Joint Angular Sensor Based on Distributed Biaxial MEMS Accelerometers

This paper presents the analysis for joint angle measurement on rigid body that is based on distributed biaxial MEMS accelerometers. It focuses on two methods, one called CMR and another DCMR, and utilizes the property of rigid body kinematics to explain their advantages and weaknesses. Unlike CMR method, DCMR method has no requirement on placing the sensors close to the joint center. This provides greater flexibility for the sensor installation. On the basis of the error model of CMR method, we give an analysis outlining the advantage of theoretically error-free DCMR method. The sensor calibration and alignment is described and both methods are characterized on a rigid body robot arm model. The experiment shows the angular error up to 0.4 rad from CMR method whereas just 0.03 rad from DCMR method. The noise level from both methods is also compared and analyzed The result reveals a larger but tunable noise for DCMR method.