Force control for an astronaut rehabilitative training robot in bench press mode

An Astronaut Rehabilitative Training Robot (ART) was developed to mitigate the effects of space adaptation syndrome (SAS), strengthen the upper limbs of astronauts, and help the astronauts to do bench press in a microgravity environment. In order to design the force controller of the cable-driven unit, the dynamic model of the cable-driven unit was built and the veracity of the model was verified through model identification which used the hardware-in-Ioop simulation tool based on dSPACE and the MATLAB-ident toolbox. A hybrid force controller was designed in order to improve the control precision and response speed of the cable-driven unit, and a compensation segment was designed based on the structure invariance principle to reduce the surplus force. The simulation results show that the hybrid force controller effectively improves the control precision and response speed of the cable-driven unit; the compensation segment reduces the surplus force significantly, and improves the loading precision as well.