Research On Electro-hydraulic Control Of Torsional Vibration Isolator Based On Combined Positive And Negative Stiffness In Parallel

The main factor that affects the passenger comfort is the low frequency vibration,which is produced during driving.And the low-frequency vibration would cause fatigue damage for the components and equipment on the vehicle,influencing its service life.The parallel structure with positive and negative stiffness is widely used in the research of low-frequency vibration isolation due to its high static and low dynamic stiffness.In this paper,taking the torsional isolator with negative stiffness structures as the research object,the research of electro-hydraulic servo control system carried out under the condition that the bearing average torque is variational.First,the mechanism and structure of the torsional isolator with negative stiffness structures is introduced.Based on the test results of the vibration reduction effect under the condition that the bearing average torque is variational,the requirements of the electrohydraulic servo controller of the torsional isolator with negative stiffness structures are determined.The main components’ mathematical models of the electro-hydraulic servo system are established.Based on the AMESim simulation platform,the physical model of the electro-hydraulic servo system is built.It provides with the theoretical basis and simulation platform for the research of electro-hydraulic servo system control strategy.The model of a positive and negative stiffness parallel torsion damper is established.And the stiffness characteristics and bearing characteristics of torsional isolator with negative stiffness structures are analyzed.Then,the control margin of the semi-active control system is calculated.Taking the stability of negative stiffness structures as the control objective,the control algorithm of electro-hydraulic servo system is studied.The simulink control system model using sliding mode variable-structure control is established.With joint simulation of AMESim and MATLAB,the motion state analysis of the negative stiffness structures is performed,which can verify the performance of such control method.Aimed at the negative stiffness structures’ motion state under sliding mode variablestructure control and the chattering problem in the switching process of the sliding mode control systems,the control algorithm of the electro-hydraulic servo system is optimized.The idea of fuzzy control is introduced into sliding mode variable structure control algorithm.The fuzzy control is used to adjust the value of the reaching law parameter in sliding mode variable-structure control,thus the control chattering of the negative stiffness structures reduce during the switching process and the motion stability of the negative stiffness structures is improved.The control strategy is validated by using d SPACE real-time simulation system and Rapid ECU rapid control prototype.The hardware-in-the-loop simulation test platform is built up.Based on the existing the torsional isolator with negative stiffness structures platform and electro-hydraulic system test bench,the experimental research is carried out under the bearing average torque changing,to verify the correctness of the control strategy of the electro-hydraulic servo system and the vibration isolation performance of the torsional isolator with negative stiffness structures.The experimental data showed that the optimal control strategy can force the negative stiffness structures move to a designated position stably with improving the vibration isolation performance of the torsional isolator with negative stiffness structures.