Papers by Author: Zhi Yong Zhang

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Authors: Xiao Yao Zhou, Zhi Yong Zhang, Lian Chao Zhang, Da Peng Fan
Abstract: A fuzzy weighted attitude estimation algorithm is proposed to settle the problem of attitude determination for Optronics Mast Systems (OMS) by combining gyros and inclinometers. Firstly, Euler representation is employed to descript attitude kinematics, and then nonlinear continuum state space model is derived, based on analysis of mathematic model of gyros and inclinometer. Secondly, EKF is used to linear and discrete the models, and a weighted measurement update equation of attitude and gyro drifts is developed under kalman Filter framework. Lastly, according to the relations between the weighted value and body motion, a weighted value determination method is proposed based on fuzzy reasoning system. The experience results show that the accuracy of attitude estimation algorithm is 0.0380. The algorithm also solves the problem of vibration disturber of inclinometer and measure error of gyros in long term.
Authors: Zhi Yong Zhang, Qing Kun Zhou
Abstract: The construction and the operating principle of the novel micro-angular vibration testbed (MAVT) are presented, the MAVT is designed to complete the angular performance testing for the micro sensor and parts such as MEMS-gyro, angular accelerometer. A systemic design procedure of the optimized flexure hinge and general voice coil actuator (VCA) to fine single-axis MAVT actuator are introduced for fast and precision actuation. A method for measuring frequency response function by means of a displacement sensor electric eddy current sensor is designed. To verify the performance of the designed MAVT, frequency response of the system are performed, the differential equation of the pull-tilting motion is established according to the Lagranges equation, the formula of the natural frequency is derived, and the model analysis of the MAVT is also carried out with the help of limited element analysis. The static stiffness experiments show that the angular stroke of the MAVT is 1° and preliminary tests performed on the closed-loop control system indicate that angular resolution of 1 can be achieved. Model experiments performed on the prototype of MAVT are presented and the theoretic result fits with the result of experiment (250Hz). For fast and precision actuation performances, design parameters are selected based on the dynamic model of VCA and flexure hinge, and design process is completed. The model results can be provided for the construction design of the MAVT. Conventional platforms of angular performance testing are bulky and costly. Analysis and experiments results indicate that the novel MAVT is an efficient platform to complete the angular performance testing for micro sensor and parts.
Authors: Ya Fei Lu, Da Peng Fan, De Jun Sheng, Zhi Yong Zhang
Abstract: A brief overview of previously built Electro-Optical Tracking system reveals a trend toward smaller, more agile systems. Steel cable drive technology is an alternative to gearbox, belt and pulleys, chains and sprocket and other currently available transmission for several significant advantages, which includes backlash free, high stiffness, high efficiency, no lubrication etc.. As a new type of drive form, there were several key tradeoffs for the cable drive application, which will be developed and subjected in detail in this paper. Firstly Transmission principle and properties of cable drive is studied. Secondly, related design considerations of cable drive will be implemented and researched in detail, including the cable selection and capstan design, cable-groove matching strategy and cable tensioning design. Finally, actual application example of precise steel cable drive is presented for an Electro-Optical tracking gimbals, and performances tested validate the significant advantages of precise cable drive technology.
Authors: Qing Kun Zhou, Sheng Jian Bai, Zhi Yong Zhang
Abstract: The design of variable structure system inputs which are constrained by saturation is studied. For a LTI system which satisfies some conditions, it is shown that appropriate bounded controllers guarantee the system’s global stability and maximize the sliding mode domain on the switching surfaces. Stability conditions of variable structure systems with constrained inputs are relaxed, and the stability of the closed-loop system is guaranteed by using passivity theory of linear passive systems. Moreover, nonlinear sliding surfaces are discussed for variable structure controller design, and a novel nonlinear switching surface is proposed. Finally, the proposed methods are applied to a 2nd order LTI system to show their usefulness.
Authors: Hua Jie Hong, W. Luo, Zhi Yong Zhang, Lian Chao Zhang, Da Peng Fan
Abstract: It is proposed that the integration of learning, researching and production provides a good solution to the problem that higher education fails to offer qualified graduates demanded by machinery manufacturing industry. This paper first analyses the weakness of enterprises in scientific research and creativity and inexperience of higher education institutes in transferring scientific achievements, then some advice is given as to how to improve the innovative integration mode followed by some successful cases. At last it goes deeper into the future tendency of this mode.
