Skid-steer kinematics for dual-arm mobile manipulator system with dynamic center of gravity

Ebersole, Benjamin Jarrett
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Skid-steer mobile vehicles bridge an important operational gap in robotics between indoor-only and outdoor-only platforms. Traditionally, skid-steer vehicles have been treated and operated as differential-drive vehicles, which is an adequate approximation with a static center of gravity (CG) coincident with the wheelbase center. With a dual-arm mobile manipulator, such as the Nuclear and Applied Robotics Group's VaultBot platform, the center of gravity's location is dynamic and the differential-drive model is no longer valid. This can result in large errors between desired and actual trajectories over even short periods of time. In this work, the degree to which the platform's behavior changes with a dynamic CG and the intuition behind these effects are discussed. Several different approaches leading to the development of a heuristic model built to improve performance, and the evaluation results of said model, are also discussed.