Abstract
Most walking assist systems reported are not available for real world environments where frequent perturbations are caused by slips, uneven terrain, slopes and obstacles. It is evident that humans are able to cope with such perturbations with reflexes that cause unconscious, relatively fixed muscular response patterns to perturbations within a short period of time. In our previous study, we showed that artificial reflexes could improve the perturbation resistance for simulated walkers, though the roles of different reflexive mechanisms were not quantitatively clarified. In this study, we focused on the different roles of reflexive muscle responses and the CPG phase modulation mechanism. By proposing and evaluating two stability criteria through a series of simulation experiments, we revealed different roles for two mechanisms in the simulated walkers. These will not only further increase the possibility of realising artificial reflexes for paralysed individuals, but also bring new insights into the field of motor control.
Highlights
Walking assist systems, such as robotic systems (Kawamoto et al 2003) and functional electrical stimulation (FES) for hemiplegic walking (Bajd et al 1997; Tong and Granat 1998; Yu et al 2002) have been widely studied for the purpose of improving daily living for paralysed individuals
The results indicated that the simulation model could display behaviour resembling that of normal human walking, and, on the occurrence of a slip perturbation, together with the central pattern generator (CPG) phase modulation, the rapid muscular response could improve perturbation resistance and maintain balance for the simulated walker
We first compare the gaits of perturbed walking of the Normal Walker and the Reflexive Walker to reveal the roles of different functional mechanisms, i.e. phase modulation, muscular reflexive patterns and afferent feedback pathway
Summary
Walking assist systems, such as robotic systems (Kawamoto et al 2003) and functional electrical stimulation (FES) for hemiplegic walking (Bajd et al 1997; Tong and Granat 1998; Yu et al 2002) have been widely studied for the purpose of improving daily living for paralysed individuals. Our ultimate goal is to realise artificial reflexes in realworld walking support systems for paralysed individuals, whose afferent and efferent neural pathways are usually weakened so that the reflexive system is impaired to a certain degree. This goal requires both a qualitative and quantitative understanding of human reflexive mechanisms during walking. It has been shown that flexor reflexes play an important role in locomotion, and these reflexes were implemented in several commercially available FES systems (Quintern 2000)
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