Performance Simulation Of ISD Suspension And Test Research Of Actuator Based On Skyhook-inertance Control

With its performance superior to the passive suspension and its cost inferior to the active suspension,the semi-active suspension has been a main technical direction of suspension system development.The skyhook-damping control is a kind of semi-active suspension control method,of which the algorithm is simple,reliable,and is able to improve the ride comfort effectively.However,skyhook-damping control can’t improve the ride comfort of the vehicle and the changed natural frequency in unload condition radically.In addition,the semi-active suspension is based on classical vibration isolation theory and SD（spring damper）suspension structure,further improvements of suspension performance is restricted as well as conventional passive suspension.With the appearance of inerter and proposal of ISD（Inerter-Spring-Damper）suspension structure,the restrained inherent concept of suspension technology development is rid of,and restrict of classical vibration isolation theory to suspension performance is broken through,providing a new platform for suspension technology development.Based on a continuously adjustable inerter developed in the thesis,this paperproposeda skyhook-inertance control method to adjust the‘soft’and‘hard’mode indirectly and developed a semi-active ISD suspension of which the inertance is adjustable.The skyhook-inertance control can achieve better adaptability in unload condition as well as road condition,improving the ride comfort effectively.Study on semi-active ISD suspension and its relating control method can not only accelerate further development of controllable suspension technology,but also lay a foundation for engineering of semi-active ISD suspension.Firstly,this paper designed a hydraulic continuously adjustable inerter and established a mathmatical model.According to theoretical analysis,the significant design parameter of hydraulic continuously adjustable inerter,that is damping inertance ratio,and relating parameters is obtained.And then,a prototype is developed.Secondly,a skyhook-inertance control method is proposed and a mechanical impedance model is established in this section.It is verified that vehicle with skyhook-inertance control has better adaptability in unload condition according to simulation analysis.Meanwhile,by adjusting the skyhook-inertance ratio b_skyky dynamically,the vehicle applied with skyhook-inertance control could adjust the‘soft’and‘hard’mode indirectly to adapt to the change of road condition,improving the ride comfort.Thirdly,based on hydraulic continuously adjustable inerter designed in the thesis,semi-active implement method of skyhook-inertanceis proposed,and a dynamic model of skyhook inerter semi-active suspension was established to study the performance benefits of skyhook inerter semi-active suspension both in time domain and frequency domain.Meanwhile,with respect to the parasitic damping problem caused by actuator device,the influence of parasitic damping on suspension performance is studied.The results show that,compared with the traditional suspension in unload condition,29.3%improvement can be achieved in terms of natural frequency of skyhook inerter suspension,and improvements of38.1%and 38.3%are obtained for the root mean square of the body acceleration and the dynamic tyre load of the skyhook inerter suspension.Under the random road input,improvement of 21.9%is obtained for the root mean square of the body acceleration compared with conventional suspension in unload condition.Further study shows that the smaller the ratio of the parasitic to the inertance is,the more obvious performance improvements is.Finally,a rig test of skyhook inertersuspensionwas carried out.The inertial characteristic and damping characteristic of the continuously adjustable inerter were studied through quasi-static characteristic tests and dynamic mechanical property tests.Test results shown that a well-designed damping inertance ratio of hydraulic continuously adjustable inerter is able to satisfy the engineering requirement of skyhook inerter suspension.