The Study On Controller Of Tractor Mounted Machine Sprayer Boom Position

Tractor mounted machines have got rapid development in agricultural production and research experiments.The precision of the position control of the sprayer boom is important criteria for the advanced degree of tractor mounted machines.There exist strong nonlinearity,uncertainty and unknown factors in the main electro-hydraulic servo system.In addition,the requirement of high accuracy for the position of spray boom has brought greater difficulties to the design of the spray boom position controller.In order to achieve the aim of fast response and high control accuracy of the position control of tractor mounted machines,a controlling scheme for its electro-hydraulic servo system has been designed.Firstly,the working mode of the spray boom system of the tractor mounted machine was introduced.The working principle of the electro-hydraulic servo system as well as the characteristics such as nonlinearity and uncertainty existing in the system has been analyzed.Then,a fuzzy controller was designed based on the characteristics of the electro-hydraulic servo system.In the design of the fuzzy control,the uncertainty of the parameters and forces in the system are handled by the fuzzy control,and then the output of the system is controlled.And the actual output value of the system should be ensured to keep track of the given input.Simulation of the system by Simulink revealed that the fuzzy controller can achieve tracking without static error.Thirdly,a Backstepping controller based on a high-gain disturbance observer was designed.The high-gain observer is used to observe the uncertain forces and parameters in the electro-hydraulic servo system,and the observed data are fed back into the system.Through a simulation,it can be concluded that by using the Backstepping controller the static output error of the system is quite small and the response speed is fast.When the system is disturbed by the uncertain force,it has little effect on the output of the system.Therefore,it can meet the requirements of precision and stability required for the design.The results show that both controllers can track the stationary error of a given signal under ideal conditions and the fuzzy controller can be realized more easily.By contrast,the Backstepping controller based on the high-gain disturbance observer has a good controlling effect on the electro-hydraulic servo system.Even when the system be disturbed,the controller can still meet the requirement of high-accuracy of the system.