Safe Operation for Autonomous Wheel Loader using Control Barrier Functions under Unknown Disturbances and Input Delay

This paper focuses on ensuring the safety of wheel loaders under constant input delays and unknown disturbances. First, a second-order sliding mode-momentum observer (SOSM-MOB) is designed to estimate the unknown bounded disturbances with finite-time convergence of disturbance estimation error; second, a momentum observer robust Control Barrier Function (MOB-RCBF) is formulated to ensure safety using SOSM-MOB and a state predictor; third, a safe operating range is found for the considered wheel loader and the usage of the proposed safety control scheme is demonstrated. Experiments conducted on an industrial wheel loader verify that the proposed control scheme ensures the safety of the considered autonomous wheel loader in the presence of unknown disturbances and input delays of approximately 40 milliseconds.