Research On Servo System Of Linear Actuator For Active Suspension

Due to the performance limitations of traditional passive suspensions,the active suspension technology that can improve driving smoothness and handling stability of the car,represents the future of car suspension system.For better driving experience,based on this technology this paper designed an effective active suspension with a linear actuator servo system.Firstly,a quarter-car driving dynamics suspension model and a road model with continuous and discrete disturbance are established.Taking the suspension system evaluation index as the optimization variable,the active suspension LQR controller is designed based on the linear optimal control strategy.Using the front suspension parameters of an SUV model,simulation verifies the effectiveness of the controller and summarizes the requirements of the driving force output system.Then,this paper analysis the structural principle of the linear actuator,using the dq-axis mathematical model and finite element simulation technology to analyze its operating characteristics and transient characteristics.A servo strategy based on magnetic field vector orientation(FOC)and current feedback decoupling is developed.Through the simulation analysis of the LQR controller and FOC servo system,it was found that the body acceleration under the two road disturbances,compared with the passive suspension,the active suspension has an improvement of more than 40%.With floating-point DSP and intelligent power module as the core,taking the safety and functionality of the system into consideration,a linear actuator software and hardware system is designed.Finally,this paper studies on the effectiveness of the servo system and the active suspension.Through the typical input signal tracking test,it is found that the response time to step signal is25 ms,and the tracking accuracy and stability error are less than 3% of the ideal value.Both simulation and test can meet the requirements of the active suspension.In the driving force tracking test,the signal response is rapid.In the active suspension hardware-in-the-loop test,the active suspension can reduce the body acceleration and suspension working space by an average of 30% under the interference of two road surfaces.It shows that the servo system this paper proposed can effectively reduce the body vibration caused by uneven road surface and improve the driving smoothness of the vehicle.