Event-Triggered Asymmetric Gain RBF-PID Control Strategy for Operational Trajectory Tracking of Unmanned Excavators

Abstract

Abstract

Valve-controlled asymmetric hydraulic cylinders inherently exhibit bidirectional dynamic asymmetry attributable to differential chamber areas and heterogeneous gravitational coupling. This study proposes an event-triggered asymmetric gain RBF-PID strategy, wherein real-time directional identification enables differentiated gain scheduling between extension and retraction strokes to compensate for direction-dependent dynamic discrepancies inherent to asymmetric actuators. A sparse RBF mechanism with heterogeneous event-triggering thresholds is further introduced to achieve synergistic coordination between adaptive compensation and computational lightweighting. Uniform ultimate boundedness of the closed-loop tracking errors is rigorously established via Lyapunov-based stability analysis. Simulation results demonstrate that steady-state errors of the three joints are constrained within ±1°; compared with standard PID, the root-mean-square error is reduced for all joints, with directional switching overshoot suppressed below 2%. Relative to conventional RBF-PID, the proposed strategy achieves an event-triggering rate below 5% while reducing FLOPs by approximately 86%, effectively reconciling the inherent conflict between tracking accuracy and computational burden.