The Roles of CPG Phase Modulation and Reflexive Muscular Patterns in Balance Recovery Reflexive Responses to Perturbation during Walking - A Simulation Study

Most walking assist systems reported are not ready for using in real-world environment, where there are frequent perturbations resulted from slips, uneven terrain, slopes and obstacles. Our ultimate goal is to realize artificial reflexes to real-world walking support systems for those paralyzed people. This goal needs both qualitative and quantitative understanding of human reflexive mechanism. Our approach includes 1. acquiring muscle activity profiles during normal walking and slip-perturbed walking by recording and processing electromyographic (EMG) of several walking-related muscles, in a human gait experiment; 2. developing a central-pattern-generator (CPG) based neuro-musculo-skeletal simulation model; 3. using muscle activity profiles of reflexive muscle responses together with a CPG-phase-modulation mechanism, to construct a rapid responding pathway, and investigating the effects of the pathway on the simulated walker, as well as verifying several hypotheses on the underlying neuro- mechanism. Experiments were performed in a walking simulation model to investigate the roles of the two functional aspects. Results showed that, 1. CPG phase modulation alone could also improve the perturbation resistance on the occurrence of a comparatively small slip perturbation, by interacting with a pre-wired sensory- feedback mechanism; 2. on the occurrence of a big slip- perturbation, together with the CPG phase modulation, the rapid muscular responses could improve the perturbation- resistance and maintain balance for the simulated walker.