Active Disturbance Rejection Control Design for the Hydraulic Actuator on Weeding Machine

A weeding machine can sometimes cause plant damage while working in the paddy field due to the seedling line bending phenomenon. Thus, we introduce a computer-vision-based automatic seedling avoidance system for the weeding machine, with a hydraulic cylinder actuator driving the weeding wheels according to the guidance information. This paper aims to study and design a Linear Active Disturbance Rejection Control (LADRC) controller for the hydraulic system. The proportional directional valve has a large input dead zone, decreasing the controller’s performance and causing oscillation of the system output near the setpoint. We designed a nonlinear dead zone compensation module and proposed a residual dead zone compensation method, taking advantage of the Extended State Observer (ESO). A well-behaved hydraulic position servo system was designed and tested in Simulink simulation and on an experimental platform based on the compensation method. The results show that the system performance meets the requirement with approximately no overshoot, response time within 0.7 s, and steady-state error within 0.7 mm on the experimental platform.