| With the perpetual innovation of the emerging technology, especially the rapid development of high and new technology, such as computer technology, electronic control, artificial intelligence and network communications, the tractor industry is influenced greatly. Taking the integrated control technology of hydromechatronics is the best project for broadening tractor function, improving its technical performance and solving numerous facing technical difficulties, and it has become the major technology trend of modern tractors and the supporting units.A new electrohydraulic hitch system for tractor is designed on the basis of the traditional tractor hitch control system (THCS), which is consisted of manipulation, hydraulic, the unit of feedback control signal. Control panel of man-machine interface is designed according to specific operational control habit. The traditional mechanical splitter is replaced by proportional solenoid valve and its supporting circuit. A position sensor, a force sensor and a speed sensor is used for gaining feedback control signal. Furthermore, the various deep-conditioning method of cultivation of tractor electrohydraulic hitch are compared and analyzed in this paper.However, the nonlinearity factors existed in the mechanical parts of the tractor hitch and the lagging characteristic of tractor hydraulic drive system, especially the particular uncertainty of working objects and conditions, making the control of the tractor hitch becomes more difficult. The conventional PID control is the most common control policy in industry. Fuzzy control is applicable to nonlinear and hysteretic system whose model is unknown and complicate. We chose the fuzzy control for the control the drive signal of tractor electrohydraulic hitch by compared the PID with the fuzzy control.Control unit of tractor electrohydraulic hitch system is consisted of hardware and software systems. According to specific requirements of the system function modules, 80C196KC microcontroller of Intel Corporation MSC-96 series is selected. For the electronic hardware system, firstly, the MCU control loop is designed. Secondly, the output circuit of the control panel instructions, showing circuit of the working state feedback, and conditioning circuit of the tillage depth and speed signals are configured. Then, according to the needs of the types and the MCU, signal conditioning circuits of position sensor, force sensor and speed sensor are designed. Finally, the serial circuit which used to communicate with PC was configured. For the software system, we used the assembly language to finish the control system program. Its main program is used to control the overall flow of the system. Its subroutines are used to implement the raise and drop of the hitch with speed adjusted. The adjustment of position and force are accomplished by the subroutines of position adjustment and force adjustment. In order to improve the security of the system, the position of hitch, loading and the slip rate of tractor were monitored by the subroutine of security. The system will automatically make alarm when working in the insecure region. At the same time, system reliability and security were improved by the Modular Design procedures.In conclusion, the testing of the whole system gained good curves of the control signal. Then the feedback signal of electrohydraulic hitch with the control signal is compared. The experiment result shows that the proposed fuzzy control can fit the application of THCS, and make the experiment obtains good performance of high precision, strong reliability, and fast response, which has a good application prospect. |
PDF Full Text Request