Design and Testing of a Low-Cost MEMS IMU Cluster for SmallSat Applications

Small satellite missions are characterized by tight constraints on cost, mass, power, and volume that generally make them unable to fly inertial measurement units (IMUs) required for orbital missions demanding precise orientation and positioning. Instead, small satellite missions typically fly low-cost micro-electro-mechanical system (MEMS) IMUs. The performance characteristics of MEMS IMUs make them ineffectual in many spaceflight applications when employed in a single IMU system configuration. The challenge for small satellite designs aiming to tackle more aggressive missions is to creatively employ advanced software algorithms coupled with embedded system architectures to create an effective precision IMU from clusters of low-cost MEMS IMUs. The objective of this work is to develop and demonstrate a MEMS IMU cluster whose composite output provides high performance while remaining within the mass, power, and volume constraints of a 1U CubeSat. Successfully achieving this objective will represent a new class of inertial navigation performance for the small satellite platform. We investigate the practical issues associated with implementing an IMU cluster in a form factor suitable for use on a 1U CubeSat. The results show that in general, simple averaging of the sensor outputs approaches the predicted square root of N improvement in performance for the RMS noise and bias stability of the sensors. However, some sensors exhibited lower performance improvements than other sensors, indicating a higher correlation between individual sensors.