Research On Dynamic Analysis And Design Of High Performance Active Vibration Isolation System Structures

High performance active vibration isolation system (HPAVIS) is one of the most necessary guarantees for ultra-precision manufacturing equipment and measuring equipment. Because different types of precision equipment need vibration isolation systems with different performance, the mechanical structural design must balance the relationship between vibration isolation performance and manufacture cost. There are two critical questions need to be solved:the contradiction between low natural frequency and large support force; the contradiction between high-and low-frequency performance. In order to fulfill three typical vibration isolation performance requirements, dynamic analysis of the vibration isolation units, structure design of the HPAVIS, and experimental evaluation are studied in this dissertation. The results offered a theoretical guidance for design of HPAVIS.To improve the HPAVIS design economy, independent component analysis method is taken to deal with the pow frequency disturbing in micro-vibration signal; and a fast calculation formula for the generic vibration criteria is deduced to evaluating the micro-vibration’s level. The dynamic model of HPAVIS is deduced. A vibration isolation strategy which combines passive isolation and shyhook damping effects is employed to solve the contradiction between high-and low-frequency performances. Based on realistic micro-vibration characteristics and precision equipment vibration isolation requirement, the HPAVIS can be classified as ultra-low NF HPAVIS (≤1Hz),low NF HPAVIS (≤2Hz), and ordinary HPAVIS (<5Hz).In the ultra-low NF HPAVIS structure design, for solving the contradiction between low natural frequency and large support force, a novel concept by combing the positive stiffness spring with negative stiffness spring in parallel is presented. In order to offer theoretical guidance for design of ultra-low NF HPAVIS, the dynamical characteristics of several negative stiffness springs are studied. Parameters which affect the stiffness nonlinear of the magnetic negative stiffness mechanism are analyzed and optimized. After that, an ultra-low NF HPAVIS structure based on positive stiffness spring with negative stiffness spring in parallel is proposed. The performance of the ultra-low NF HPAVIS is measured. The results show that NF is about1Hz, and the transmissibility after2Hz is less than-20dB, the transmissibility after10Hz is less than-40dB.In low NF HPAVIS structure design, in order to overcome the tradeoff between the stiffness and static displacement in coil steel spring, the airspring and pendulum are taken as vibration isolation units. By theoretical derivation, experimental verification and simulation analysis, analytical models of the airspring and pendulum are established, and dynamics characteristics are analyzed. Based on the unit level analyses, the structure of the low NF HPAVIS based on airspring and pendulum is proposed and the prototype is designed. Then the6-DOFs dynamic model of low NF HPAVIS is deduced by Newton-Euler method, and the configuration of the actuators and senses are discussed. At last the low NF HPAVIS structure is validated through the experiments. The results demonstrate that the NF of the low NF HPAVIS is lower than2Hz, and the transmissibility at NF is less than-5dB.In ordinary HPAVIS structure design, the vibration isolation unit and platform are the key components having the great impact on the performance of HPAVIS. By employing particle swarm optimization approach, parameters of the coil steel spring are optimized. Besides, a box-shaped platform which has high stiffness, high modal frequency, and light weight is proposed and applied in ordinary HPAVIS. Then the prototype of the ordinary HPAVIS is manufactured and tested. The results show that the NF of the ordinary HPAVIS is lower than5Hz.Structure design of HPAVIS is the critical technology to realize the performance of HPAVIS. The research contents, methods and experimental conclusions are instructive and meaningful to HPAVIS structure design for requirements of different applications.