DIFFERENTIAL AND INTEGRAL SLIDING MODE ADAPTIVE CONTROL ALGORITHM FOR DRAFT AND POSITION INTEGRATED CONTROL OF ELECTRO-HYDRAULIC HITCH IN AGRICULTURAL TRACTOR
The accuracy of tractor plowing is an important link to ensure the quality of agricultural crops. The integrated control of draft-position in plowing is an effective plowing precision control technology which can be used to improve the tractor's plowing efficiency. The hydraulic system of the tractor hitch has the characteristics of large load and complex working environment. A differential and integral sliding mode adaptive controller (DI-SMAC) is designed for the tractor hitch hydraulic system with strong nonlinearity, uncertainty and time-varying parameters. Compared with the traditional PID controller, integral sliding mode adaptive controller(I-SMAC) and differential and integral sliding mode adaptive controller(DI-SMAC) in the electro-hydraulic hitch control system, the numerical simulation verifies the advantages of the differential and integral sliding mode adaptive controller. The real test platform of the agricultural tractor is built. The test results show that the DI-SMAC can realize the integrated control function of draft-position. In the position control mode, there is no static error, and the anti-interference ability is strong; Under the draft control mode, compared with the traditional PID controller, the range of traction error of differential and integral sliding mode controller is reduced by 32.9%, and the standard deviation is reduced by 38.6%; When the weight coefficient is changed, the traction force and tillage depth fluctuation are different with different weight coefficients. It shows that the DI-SMAC is stable and effective, and the developed method is expected to provide technical support for the fine plowing operation of tractors.
Abstract in Chinese