Study on Oil Pressure Characteristics and Trajectory Tracking Control in the Electro-hydraulic Servo System of a Torsional Isolator with Negative Stiffness Structures

Abstract

In this paper, a semi-active torsional isolator with negative stiffness structures is presented, which can be extensively applied in low frequency torsional vibration isolation due to its high static load bearing capacity and low dynamic stiffness. The model and working principle of this semi-active torsional vibration isolator have been presented first. From the working principle of the isolation system, controlling the position of the negative stiffness structure is an effective method to achieve better vibration isolation performance during the different working conditions of the system. Then the dynamic models of negative stiffness Structure and electro-hydraulic servo system are built. Considering the nonlinearity of the electro-hydraulic servo system, a trajectory tracking model of oil pressure in electro-hydraulic system based on dynamic models of torsional isolator with negative stiffness structures and hydraulic control system are built. The sliding mode variable structure control method is used to achieve the working conditions of the average torque changes. Finally, the tracking effect is analyzed by numerical simulation. The results showed that oil pressure could follow the optimal trajectory by the sliding mode variable structure control method well and stably, and the vibration isolation performance of the isolator could be improved.