| Currently the automatic identification method of road surface for vehicles has matured.However,there is rare research about the automatic identification of soft soil surface for tractor.Being different from the purpose of road surface identification,the soft soil surface identification based on the relationship between adhesion coefficient and slipping rate is to modify plowing depth more efficiently.When a tractor plows in field,the best plowing depth consists of basic depth and modified one,between which the later one is the core of automatic control strategy.The purpose of keeping a tractor work under the best plowing depth is to keep its slipping rate below the best threshold.Practically every kind of surface has its corresponding slipping rate threshold.Therefore,it is necessary to identify those different surfaces and match them with the characteristics stored in electric control unit to get their best threshold,and then keep the actual slipping rate with the best range.An automatic identification method of soft soil surface for tractor based on real-time monitoring of adhesion coefficient of tractor’s driving wheel was studied in this paper.The identification method was conducted according to the scheme that theoretically analyzing,then modeling and simulating,and finally testing on real tractor.Firstly,based on the research of identification method for double-wheel driving tractor,by analyzing tractor dynamics and dynamics of rear driving wheel,that there is load transferring phenomenon when tractor plows was concluded in this paper.The corresponding identification methods under two conditions of plowing and running without plough were proposed by theoretically analyzing and conducting.Secondly,in order to testify the feasibility of the identification method,a diesel engine model was established in Matlab.Selecting the relationship between tire and surface including soft soil,stubble land with C1=900 and C1=700,the simulation model of surface identification was established according to the interaction with diesel model and tire-wheel model.The model’s input is the driver’s intention that is fuel consumption and its output is the identifying result that is surface’s type.Tests under different working conditions were conducted to preliminarily verify the feasibility.Finally,a real test tractor was rebuilt using related sensors and the date acquisition program was established in LabVIEW.Real tractor tests under two different working conditions of plowing and running without plough were conducted.The results showed that,the tractor could identify the surface’s type(stubble land)under two conditions,which means the method proposed in this paper is plausible. |
