Research On Active Suspension Control Algorithm Of Wheel Tractor

Wheel tractors are commonly used for traction and driving machinery in agricultural production operations.Because of their advantages of simple operation,large traction,adaptability to dry land and paddy fields,and convenient maintenance,they have been widely used in farmland operations and rural transportation.When driving on a field road,the accelerated acceleration of the tractor will resonate with the tire,resulting in insufficient comfort.When the agricultural implement is suspended,the balance of the center of gravity will easily cause the influence of the balance to restrict the driving stability.The traditional passive vibration reduction method cannot be well satisfied Suspension performance limits the further improvement of the performance of wheeled tractors.Because the active suspension system can dynamically adjust the stiffness and damping characteristics according to the road conditions under the action of the actuator,its application in wheeled tractor vibration reduction has a good application prospect.In view of the fact that actuators usually have nonlinear dead zones in actual control systems,the control signals cannot be output in specific zones of the dead zones.The dead zone phenomenon will cause steady-state errors of the control system and reduce the active suspension control performance.Therefore,it is of great significance to discuss the control algorithm of the active suspension system of the wheeled tractor with actuator dead zone.The main research work of this paper is as follows:(1)By describing the characteristics of the dead zone,the dynamic model of the active suspension with the characteristics of the active dead zone is established,the dynamic characteristics of the wheeled tractor suspension system are analyzed,and the equation of state is obtained.(2)For an active suspension system with dead zone input,an optimal control method is proposed.In the optimal controller design,by describing the dead zone in sections,within the dead zone range,it is equivalent to the passive suspension.Outside the dead zone range,it is equivalent to adding a dead zone feature to the traditional active suspension model input.The active suspension closed-loop system models in different dead zones are derived respectively.Discretization according to time history,through an iterative solution method,obtains the active suspension system response with actuator dead zone characteristics.(3)Robust control has better anti-interference performance for systems with uncertain parameters.A low-pass filter is used to simulate the dead zone as the input of the uncertain state space model of the actuator.A robust control scheme is proposed to study the robust control effect.At the same time,a single algorithm has limitations,integrating the advantages of adaptive and repetitive algorithms separately,carrying out robust adaptive and robust repetitive control,considering the specific parameters of the dead zone,and expressing the dead zone as a combination of linear input and bounded interference.The inverse of the zone achieves a certain offset effect,calculates the existence of the dead zone control law to obtain the active control force,and adjusts the adverse effects caused by the dead zone in the system.Lyapunov stability theory is used to prove the stability of the robust adaptive system,while considering the effect of the size of the dead zone parameters on the controller adjustment.(4)The simulation results show that the performance of the active suspension system with the optimal control scheme under the dead zone condition is not good enough to obtain good performance of the active suspension system.Robust controller adjustment can effectively reduce the negative impact of the dead zone on the system,effectively reduce the negative impact of the dead zone on the system,and ensure the stability of the active suspension system.Robust two integrated control algorithms can ensure the stability of the system,the robust repeat control has better adjustment performance,and the tracking accuracy is better than the robust adaptive control.Comparing the impact of the dead zone parameters on the system,it is found that within the dead zone range,as the interval increases,the system’s operating power demand is greater;as the slope increases,the output suppression of the actuator is more obvious.