Haptics is defined as a technology that transmits tactile information using sensations such as vibration, touch, and force feedback. Virtual reality systems and real-world technologies use haptics to enhance interactions with humans. This article covers the meaning, types, and importance of haptics.
What Are Haptics?
Haptic technology transmits tactile information using sensations such as vibration, touch, and force feedback. Virtual reality systems and real-worth technologies use haptics to enhance interactions with humans.
One of the goals of haptics is to allow a virtual reality system to make humans feel as if the experiences it portrays are ‘real’. A commonplace haptic technology is mobile phone vibrations during gaming to boost immersion.
Haptics leverage force and tactile feedback to enable users and computers to interface with each other. The former simulates certain physical features of the object being virtualized, such as pressure and weight. The latter portrays the object’s texture (for instance, smoothness or roughness).
How exactly do haptics work? Before we dive into the workings of this technology, let’s first understand the role of the human skin. This complex organ is full of touch receptors and nerve endings called the somatosensory system. This system notifies the brain of heat, cold, pain, and other sensations that humans feel.
Touch receptors transmit sensations by conveying signals to the closest neuron, which then signals the next closest neuron until the brain receives the signal. The brain then determines the response to the sensation. This entire process takes under a second.
Audio and graphics stimulate our sense of sound and sight to transmit information. Similarly, haptics stimulates our somatosensory system to pass on information and provide context. For instance, when a user holds down an application icon on the app tray of an Apple iPhone, their finger experiences a ‘pull’ sensation. The haptic motors of the iPhone generate this sensation to communicate that the app is ready to be moved, deleted, or categorized.
The vibrations, forces, and other movements of haptic systems are created mechanically using different methods. The most common method is an eccentric rotating mass (ERM) actuator. The rapid spinning of the ERM causes instability in the force from the weight, leading to movements in the motor and, subsequently, haptic feedback.
Linear resonant actuators (LRA) are another method to create haptic feedback. In this method, a magnet joined with a spring is bound by a coil and secured using an outer layer. The coil is electromagnetically energized to drive the magnetic mass to vibrate, creating a feedback sensation.
Apart from LRA and ERM, other emerging technologies are also being used to provide haptic feedback in more accessible and realistic ways. Experts use Haptics for functions such as teaching, training, entertainment, and remote hands-on operations.
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Types of Haptic Technologies
Haptics come in numerous types that are classified based on usage, feedback, and modality. Let’s understand more about the types of haptic technologies.
Based on usage
Graspable devices (think joysticks) are a standard haptic technology that generates kinesthetic feedback. The tactical vibrations, movements, and resistance caused by these devices enable users to increase immersion in gaming and even operate robots more effectively in remote or virtual conditions.
Interesting examples of this technology in action include bomb disposal and space exploration. In the latter use case, astronauts or on-ground personnel use haptics-controlled robots to repair equipment (such as spacecraft parts or satellites) without leaving the vessel or even Earth.
Touchable haptic technology is prevalent in consumer applications; think smartphones that respond to taps, rotations, and other user movements. Advances in the touchable haptics space will soon enable the technology to replicate object movements and textures (known as haptography).
For instance, companies could leverage programmable textures to allow customers to feel clothing materials such as cotton or silk before purchasing, all from the comfort of their homes.
Wearable haptic technology simulates a sensation of contact by leveraging tactile stimuli, including pressure, vibration, and even temperature.
A fast-emerging use case of wearable haptics is virtual reality (VR) gloves that mimic real-world sensations and transmit and receive inputs from users controlling their virtual avatars or remote robots.
Based on feedback
1. Force feedback
This form of haptics originated in the late 1960s, making it one of the oldest and most well-studied types of this technology. It stimulates human skin, muscles, and ligaments, unlike other haptics types that generally affect only the top layers of skin receptors.
This type of haptics comes in two styles for emulating human body parts: biomimetic and non-biomimetic. Biomimetic devices resemble human limbs in form and move with them. An example is exoskeletons–devices that are an ‘addition’ to the human body.
A constraint faced in the case of biomimetic devices is difficulty in development. These devices need to replicate human limb movement and functionality for different body sizes without hampering freedom of movement. This issue is not faced with non-biomimetic devices, which are distinct from the human body.
Apart from form, force feedback equipment can be classified based on the direction of the applied power. This classification includes active and resistive devices. The former restrict user movement and leverages motors to drive activity. They can simulate numerous interaction types and are generally robust but difficult to control. The latter limit user movement using a brake system.
2. Vibrotactile feedback
This common type of haptics uses vibrostimulators that apply pressure to the human skin. Vibrotactile feedback targets the skin’s definite receptors that resemble the structure of onion layers and can sense vibrations of up to 1000 hertz.
