Honghao Yue

Parametric Design and Multiobjective Optimization of Maglev Actuators for Active Vibration Isolation System

The microvibration has a serious impact on science experiments on the space station and on image quality of high resolution satellites. As an important component of the active vibration isolation platform, the maglev actuator has a large stroke and exhibits excellent isolating performance benefiting from its noncontact characteristic. A maglev actuator with good linearity was designed in this paper. Fundamental features of the maglev actuator were obtained by finite element simulation. In order to minimize the coil weight and the heat dissipation of the maglev actuator, parametric design was carried out and multiobjective optimization based on the genetic algorithm was adopted. The optimized actuator has better mechanical properties than the initial one. Active vibration isolation platforms for different-scale payload were designed by changing the arrangement of the maglev actuators. The prototype to isolate vibration for small-scale payload was manufactured and the experiments for verifying the characteristics of the actuators were set up. The linearity of the actuator and the mechanical dynamic response of the vibration isolation platform were obtained. The experimental results highlight the effectiveness of the proposed design.

Measurement Model and Precision Analysis of Accelerometers for Maglev Vibration Isolation Platforms.

High precision measurement of acceleration levels is required to allow active control for vibration isolation platforms. It is necessary to propose an accelerometer configuration measurement model that yields such a high measuring precision. In this paper, an accelerometer configuration to improve measurement accuracy is proposed. The corresponding calculation formulas of the angular acceleration were derived through theoretical analysis. A method is presented to minimize angular acceleration noise based on analysis of the root mean square noise of the angular acceleration. Moreover, the influence of installation position errors and accelerometer orientation errors on the calculation precision of the angular acceleration is studied. Comparisons of the output differences between the proposed configuration and the previous planar triangle configuration under the same installation errors are conducted by simulation. The simulation results show that installation errors have a relatively small impact on the calculation accuracy of the proposed configuration. To further verify the high calculation precision of the proposed configuration, experiments are carried out for both the proposed configuration and the planar triangle configuration. On the basis of the results of simulations and experiments, it can be concluded that the proposed configuration has higher angular acceleration calculation precision and can be applied to different platforms.

Research on the 2-degree-of-freedom electromagnetic actuator in space:

To meet space science experiments in micro-gravity environment, micro-spacecraft vibration isolation technology was developed in recent years. A new kind of 2-degree-of-freedom electromagnetic actuator based on Lorentz principle was developed in this article. The composition and working principle of the actuator were introduced, the parametric model for electromagnetic actuator was established, the structural optimization was carried out with the help of genetic algorithm in the MATLAB toolbox, and the final optimal structural parameters were obtained. For achieving the magnetic induction intensity in radial and axial directions, theoretical model for electromagnetic characteristics of the 2-degree-of-freedom actuator was established, and the expression for electromagnetic force was obtained. A static electric–magnetic coupling simulation of the whole actuator and also the experiments for measuring magnetic induction and magnetic force were carried out, and the correctness of theoretical model was verified.

Study of space micro-vibration active isolation platform acceleration measurement

In order to realize the vibration isolation performance of space micro-vibration active isolation platform, it is necessary to measure the vibration accurately. A kind of nine accelerometers allocation scheme containing redundant information is proposed and the corresponding formulae are presented. Then, with the method of using linear accelerometers to measure six degrees-of-freedom (DOF) acceleration, the Kalman filter algorithm is applied for the processing of the acceleration signal. Both simulation and experiment results show that the use of redundant information and Kalman filter can reduce noise and improve accuracy effectively.

Application of Gene Structure and Mitosis Concepts to the Study and Design of Folding Mechanisms

The goal of this study was to develop a novel approach to the study and design of metamorphic mechanisms, based on a consideration of gene structure, mitosis, and cell fusion. In this study, we treat kinematic pairs as basic connection units that function similarly to the base pairs in DNA molecules and present expressions for the configuration of each kinematic pair in a mechanism. We also develop some methods to describe changes in the number of links, number of kinematic pairs, and pair features (type and configuration) during the folding process. Finally, we propose a method based on mitosis and cell fusion for studying the folding process and innovating mechanism design. In this method, a mechanism is first decomposed into some basic kinematic chains, and then these chains (with folding function) are fused into one complete mechanism. Two examples are presented to demonstrate the use of the methods proposed in this study. Overall, we found that, for innovation in mechanism design, it is useful to consider gene connection and mutation as well as mitosis and cell fusion.

