Design of a Maglev Inertial Actuator with High Mass Power Ratio for Lateral Vibration Control of Propulsion Shafting

The maglev inertial actuators with high power and mass maybe effective for lateral vibration control of a propulsion shafting. But the mass power ratio of the actuators currently in use is too small to meet the requirements. In the paper, a maglev inertial actuator was innovatively designed with high mass power ratio. The structure of the magnetic circuit assembly and the suspending assembly were designed and optimized. To verify the property of the proposed maglev inertial actuator, a prototype with mass less than 8 kg was developed and tests were carried out. The minimum effective output force can reach 200 N within the frequency band of 20–300 Hz. A lateral vibration of a propulsion shafting system was constructed and the active control effect was tested. The experimental results show that the proposed maglev inertial actuator has a good effect on lateral vibration control of shafting.

Design, Optimization and Experimental Verification of a Metal Rubber Isolator for Momentum Wheels

The inertial actuator, such as momentum wheels, is the key mechanical component of spacecraft for attitude stability and accuracy maintenance. However, the inertial actuators are under excessive vibration during the rocket launch phase. In order to prevent the inertial actuators from structural damage and equipment failure, isolating vibration from the base must be considered. Metal rubber (MR) is a kind of porous functional damping material, manufactured through the process of entangling, stretching, weaving and molding of metallic wires. With its excellent mechanical properties of high damping, designable stiffness and environmental adaptability, MR is widely used in the area of aerospace and aviation for vibration isolation. To this end, a method to design and optimize a MR isolator for momentum wheels is developed. The MR isolator consists of a transverse groove spring and MR in parallel. A FEM model coupling the transverse groove spring and the simplified momentum wheel is established to assist in the optimization of the configuration of the spring, and the goal is to minimize the frequency bandwidth of the first six modes. The influence of the parameters on the frequency of the first six modes is also discussed. The MR is then designed to provide damping and additional stiffness. Finally, the performance of the MR isolator is analyzed by simulation and verified through experiments.

Nonlinear Stochastic Optimal Control Using Piezoelectric Stack Inertial Actuator

An optimal control strategy for the random vibration reduction of nonlinear structures using piezoelectric stack inertial actuator is proposed. First, the dynamic model of the nonlinear structure considering the dynamics of a piezoelectric stack inertial actuator is established, and the motion equation of the coupled system is described by a quasi-non-integrable-Hamiltonian system. Then, using the stochastic averaging method, this quasi-non-integrable-Hamiltonian system is reduced to a one-dimensional averaged system for total energy. The optimal control law is determined by establishing and solving the dynamic programming equation. The proposed control law is analytical and can be fully executed by a piezoelectric stack inertial actuator. The responses of optimally controlled and uncontrolled systems are obtained by solving the Fokker–Planck–Kolmogorov (FPK) equation to evaluate the control effectiveness of the proposed strategy. Numerical results show that our proposed control strategy is effective for random vibration reduction of the nonlinear structures using piezoelectric stack inertial actuator, and the theoretical method is verified by comparing with the simulation results.

Design of Tuneable Vibration Absorber by Using Inertial Actuator with Proof-Mass Acceleration Feedback

This study is concerned with design of a tuneable vibration absorber by using an inertial actuator (IA) with its proof-mass acceleration used as feedback signal. Acceleration feedback control loop can produce virtual mass effect, and the natural frequency of the IA can be shifted. The main advantage of the proposed IA-based tuneable vibration absorber is that the control loop is very simple and does not require any low-pass filter or integrator. Finally, the experimental results are presented to verify the tuning capability and control performance of the proposed vibration absorber.