Controller Design For Spray Boom Position Based On Backstepping Method

In the development of modern agriculture,the control of pest tends to be intelligent and mechanized.In the investment and application of large-scale plant protection machinery,it not only improves the spraying efficiency,but also reduces environmental pollution.Among them,spraying precision is one of the important measures for agricultural plant protection.However,due to the complexity of the road conditions,the irregular movement of the boom is caused.Irregular movement of the spray boom may cause overlap and leak spray of the vegetation.In severe cases,the end of the spray boom touches the vegetation and even touches the ground.Therefore,position control system of spray boom is needed to explored,which is of great significance for improving the spray efficiency of the spray boom and reducing environmental pollution.In this thesis,a two-symmetric hydraulic cylinder electro-hydraulic servo system model is established for the existing boom structure.The working principle of the electro-hydraulic servo system and the characteristics of the spray boom position control system with nonlinear and uncertain parameters are analyzed.A new Lyapunov function is constructed.Then an adaptive backstepping control method is designed,which solves the problem of boom vibration,tilt and drift of uncertain parameters.The controller ensures that the spray boom is balanced and always maintains a certain height with the ground during the walking of the sprayer.Compared with the backstepping control algorithm without adaptation,the controller effectively suppresses the influence of uncertain parameter perturbations caused by changes of environment.However,the adaptive backstepping controller does not take into account external disturbances and other drift of parameters caused by changes of environment,and an adaptive backstepping robust H_?controller is designed.The Lyapunov method is used to construct the storage function of the system,and the control algorithm of the linear part of the system equation is designed,which obtain the"virtual"robust H_?control law.Then through the adaptive backstepping method,the system's global control law and adaptive law are obtained.The controller,that combined global control law with adaptive law,not only solves the nonlinear characteristics of the system and directly considers the influence of the parameter disturbance on the system,but also effectively suppresses the influence of the disturbance on the output.MATLAB simulation shows that the two controllers have good control performance for nonlinear electro-hydraulic servo systems.The adaptive backstepping robust H_?controller proposed in this thesis makes up for the shortcomings of the adaptive backstepping controller,which take into account external disturbances and other drifts of parameter caused by environmental changes.The adaptive backstepping robust H_?controller has stronger robustness.