IMUs play a crucial role in vehicles ranging from motorcycles to spacecraft. They serve as attitude and heading reference systems for UAVs as well as augmenting GPS reliability in challenging environments like tunnels or areas containing electronic interference.
Establish static IMU sensor calibration to account for any manufacturer biases or misalignments, then proceed with dynamic calibration using controlled movements to test how well sensors follow the device over time.
Inertial Measurement Unit (IMU)
An IMU (Inertial Measurement Unit) sensor tracks an object’s acceleration and angular velocity over time. IMUs also often track Earth’s magnetic field strength and air pressure for time series data that can be utilized for various applications.
IMUs are becoming more prevalent due to advances in sensors, miniaturization and reduced power consumption. Strict safety requirements imposed upon industries like automotive and aviation necessitate high-precision IMUs for safe operations.
IMUs must be calibrated using specialized equipment and temperature-calibrated to maintain accuracy. The calibration process requires the sensor to undergo various test forces and environmental conditions in order to test its response in certain operating conditions, something critical for UAV inertial navigation systems that rely on accurate sensors to operate reliably. IMUs can be divided into performance classes based on their in-run bias stability specifications; tactical- and industrial-grade IMUs offer lower bias stability which are better suited for demanding applications like UAV navigation; placement should avoid dynamic magnetic interference sources like high current wiring, servos or solenoids to ensure optimal results.
IMU Applications
IMU sensors provide real-time information on linear acceleration and angular rate that is essential to flight control systems and autopilots, including Attitude and Heading Reference Systems (AHRS), which provide real-time roll, pitch, yaw heading information as well as Inertial Navigation Systems (INS) which determine velocity and position.
There can be some challenges associated with IMUs, including drift and susceptibility to external noise such as vibrations, electromagnetic interference and temperature fluctuations. To address these concerns, they must be periodically calibrated in order to maintain accuracy and reliability during extended use periods.
Industrial and tactical-grade MEMS IMUs offer an ideal balance of performance, SWaP and cost for unmanned system applications. MEMS technology’s small size, low power consumption and temperature stability makes these ideal sensors for drone applications which require sensor fusion such as attitude, altitude and GPS data fusion, with rates being used later for camera stabilization purposes.
IMU Technology
An IMU uses accelerometers and gyroscopes to measure linear acceleration and rotational rate respectively, with some IMUs offering heading reference magnetometers – making them nine-axis systems.
Integral to aircraft and spacecraft, IMUs provide real-time data on attitude and angular velocity of vehicles for use by navigation and autopilot systems as well as radar/targeting systems. They play an essential role in maintaining precise orientation during maneuvers on military vehicles or missiles.
Although IMUs can be highly versatile tools, they may still be susceptible to various sources of noise that impede their accuracy, including vibrations, electromagnetic interference and temperature fluctuations. As a result, these factors require them to be calibrated periodically – an effort which requires special equipment and expertise – and could even cause drift over time that could compromise precision and reliability of measurements unless addressed via post-installation calibration.
IMU Development
IMUs provide raw measurements such as angular rates and linear accelerations that can be fed into Inertial Navigation Systems (INSs), which use them to compute relative position and orientation. Simpler versions called Attitude and Heading Reference Systems can also be used to guide Unmanned Air Vehicles (UAVs), drones, vehicles, missiles, ships or satellites.
IMUs may experience drift over time, necessitating regular calibration in order to maintain accuracy. Furthermore, environmental factors like vibrations, electromagnetic interference and temperature can add noise into their data output and require complex signal processing algorithms to filter them out – further increasing complexity during IMU development.
Quartz MEMS tactical-grade IMUs provide the ideal balance of performance, SWaP and cost for UAV applications. Their one-piece inertial sensing element features a precisely vibrating crystal that converts angular rate into DC signals; unlike RLG and FOG technologies they have exceptional temperature stability as well as shock and vibration resistance making them the ideal choice for UAV platforms.