Research On Semi-active Control Of Rail Vehicle Suspension System

With the acceleration of the speed of our rail vehicles,the margin of stability and safety of vehicle operation is gradually shrinking.At present,the vertical stability of rail vehicles in my country can basically meet the requirements,but the lateral vibration of the vehicle body leads to poor lateral stability of the vehicle,and its safety is also affected.One of the reasons is that the traditional passive control suspension system is difficult to meet the higher requirements for stability and safety when the vehicle runs at high speed due to the limitation of parameters.Therefore,improving and upgrading the control of rail vehicle suspension systems is one of the effective ways to improve vehicle dynamics.In this paper,taking a certain type of rail vehicle as the research object,the simulation software Simpack and Matlab/Simulink co-simulation method are used to simulate and analyze the vehicles whose secondary suspension lateral shock absorbers adopt passive control,skyhook damping control and fuzzy skyhook control respectively.The work content and results are as follows:(1)A fully passively controlled vehicle dynamics model was built through the software Simpack,and its dynamic performance in straight and curved segments was analyzed.The results showed that with the increase of vehicle speed,the vehicle dynamics index became larger and larger,and when the vehicle speed was 250 km At /h,the Sperling index is 2.396,and the maximum wheel load reduction rate is 0.79,all close to the limit.It shows that it is difficult for a completely passively controlled suspension system to meet the higher requirements for stability and safety when the vehicle is running at high speed.(2)The co-simulation platform is built by the simulation software Matlab/Simulink and Simpack,and the feasibility and correctness of the co-simulation platform are verified.Based on the switch-type skyhook damping control algorithm,a control system is built in Simulink,with the vehicle model in Simpack is co-simulated to realize the semi-active control of the lateral shock absorber of the secondary suspension of the vehicle.The simulation results show that compared with passive control,the Sperling index dropped from 2.396 to 1.93,and the stability increased by 19.4%;and for the safety of the vehicle,the two control indexes alternately took the upper hand,which proves that the switch-type ceiling damping control can effectively improve the running stability of the vehicle compared with the passive control.performance,but it cannot be improved or even reduced the operating safety of the vehicle.(3)In order to solve the problem of the skyhook damping control strategy,fuzzy control theory was introduced into the switch-type skyhook damping control method,and a new control method—fuzzy skyhook damping semi-active control was established The research results show that the improvement rate of Sperling index is 16.5-19.4% and 26.3-28.2%respectively for vehicles using switch-type skyhook damping semi-active control and fuzzy skyhook semi-active control,and the average value of safety index of fuzzy skyhook control is always the smallest.Therefore,it is proved that the fuzzy skyhook damping semi-active control can more effectively improve the running stability of the vehicle,and also has advantages compared with the other two controls in the running safety of the vehicle.The research results lay a foundation for improving the ride comfort of rail vehicles and ensuring the safe and stable operation of the vehicles,and have certain theoretical and application values.