Subject-specific compliance control of an upper-limb bilateral robotic system

This paper proposes a new compliance control strategy on a robot-assisted bilateral upper limb rehabilitation system. The robotic compliance regulation was achieved by modifying predefined training trajectories in real time, based on measured human–robot interaction force and human users’ position within subject-specific workspace. Experimental data were collected from healthy subjects, and indicate that human users can follow predefined training trajectories well under real-time compliance variation, with the maximum normalized root mean square error (NRMSE) value no greater than 1.44%. Preliminary findings are encouraging, which demonstrates the availability of the proposed subject-specific compliance adaptation strategy, and the potential with enhanced training safety and efficacy. Future work will consider conducting a direct comparison between a bilateral upper limb rehabilitation device (BULReD)-assisted compliance training with or without subject-specific adaptation on a large sample of participants with upper limb disabilities.