# Piezo Haptics Lexicon

Learn the technical vocabulary behind haptic technologies.

Don't hesitate to use the keyword search bar below.

• ### Acceleration

Acceleration is the rate of change of the velocity of an object with respect to time.

Normally measured in meter/second2, haptics acceleration is measured with the g-force. 1 G equals the gravitational acceleration on Earth (9.8 m/s2).

 https://en.wikipedia.org/wiki/Acceleration

• ### Actuator

An actuator is a component of a machine that is responsible for moving and controlling a mechanism or system.

In haptics, the actuator is the component that creates and controls the vibration. It is normally composed of a mass and an engine to accelerate the mass.

 https://en.wikipedia.org/wiki/Actuator

• ### Bandwidth

Bandwidth is the difference between the upper and lower frequencies in a continuous band of frequencies. It is typically measured in hertz.

In haptics bandwidth represents the lower and upper end of frequencies were the actuator can generate the best tactile feedback quality.

• ### Damping

Damping is an influence within or upon an oscillatory system that has the effect of reducing, restricting or preventing its oscillations. In physical systems, damping is produced by processes that dissipate the energy stored in the oscillation.

The damping ratio is a dimensionless measure describing how oscillations in a system decay after a disturbance. Many systems exhibit oscillatory behavior when they are disturbed from their position of static equilibrium. A mass suspended from a spring, for example, might, if pulled and released, bounce up and down. On each bounce, the system tends to return to its equilibrium position, but overshoots it. The damping ratio is a measure describing how rapidly the oscillations decay from one bounce to the next.

 https://en.wikipedia.org/wiki/Damping_ratio

• ### Driver

In electronics, a driver is a circuit or component used to control another circuit or component.

They are usually used to regulate current flowing through a circuit or to control other factors such as other components, some devices in the circuit. An amplifier is considered a driver for piezo haptic actuators.

 https://en.wikipedia.org/wiki/Driver_circuit

• ### Eccentric Rotating Mass (ERM)

Haptic actuator based on unbalanced mass rotation. The eccentric mass is bonded to a shaft that is rotated by a DC motor.

• ### Engine

An engine or motor is a machine designed to convert one form of energy into mechanical energy.

 https://en.wikipedia.org/wiki/Engine

• ### Fall time

Time taken for the amplitude of a pulse to decrease (fall) from a specified value.

https://en.wikipedia.org/wiki/Fall_time

• ### Force

A force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and represented by the symbol F.

 https://en.wikipedia.org/wiki/Force

• ### Frequency

Frequency is the number of occurrences of a repeating event per unit of time.

In haptics, frequency represent the occurrences of voltage cycles in a second and is calculated in Hertz (Hz)

 https://en.wikipedia.org/wiki/Frequency

• ### Haptic

The word haptic, from greek ἁπτικός (haptikos), means “relating to the sense of touch” and comes from the Greek verb ἅπτεσθαι (haptesthai) which means “to touch.”

Touch is a powerful sense. In technology, haptic feedback is a way to transmit different information with vibrations, impulses or movements. This information can be added to smartphones, game controllers and every device using user interface.

Nowadays, high definition haptic feedback can create textures and transmit detailed information to the user. Thanks to our piezoelectric driver technology, system integrators can simultaneously implement high definition haptic feedback and reduce power consumption compared to other advanced technologies.

• ### Linear Resonant Actuator (LRA)

Haptic actuator based on a magnetic mass moved at its natural resonance with a voice coil.

• ### Mass

Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied.

The basic SI unit of mass is the kilogram (kg).

 https://en.wikipedia.org/wiki/Mass

• ### Piezoelectric Actuator

Haptic actuator based on the piezoelectric effect.

• ### Piezoelectric Effect

Piezoelectricity is the electric charge that accumulates in certain solid materials in response to applied mechanical stress. The word piezoelectricity means electricity resulting from pressure and latent heat

The piezoelectric effect results from the linear electromechanical interaction between the mechanical and electrical states in crystalline materials with no inversion symmetry. The piezoelectric effect is a reversible process: materials exhibiting the piezoelectric effect also exhibit the reverse piezoelectric effect, the internal generation of a mechanical strain resulting from an applied electrical field.

 https://en.wikipedia.org/wiki/Piezoelectricity

• ### Resonance

Resonance describes the phenomena of amplification that occurs when the frequency of a periodically applied force is in harmonic proportion to a natural frequency of the system on which it acts. When an oscillating force is applied at a resonant frequency of a dynamical system, the system will oscillate at a higher amplitude than when the same force is applied at other, non-resonant frequencies.

Frequencies at which the response amplitude is a relative maximum are also known as resonant frequencies or resonance frequencies of the system. Small periodic forces that are near a resonant frequency of the system have the ability to produce large amplitude oscillations in the system due to the storage of vibrational energy.

 https://en.wikipedia.org/wiki/Resonance

• ### Rise time

Rise time is an analog parameter of fundamental importance in high speed electronics, since it is a measure of the ability of a circuit to respond to fast input signals.

In haptics, rise time is the time an actuator takes to reach full amplitude from its inertial state.

In haptics, fall time refers to the time the actuator takes to reach its inertial state from its full amplitude.

 https://en.wikipedia.org/wiki/Rise_time

• ### Waveform

The waveform of a signal is the shape of its graph as a function of time, independent of its time and magnitude scales and of any displacement in time. In electronics, the term is usually applied to periodically varying voltages, currents, or electromagnetic fields.

In piezo haptics, the waveform is a graphical representation of voltage variation applied to the actuator as a function of time.

 https://en.wikipedia.org/wiki/Waveform