Acceleration

A vector with a magnitude and direction in units of distance/time², expressed as m/s² or g.

Accelerometer

A sensor that measures the rate of change in velocity over time.

Attitude Heading Reference System

A system which estimates the body angles of a vehicle with respect to the local level coordinate system. Typically outputs Euler Angles or Quaternions.

Bandwidth

The frequency range over which the sensor will respond to an input with less than -3 dB attenuation.

Bias

The sensor signed output with no input present.

Bias - Accelerometer

The accelerometer output with no input acceleration present. Bias is a signed quantity usually expressed in units of acceleration.

Bias - Gyroscope

The gyroscope output with no input angular rate present. Bias is a signed quantity usually expressed in units of °/s.

Cross-Axis Sensitivity

The maximum sensitivity in the plane perpendicular to the measuring direction relative to the sensitivity in the measuring direction.

Dynamic Range

The maximum positive and negative input that can be measured without clipping or distortion.

Gauss

The centimeter-gram-second unit of magnetic flux density, equivalent to 10^–4 tesla.

Gravity (g)

The force of attraction between all masses in the universe. The Earth's average gravitational force is 9.81 m/s²

Gyroscopes

A sensor that measures the rate of angular change over time.

I²C - Inter-Integrated Circuit

Multi master communication bus that enables communications between ic processors and ic peripherals. More Information

Inertial Measurement Unit

A device that measures linear and angular motion in 3 dimensions without external reference. May include triaxial magnetometers and provice analog or digital outputs. Note: The performance of the inertial measurement unit is highly dependant on the sensors it employs for angular rate and acceleration measurement.

Inertial Navigation System

A system that estimates the vehicle’s position, attitude, and velocity as a function of time in the specified navigation frame using the outputs of an IMU, a reference clock, and a model of the gravitational field. System initialization is required and consists of providing the position, either providing the linear velocity or the information that the system is stationary on the earth, and determining the attitude by gyrocompass alignment or transfer alignment. Usually includes a GPS.

Magnetometer

An instrument that measures the magnitude and direction of a magnetic field.

Noise - Accelerometer

Uncorrelated random deviation in the accelerometer output signal over a specified bandwidth that is typically expressed as an RMS or 1 sigma value in g or mg.

Noise - Gyroscope

Uncorrelated random deviations in the gyroscope output signal that are typically expressed as an RMS or 1 sigma value in deg/s.

Noise Density - Accelerometer

The accelerometer noise power spectral density expressed in ug/Hz^1/2 or mg/Hz^1/2. Conversion to 1 sigma noise is completed by multiplying by the root of the bandwidth.

Noise Density - Gyroscope

The gyroscope noise power spectral density expressed in °/s/Hz^1/2. Conversion to 1 sigma noise is completed by multiplying by the root of the bandwidth.

Non-linearity

The maximum deviation of output voltage from a best fit straight line, which is divided by the sensitivity of the device and expressed as a percentage of Full-Scale Output.

RS422

A balanced differential communication protocol used to transmit and recieve information between electronic equipment. More Information

Repeatability

The closeness of agreement among measurements of the same variable, repeated under the same conditions when operation is interrupted between the measurements. Also referred to as Bias Repeatability

Scale Factor

The ratio of the change in output to a unit change of the input.

Scale Factor - Accelerometer

The ratio of the change in output to a unit change of the input thus given in mV/g, V/g or bits/g.

Scale Factor - Gyroscope

The ratio of the change in output to a unit change of the input given in mV/°/s, V/°/s or bits/°/s.

Triaxial

A coordinate reference system having 3 orthogonal axis with each having a positive and negative direction.

UAS - Unmanned Aircraft System

Term used and adopted by the United States DoD to replace all terms used to describe aircraft without aircrew onboard.