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dc.contributor.authorGrewal, Anoop
dc.identifier.otherbibid: 9255146
dc.description.abstractThe main aims of a bipedal walking robot are to avoid falling and to generally move forward. Towards this end we consider controller reduction. This includes: What is the minimal set of states that a controller needs to sense in order to decide the required control actions? What is the minimal set of control actions that a controller needs to provide in order to reach the desired goals? The minimal set of states and control actions needed indicate that a simpler and reduced model of a bipedal robot can be used to control the balance and locomotion of a walking robot. Our primary approach is based on viable and controllable regions. The N-step viable region is the set of all states from where a robot can take at least N steps and not fall down. The N-step controllable region is the set of all states from where a robot can reach the desired goal (e.g., a given walking speed and step-length) in at most N steps. The similarity in sizes between these regions, for a full-order versus a reduced-order controller, are measures of the efficacy of the reduced controller. The compass-gait walking model, actuated by a hip motor and an impulsive push-off, is used as a testbed for developing and testing the controller-reduction principles. We show that a controller that commands only step-length and push-off, controls the robot almost as well as the most general controller that can swing the leg in arbitrary ways. In this reduced controller, the step-length and push-off are decided based on a single state variable, just after the heel-strike. This reduced controller covers a large fraction of the full controller's viable and controllable regions. The success of this reduced controller suggests that a point-mass model with foot placement (i.e., step-length) and push-off can be used by high-level walking controllers. Other separate projects described in this dissertation are 1) state estimation for the bipedal robot 'Cornell Ranger', 2) controllability analysis of a bicycle in zero gravity, 3) design of chains that can fall faster than gravity, and 4) notes on optimal stabilizing controllers for optimal trajectories.
dc.subjectChain paradox
dc.subjectViability kernel
dc.titleModel Reduction And Controller-Design Simplification For Bipedal Robots
dc.typedissertation or thesis
dc.description.embargo2020-08-17 and Applied Mechanics University of Science, Theoretical and Applied Mechanics
dc.contributor.chairRuina,Andy Lee
dc.contributor.committeeMemberHencey,Brandon M.

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