Design And Research Of Quasi Zero Stiffness Vibration Isolation Platform For Three DOF Parallel Mechanism

Low-frequency,multi-directional vibration isolation system has always been a difficult and hot spot in the field of vibration control.The quasi-zero stiffness system is an effective way to achieve low-frequency or ultra-low frequency vibration isolation.This subject designed a new quasi-zero stiffness vibration isolation platform based on the 3P-Delta parallel mechanism to achieve the purpose of low frequency and multi-directional vibration isolation.The main research contents and results of this article are as follows:(1)A new 3P-Delta parallel mechanism with three translation degrees of freedom was designed based on the configuration evolution method.The kinematics model of the 3P-Delta parallel mechanism was established,and its position inverse solution,forward position solution and velocity Jacobian were calculated.(2)According to the quasi-zero stiffness theory,the conditions for the system to obtain quasi-zero stiffness were calculated,and the influence of the structural parameters such as the pre-compression of the horizontal spring and the spring stiffness on the static characteristics of the zero-stiffness system was discussed.Using the harmonic balance method,the amplitude-frequency characteristic and vibration displacement transfer rate of the quasi-zero stiffness system were obtained.The jump phenomenon in the amplitude-frequency characteristic curve was analyzed.The effect of the excitation amplitude on the vibration displacement transfer rate curve was discussed.(3)Combining the principle of negative stiffness mechanism and parallel mechanism,a quasi-zero stiffness vibration isolation platform of 3P-Delta parallel mechanism was designed.Through theoretical calculations,the mechanical characteristics of the vibration isolation platform in the respective degrees of freedom were studied.The quasi-zero stiffness vibration isolation platform has approximately linear static characteristics in the X and Y directions,and quasi-zero stiffness characteristics in the Z direction.Test verification was conducted on the vibrationisolation platform.(4)A virtual prototype model of the quasi-zero stiffness vibration isolation platform of the 3P-Delta parallel mechanism was established with ADAMS software.The kinematics simulation results are compared with the theoretical calculation results to verify the correctness of the virtual prototype model.(5)Through the simulation of ADAMS virtual prototype,the dynamic characteristics of the quasi-zero stiffness vibration isolation platform of the 3P-Delta parallel mechanism are studied,and the frequency response and vibration of the quasi-zero stiffness vibration isolation platform of the 3P-Delta parallel mechanism in the Z direction and horizontal direction are obtained.The displacement transmission rate,the Z-direction natural frequency of the vibration isolation platform obtained from the peak of the frequency response curve is basically consistent with the theoretical calculation result.The simulation shows that the quasi-zero stiffness vibration isolation platform of the 3P-Delta parallel mechanism is a quasi-zero stiffness vibration isolation system in the Z direction,which has a very low natural frequency and vibration displacement transmission rate,and is approximately a linear vibration isolation system in the horizontal direction.