Semi-active Vibration Reduction Control System Of Agricultural Vehicles Seat Based On Magnetorheological Damper

With the rapid development of automotive technology, all kinds of new technology is also applied to the agricultural vehicles, and the requirements of ride comfort and operation stability are getting higher and higher. Agricultural vehicles (tractors for example) working in the fields, whose speed is generally less than25km/h, the vibration is not only caused by road roughness, but also by its engine vibration impact. The tractor seat is usually made into the device which directly connects driver with the body of tractor, tractor seat is the main source of the vibration caused by the tractor to the driver. Most of tractor seats lack a good shock absorber, or just rely on the ordinary seat cushion or spring acts as a damping device, drivers operating in agricultural fields will be in the low frequency and high amplitude state of whole body vibration, which is a great deal of damage to the health of the drivers. Magnetorheological damper device with its simple structure, low energy consumption, non environmental pollution and an adjustable output power characteristics are increasingly being used in the field of automobile manufacturing, therefore, the magnetorheological damper applied to the tractor seat may reduce the vibration suffered by the driver, who are operating the tractor, which is also the starting point and the goal of this article.To begin with, this paper introduced the characteristics of the magnetorheological fluid and the vibration reduction principle of magnetorheological damper, magnetorheological damper as a semi-active control components, then represented the relationship curve between magnetorheological fluid shear yield stress and the magnetic field strength, and the relationship curve between the viscous damping coefficient and the shear strain relationship curve, and then, starting with its mechanical model, established of a single freedom degree of mechanical model of the tractor seat suspension based on the Bingham model and theoretical analysis. Magnetorheological damper controller is built based on TI Corporation’s C2000series TMS320F2812DSP chip as the main control chip and the MAX3000A series EPM3128ATC144-10the CPLD chip as auxiliary control chip, with the advantages combination of traditional PID control and fuzzy control, determined the Fuzzy-PID control strategy, using fuzzy toolbox of MATLAB simulink model, obtained the fuzzy relationship between e and ec for the input fuzzy variables and Kp、K1, KD for output fuzzy variables by numerical simulation, designed of the signal D/A conversion circuit and magnetorheological damper drive current adjustable circuit, generated the program codes which can be compiled by CCStudio software with MATLAB and DSP, summarized code programming curing to the Flash as well. With analysis of installation methods influences on high frequency characteristics, a vibration test platform are set up based on DC-2200-26electric vibration system, its no-load characteristics are measured and the intercept point characteristics are calculated, low-frequency vibration on tractor driving were simulated and analyzed, operation processes of the vibration system and testing precautions are made a summary.