A miniature, low-cost MEMS AHRS with application to posture control of robotic fish

Inertial sensing is of paramount importance for a wide variety of navigation, guidance and control tasks. Historically, application of inertial sensing was limited to high-performance, high-cost aerospace and military fields. Recent MEMS technology has enabled miniaturization, mass production, and cost reduction of inertial sensors. This paper presents the development and robotic application of a miniature, low-cost AHRS unit based on MEMS technology. The sensor suite includes a tri-axis gyroscope, a tri-axis accelerometer and a tri-axis magnetometer. Fusion of the sensor measurements is achieved with a quaternion-based EKF algorithm. The performance of the AHRS unit is evaluated with a rotating platform and the results suggest numerous application possibilities. As an application case, the AHRS unit is employed for posture measurement of a robotic fish. By adjusting the lift forces produced by pectoral fins on both sides, the robotic fish can maintain desired posture during highspeed swimming.