Design and Experimental Study of a VCM-Based Stewart Parallel Mechanism Used for Active Vibration Isolation

Weichao Chi,Dongwei Wang,Dengqing Cao,Wenhu Huang,Jie Tang,Yifan Nie

doi:10.3390/en8088001

Abstract

This paper presents the design and experimental study of a voice coil motor (VCM)-based Stewart platform used for active vibration isolation. The high precision payloads carried on the satellites always require an extremely stable environment to work properly. Installing a vibration isolation device between the vibration sources and precision payloads is an efficient method for dissipating vibration energy. A Stewart platform with active damping is designed to isolate the vibration transferring from the satellite to the payloads in six degrees-of-freedom. First, the kinematics and dynamical equations of a Stewart platform with spherical joints at both the base and top of each leg are established with Newton-Euler Method in task space and joint space. Second, the H∞ Control Theory is employed to design a robust controller for the linearized system with parameter uncertainty, noise and sensor errors. Finally, an experimentation study on the vibration of the payload supported by a Stewart platform with VCM actuator is conducted. The feasibility and effectiveness of the vibration isolation system are verified by comparing the amplitude-frequency characteristics of the active control system with that of the passive control system and the system without damping.

Highlights

In aerospace engineering, an extremely stable environment is increasingly desired to ensure high precision payloads such as cameras, telescopes, interferometers and laser communicators etc. carried on satellites can work properly
A voice coil motor (VCM)-based Stewart platform used for active vibration isolation of the payload carried on spacecraft has been studied in several aspects
The kinematics and dynamical equations of the Stewart platform with spherical joints at both the base and top of each leg have been established with the Newton-Euler Method in task space for the purpose of fully isolating the payload from the vibration source in multiple DOF

Summary

Introduction

An extremely stable environment is increasingly desired to ensure high precision payloads such as cameras, telescopes, interferometers and laser communicators etc. carried on satellites can work properly. Satellites always carry several vibration sources such as reaction wheels, solar array drives and cryo-coolers, etc. Under such conditions vibration isolation systems which are fixed between the vibration sources and precision payloads to prevent the transmission of vibrations have become critical components. Passive damping methods are widely used in the vibration isolation of structures due to the reliability and lower cost of a passive device. They consist of mass-spring-damper systems whose parameters are adjusted for the whole structure and do not need a power input. Employing a nonlinear passive isolator may be a practical way to overcome the vibration amplification problem in traditional linear passive isolation (see the study on the resonant responses of a nonlinear oscillator under harmonic excitations in [1,2])

Methods

Results

Conclusion