Fig. 1: Proposed power-free knee rehabilitation robot, realization and comparison.

a Existing hospital-based rehabilitation devices. These devices are bulky and need additional power supplies. b Proposed home-based isokinetic training robot. The proposed isokinetic training robot is power-free and highly integrated. c Explosion Assembly. During the training, the rotation center of the knee joint and the motor are concentric. d Isokinetic realization and energy regeneration. The isokinetic training robot can generate energy while training. A desired constant velocity is predetermined. The velocity is monitored via angle sensors and the motor output resistance is modulated to ensure the actual velocity closely approximates the predetermined desired velocity. The controlled resistance is adjusted and the negative mechanical work during training is harvested. The harvested energy is subsequently channeled to power the control circuit, sensors, and other usage. e Comparison. A comparison between commercial isokinetic training robots and our proposed isokinetic training robot. The consumed power and weight of our robot are both dramatically reduced. f CONSORT diagrams of subjects.