These devices are economical, simple, and easy to control and power. They are commonly seen in cell phones, game controllers, automobile steering wheels, and smartwatches. However, vibrating motors have certain limitations–they are not ideal for simulating a wide variety of sensations and can be hard to miniaturize efficiently.
A typical example of this feedback type in action can be seen in smartphones–the user experiences a vibration that feels like a physical button being pressed when interacting with the touchscreen.
3. Electrotactile feedback
Electrotactile stimulators apply electrical impulses that affect receptors as well as nerve endings. These devices can transmit numerous sensations to users, some of which cannot be produced by other feedback methods.
Haptics using this feedback methodology can take many forms based on the frequency and intensity of the stimuli the human skin is subjected to. Sensations can occur based on voltage, current, waveform, material, contact force, electrode size, skin type, and even hydration.
Unlike vibrotactile or force feedback, electrotactile feedback systems do not rely on moving mechanical parts. Another feature that sets these types of haptic devices apart is the assembly of electrodes into compact arrays for implementing electrotactile displays. As electrical signals serve the human nervous system’s basis, this haptic feedback is highly suitable for simulating real-world sensations.
4. Ultrasonic tactile feedback
This haptic technology uses ultrasound emitters (high-frequency sound waves) to generate subtle feedback. These devices use a transmission principle known as acoustic time reversal, where the emitter’s location may differ from the intended target for the signal on the human body.
Haptic feedback fields are helpful when ultrasound feedback needs to be transmitted to body parts with a larger surface area. These fields combine several emitters to create invisible but tangible interfaces of ultrasound waves in midair. These interfaces create turbulence that the human skin can feel.
A vital advantage of this haptic technology is its independence from user-worn accessories. However, this arrangement is often less economical than other haptic feedback types.
5. Thermal feedback
Thermal feedback haptics leverage actuator grids in direct contact with the human body. Thermoelectric diodes that rely on the Peltier effect are used in these systems. Numerous tiny units or very precise placements of the stimulus to elicit the desired simulation effect are not required here.
However, temperature management can be complex, as heat or cold cannot simply disappear from any surface and must be transferred according to the law of energy conservation. The transfer must also take place swiftly to ensure accurate simulation. As such, these devices can be highly energy-intensive and complex.
Based on modality
Vibration is a standard modality in most haptics. Technology such as eccentric rotating mass and linear resonant actuators that have been discussed above fall under this category. It is seen in wearables, mobile phones, controllers, and many other device types.
However, not every vibrating device can be categorized under haptics. The distinction lies in the intention and the complexity of the vibration patterns. Regular vibrating devices usually emit a single waveform in a continuous, monotonous intensity for the duration of the communication. On the other hand, haptics conveys information using advanced waveforms.
Simply put, a sensation that conveys ‘general’ information rather than a ‘specific’ intent is a simple vibration. Think smartphones–a device vibrating during a call is simply vibration. In contrast, a vibration of an exact intensity in a particular part of the device during a gaming session can indicate specific information, such as a collision in a racing game.
Haptics using this modality is mounted on the user’s body and simulate movement, mass, and shape.
Smart screens lack the familiar tactical feedback of mechanical buttons. Simulated buttons leverage audio and haptic feedback to replicate the sensation of a mechanized pressure pad under the user’s finger.
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Importance of Haptics
Haptic technologies play an essential role in several industries. Following are the everyday use cases for haptics.
1. The metaverse
Today, the term metaverse is heard in tech news frequently. The concept is skyrocketing in popularity, and companies across industry verticals are bracing for it to revolutionize life as we know it. Haptics is expected to be one of the most adopted technologies in this space, complementing the rise of the metaverse.
The ultimate goal of the metaverse is to replicate reality in a virtual environment that is close to indistinguishable from the real world. Naturally, this requires immersion across all human sensations, not just sight and sound. Highly effective haptics are critical for this collective vision of the tech industry to succeed.
Let’s look at how Meta, arguably the most prominent player in the metaverse space, positions its use of haptics. The Facebook company announced its rebranding in October 2021; however, it had dealt with immersive technologies long before that.
The first significant leap toward haptics superiority was through Meta’s acquisition of Oculus in 2014 for $2 billion. Since then, the company has been acquiring new augmented reality (AR) and virtual reality (VR) IPs and investing in building its own solutions. Mentions of haptics were floating around as early as 2019.
Facebook Reality Labs (earlier known as Oculus Labs) has shown promising progress in immersive solutions research. For instance, recently unveiled haptics-enabled devices are designed to reduce input latency during gaming.
