Controller with HD Haptics, with haptic force actuators on both sides of the controller, by Valve.
- 2017: The Nintendo Switch's Joy-Con, introducing the HD Rumble feature, developed with Immersion and using Alps actuators.
- 2018: The Razer Nari Ultimate, gaming headphones using a pair of wide frequency haptic drivers, developed by Lofelt.
- 2019: The Sony PlayStation 5 controllers can adapt the resistance of the trigger controls, such as simulating the increasing resistance felt while drawing the string of a bow, as well as more precise haptic feedback through voice coil actuators.
In 2008, Apple Inc.'s MacBook and MacBook Pro started incorporating a "Tactile Touchpad" design with button functionality and haptic feedback incorporated into the tracking surface. Products such as the Synaptics ClickPad followed.
In 2015, Apple introduced "Force Touch" trackpads onto the 2015 MacBook Pro which simulates clicks with a "Taptic Engine".
Tactile haptic feedback is common in cellular 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. The Nexus One features haptic feedback, according to their specifications. Samsung first launched a phone with haptics in 2007.
Surface haptics refers to the production of variable forces on a user's finger as it interacts with a surface such as a touchscreen. Tanvas uses an electrostatic technology to control the in-plane forces experienced by a fingertip, as a programmable function of the finger's motion. The TPaD Tablet Project uses an ultrasonic technology to modulate the apparent slipperiness of a glass touchscreen.
In 2013, Apple Inc. was awarded the patent for a haptic feedback system that is suitable for multitouch surfaces. Apple's U.S. Patent for a "Method and apparatus for localization of haptic feedback" describes a system where at least two actuators are positioned beneath a multitouch input device, providing vibratory feedback when a user makes contact with the unit. Specifically, the patent provides for one actuator to induce a feedback vibration, while at least one other actuator uses its vibrations to localize the haptic experience by preventing the first set of vibrations from propagating to other areas of the device. The patent gives the example of a "virtual keyboard," however, it is also noted that the invention can be applied to any multitouch interface.
Haptics are gaining widespread acceptance as a key part of virtual reality systems, adding the sense of touch to previously visual-only interfaces. Systems are being developed to use haptic interfaces for 3D modeling and design, including systems that allow holograms to be both seen and felt. Several companies are making full-body or torso haptic vests or haptic suits for use in immersive virtual reality to allow users to feel explosions and bullet impacts.
Teleoperators and simulators
Teleoperators are remote controlled robotic tools. When the operator is given feedback on the forces involved, this is called haptic teleoperation. The first electrically actuated teleoperators were built in the 1950s at the Argonne National Laboratory by Raymond Goertz to remotely handle radioactive substances. Since then, the use of force feedback has become more widespread in other kinds of teleoperators, such as remote-controlled underwater exploration devices.
Devices such as medical simulators and flight simulators ideally provide the force feedback that would be felt in real life. Simulated forces are generated using haptic operator controls, allowing data representing touch sensations to be saved or played back.
Haptic feedback is essential to perform complex tasks via telepresence. The Shadow Hand, an advanced robotic hand, has a total of 129 touch sensors embedded in every joint and finger pad that relay information to the operator. This allows tasks such as typing to be performed from a distance. An early prototype can be seen in NASA's collection of humanoid robots, or robonauts.
Medicine and dentistry
Haptic interfaces for medical simulation are being developed for training in minimally invasive procedures such as laparoscopy and interventional radiology, and for training dental students. A Virtual Haptic Back (VHB) was successfully integrated in the curriculum at the Ohio University College of Osteopathic Medicine. Haptic technology has enabled the development of telepresence surgery, allowing expert surgeons to operate on patients from a distance. As the surgeon makes an incision, they feel tactile and resistance feedback as if working directly on the patient.
Haptic technologies have been explored in virtual arts, such as sound synthesis or graphic design and animation. Haptic technology was used to enhance existing art pieces in the Tate Sensorium exhibit in 2015. In music creation, Swedish synthesizer manufacturer Teenage Engineering introduced a haptic subwoofer module for their OP-Z synthesizer allowing musicians to feel the bass frequencies directly on their instrument.
Force-feedback can be used to increase adherence to a safe flight envelope and thus reduce the risk of pilots entering dangerous states of flights outside the operational borders while maintaining the pilots' final authority and increasing their situation awareness.
With the introduction of large touchscreen control panels in vehicle dashboards, haptic feedback technology is used to provide confirmation of touch commands without needing the driver to take their eyes off the road. Additional contact surfaces, for example the steering wheel or seat, can also provide haptic information to the driver, for example, a warning vibration pattern when close to other vehicles.
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