Research On Synthetic Control Approach For Simultaneous Active Vibration Suppression And Posture Adjustment Of High Clearance Sprayer

Active suspension system of the large-scale high clearance self-propelled sprayer is a multifunctional system including supporting vehicle body,suppressing.vibration,changing wheel span and adjusting posture of the sprayer,which plays an important role in promoting the operational stability,the ride comfort,driving safety and environmental-friendliness.The system is not only the focus of the field of sprayer research,but also the development trend of the propelled system of advanced sprayer.It is a significant mission of the suspension system that simultaneously active suppressing vibration and vehicle body gesture control in extreme condition.However,there is an integration relationship between the acceleration and suspension displacement,resulting in making the stability of vehicle body gesture into consideration in the manipulation process of the mass acceleration minimization of tire spring.On the contrary,it is necessary to consider how to avoid the excessive vehicle acceleration giving rise to decline of riding comfortability.Therefore,it is the key and difficulty of control algorithm design that how to balance the two indexes.As one kind of large agricultural machines,the eigenfrequency of spray suspension is in the low frequency range.Considering the reality of field roads,the main excitation caused by the road surface has the characteristic of large amplitude and low frequency.Whereas,because of the nonlinear characteristic of the system and interference from ambient noise,the higher frequency components can always be detected from state variable in the system,which will dramatically influence the effect of subsequent control.Based on the above phenomenon,the vibration of sprayer suspension has an apparent characteristic of frequency domain,which means it is of vital significance in the area of designing the controller with excellent performance in the finite low frequency response vehibandwidth,suppressing nonlinear performance of the system and feedback impact of all kinds of interference in the high frequency domain as far as possible to promote the suppressing vibration property of closed loop system suspension after control.Based on it,this dissertation presented a design method of controller combined with active suppressing vibration of sprayer suspension and the whole gesture of the vehicle in the frame of finite frequency domain property condition constraints and the theory of time-frequency analysis.The main research work includes:(1)By comparative analysis of articles,the trend of research and development of large-scale high clearance self-propelled sprayer and suspension was clarified.The necessity of active hydro-pneumatic suspension of sprayer was analyzed and discussed from the area of design,manufacture,control,and future maintenance.Ultimately,the system design scheme of active hydro-pneumatic suspension and suppressing vibration of the whole vehicle was determined.(2)According to the relevant theory such as fluid mechanics,equation of gas state and so on,mathematical model of hydro-pneumatic spring was constructed and analyzed the nonlinear characteristic such as stiffness and damping.Based on this,the specific parameters of hydro-pneumatic suspension was designed to meet the requirements of the research group.Nonlinear mathematical model of active hydro-pneumatic suspension was demonstrated and then developed the state equation after linearization and transformation to solve the controller.Synthesizing the above results,the vehicle kinetic model with active hydro-pneumatic suspension is established including seven degrees of freedom,which lays the foundation for the final integrated control simulation and experiment.The manipulation scheme of suspension was developed,which was suppressing vibration oriented and gesture adjustment with auxiliary.The internal and external loop control mode with active hydro-pneumatic suspension H? control and PID control in the time-frequency domain was adopted.Moreover,according to the feature of sprayer working condition,the comprehensive control strategy of the whole vehicle was utilized.(3)For the requirements of active suppressing vibration control and vehicle gesture adjustment simultaneously,the design procedure of active suspension external controller could transformed into the solution problem of feedback controller with H? static output of finite frequency domain of multi-object in a direct feedthrough system.Based on GKYP lemma and the demonstration procedure in the papers,the necessary and sufficient condition of existing controller of matrix inequalities were derived.And then,iteration solution algorithm of controller gain was deduced.(4)In order to cope with the issue about system nonlinearity and decline of manipulation performance caused by high frequency disturbance from noise,an inner time-frequency PID control strategy about active suspension was presented to suppress the high frequency signal of the system.That is to say,at the same time of finite low frequency performance promotion,the interference and control instability phenomenon caused by high frequency signal was weakened.Therefore,to descend the curb algorithm dependence on chip,it is necessary to rapid divide frequency on system collected feedback signal.Based on discrete wavelet transform,the basic model of its decomposition and reconstruction was studied and signal decomposition and restructuring matrix algorithm based on symmetric extension at both ends was deduced.As a result,the amount of the signal decomposition operation was reduced effectively without distortion of the signal components.(5)The synthetical controller prototype of the whole vehicle suspension was developed.Based on hardware-in-loop simulation technology,semi-physical experiment platform of hardware-in-loop system about active suppressing vibration system of large-scale high clearance self-propelled sprayer and gesture adjustment of the whole vehicle was constructed and relevant experimentally verified.Through this research,the sprayer can perform profiling spray operation on the slope while ensuring driver's ride comfort and machine stability,which reducing the vibration of the whole vehicle and spray pole and prolonging the service life of the components.And then it ensures the quality of spraying and enhances the driving safety and environmental adaptability of the sprayer under complex conditions.The research content can also provide reference for design control and development of other types of active suspension systems.