Position Tracking of a Passive Rehabilitation Robot

This paper presents a position tracking system for real-time position estimation of a passive rehabilitation robot. The table-top robot shall be used for upper limb rehabilitation by stroke patients. Accurate estimates of the robot's position are determined by fusing data from two sensors: a laser optical sensor and a webcam. The laser optical sensor is mounted underneath the robot and tracks the motion of the robot relative to the surface on which the robot is used. The webcam is positioned above the robot and mounted on a stand fixed to the surface. The webcam detects the robot's motion relative to a fixed absolute coordinate system and supplies data at a lower frequency than the optical sensor. A data fusion scheme is implemented and validated in experiments where markers are moving along circular and pentagram trajectories. After the fusion is completed, a Kalman filter is implemented to investigate if it can improve the accuracy of the fusion tracking system. The results demonstrate that the developed fusion position tracking system can reliably track the robot’s position with greater accuracy than would be possible with the webcam or the optical sensor tracking systems on their own.