This paper presents a 3-DOF compact rehabilitation
robot, involving mechanical structure design, control system
design and gravity compensation analysis. The robot can simultaneously provide assistance for pronation/supination(P/S),
flexion/extension(F/E) and adduction/abduction(A/A) joints rehabilitation training. The P/S and F/E joints are designed to
be driven by cable transmission to gain a high backdrivability,
and an adjustment plate is adopted to decrease the distance
between the rotation axis of F/E joint of the human wrist and the
robot. In addition, gravity compensation is considered to offset
the impact of self-gravity on the performance of the controller. A
“moving window” control strategy based on impedance control is
proposed and implemented on the robot. A comparison between
the “moving window” control and classical impedance control
indicates that the former has more potential to stimulate the
voluntary efforts of the participant, and has a less limitation
moving in a fixed reference trajectory. Meanwhile, the results
also validate the feasibility and safety of the wrist robot system.