Research Of Header Height Automatic Controlling System Based On Ultrasonic Sensor

Combine as an important component in the agricultural machinery. It has an irreplaceable role in modern agricultural production. The research and development of combine will focus on capability improving, safety and comfort, automation in the field of agricultural machinery. If the header height isn't adjusted properly, it may lead to enginery block and mechanical fault, directly affect harvesting efficiency. In the past, the header working height was adjusted by mechanical profile mechanism or manual work. But it is poor in real-time and accuracy, and it can not acquire the header height data, so it is very necessary to study the header height automatic controlling system. There will lay the foundation for the development of intelligent combine.In this paper, based on the analysis of foreign header height control system, a real-time monitoring and control system was designed for controlling header height error, reducing harvest losses, stability threshing cylinder load and increasing machine performance.This paper describes the ultrasonic technology development and application. On the basis of the ultrasonic sensors and distance measurement principle, the scheme of system is designed. According to the requirement of combine, the minimum height is determined. The system design includes two major parts about the hardware and the software. The hardware design mainly include ultrasonic receiving and transmitting circuits, display circuit, temperature measurement circuit, serial communication circuits, power supply circuit, microprocessor reset circuit, clock circuit and hydraulic enforcement mechanism. The PID control algorithm as a control strategy, the software is developed in uVision3 development environment by C51 language. The software includes main program, distance measurement program, display program, temperature measurement program and serial communication program.Through the test of function, the distance measurement circuit designed by us can achieve ultrasonic sensor distance measurement requirements. From the testing results, the accuracy of distance measurement module can meet the minimum height requirements of combine header height, the value is 100mm. Through analyzing the testing results, a small area ranging result is stabile. By analyzing distance measurement system error and optimizing testing data, a strong theoretical basis is acquired for improving the accuracy of ultrasonic distance measurement.Through the simulation debugging to the overall design of system , the result showed that the automatic control system running stable, easy to operate, facilitate further development, basic achieve the desired design requirements.