Design and Test of an Intelligent Control System for Agricultural Materials Unloading Equipment

In order to solve the problem of the low automatic level of unloading agricultural materials from trains, an intelligent control system for the electric forklift was developed. It is verified that the electric forklift based on the control system can move automatically in the narrow wagon and unload safely and efficiently. First, the framework of the control system was established with main functions determined as obstacle detection, speed control and automatic steering. The ultrasonic distance-measuring sensor was chosen for the obstacle detection unit, and the stepper motor was applied in steering while both the speed detection and control unit were included in the system. Second, the circuit of this intelligent control system was designed. Based on MC9S12XS128, modules including power supply, obstacle detection, steering control, speed detection and control, communication and debugging were designed. Then, the integral controller was implemented completely. Third, the application software was developed for the intelligent control system based on the steering and speed control strategies. The algorithm of detecting obstacle as well as sensing the speed and steering angle were implemented by programming. As a result, functions including straight driving, automatic steering and steering maintaining were realized. In addition, programs for button switch, TFT display, CAN bus and SCI were developed. Last but not least, experiments of speed control, steering control and integrated control were carried out to validate the reliability of this control system. The PID control parameters of the speed and the steering response of the stepper motor were obtained from the experiments. Experiments proved that with the control of the designed system, the electric forklift’s safe automatic driving in the narrow train wagon can achieve its stable performance.