| With the perfection of computer control technology,control theory and sensory measurement technology,the application of active vibration reduction technology in fields of aerospace,engineering machinery,vehicle and buildings and so on is wider and wider.However time-delay phenomenon existed in control system inevitably in actual practical application,which would have some influences on stability of system and control performance of control system,so researching and designing control system with time-delay factors has profound theoretical significance and high value of practical application.In this paper,time-delay damping control is introduced into vehicle control theory and the utilization of time-delay factor is studied in the vehicle engineering,its main contents as follows:1.Time delayed active control technology is applied to 1/4 nonlinear vehicle suspension model to suppress the car-body vibration.The method of multiple scales is employed to deduce the relationship between the vibration of the primary system and the delay,and analyze the stability of the system.The RMS(root mean square)of the system vibration amplitude is used as the optimized object function,whose optimal feedback gain and time delay are obtained by optimization technique,and time domain simulation and analysis is presented.The results show that the damping effect of suspension system can be effectively improved by using the nonlinear and time-delay feedback control.2.A two-degree-of-freedom dynamics system is established,which is based on the nonlinear suspension system with time-delay damping control.At first,numerical simulation analysis is done for dynamics system,which is used to study chaos dynamic properties of nonlinear suspension system with time-delay.Then,the optimal time-delay and feedback gain are obtained by using optimization method with objective function of root mean square of the main system amplitude,and it is compared with the nonlinear suspension system with no delay.At last,the paper investigated the effect of delay control parameters on the behavior of system dynamics,and the results show different bifurcations and different routes to chaos under different control parameters based on the same system.The results show that reasonable selection of time delay control parameters can avoid the chaos phenomena and improve the quality of system and the vibration reduction and the quality improvement of system can be achieved at the same time.The different bifurcation and their different routes to chaos are also found.3.Experimental study was conducted for time-delay damping control of car body.For design of test bed and measurement and control system,it primarily designed the whole structure of test bed and the electromagnetic actuator was designed according to the control requirement.By experiment,the mechanical property parameters of the electromagnetic actuator were also obtained.And then,appropriate measuring transducer was selected to design measurement and control circuit and software control model to make further preparation for experiment.At last,time-delay control test was performed respectively under step excitation and harmonic excitation and excellent damping effect was obtained in both experiments and the effect of time-delay control on system damping was testified.Study in the paper indicated that time-delay damping has good application value in vehicle engineering.Though it may worsen the dynamic behavior of system,the time-delay control parameters that are reasonably selected can restrain vibration of car body and meanwhile improve the nonlinear kinetics behavior of system,transforming adverse effect into favorable function,and provide a theoretical basis and reference for simulated analysis and the optimal design of the suspension system. |
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