Research For Application Of Automatic-shift Control System In Tractors

Automatic transmission has a large number of applications in the car, but the tractor withautomatic transmission is still in its infancy, the development and application of the automatictransmission control system is not mature, most of the domestic tractors use traditionalmanual mechanical gearbox. In addition, tractors compared with cars, have changingoperating conditions and the complexity of the shifting process. The drivers need for frequentoperation, it could divert driver’s attention, thus affecting driving safety. Therefore, using areasonable draw automotive automatic transmission control technology, to solve the tractors’gearbox automatic control shift, to vigorously promote the agricultural machinery reducingthe labor’s intensity of the driver must be considered.In this paper, according to the engine speed characteristics and energy characteristicequation to determine the engine speed, throttle rod displacement and speed of operation ofthe three parameters to control the shift. For different conditions of tractor operations, puttingforward two shift modes of field operations and transport operations conditions, and usingtwo different control modes. Each shift mode can be automatically switch the stalls.By researching the control parameters, put forward several shift mode, research anddesign of the automatic transmission control system. This system includes a hardware partand a software part. Designing the hardware part include of studying and selection of the ofthe chips, the choice of sensor circuit design, the function keys circuit design, the design ofthe electromagnetic valve driving circuit, A/D conversion circuit design and thecommunication circuit design. The software study design uses SCM C51language to program,several modules including the main program module, A/D conversion subroutine module,display subroutine module, button subroutine module and the electromagnetic valve drivingsubroutine module.After designing a circuit diagram with Altium Designer6.9, simulation schematic diagramwas made in Proteus, using Keil uVision2software compile each module subroutine. After theco-simulation of the control system. Verifying the correctness of the program and thefeasibility of the circuit diagram. Manufacture the welded microcontroller board, Keil uVision2generates C51language program to ‘*. Hex’ file. With the application of thedownload software STC_ISP_V3.1to burn the Hex file in a SCM to run and debug. Bydebugging the control system hardware and software, further inspected its feasibility.Continue to run, debug and modify the control system, the final results show that thecontrol system can be run in accordance with the expected shift mode, according to theintention of the driver and the external load and speed changes, the tractor’s transmissioncould automatically switch the gears.