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An accelerometer measures proper acceleration, which is the acceleration it experiences relative to freefall and is the acceleration felt by people and objects. [2] Put another way, at any point in spacetime the equivalence principle guarantees the existence of a local inertial frame, and an accelerometer measures the acceleration relative to that frame. [4]
A piezoelectric accelerometer is an accelerometer that employs the piezoelectric effect of certain materials to measure dynamic changes in mechanical variables (e.g., acceleration, vibration, and mechanical shock). As with all transducers, piezoelectrics convert one form of energy into another and provide an electrical signal in response to a ...
Inertial measurement unit. An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the orientation of the body, using a combination of accelerometers, gyroscopes, and sometimes magnetometers. When the magnetometer is included, IMUs are referred to as IMMUs.
Allan variance is defined as one half of the time average of the squares of the differences between successive readings of the frequency deviation sampled over the sampling period. The Allan variance depends on the time period used between samples, therefore, it is a function of the sample period, commonly denoted as τ, likewise the ...
An accelerograph can be referred to as a strong-motion instrument or seismograph, or simply an earthquake accelerometer.They are usually constructed as a self-contained box, which previously included a paper or film recorder [1] (an analogue instrument) but now they often record directly on digital media and then the data is transmitted via the Internet.
Three-Axis Acceleration Switch. The three-axis acceleration switch is a micromachined microelectromechanical systems (MEMS) sensor that detects whether an acceleration event has exceeded a predefined threshold. [1] It is a small, compact device, only 5mm by 5mm, and measures acceleration in the x, y, and z axes. [2] It was developed by the Army ...
An inertial navigation system (INS; also inertial guidance system, inertial instrument) is a navigation device that uses motion sensors (accelerometers), rotation sensors (gyroscopes) and a computer to continuously calculate by dead reckoning the position, the orientation, and the velocity (direction and speed of movement) of a moving object ...
It works by using the accelerometer in the watch, which detects small movements at the wrist that could be signs of interruptions to normal respiratory patterns during sleep, Apple explains in the ...