The Basics of MEMS IMU/Gyroscope Alignment

Sensor misalignment is often a key consideration for high performance motion control systems that use MEMS inertial measurement units (IMUs) in their feedback loops. For the gyroscopes in the IMU, sensor misalignment describes the angular difference between each gyroscope’s axis of rotation and the system defined inertial reference frame, also known as the global frame. Managing the impact that misalignment has on sensor accuracy can require unique packaging, special assembly processes, or even complex inertial testing in the final configuration. All of these things can have a major impact on important project management metrics such as schedule, investment, and the total cost associated with the IMU in each system. Therefore, sensor alignment is a metric that warrants consideration during early stages of the design cycle, while there is time to define the system architecture around the most efficient solution. After all, nobody wants to burn through 80% of their project schedule and budget to find out that their inexpensive sensor requires hundreds, maybe even thousands, of dollars in unexpected cost adders to meet nonnegotiable deliverables to their end users. Ouch!