PID-Based Design of Automatic Control System for a Travel Speed of the 4UM-120D Electric Leafy Vegetable Harvester

The study developed a PID-based automatic control system for travel speed based on the analysis of the entire machine structure of the 4UM-120D electric leafy vegetable harvester to enhance the operation quality of the harvester and lessen the workload of operators. Taking the system adjustment time during the process of starting and maintaining the travel speed of the harvester within ±2% of the set value as the main evaluation index, the Box–Behnken test method was applied based on the single-factor test, and the proportional coefficient Kp, the integral coefficient Ki and the initial value U of the travel motor drive voltage of the PID control algorithm were used as the test factors, and the PID-based 4UM-120D electric leafy vegetable harvester travel speed automatic control system operating parameters based on PID was studied in a three-factor, three-level experiment, and a multiple regression model of evaluation indexes on each factor was established to analyze the influence of each factor on system rapidity and to obtain the optimal operating parameters. The test findings demonstrated that the beginning value of the driving voltage of the travel motor U, the integration factor Ki, and the proportionality factor Kp had the largest to smallest influences on the system regulation time. When the initial value of the driving voltage of the travel motor was 1.81 V, the integration factor was 0.020, the proportionality factor was 0.127, the system regulation time was 2.14 s, and the relative error was 1.8% compared with the optimized value. The results of the study could provide a way to improve the operation quality of leafy vegetable harvesters and reduce the work intensity of operators