Appraise and analysis of dynamical stability of cable-driven lower limb rehabilitation training robot

This paper presents a problem that traditional methods cannot evaluate the dynamical stability of the under-constraint cable-driven lower limb rehabilitation training robot (CLLRTR). An analytical method is presented to evaluate the dynamical stability of CLLRTR. Firstly, position performance factor, posture performance factor and cable tension performance factor are defined based on the kinematics and dynamics of CLLRTR. An appraisal index and method of the dynamical stability for CLLRTR with the hybrid force-position-pose approach is proposed by using the weighted average method among three performance factors. Secondly, the stable workspace and robustness workspace with the external forces are defined according to the stability margin. Finally, the simulation analysis and the experimental study are used to illustrate the distribution of the dynamical stability in the whole workspace of CLLRTR. The results show that the experimental results are the same as the theoretical simulation analysis results. So the appraisal index of the dynamical stability can be used to evaluate the dynamical stability of CLLRTR. It will provide a foundation for the trajectory planning and control strategy of CLLRTR training pattern.