Development of a hydraulic variable-diameter threshing drum control system for combine harvester part II: Controller design and field performance

It is important to adjust the diameter of the hydraulic variable-diameter threshing drum adaptively according to the change of feeding rate for the combine harvester . To solve the problem that the drum diameter cannot be adaptively controlled, the variable universe fuzzy PID (VUFPID) controller with adaptive contracting-expanding factor was developed and its field performance was verified. The VUFPID controller with adaptive contracting-expanding factor and the fuzzy PID controller were established using MATLAB, and the simulation was compared and analysed. The simulation results showed that the VUFPID controller with adaptive contracting-expanding factor had better control characteristics. Field experiment results showed that the adaptive control system can adjust the drum diameter to change the threshing gap in real time according to the change of feeding rate. When the adaptive control system was turned on, the average grain entrainment loss rate was reduced by 8.72 % compared with that without the adaptive control system. • Design and development of the variable-diameter control system is presented. • VUFPID control method with adaptive contracting-expanding factor is proposed. • Better control characteristic of this method is proved by MATLAB simulation. • A significant success is achieved when using the developed system at field.