Adaptive sliding mode and safety control for excavators using Kinematic Control Barrier Function and sliding mode disturbance observer

Abstract

Excavators have complex structures, large load, and often works in scenarios with safety hazards. Existing methods overlook control-level safety and over-prioritize accuracy, neglecting input smoothness. To address these challenges, a Barrier Functions Adaptive Sliding Mode (BFASM) safety control method based on Kinematic Control Barrier Function (KCBF) and Sliding Mode Disturbance Observer (SMDO) is proposed. Specifically, a virtual motion trajectory tracking controller is established and CBF provides safe joint velocity inputs for system. A Barrier Function (BF)-based anti-saturation adaptive sliding mode controller is proposed. SMDO is used to estimate the lumped disturbance. BF is used to design the bounded adaptive control gain to ensure that sliding variables remain in predefined neighborhoods of zero, and its size does not depend on disturbance boundary. Simulation results demonstrate that the proposed safety controller effectively ensures safety and the tracking controller keeps errors within a predefined range of 1° with no chattering of control inputs.