An Approach to Consider Upper Limb Kinematics for the Improvement of Motion Control in a Two Arm Robotic Rehabilitation System

REHAROB is a robotic system for upper limb physiotherapy including two co-operating robotic arms. The original version of the system included two independent standalone outer-loop force controllers of the two robotic arms. During the manual walk-through programming of the robotic system it was entirely the task of the physiotherapist to consider the human anatomic movements of the upper limb, and ensure the synchronized movement of the two robotic arms. Among other tasks the operator had to contribute actively to overcoming the instabilities caused by the interference of the two separated controls. The authors have modified and upgraded the motion controller of REHAROB to administer the kinematical constraints of the human arm, to which the two robots are connected. This paper presents the new co-operative control method of REHAROB. The method requires no additional sensors or extensive calibration process. The new control concept was implemented and clinically tested. The approach is general and can be extended to any multiple arm lower or upper limb robotic exercising device.