Haptics is also the natural choice for users interacting with virtual worlds realistically and freely. With haptic tech, ‘clunky’ user behavior (like tapping on a touchscreen or pressing a button on a handheld remote control) is replaced with seamless zooming, pinching, pushing, touching, dragging, and other object-oriented interactions.
The gear (most likely gloves) that will enable these interactions will be powered with more than just haptics. They will also include electromyography (EMG) for translating the electrical signals that transmit human thoughts into inputs that computers can read.
How would haptics work in the metaverse? Every time users provide input, they will receive feedback or a reaction. For instance, a user pushing an object in the metaverse could ‘feel’ its resistance and weight. Users would feel it leaving their fingers if a rock is tossed across a virtual pond. That’s the magic of haptics!
2. Space exploration
The metaverse is not the only exotic environment that haptics is making waves in. The technology has also reached space, with ground crews and astronauts using it for various applications, including space exploration.
For instance, haptics plays a vital role in the European Space Agency’s METERON project. This program focuses on developing robot interfaces, communication networks, and associated hardware and software to control robots remotely in space.
Space agencies can also potentially leverage haptic technology to build infrastructure on other planets or satellites using robots controlled by humans from Earth. This may sound ambitious today; however, space agencies have already adopted complex haptics for existing space-related applications. Further developments are only natural.
On the aviation front, haptics enables flight crews to rapidly gain awareness of operational issues. For instance, steering equipment is infused with haptic tech to notify pilots if they are entering dangerous flight conditions.
Even without imminent danger, haptic feedback is leveraged in aviation to boost the overall situational awareness of the pilots and notify them of the airplane’s conditions. For instance, haptics give pilots information about flight control and help manage the flight regime safely and economically.
Haptic tech is also one of the solutions that helps ensure compliance with flight envelope protection measures. Haptic actuators are mounted on various components within the cockpit and among the controls. They physically interact with the body of the pilots and transmit the requisite information rapidly and effectively.
Haptics doesn’t just play a role in live flights but is also used to transmit realistic sensations during flight simulations. This allows flight trainees to experience events they would otherwise only face if they happened to them in real life. For instance, rain, storms, and damaged engines can be simulated using haptics-enabled simulators.
Haptics has the potential to expand driver-vehicle communications and enhance the general usability of vehicles. Haptic components can be inserted directly into various vehicle user interface (UI) parts, including the steering wheel, pedals, seatbelts, dashboard, and seat.
These tactile interfaces are then used to give the driver force or touch feedback. For instance, a vibrating seat can notify the driver if pedestrians are likely to cross the road in front of them.
5. Robot teleoperations
Teleoperators rely on haptics to receive critical feedback from remote robotic tools. In some cases, operators are notified of the forces that the robot is exposed to in real-time. This enables them to carry out tasks with accuracy and precision. For instance, robots regularly manage toxic substances and defuse explosives.
Haptics plays a vital role in several aspects of modern healthcare. Take minimally invasive surgery, for example. Here, the controls of specialized laparoscopic tools are equipped with force and tactile feedback to enable doctors to examine tissues and diagnose abnormalities remotely and accurately.
Haptics also give surgeons greater control over robotics-powered medical procedures. Surgical robots enable doctors to conduct operations in spaces that are too tiny for human hands, use small tools, or even carry out operations while sitting in another part of the world. Adding haptic feedback to robotic teleoperations for surgery enhances accuracy and minimizes operation time. The risk of tissue damage is also noticeably reduced.
Additionally, haptics plays a role in training medical practitioners. For instance, medical students can practice on virtual patients, getting a ‘feel’ for actual incisions and suturing without risking the well-being of another human being. Dental simulators are another example of this technology in action–dental students can drill teeth and cut gums in virtual reality, with haptics simulating real-world sensations and outcomes.
Movie theater seats and immersive gaming sets in shopping malls and theme parks are powered by haptics to simulate explosions, weather effects, and other environmental and human conditions. Controllers such as gamepads, joysticks, jet seats, and steering wheels transmit physical sensations to gamers using electrotactile or force feedback as video games strive to recreate the reality of virtual scenarios.
And that’s not all! Haptics also reach home users beyond gaming controllers and VR headsets. For instance, haptic-powered vests that anyone can buy online deliver low frequencies to different parts of the human body once worn. These vests are combined with compatible home entertainment devices to enhance the sensations experienced when consuming media such as video games and movies.
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Numerous haptic configurations exist, each with a specific set of use cases. Haptic technology has reached consumers from all walks of life and is only expected to expand with the rapid popularization of the metaverse. But that’s far from the only application of haptics. In its various forms, this technology is being used in medicine, entertainment, automobiles, and many other segments.
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