Research On Synthesis Optimization And Control Of Vehicle ISD Suspension Based On ADD Positive Real Network

As a new type of two-terminal mass element,the introduction of inerter makes up for the lack of mass impedance in the mechanical network based on "spring-damper" in traditional vehicle suspension system.It provides a new theoretical basis for further improving the performance of vehicle suspension,and becomes one of the hot spot in the field of vehicle engineering and vibration control.Based on the electromechanical similarity theory,the vehicle passive ISD suspension including "Inerter-Spring-Damper" is a typical passive mechanical network system.The introduction of mass impedance can significantly improve the vibration transmission characteristics of suspension system in low frequency band,but the effect is not so obvious in other frequency bands.Therefore,considering the features of vehicle ISD suspension in low frequency,how to isolate the vibration in the middle-high frequency range to obtain a wide frequency range transmission characteristics has important engineering value and research significance.Aiming at the vibration suppression problem of vehicle ISD suspension in wide frequency bands,this paper applies ADD network synthesis theory which combines the vibration suppression advantages of ADD theory in high frequency bands with passive network synthesis methods of ISD suspension in low frequency bands.The vehicle ISD suspension with a new type of ball screw mechatronic inerter is taken as the object of analysis.In this paper,the problem of keeping the vibration down in wide frequency domain of vehicle suspension has been transformed into a positive real optimal control problem based on ADD network synthesis.This paper has deeply studied the following problems,including creative design method of mechatronic inerter,coupling mechanism of ADD control theory and positive real network synthesis,positive real optimization design method of ISD suspension,and dynamic modeling of vehicle ISD suspension based on add positive real network and coordinated control mechanism.The purpose is to further improve the dynamic performance of vehicle ISD suspension system and provides a new guidance for suspension system design and control.Firstly,a steady-state switching design method for the mechatronic inerter has been proposed by studying the inertial inverse effect of the flywheel in the ball-screw inerter when it changes direction.The coupling design of ball screw inerter and unidirectional clutch is carried out to reduce the influence of inertial inverse effect on the ideal mechanical output in the flywheel reversing process.Through the analysis of the working process,the dynamic model of ball screw inerter and rotary motor is built,the dynamic model of a new type of mechatronic inerter is constructed,the mechanical properties output of the mechatronic inerter is simulated and analyzed,the influence law of motor inductance and resistance on the performance output is studied,and the non-linear factors of the mechatronic inerter are summarized.These lay the foundation for the dynamic modeling of vehicle ISD suspension system.Secondly,an ideal model optimization design method of vehicle ISD suspension based on ADD positive real network has been proposed by studying the coupling mechanism between ADD control and positive real network.The wide frequency domain vibration suppression of vehicle ISD suspension is transformed into a real optimization control problem based on ADD network synthesis.The ideal model of vehicle ISD suspension based on ADD positive real network is constructed,which utilizes the characteristics of passive vehicle ISD suspension network with inerter to suppress the low frequency vibration and classical ADD control to suppress the middle-high frequency vibration.The effect of the first-order ADD positive real network and the second-order ADD positive real network on the performance improvement of suspension system is simulated and analyzed,which illustrates that the performance of suspension would increase with the order of positive-real networks.The theory has proved that ADD network synthesis method can realize wide frequency vibration suppression of vehicle ISD suspension,which provides theoretical support for the dynamic modeling and control of vehicle ISD suspension.Thirdly,the dynamic model of vehicle ISD suspension based on ADD positive real network and its coordinated control mechanism has been constructed.Considering the constraints of the positive real mechanical network system and the dynamic performance of suspension,the second-order ADD positive real network is taken as the ideal reference model of vehicle ISD suspension system.By designing error dynamic equation and sliding mode switching function,a sliding mode variable structure control system based on Radial Basis Function(RBF)neural network is constructed,which realizes the dynamic coordinated control of vehicle ISD suspension using the new type of mechatronic inerter.Then,the Lyapunov function method is used to analyze the system stability.Under different road input conditions,the vibration isolation performance of vehicle ISD suspension system is simulated and studied.The root mean square of vehicle body acceleration decreases by 26.7% compared with that of passive suspension,and 15.2% compared with that of passive ISD suspension.The goal of isolating the wide range vibration of vehicle ISD suspension is achieved by means of ISD suspension network in low frequency vibration and ADD control in middle-high frequency vibration.Fourthly,a prototype of new type of ball screw mechatronic inerter is developed and its mechanical properties are tested.Through the structure selection and parameter design of ball screw inerter,rotary motor and unidirectional clutch,a new prototype of mechatronic inerter is developed.By comparing the mechanical properties of the traditional ball screw inerter with that of the new ball screw inerter,the effectiveness of the steady-state switching design method of the new ball screw inerter is verified.The mechanical properties of mechatronic inerter with and without external loads are tested.The mechanical output characteristics of the prototype of the new ball screw type mechatronic inerter are analyzed by means of system identification method.The dynamic performance of the new mechatronic inerter is verified.Finally,a prototype of the vehicle ISD suspension system has been built to test its performance.The vehicle ISD suspension control system is developed by employing the dSPACE development of prototype system.Taking the traditional passive suspension as the contrast object,the working performance of suspension system is tested under different road input conditions.Results indicate that,under sinusoidal displacement input conditions,the root-mean-square of vehicle body acceleration significantly decreases in wide frequency.Under the random road displacement input conditions,the root-mean-square of vehicle controllable ISD suspension's vehicle body acceleration declines up to 24.5% compared with that of traditional passive suspension,and the maximum reduction is 12.7% compared with that of vehicle passive ISD suspension.Under the impulse road input condition,the peak-to-peak value of vehicle controllable ISD suspension's vehicle body acceleration decreases by 22.9% compared with that of passive suspension,and 11.5% compared with that of passive ISD suspension.Experimental results showes that,the vehicle controllable ISD suspension can improve the suspension performance effectively and isolate the wide frequency vibration.To sum up,this paper has studied the integrated optimization and control of vehicle ISD suspension based on ADD positive real network and has realized the goal of wide frequency range vibration isolation,through combining the ideas of using the positive-real vehicle ISD suspension system to suppress low frequency vibration and classical ADD control to suppress middle-high frequency vibration.The research will provide theory evidence and methodological guidance for further enriching the design and dynamic control of vehicle ISD suspension system.