On the dynamics of a quadruped robot model with impedance control: Self-stabilizing high speed trot-running and period-doubling bifurcations
Author(s)Lee, Jongwoo; Hyun, Dong Jin; Ahn, Jooeun; Kim, Sangbae; Hogan, Neville
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The MIT Cheetah demonstrated a stable 6 m/s trot gait in the sagittal plane utilizing the self-stable characteristics of locomotion. This paper presents a numerical analysis of the behavior of a quadruped robot model with the proposed controller. We first demonstrate the existence of periodic trot gaits at various speeds and examine local orbital stability of each trajectory using Poincar`e map analysis. Beyond the local stability, we additionally demonstrate the stability of the model against large initial perturbations. Stability of trot gaits at a wide range of speed enables gradual acceleration demonstrated in this paper and a real machine. This simulation study also suggests the upper limit of the command speed that ensures stable steady-state running. As we increase the command speed, we observe series of period-doubling bifurcations, which suggests presence of chaotic dynamics beyond a certain level of command speed. Extension of this simulation analysis will provide useful guidelines for searching control parameters to further improve the system performance.
DepartmentMassachusetts Institute of Technology. Department of Mechanical Engineering; Massachusetts Institute of Technology. Newman Laboratory for Biomechanics and Human Rehabilitation
2014 IEEE/RSJ International Conference on Intelligent Robots and Systems
Institute of Electrical and Electronics Engineers (IEEE)
Lee, Jongwoo, Dong Jin Hyun, Jooeun Ahn, Sangbae Kim, and Neville Hogan. “On the Dynamics of a Quadruped Robot Model with Impedance Control: Self-Stabilizing High Speed Trot-Running and Period-Doubling Bifurcations.” 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems (September 2014).
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