Feedback control of compost turning machine based on DDPG improved PID algorithm

During the process of composting and fermentation for agricultural wastes, the water content of materials has changed, which will lead to the change of the load of the compost turning operation. However, the existing operation of the compost turning machine was mainly by manual operation, which led to low operation efficiency and easy to cause failure in the process of machine operation. Aiming at the problem of inaccurate regulation during manual operation of the compost turning machine, the relationship model for the operation load of the compost turning machine between the moisture content of the composting material and the moving speed of the machine was established through the experiments. Combined with the variable frequency speed control model of the machine, the speed control system of the compost turning machine was optimized by using DDPG（Deep Deterministic Policy Gradient） improved PID algorithm. The Simulink simulation results showed that compared with the traditional PID algorithm, the DDPG improved PID algorithm reduced the overshoot by 6.7%, the adjustment time by 2.5 s, and the anti-disturbance and follow-up performance were better. The field test results of compost turning operation showed that the control mode of DDPG improved PID algorithm was 4% lower than that of traditional PID algorithm under overshoot, and the adjustment time was reduced by 2 s. Compared with manual control, the adjustment time was reduced by 6 s.