Dynamic Model Formulation and Calibration for Wheeled Mobile Robots
Dynamic Model Formulation and Calibration for Wheeled Mobile Robots Neal A. Seegmiller CMU-RI-TR-14-27 Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Robotics. The Robotics Institute Carnegie Mellon University Pittsburgh, PA 15213 Thesis Committee: Alonzo Kelly (Chair) David Wettergreen George Kantor Karl Iagnemma Defended on: October 23, 2014 Copyright c 2014 Neal A. Seegmiller Keywords: wheeled mobile robots, kinematics, dynamics, wheel slip, wheel-terrain interac- tion, calibration, model identification, motion planning, model predictive control dedicated to my parents, who supported my academic pursuits from the beginning iv Abstract Advances in hardware design have made wheeled mobile robots (WMRs) ex- ceptionally mobile. To fully exploit this mobility, WMR planning, control, and es- timation systems require motion models that are fast and accurate. Much of the published theory on WMR modeling is limited to 2D or kinematics, but 3D dynamic (or force-driven) models are required when traversing challenging terrain, executing aggressive maneuvers, and manipulating heavy payloads. This thesis advances the state of the art in both the formulation and calibration of WMR models We present novel WMR model formulations that are high-fidelity, general, mod- ular, and fast. We provide a general method to derive 3D velocity kinematics for any WMR joint configuration. Using this method, we obtain constraints on wheel- ground contact point velocities for our differential algebraic equation (DAE)-based models. Our “stabilized DAE” kinematics formulation enables constrained, drift- free motion prediction on rough terrain. We also enhance the kinematics to predict nonzero wheel slip in a principled way based on gravitational, inertial, and dissi- pative forces.
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