What is Haptics?
Haptics in product design refers to how information can be communicated through the sense of touch using science and technology, so when virtual objects are touched, they seem real and discernible. Haptics for the sense of touch is similar to what displays, and optics are for sight and audio or alarms for hearing. There are many reasons why product designers are exploring the human touch and think it is important to consider haptics in product design.
With 18,000 mechanoreceptors in one hand – 31% of the total amount in the body – our fingers are tremendous tools that engineering product designers are increasingly considering when creating products such as tactile electronic displays, game controllers, smartwatches, smart wearables, and phones.
The word Haptics derives from the Greek word Haptikos, which means a sense of touch. The first-ever haptic technology device was Motorola‘s world’s first vibrating phone, which provided haptic feedback in the form of vibrating sensation.
Although Haptics is frequently used as a broader term to include both haptic technology and haptic feedback, there is a marginal difference between them when it comes to haptics in product design. Haptic feedback is about how the sense of touch is used to communicate with the user. But Haptic technology refers to techniques and technology, which uses force, vibration, heat, or motion to imitate tactile sensations through various haptic actuators.
What is Haptic feedback?
Haptic feedback simulates the sense of touch to communicate with the user and generally refers to the mode of communication rather than a specific application or technology. Visual and audible feedbacks are used everywhere for many different purposes, from blinking the phone notification LED to smoke detectors alarms. These explore two of the five senses – sight and hearing. Haptic explores another human sense, touch and has a variety of ways to communicate.
There are two categories of Haptic feedback viz; Kinesthetic and Tactile. Kinesthetic haptic feedback refers to the information acquired by the sensors in your muscles, joints, and tendons. Imagine you are holding an electric toothbrush with it switched on. Kinesthetic perception gives you feedback on its size, weight, and position about your own body and conveys it to the brain to process.
Tactile refers to the information acquired through the sensors that are in your skin. The tactile perception would give the user feedback on the toothbrush’s surface texture, vibration, pressure, and temperature.
Types of Haptic feedback
Haptic feedback can be grouped into the following five categories.
- Vibrotactile feedback
- Force feedback
- Electro tactile feedback
- Ultrasound tactile feedback
- Thermal feedback
Vibrotactile feedback communicates with the user by using vibration to simulate the skin. Mobile phones or tablets vibrating when users interact with the touchscreen to imitate a physical button input is the most popular form of haptic vibrotactile feedback.
A vibration is either an oscillating, reciprocating, or other periodic motion of a rigid or elastic body displaced from a position or state of equilibrium.
Comparatively, the vibrotactile feedback system is simple, cheap, easily powered and controlled. It has been in use in many devices, for example, mobiles phones, steering wheels, game controllers, and smartwatches. It requires hardly any tracking parameters and has a small power consumption.
But the downside is that vibrating motors cannot stipulate the depth and diversity of sensations. It may be irritating as compared with other stimulators. Further vibration motors are difficult to miniaturize efficiently and could negatively affect ligaments and joints.
Motors are used in force feedback systems to manipulate the movement of an item held by the user. Force feedback is used in car video games and simulators, where the steering wheel is forced to turn on the user’s hands to replicate the forces encountered when cornering a vehicle.
Electro tactile feedback
Electro tactile feedback uses electrical current to stimulate the skin nerves via electrodes placed on the skin’s surface. It affects not only the receptors but also the nerve ending with electrical impulses. Electrical impulses can activate any sensation by sending a small pulse to the electrode with varying amplitude, frequency, and amperage.
This feedback has numerous forms depending on the intensity and frequency of the stimulus provided to the wearer’s skin. The sensation can also differ depending on the pulse voltage and current, waveform, electrode size, material, and skin type.
There are two types of electrostimulation systems in electro tactile. Viz: Transcutaneous Electrical Neural (or Nerve) Stimulation (TENS) and Electrical Muscle Stimulation (EMS). You can read the difference between the two here.
The main advantage of the electro tactile feedback system is that it has no mechanical or moving parts compared to a vibrotactile or force feedback system. Unlike other feedback systems, electro tactile can simulate a broad range of sensations. One more advantage of electro tactile feedback is that the electrodes can be assembled into any compact arrays and could be used to implement electro tactile displays.
Ultrasound tactile feedback
Ultrasound waves are used in this haptic feedback to send sensations through the air and directly onto the user’s hands. Users can interact with virtual objects, perceive or feel buttons without touching them and detect mid-air gestures. These ultrasound feedbacks are achieved by using one or multiple emitters.
The main benefit of ultrasound technology is that the user does not need to wear any accessories. But this type of haptic feedback is quite expensive as compared to vibrotactile or electro tactile haptic feedback.
Thermal feedback system
Thermal haptic feedback uses human skins sensitivity to communicate via various techniques and technologies. Specific sensory receptors called thermoreceptors found in the skin’s dermis are responsible for temperature sensitivity.
The warmth you feel inside when you are holding a warm cup of water is because of the thermoreceptors in your skin. If the temperature is around 40oC or above, nociceptors would come into play and send pain signals to your brain.
The main advantage of the Thermal haptic feedback system is that it has no mechanical or moving parts as compared to a vibrotactile or force feedback system. The biggest drawback of the thermal feedback system is its large power requirement, as it relies on energy transfer.
Haptic technology refers to techniques and technologies, which uses force, vibration, heat, or motion to imitate tactile sensations through various haptic actuators.
How does Haptic technology work?
A typical Haptic technology system is composed of a touch device with a capacitive button, processor, drive circuit and an actuator. The input of the haptic technology system might be a touch consisting of a capacitive button that serves as an input to a touch screen device, it detects touch pressure which is then sent to the processor in the form of a signal. The Onward processor generates a specific waveform according to the touch and finally, the actuator is there to create movements based on the waveform produced by the processor as illustrated in the figure down below.
Haptic actuator types
Other than the well-known small motors used in mobile phones, gaming controllers, and wearables, there are five main types of haptic technology actuators.
- Eccentric Rotating Mass (ERM)
- Linear Resonant Actuators (LRA)
- Piezo Haptic actuator
- Thermal haptic actuator
- Solenoid actuator
- Ultrasonic transducer or sensor