Active Control For Vehicle Active Suspension System With Proportional Differential Slinging Mode Observer

Automobile suspension system is a very important component in the vehicle.A welldesigned suspension system can improve the overall performance of the vehicle chassis,improve the comfort of the passengers and ensure the safety of the vehicle.With the further improvement of the living standard,people put forward higher requirements for the comfort of the car.Once the traditional passive suspension is designed,the system parameters cannot be changed,which limits the further improvement of vehicle performance.Active suspension has external energy and can continuously adjust the energy flow to adapt to a wide range of external interference,so as to meet the requirements of vehicle comfort.The core of active suspension design is the control strategy,and its effectiveness and related data processing scheme are related to the performance of active suspension system.This topic aims at the core problem in the design of automobile active suspension system--control algorithm design for theoretical research and experimental verification,so as to improve the ride comfort and driving safety performance.The main research content can be summarized as follows:(1)In order to accurately measure suspension state variables and uncertainties,a proportional differential sliding mode observer is designed for the nonlinear active suspension system with uncertainty.The established proportional differential sliding mode observer is used to estimate the state and uncertainty of the system.According to the estimation of the observer,the corresponding control feedback strategy can be designed.The closed-loop system is stable and can offset the influence of uncertainty and external disturbance on the active suspension system.(2)In order to better deal with the nonlinear problem,a differential geometry method is proposed to linearize the nonlinear suspension system.The sliding mode surface function is defined and the sliding mode controller is designed by isokinetic approximation law.Then,according to the Hurwite stability condition satisfied by the equivalent equation of sliding mode motion,the sliding mode surface coefficient is selected.The fuzzy controller can adjust the switching control gain adaptively according to the condition of sliding mode surface arrival to realize buffeting effect of sliding mode control force and reduce control energy consumption.(3)In order to ensure the stability of nonlinear active suspension with uncertainty,actuator faults,sensor faults and external disturbances,the technology of fault detection,diagnosis and isolation of active suspension is proposed.Through LMI optimization,the reachability condition of estimation error dynamics is established,which facilitates the determination of design parameters.Then,based on fault reconstruction,a fault tolerant controller is designed to maintain the stability of the suspension system.(4)In order to realize the active suspension pitch angle fast stability and reduce energy consumption,a compound adaptive inversion control is proposed.Simulation results show that compared with the traditional adaptive controller based on projection operator,the composite adaptive inversion controller can effectively improve the ride comfort,running stability and driving safety of vehicles.Finally,the power calculation formula is introduced.According to the simulation results,the composite adaptive algorithm is slightly better than the conventional adaptive algorithm in energy saving.