First steps toward closing the loop on walking: from human walking to hybrid systems to robotic walking and back - Rehabilitation Institute of Chicago

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Fri Jan 7

Speaker: Aaron Ames (Texas A&M University)

Title: First steps toward closing the loop on walking: from human walking to hybrid systems to robotic walking and back

Abstract:  Bipedal walking provides a quintessential example of complex dynamically stable behavior.   Hybrid systems---systems with both continuous and discrete behavior---provide a modeling paradigm in which to capture the behavior of highly complex systems.   Bipedal walking robots are naturally modeled as hybrid systems, and it is the confluence of these two areas---bipedal walking and hybrid systems---that affords a unique opportunity to further the understanding of each of these areas. The applications of these ideas are far reaching, resulting in new research directions in hybrid systems and in a new understanding of the fundamental mechanisms underlying walking.

This talk discusses the first steps toward closing the loop on bipedal walking: generating mathematical models for human walking, developing control laws that yield walking for bipedal robots using these formal models, and comparing the resulting robotic walking to the human walking data from which the model was derived. I begin by considering human walking data which is used to construct a hybrid system. The discrete behavior, or phases, of the hybrid system are dictated by the discrete phases in the human walking data (heel lift, knee strike, heel strike, etc.), and the continuous behavior of the hybrid system on every phase is given by the equations of motion obtained by considering the human configuration through the discrete phase. I then consider a bipedal robot which is modeled by this hybrid system; this model assumes a temporal ordering and structuring of discrete events that are anthropomorphic in nature. Control laws are constructed for this bipedal robot by combining human-inspired local control laws. The end result of combining all of these approaches in an integrative fashion is stable walking for the bipedal robot. Given the anthropomorphic motivation for its model and controllers, it is not surprising that this walking is remarkably human-like.

Host: Eric Perreault