Calibration platform for wearable 3D motion sensors

Abstract

With the development of microelectromechanical system technologies, wearable motion sensors (WMSs) have played an increasingly significant role in the design of exoskeletons, where the WMSs are used for motion detection, orientation estimation, or position estimation. For these applications, the accuracy of the WMSs will affect the overall performance of the exoskeletons. The purpose of this chapter is to present an evaluation platform for assessing the accuracy of WMSs, assisting to develop or choose proper WMSs for exoskeletons. The presented evaluation platform is an instrumented gimbal with three rotation axes. Each axis is equipped with a DC motor and an absolute encoder. Thus, each axis can be controlled independently, and the rotation angle around each axis can be output accurately. In addition, each axis can rotate continuously via the equipped electrical slip rings. One of the major advantages of the instrumented gimbal is that it can be used for accurate motion analysis without needing any additional equipment. In order to verify the function of the platform, validation experiments were conducted, including a static accuracy test, and dynamic accuracy test with and without magnetic disturbances. Results show that the designed gimbal has good potential for evaluating the orientation of WMSs under different conditions.