Optimal layout method of distributed locking device of satellite based on plant root growth theory

The method of determining the optimal direction of satellite locking point is extended from the mechanical stability principle of plant roots growth under external loads. The method of topological optimization of the number and location of satellite locking units was proposed based on the adventitious root growth pattern of monocotyledons. Inspired by the fibrous root growth rhythm, the method for topological optimization of the effective contact interface shape of the satellite locking units is presented. A satellite finite element model and three-dimensional spring support model are established to lay the foundation for system frequency analysis. Parallel algorithm is used to optimize the position of the main locking points. One-dimensional search method is adopted to select the growth positions of the secondary locking points with the goal of maximizing fundamental frequency of the system. The relationship between the locking stiffness and system fundamental frequency is explored. Finally, the optimization results of this method are compared with those of conventional methods; the comparison demonstrated that the fundamental frequency of the locking system is significantly enhanced by the proposed method.

Research on folding suspension of multi-constrained rover based on the variation and fusion of rods and pairs

Planetary rovers with folding functions can solve the contradiction between the limited space of the vehicle and the functional diversity of the rover and greatly improve the efficiency–cost ratio of space launch activities. In this article, the multi-constrained quadrilateral suspension is considered based on the practical requirements of planetary detection. Based on graph theory and metamorphic theory, the structural characteristics and movement patterns of the rover are analyzed, the configuration transforming process of adding or decreasing the number of rods and kinematic pairs during folding is studied, and the corresponding mathematical model is established. The suspension of the rover is divided into three basic units, and the folding study is performed around each unit. The folding set of each unit type is given, and a feasible folding set is selected for each type of unit according to their structural characteristics and constraint conditions. At the same time, 15-folding schemes for the rover are given, and the optimal scheme is determined. According to the final folding scheme of the rover, the principle prototype of the rover is developed, and the functional experiment of the folding and unfolding is performed. The experimental results verify the feasibility and rationality of the folding scheme, indicating that the developed detection vehicle has a large fold ratio, which can fully adapt to the limited space inside the rocket. The theoretical and technical results can provide technical support for the engineering application of subsequent rovers with folding.

Research on a low-impact unlocking trigger device of heavy load based on shape memory alloy fiber:

With the increasingly precise and sensitive nature of space payload, the impact and vibration of the on-orbit unlocking process have become more serious. There is a particular need to develop a device to replace the traditional pyrotechnic device for the reliable connection and low-shock separation for space payloads. In this article, according to the demand of low impact and rapid release of space heavy load, an unlocked trigger device based on shape memory alloy fiber was proposed. Based on the material characteristics of shape memory alloy, the theoretical modeling and analysis of the unlocking trigger device were performed. Combined with the constitutive equation of shape memory alloy and typical boundary conditions, the stress–strain–temperature relationship of shape memory alloy fiber under one-dimensional state was deduced and obtained. A comprehensive performance test of the unlocking trigger device was designed and produced based on the requirement of the space application environment, and the response characteristics and actuation characteristics of shape memory alloy actuator were obtained. Based on the design requirements, a development and experimental study of the prototype shape memory alloy unlock trigger device was conducted. The results demonstrate that the unlocking device based on a shape memory alloy fiber designed in this article has fast unlocking response characteristics and good environmental adaptability, which can provide technical support for space applications of large space load and low-impact locking mechanisms.

Simulation of Multi-Closed Loop Control With Feed Forward Control of Micro-Vibration Isolation Platform

Micro vibration in the ideal-zero gravity environments has complicated science experiment results. A magnetic levitation vibration isolation platform is needed to isolate the vibration source to provide acceptable acceleration level in low frequency range. The configuration of the Lorentz actuators is discussed in the paper. And the modeling of the transformation matrix from the force to the current is deduced. In order to generate desired force, the current is needed to predict precisely. To study the characteristics of the system, the single degree of freedom system is analyzed. A multi-closed loop control scheme is put forward to achieve vibration isolation control. To evaluate the effect of each control parameter, frequency domain analysis of the transfer function is simulated. In order to further increase the control effectiveness, a feed forward compensation control algorithm is added to control the vibration of cables that connect the upper platform and the base. By regulating these control parameters, bode curves can be obtained. Comparing the two methods, it can be concluded that the control method with feed forward compensation is better than the one without that.Copyright