Design And Control Of Vehicle Dynamic Inertial Suspension Based On General Skyhook-groundhook Hybrid Principle

The proposed concept of inerter triggered a paradigm shift in mechanical dynamics research.The mechanical network has evolved from a "mass-spring-damper" network with a single-terminal element: mass to an "inerter-spring-damper" network with a two-terminal element: inerter.The mechanical network can correspond with electrical network strictly with the concept of inerter.The research methods and technologies for filtering in the electrical network can be transferred to solve the problems of vibration transmission and suppression in mechanical network.In recent years,the vehicle dynamic inertial suspension system with "inerter-spring-damper" elements has gradually become one of the state-of-the-art in the field of the vehicle suspension.How to effectively use the inerter,match the inerter with the suspension control strategy,innovate the suspension design,and further improve the vehicle ride comfort and road friendliness are the core issues of the next generation suspension.In this dissertation,a general skyhook-groundhook hybrid（Gen Hook）principle is proposed.To improve the performance of the vehicle’s ride comfort and road friendliness,the design of vehicle dynamic inertial suspension with Gen Hook（Gen Hook suspension）is researched.The research aims are:（1）solve the conflict among performance indexes of "spring-damper" suspension,further apply the inerter in mechanical network and control;（2）improve the ride comfort and road friendliness performance of vehicle;（3）provide a new research perspective for suspension design and control.This dissertation reveals the limitations in impedance matching and control phase of conventional skyhook damper theory,conventional ground damper theory,and conventional hybrid damper theory.The Gen Hook principle is proposed based on the electrical-mechanical analogy and control principle to break the limitations of conventional skyhook-groundhook theory.The hybrid mechanism,dynamic inertial suspension model,and the phase-difference of control strategy are analyzed.The vibration isolation performance of Gen Hook suspension is simulated and compared with conventional passive suspension.The vibration suppression of general mechanical network elements is analyzed based on Gen Hook principle.The "body-dynamic inertia suspension-tire" coupling model is established.The Gen Hook suspension is designed by the structure method and impedance method,respectively.The adaptive step-length artificial fish swarm algorithm is used to optimize the Gen Hook suspension parameters.The random road input simulation results of the Gen Hook suspension reveal that compared with conventional suspension,the performance of the ideal model of Gen Hook suspension is significantly improved.To realize the coefficient adjustment of the inerter,this dissertation designs a controllable fluid inerter（CFI）device on the basis of the electro-hydraulic analogy.A linear CFI model and two nonlinear models of CFI device are established,analyzed,and compared.Besides,the adverse effects of the mixed gas condition on the CFI device are researched.It provides a good theoretical foundation for the manufacture of CFI devices.A prototype of the CFI device is manufactured and its bench test is carried out.The test results show that the CFI device realizes the coefficient adjustment and can meet the requirement of the controllable strategy of Gen Hook suspension.The cooperative control between the damper and the inerter is required to semi-active realization of the ideal model of Gen Hook suspension.The selection,modeling,and testing for the magnetorheological damper are accomplished.The magic formula mechanical model of the magnetorheological damper was established.The main parameters of magnetorheological damper were identified with bench tests,and the mapping relationship between its output force and its control current is established.A vehicle suspension with general hybrid control（GHC）suspension is proposed.The CFI device and magnetorheological damper device are coordinately controlled to realize the control force of the ideal Gen Hook suspension.The force transmission characteristics of the ideal Gen Hook suspension are studied.Random road simulation results show that,compared with conventional suspension,can improve the vehicle body acceleration root-mean-square value more than 20% at speeds of 10 m/s,20 m/s,and 30 m/s.Meanwhile,the suspension dynamic stroke and dynamic tire load root-mean-square value are also improved about 10%.Based on the prototype of the CFI device,a model of the vehicle GHC suspension is established on the hydraulic excitation platform.Taking the conventional "spring-damper" suspension as a reference,the vibration isolation performance of the GHC suspension is tested and analyzed under the conditions of sinusoidal road and random road,respectively.The sinusoidal test results show that:the GHC suspension enhances the suspension performance significantly at high frequency signal.Under random road conditions,the GHC suspension is tested at speeds of 10 m/s,20 m/s,and 30 m/s.The random test results show that: the root-mean-square of body acceleration is reduced by 16.65%,17.32%,and 16.24%,respectively.The root-mean-square value of the suspension dynamic stroke is reduced by 10.89%,11.60%,and 11.86%,respectively.And the root-mean-square value of the tire dynamic load is reduced by 9.96%,11.64%,and 12.13%,respectively.The Gen Hook principle proposed in this dissertation guides the design of vehicle dynamic inertial suspension.The GHC suspension can significantly improve the vehicle’s ride comfort and road friendliness.This dissertation provides novel ideas to improve the research of suspension vibration isolation and can extend application the engineering vibration isolation area.