Realization of a 9-axis inertial measurement unit toward robotic applications

We report on the integration of a 9-axis IMU with a 2-axis inclinometer which yields precise body orientation with respect to the gravity. Thus, a pre-treatment of gravity compensation for accelerometers of the previously-developed 9-axis IMU can be done correctly in real-time. The integrated system is capable of delivering desired linear acceleration, angular acceleration, and angular velocity states in normal gravitational environment. In addition, the system also releases the requirement of accelerometer installation at the center of mass as in the traditional IMU, and it derives the angular acceleration via simple matrix operation. Thus, the proposed system can potentially be utilized in the legged robots where the COM moves due to motion of the limbs.