Active disturbance rejection control system for rotary tiller tillage depth based on an improved snake optimizer

To address the challenge of low tillage depth precision in self-propelled electric rotary tillers operating under complex field conditions, this study proposes an active disturbance rejection control (ADRC) strategy with online parameter tuning realized by an improved snake optimizer (ISO). The ISO integrates three enhancement mechanisms—a multi-strategy chaotic system for population initialization, an anti-predator strategy for escaping local optima, and bidirectional population evolution dynamics for balancing exploration and exploitation. Sensor fusion of LiDAR terrain perception and displacement signals is accomplished through an extended Kalman filter, while a refined nonlinear function is embedded into both the extended state observer and the nonlinear state error feedback to strengthen disturbance estimation and compensation. Field experiments conducted in tea plantations at forward speeds of 0.72 and 1.20 km/h with target tillage depths of 50.00 and 90.00 mm show that the proposed ISO-ADRC system achieves a maximum depth deviation of 2.5 mm, an average standard deviation of 0.58 mm, and a coefficient of variation (CV) of (0.92±0.30)%. Compared with fuzzy PID, conventional ADRC, and IPSO-ADRC, the CV is reduced by 85.40%, 79.70%, and 20.00%, respectively. Simulation results further reveal a settling time of 0.102 s with zero overshoot and robust tracking performance under terrain disturbances. The proposed ISO-ADRC offers a compact electromechanical solution for precision tillage in tea plantation operations, serving as an effective alternative to conventional electro-hydraulic systems.