Design of Adaptive Sensor Coupling-based Upper Limb 7-DOF Exoskeleton for Smooth Human Motion Tracking: ASC-EXO

Abstract

The conventional sensor coupling of the sensor in an exoskeleton robot suffers from inaccurate human motion tracking due to irregular inertial loading on the sensor axis. It may cause sensor axis misalignment, performance degradation and damage the sensor permanently, especially in the multiple degrees of freedom (DOF) exoskeleton robot. In this paper, we proposed a novel design of an adaptive sensor coupling-based 7-DOF exoskeleton (ASC-EXO) for motion tracking and tele-manipulation. The adaptive sensor coupling mechanism has been designed based on the flexure structure cantilever with a slew ring, which suppresses irregular inertial loading on the sensor and is stiff enough along the sensor rotation in the z-axis and compliant on the other axes. The slew ring allows smooth joint rotation. Further, the sensor values are improved by a Butterworth filter. As a result, the adaptive sensor coupling suppressed the sensor noise 20 times more than the conventionally coupled sensor with the robot joint. Finally, we developed a prototype of the 7-DOF exoskeleton (ASC-EXO) using adaptive sensor coupling for smooth human motion tracking. The performance evaluation of adaptive sensor coupling and human motion tracking is presented. In addition, we demonstrated smooth control of the slave robot (KUKA) using the exoskeleton (ASC-EXO) as a master device.