Mechanical Development and Preliminary Control Results of a Cable-Driven Robotic Platform for Whole-Body Rehabilitation.

To promote whole-body rehabilitation in the early post-injury phase, a system is desirable to provide user transfer, automatic posture change and therapy for various arm-leg movements. This work aimed to present a cable-driven robotic platform that can provide whole-body rehabilitation for the user in a lying position and to demonstrate preliminary results for generation of 3D leg movements. Seventeen compact cable-driven actuators (CDAs) were designed and mounted on a robotic frame. One CDA is the drive for a lift mechanism, while the other 16 CDAs work jointly to change the user's posture and to produce arm-leg movement therapy. The kinematics for production of two representative leg movements were analysed. Using PID and impedance algorithms, a CDA alone provided user-defined resistive training with position guidance (force error: $\mathbf{3. 5 ~ N}$ and position error: $\mathbf{2 1. 4 ~ m m}$). Preliminary control of six CDAs demonstrated the system's ability to produce a 3D leg movement in a back-lying position (mean force error: 12.8 N, mean position error: $\mathbf{5 2. 1 ~ m m}$) and a walking-like leg movement in a side-lying position (mean force error: $\mathbf{1 3. 7 ~ N}$, mean position error: $\mathbf{5 7. 0 ~ m m}$). Through concept description, prototype development, and preliminary control testing, the study showed that the proposed cable-driven robotic platform could potentially offer convenient user transfer, automatic posture change and synchronised 3D arm-leg movement therapy. Future work will present kinetic analysis and control strategies for automatic posture change and arm movement assistance.