Reha-maus: A novel robot for upper limb rehabilitation

This paper presents a novel robot-aided rehabilitation system for upper limbs. The overall concept, the robotic system, and the position control strategy are described. An initial indication of its performance is provided. A Figure shows a prospective application scenario of the Reha-Maus. The lower right arm of a patient is pivoted on the moving robotic platform. Human-device interaction forces are measured by a force sensor underneath the arm support. Arbitrary motion, i.e. planar robot translation and rotation, on the application surface is facilitated by three assembled omni-wheels. Their design allows for low-friction rolling perpendicular to the attached motor shaft. Each omni-wheel is driven by a DC motor with gear and encoder. Furthermore, separate external power electronics provide analogue current controllers for each motor. A compact, yet powerful device design is achieved by mounting the high-performance drives along the edges of an equilateral triangle. The configuration is capable of producing a pre-determined range of force (0 - 55 N) and velocity (translational 0 - 0.6 m/s, rotational 0 - 9 rad/s). The robot weighs 2.8 kg and has a diameter of 300 mm. At this stage of development, absolute position information is gathered by an infrared camera. A real time Linux-based computer interface allows for the use of advanced control algorithms that have been implemented using Scilab/Scicos and the HART toolbox.