Non-linear observer for slip parameter estimation of unmanned wheeled robots

Accurate estimation of a wheeled vehicle is essential to increase the vehicle´s tranversibility choices in rough terrain. The knowledge of slip parameters can be used in the development of higher-level strategic control of unmanned ground vehicles such as path planning, trajectory tracking and traction control. In this paper, a sliding mode observer is developed to estimate slip parameters based on the kinematic model of a wheeled vehicle and on-board measurements. The sliding mode observer is proven to converge after a finite time. The sliding mode observer is validated against experimental data obtained from specially designed test rigs, showing very good slip estimation. The robustness and superior performance of the sliding mode observer is demonstrated using experimental results.