- An inertial measurement unit such as the ArduPilot “OilPan.” Usually has at least three accelerometers (measuring the gravity vector in the x,y and z dimensions) and two gyros (measuring rotation around the tilt and pitch axis). Neither are sufficient by themselves, since accelerometers are thrown off by movement (ie, they are “noisy” over short periods of time), while gyros drift over time. The data from both types of sensors must be combined in software to determine true aircraft attitude and movement to create an AHRS. One technique for doing this is the Kalman filter.
- An inertial measurement unit (IMU) is an electronic device that measures and reports a craft’s velocity, orientation, and gravitational forces, using a combination of accelerometers andgyroscopes, sometimes also magnetometers. IMUs are typically used to maneuver aircraft, including unmanned aerial vehicles (UAVs), among many others, and spacecraft, including satellitesand landers. Recent developments allow for the production of IMU-enabled GPS devices. An IMU allows a GPS receiver to work when GPS-signals are unavailable, such as in tunnels, inside buildings, or when electronic interference is present. A wireless IMU is known as a WIMU.
The IMU is the main component of inertial navigation systems used in aircraft, spacecraft, watercraft, and guided missiles among others. In this capacity, the data collected from the IMU’s sensors allows a computer to track a craft’s position, using a method known as dead reckoning.