Decoupling Algorithms for the Gravitational Wave Spacecraft

The gravitational wave spacecraft is a complex multi-input multi-output dynamic system.The gravitational wave detection mission requires the spacecraft to achieve single spacecraft with two laser links and high-precision control.Establishing one spacecraftwith two laser links,compared to one spacecraft with a single laser link,requires an upgraded decoupling algorithmfor the link establishment.The decoupling algorithmwe designed reassigns the degrees of freedomand forces in the control loop to ensure sufficient degrees of freedomfor optical axis control.In addressing the distinct dynamic characteristics of different degrees of freedom,a transfer function compensation method is used in the decoupling process to further minimize motion coupling.The open-loop frequency response of the systemis obtained through simulation.The upgraded decoupling algorithms effectively reduce the open-loop frequency response by 30 dB.The transfer function compensation method efficiently suppresses the coupling of low-frequency noise.

A slope-based decoupling algorithm to simultaneously control dual deformable mirrors in a woofer–tweeter adaptive optics system

We propose a slope-based decoupling algorithm to simultaneously control the dual deformable mirrors （DMs） in a woofer-tweeter adaptive optics system. This algorithm can directly use the woofer＇s response matrix measured from a Shack-Hartmann wave-front sensor to construct a slope-based orthogonal basis, and then selectively distribute the large- amplitude low-order aberration to woofer DM and the remaining aberration to tweeter DM through the slope-based orthogonal basis. At the same moment, in order to avoid the two DMs generating opposite compensation, a constraint matrix used to reset tweeter control vector is convenient to be calculated with the slope-based orthogonal basis. Numeral simulation demonstrates that this algorithm has a good performance to control the adaptive optics system with dual DMs simultaneously. Compared with the typical decoupling algorithm, this algorithm can take full use of the compensation ability of woofer DM and release the stroke of tweeter DM to compensate high-order aberration. More importantly, it does not need to measure the accurate shape of tweeter＇s influence function and keeps better performance of restraining the coupling error with the continuous-dynamic aberration.

Reliability-based multidisciplinary design optimization using incremental shifting vector strategy and its application in electronic product design

Use of multidisciplinary analysis in reliabilitybased design optimization(RBDO) results in the emergence of the important method of reliability-based multidisciplinary design optimization(RBMDO). To enhance the efficiency and convergence of the overall solution process,a decoupling algorithm for RBMDO is proposed herein.Firstly, to decouple the multidisciplinary analysis using the individual disciplinary feasible(IDF) approach, the RBMDO is converted into a conventional form of RBDO. Secondly,the incremental shifting vector(ISV) strategy is adopted to decouple the nested optimization of RBDO into a sequential iteration process composed of design optimization and reliability analysis, thereby improving the efficiency significantly. Finally, the proposed RBMDO method is applied to the design of two actual electronic products: an aerial camera and a car pad. For these two applications, two RBMDO models are created, each containing several finite element models(FEMs) and relatively strong coupling between the involved disciplines. The computational results demonstrate the effectiveness of the proposed method.

Performance of an Adaptive Optics System with Dual Deformable Mirrors

One deformable mirror （DM） in conventional adaptive optics system can not meet the needs of large scale and high order aberration compensation. In this paper, a dual DMs way is presented, which needs the decoupling of dual DMs. In dual DMs adaptive optics （AO） system, the decoupling algorithm of dual DMs is deduced. Stroke of one of DMs is large, spatial frequency of the other is high. According to the algorithm, the large stroke DM （LSDM） corrects low order aberration only, and the high spatial frequency DM （HSFDM） corrects other aberration. The experimental result for two 61-DM AO system is presented. The result indicates that the experimental performance of dual DMs AO system is almost the same with that of the conventional AO system using single DM with ideal stroke and equivalent spatial frequency.

A New Design Method for Realizing Accurate Track of Hybrid-driven Five-bar Mechanism

The concept of virtual slider crank mechanism is proposed and decoupled to obtain parameters of controllable five bar mechanism without any principle error for any given trajectory. The model is simple and easy to solve. This method has no convergence,flexible workspace and singularity of the mechanism problem. Through this method,we don’ t need any curve to fit the trajectory point. Using MATLAB program to calculate,the computation time can be reduced to less than 3% of the original. Finally,an example is given to illustrate the method which is meanwhile compared with the traditional five bar design method.

Design and calibration of spoke piezoelectric six-dimensional force/torque sensor for space manipulator

The large manipulator outside the space cabin is a multi-degree of freedom actuator for space operations.In order to realize the automatic control and flexible operation of the space manipulator,a novel spoke structure piezoelectric six-dimensional force/torque sensor with redundancy ability,high stiffness and good decoupling performance is innovatively proposed.Based on the deformation coordination relationship,the redundancy measurement mechanism is revealed.The mathematical models of the sensor with and without branch fault are established respectively.The finite element model is established to verify the feasibility of structure and redundancy measuring principle of the sensor.Depending on the theoretical analysis and simulation analysis,the prototype of the sensor is developed.Static and dynamic calibration experiments are carried out.The actual output voltage signal of the six-dimensional force/torque sensor is collected to establish the equation between the standard input applied load and the actual output voltage signal.Based on ant colony optimized BP algorithm,performance indexes of the sensor with and without branch fault are analyzed respectively.The experimental results show that the spoke piezoelectric sixdimensional force/torque sensor with the eight-point support structure has good accuracy and reliability.Meanwhile,it has strong decoupling characteristic that can effectively shield the coupling between dimensions.The nonlinear errors and maximum interference errors of decoupled data with and without branch faults are less than 1% and 2%,respectively.The natural frequency of the sixdimensional force sensor can reach 2856.45 Hz and has good dynamic characteristics.The research content lays a theoretical and experimental foundation for the design,development and application of the new six-dimensional force/torque sensors with redundancy.Meanwhile,it will significantly improve the research level in this field,and provide a strong guarantee for the smooth implementation of force feedback control of the space station manipulator project.