Inertial measurement unit in the context of "Spatial computing"

A head-mounted display (HMD) is a display device, worn on the head or as part of a helmet (see helmet-mounted display for aviation applications), that has a small display optic in front of one (monocular HMD) or each eye (binocular HMD). HMDs have many uses including gaming, aviation, engineering, and medicine.

Virtual reality headsets are a type of HMD that track 3D position and rotation to provide a virtual environment to the user. 3DOF VR headsets typically use an IMU for tracking. 6DOF VR headsets typically use sensor fusion from multiple data sources including at least one IMU.

An aeroshell is a rigid heat-shielded shell that helps decelerate and protects a spacecraft vehicle from pressure, heat, and possible debris created by drag during atmospheric entry. Its main components consist of a heat shield (the forebody) and a back shell. The heat shield absorbs heat caused by air compression in front of the spacecraft during its atmospheric entry. The back shell carries the load being delivered, along with important components such as a parachute, rocket engines, and monitoring electronics like an inertial measurement unit that monitors the orientation of the shell during parachute-slowed descent.

Its purpose is used during the EDL, or Entry, Descent, and Landing, process of a spacecraft's flight. First, the aeroshell decelerates the spacecraft as it penetrates the planet's atmosphere and must necessarily dissipate the kinetic energy of the very high orbital speed. The heat shield absorbs some of this energy while much is also dissipated into the atmospheric gasses, mostly by radiation. During the latter stages of descent, a parachute is typically deployed and any heat shield is detached. Rockets may be located at the back shell to assist in control or to retropropulsively slow descent. Airbags may also be inflated to cushion impact with the ground, in which case the spacecraft could bounce on the planet's surface after the first impact. In many cases, communication throughout the process is relayed or recorded for subsequent transfer.

A guidance system is a virtual or physical device, or a group of devices implementing or controlling the movement of a ship, aircraft, missile, rocket, satellite, or any other moving object. Guidance is the process of calculating the changes in position, velocity, altitude, and/or rotation rates of a moving object required to follow a certain trajectory and/or altitude profile based on information about the object's state of motion.

A guidance system is usually part of a Guidance, navigation and control system, whereas navigation refers to the systems necessary to calculate the current position and orientation based on sensor data like those from compasses, GPS receivers, Loran-C, star trackers, inertial measurement units, altimeters, etc. The output of the navigation system, the navigation solution, is an input for the guidance system, among others like the environmental conditions (wind, water, temperature, etc.) and the vehicle's characteristics (i.e. mass, control system availability, control systems correlation to vector change, etc.). In general, the guidance system computes the instructions for the control system, which comprises the object's actuators (e.g., thrusters, reaction wheels, body flaps, etc.), which are able to manipulate the path and orientation of the object without direct or continuous human control.

An attitude and heading reference system (AHRS) consists of sensors on three axes that provide attitude information for aircraft, including roll, pitch, and yaw. These are sometimes referred to as MARG (Magnetic, Angular Rate, and Gravity) sensors and consist of either solid-state or microelectromechanical systems (MEMS) gyroscopes, accelerometers and magnetometers. They are designed to replace traditional mechanical gyroscopic flight instruments.

The main difference between an Inertial measurement unit (IMU) and an AHRS is the addition of an on-board processing system in an AHRS, which provides attitude and heading information. This is in contrast to an IMU, which delivers sensor data to an additional device that computes attitude and heading. With sensor fusion, drift from the gyroscopes integration is compensated for by reference vectors, namely gravity, and the Earth's magnetic field. This results in a drift-free orientation, making an AHRS a more cost effective solution than conventional high-grade IMUs that only integrate gyroscopes and rely on a high bias stability of the gyroscopes.In addition to attitude determination an AHRS may also form part of an inertial navigation system.

An inertial platform, also known as a gyroscopic platform or stabilized platform, is a system using gyroscopes to maintain a platform in a fixed orientation in space despite the movement of the vehicle that it is attached to. These can then be used to stabilize gunsights in tanks, anti-aircraft artillery on ships, and as the basis for older mechanically based inertial navigation systems (see Inertial measurement unit).