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Title Preview control of high mobility tracked vehicle suspension
Author Kim, Younsun
Type KAIST Ph.D. Dissertation
Year of Pub. 2003
The role of suspension system in tracked vehicles is important because the driving and running conditions of such vehicles are very severe. It reduces the vibration and shock which are generated by road profile in running condition. As the tracked vehicle’s running speed increases, undesirable vibration generated by road profile can be increased, particularly in the situation of field running. Because the excessive vibration can harm the operation ability of crewmen and stability of complex equipments, the maximum running speed is limited. In this study, to improve the performance of the tracked vehicle system, we examined the feasibility of using the active preview control for the tracked vehicle’s suspension system. Firstly, we developed a linear model of a tracked vehicle without the track subsystem. We proposed linear optimal preview controller for the linearized tracked vehicle system. To avoid the complexity of modeling the track subsystem and kinematical nonlinearity in trailing arm suspension system, we classified these as unknown dynamics and disturbances. We used Time Delay Control(TDC) method to make sprung mass dynamics follow that of linear preview controlled tracked vehicle model. We have verified by computer simulation that the proposed method shows good robustness to some uncertainty in modeling including the case when the actual unsprung mass is assumed to be twice heavier than the model parameters. To verify the performance of the proposed preview controller, we carried out the simulation with a multibody dynamics program realizing realistic tracked vehicle model including detailed track dynamics. We proposed a method to apply a robust $H_infity$ preview control to the tracked vehicle system. To derive the robust $H_infity$ preview control theory, we modified a robust control theory for linear discrete-time systems with norm bounded nonlinear uncertainties by augmenting previewed road profile signal. Through computer simulation with a simple tracked vehicle model, we verified that the robust preview controller can make the system stable even with system uncertainty. However, improvement in the ride comfort is not significant because of the conservatism in robust controller design.