Glossary

Alphabetical list of terms used within the MotionStack documentation.

Accuracy

The maximum amount of offset an estimated value is from a target value. Low accuracy is generally the cause of lag when the estimated value is visualized.

Bias

The difference between the estimated value and the actual value, given a particular set of conditions. Under stationary conditions, sensor bias is the offset from zero.

Inertial Navigation System (INS)

A combination of IMU sensors and a co-processing unit, used to report position and direction data for navigation. The IMUs may or may not be MEMS sensors.

Linear Acceleration

The rate of change of velocity of a moving object with respect to time.

Dynamic Linear Acceleration is linear acceleration due to the force of physical displacement of the measurement unit.

Static Linear Acceleration is linear acceleration due to the force of gravity on the measurement unit.

Micro-Electro-Mechanical Systems (MEMS)

Miniature mechanical devices and structures built using micro-fabrication techniques. They are generally used to measure dynamic and electromagnetic forces. Examples are the accelerometer, gyroscope, and magnetometer. MEMS sensor is a miniaturized Inertial Measurement Unit (IMU).

Precision

The amount of variance in the offset an estimated value is from a target value. Low precision is generally the cause of jitter when the estimated value is visualized. Higher precision gives more reproducible measurements.

Sensitivity

The ratio of change in input to change in output. There are two ways to measure sensitivity.

  1. The amount of change in the input parameter needed to produce a standard change in the output parameter.
  2. The amount of change in the output parameter as a result of a given amount of change in the input parameter.