Stochastic Optimal Control Of Random Vibration Of Strongly Nonlinear Tank Model

Tank vehicles often travel on rough roads,and excessive body vibration will seriously affect the operational performance and battlefield viability of tank vehicles.Therefore,the vibration control of tank vehicles is an important research topic.The use of intelligent suspension can make driving stable and improve the operational performance of tanks.However,the current researches on intelligent suspension are mostly based on linear two-degree-of-freedom suspension model.The torsion-bar-support suspension used in tank vehicles leads to the strong nonlinear vibration due to bar rotation.The nonlinear random vibration control of tank vehicles is very different from that of other ordinary vehicles.Therefore,the stochastic optimal control of the random vibration of the non-linear tank model is a new research area.Based on this background,the main work of this paper can be concluded as follows:1 Based on a more practical and complicated nonlinear vehicle system with torsion-bar-support suspension,the vertical coupling motion between suspension and wheel is considered,and the MR damper is used for the vibration control of the vehicle system under random road excitation.The dynamic differential equations of the two-DOF vehicle system with MR damper are established.According to the stochastic dynamic programming principle,the Hamilton-Jacobi-Bellman(HJB)equation is established.Based on the equation and control boundedness of the MR damper,the feedback control law is designed by Bang-Bang control.By comparing the response of semi-active control and passive control under random road excitation with different strengths and speeds,the control effectiveness of the proposed strategy is evaluated.In the actual control system,control delay is unavoidable.For time-delay control systems,the current control force is determined by the state before r seconds(time delay),and then the influence of control time delay is analyzed.The numerical results show that the designed feedback control law can greatly reduce the random vibration of tank system,and the control delay will reduce the effectiveness of the proposed strategy.2 For the asymmetric non-linear dynamic equation of the two-degree-of-freedom tank model,it is found that the displacement response center of the system deviates from the equilibrium position.Therefore,in view of this special phenomenon,a simplified one-degree-of-freedom system equation is constructed,and the "zero drift"phenomenon of the response is studied by Harmonic Balance Method,so as to explore the causes of the "zero drift".The numerical results show that the main reason for the"zero drift" is the asymmetric term in the system equation.When the asymmetric term disappears,the "zero drift" phenomenon also disappears.3 For the uncertainty of control system model,minimax optimal control is used as a robust control strategy.By considering the boundedness of the uncertain parameters and MR damper control,the optimal control law of the worst-perturbation system is designed based on the programming equation and constraints,which has good robustness;Numerical results illustrate that the proposed minimax semi-active bounded control can effectively mitigate the nonlinear stochastic vibration of the uncertain torsion-bar-suspension vehicle system under random road excitation.4 For the partially observable nonlinear system,considering the influence of observation noise and the boundedness of MR damper control,the optimally estimated state is determined by the observation based on the extended Kalman filter,then the optimal control law dependent on the estimated state is determined;The numerical results illustrate that the designed optimal control strategy for partially observable nonlinear systems has good control effectiveness and robustness.