Research On Active Control Strategy Of Boom Position Of Plant Protection Machinery

Due to the complicated road conditions,driving conditions and weather conditions during the spraying operation of the plant protection machinery,the plant protection machinery generally has problems such as the occurrence of failure of the operating parameters of system and low spraying efficiency,and which result in waste of pesticides and environmental damage.Small disturbance excitation can cause the ends of spray boom vibrate violently,too high or too low of height can also result in overdose or underdose.In addition,the boom may also scratch agricultural plants,or even the ends of the boom can be damaged.This phenomenon can seriously affects the spray effect and work efficiency.Therefore,it is important to study the precise control of the position of the spray boom of the plant protection machinery.The main research works of this thesis is as following:(1)Considering the two-degree-of-freedom plant protection machinery suspension boom system with low cost and small-scale operation requirements.A uncertainty factors such as linearization,fault of active and passive components,and the model error of the system itself are fully considered in the modeling process.A fourth order linear state space model with uncertainty is established.A robust output tracking controller for the boom position of the plant protection machinery is designed,which proves the stability and progressive tracking of the closed-loop system.A simulation results verify the effectiveness of the algorithm.(2)Considering the large-scale plant protection machinery with high cost and large-scale operation requirements,in order to improve the anti-rolling stability of the spray boom better,a nonlinear model of spray boom fixed on the suspension system with multi-degree-of-freedom is established.The research of controller is carried out aimed at adjusting the height of the boom position and the angle generated by the tilt.The backstepping control algorithm is used to design the active control law.A simulation results verify the effectiveness of the algorithm,the controller can effectively reduce the vibration amplitude of the suspension and improve the stability of the boom operation.(3)A electro-hydraulic servo system is used as the execution drive mechanism of the active control force to control the suspension boom system of the plant protection machinery.A complete nonlinear model is established by further including the electro-hydraulic servo system and the unmodeled dynamic factors.Firstly,the fuzzy PID intelligent control algorithm is used to design the position servo controller of the spray boom of the plant protection machinery,and the simulation tracking the values designated as canopy height of crops of is carried out.A simulation results verify the effectiveness of the composite fuzzy control algorithm.To further improve the control precision and stability of the boom position,the dynamic surface is designed based on backstepping control algorithm.The complete state space model with electro-hydraulic servo system has been transformed into a strict feedback form.The RBF network is used to approximate the nonlinear term,the damping term is introduced to compensate the influence of the disturbances on the system,and the dynamic surface control is used to design the servo controller.Simulation results show that the tracking error of the system is located in the allowed area and the response is fast.A position servo controller designed has a good tracking performance and the ability to compensate for uncertain parameter changes.It meets the control accuracy and stability requirements in the operation of the spray.