Design Of The Strategy For Semi-active Suspension With Double Skyhook Control By Hardware-in-the-loop Simulation

Semi-active suspension can take into account the requirements of vehicle handling stability and ride comfort,and meet the goal of pursuing the best cost performance.It has become the main direction of development suspension systems.The main research of semiactive suspension is focused on the design of the control strategy and the adjustable shock absorber.As the earliest proposed control strategy,Skyhook damping control strategy is widely used in semi-active suspension systems for its simple and reliable performance,the skyhook damping control can be used to change the "soft and hard" of the suspension by dynamically adjust the damping value,which can improve the performance of the car in various road conditions.However,the skyhook damping control cannot change the natural frequency of the car,so the ride comfort is quite different under empty and full load conditions.On the contrary,the semi-active suspension with skyhook inertance control can improve the ride comfort of the vehicle under different load conditions,but does not involve damping adjustment,so it cannot adapt to complex road conditions.Therefore,this paper combines the characteristics of the skyhook inertance control and the skyhook damping control to propose a double skyhook controlled semi-active suspension and its semi-active implementation plan,and builds a Hardware-in-loop simulation platform based on the controller in loop to verify the logical correctness and feasibility of the double skyhook control strategy.The double skyhook control strategy is expected to solve the problem that the existing semi-active control suspension cannot adapt to the load and road conditions at the same time.Firstly,the electromechanical similarity theory and the load adaptability principle of skyhook inertance control with the road condition adaptability principle of skyhook damping control are introduced to propose the ideal double skyhook suspension system.According to the load and road conditions,the control parameters of the double skyhook suspension are determined and optimized based on the genetic algorithm.The impedance model of the double skyhook suspension is established based on the electromechanical similarity theory.The load adaptability and road condition adaptability of the double skyhook suspension is theoretically verified through frequency domain simulation.Secondly,considering the practical application of engineering,an actuator with combined adjustable inertance and damping is designed.A mathematical model of the inertial force and damping force are established for the proposed actuator.The coupling relationship between the inertance and damping force are defined.The characteristic of the actuator’s output force changing with the displacement of the valve is found.Thirdly,the controller of the double skyhook control semi-active suspension is designed,and a hierarchical control strategy is proposed.The upper control strategy statically adapts the inertance of the double skyhook system according to the load changes,and dynamically adapts the damping value of the double skyhook system according to the changes of road conditions.The lower-level control strategy tracks the changes in the inertial force and damping force of the upper-level control strategy,and adjusts the actuator to simulate the inertial force and damping force of the ideal double skyhook suspension system.A dynamic model of the semi-active suspension based on double skyhook control is built and analyzed in the time domain and frequency domain.The results show that the semi-active suspension proposed has load and road condition adaptabilityFinally,in order to verify the effectiveness of the semi-active control strategy of the double skyhook control,a hardware-in-the-loop simulation platform was built based on the controller in loop,and the hardware-in-the-loop experiment was carried out.The simulation results were basically consistent with the test results,which verified the control strategy of the double skyhook control is logical correctness and feasibility.