Dynamic Walking 2010. Aaron Ames. First steps toward closing the loop on walking: from human walking to hybrid systems to robotic walking and back
This talk discusses the first steps toward closing the loop on walking: generating mathematical models for human walking, developing control laws that yield walking for 3D bipeds 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 are given by the equations of motion obtained by considering the human configuration through the discrete phase. I then consider a 3D 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 with techniques utilized in the dynamic walking community: passive walking inspired control, geometric reduction, and input/output linearization through the use of virtual constraints. The end result of combining all of these approaches in an integrative fashion is stable walking for the 3D bipedal robot. Given the anthropomorphic motivation for its model and controllers, the walking is remarkably human-like.