The control of field robots in varying and uncertain terrain conditions presents a challenge for autonomous navigation. Online estimation of the wheel-terrain slip characteristics is essential for generating the accurate control predictions necessary for tracking trajectories in off-road environments. Receding horizon estimation (RHE) provides a powerful framework for constrained estimation, and when combined with receding horizon control (RHC), yields an adaptive optimisation-based control method. Presently, such methods assume slip to be constant over the estimation horizon, while our proposed structured blocking approach relaxes this assumption, resulting in improved state and parameter estimation. We demonstrate and compare the performance of this method in simulation, and propose an overlapping-block strategy to ameliorate some of the limitations encountered in applying noise-blocking in a receding horizon estimation and control (RHEC) context.
Kinematic representations relating perturbations to vehicle slip are presented in @cite_28 for four general WMR configurations, classifying slip perturbations as input-additive, input-multiplicative or matched unmatched. These are utilised in @cite_21 to design path following controllers which, assuming no other disturbances, apply backstepping techniques and prove the ultimate boundedness of the tracking errors.
@cite_28 @cite_21
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This paper aims to give a general and unifying presentation on modeling of wheel mobile robots (WMRs) in the presence of wheel skidding and slipping from the perspective of control design. We present kinematic models that explicitly relate perturbations to the vehicle skidding and slipping. Four configurations of mobile robots are considered, and perturbations due to skidding and slipping are categorically classified as input-additive, input multiplicative, and or matched unmatched perturbations. Furthermore, we relate the WMR's maneuverability with the vehicle controllability that provides a measure on the WMR ability to track a trajectory in the presence of wheel skidding and slipping. These classifications and formulations lay a base for the deployments of various control design techniques to overcome the addressed perturbations. This paper addresses the path following control problem of wheeled mobile robots in the presence of wheel skidding and slipping. A conditional global positioning system (GPS)-based path following controller is proposed for four generic WMRs to achieve high-precision path following performance. The proposed controller utilizes real-time kinematic-GPS and other aiding sensors to determine the robot's pose and wheel skidding and slipping perturbations to achieve accurate path following control. The reported simulation and experimental results suggest that with this control scheme, the WMRs are able to maneuver with precision. © 2009 Wiley Periodicals, Inc.