A Foot Placement Strategy for Robust Bipedal Gait Control
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Date
2008-05-23T14:31:56Z
Authors
Wight, Derek L.
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
This thesis introduces a new measure of balance for bipedal robotics called the foot placement estimator (FPE). To develop this measure, stability first is defined for a simple biped. A proof of the stability of a simple biped in a controls sense is shown to exist using classical methods for nonlinear systems. With the addition of a contact model, an analytical solution is provided to define the bounds of the region of stability. This provides the basis for the FPE which estimates where the biped must step in order to be stable. By using the FPE in combination with a state machine, complete
gait cycles are created without any precalculated trajectories. This includes gait initiation and termination. The bipedal model is then advanced to include more realistic mechanical and environmental models and the FPE approach is verified in a dynamic simulation. From these results, a 5-link, point-foot robot is designed and constructed to provide the final validation that the FPE can be used to provide closed-loop gait control. In addition, this approach is shown to demonstrate significant robustness to external disturbances. Finally, the FPE is shown in experimental results to be an unprecedented estimate of
where humans place their feet for walking and jumping, and for stepping in response to an external disturbance.
Description
Keywords
Foot Placement Estimator, Zero Moment Point, legged locomotion, robot dynamics, gait synthesis, underactuated system, walking, inverted pendulum, control, bipedal robot