Authors: Qing Kun Zhou, Ya Fei Lu, Da Peng Fan, Zhi Yong Zhang, Lian Chao Zhang
Abstract: A novel compliant linear buffer mechanism (CLBM) is designed for impact isolation. In view of the incompatible relationship between frequency characteristic and parasitic error of compliant linear mechanism, the mixed compliant linear mechanism(MCLM) is proposed by combining the Lumped Compliant Mechanism(LCM) and the Distributed Compliant Mechanism(DCM).The topology matrices for four kinds of parallelogram linear compliant mechanisms are built through the method of type synthesis. The characteristic polynominal (CP) for the compliant mechanism matrices[CM] are calculated for the isomorphism detection of compliant mechanism. The finite element analysis (FEA) model of these four kinds of linear compliant mechanism is built to complete numerical analysis on the structure frequency and parasitic error with different sizes, and the relationship between the frequency characteristic and parasitic error of the compliant linear mechanism is found out. MatlabTM software is used to obtain the functional formulas by the method of polynomial curve fitting (PCF) for The FEA results show that the structure configuration of MCLM can achieve a higher structure frequency and a greater kinetic precision over the pure LCM and DCM at the same time, and also indicates that the analysis method of frequency characteristic and parasitic error for compliant mechanism is efficient and should be effective on the structure optimization of the novel CLBM.
Authors: Ya Fei Lu, Xiao Yao Zhou, Da Peng Fan, Zhi Yong Zhang
Abstract: Butterfly pivot is a large-travel rotational flexure pivot, which can provide elastic support for the rotational shaft in several ten degrees. Rotational precision is of great important for its application. Because of the complex structure, rotational precision is always taken with Finite Element Method (FEM), which is not suitable for design and optimize parametrically. The structure property of the butterfly pivot is analyzed before the precision analysis. Four-Blade Isosceles-Trapezoid Element is present as the basic structure unit of the Butterfly Pivot. And then, Rotational precision of the Four-blade Isosceles-Trapezoid unit is calculated and analyzed. The Self-Compensation performance of the butterfly Pivot is also studied. Work in this thesis can validate the high rotational precision of the butterfly pivot.
Authors: Ya Fei Lu, Qing Kun Zhou, De Jun Sheng, Da Peng Fan, Zhi Yong Zhang
Abstract: Butterfly pivot is a large-travel rotational flexure pivot, which can provide elastic support for the rotational shaft in several ten degrees. Because of the complex structure, stiffness calculation of butterfly pivot is always completed by the method of Finite Element Analysis (FEA), which is not suitable for parameter design and optimization. The serial structure of four-blade isosceles-trapezoid (FBIT)is proposed to simplified the complex structure of the butterfly pivot. The FBIT is analyzed and the theoretical formula of stiffness calculation for rotation stiffness is derived in detail based on the essential theory of Mechanics of Materials. Design and optimization of rotation stiffness for each element can be achieved easily with the obtained the theoretical formula of rotation stiffness. The total rotation stiffness of the whole butterfly pivot is calculated and the rotation stiffness comparison between using the theoretical method and by the method of FEA is performed. The error between the theoretical rotation stiffness and the result of the FEA is less than 10%. It is acceptable and without any influence on the validity of the work and concept presented in this paper.
Authors: Ya Fei Lu, Mo Hei, Zhi Yong Zhang, Da Peng Fan
Abstract: Precise cable drive has been developed as an alternative transmission element to gearbox, belt and pulleys, chains and sprocket in Electro-Optical Tracking system. Precise cable drive has several significant advantages including backlash free, high stiffness, high efficiency, no lubrication etc. This paper develops analytical methods to predict the transverse oscillation frequency of precise cable drive to enable designers to better assess dynamic performance in the design study phase. Theoretical formulation of transverse oscillation equation for precise cable drive is carried out based on Hamiltons principle taking into account flexural rigidity of cable. Furthermore, the transverse oscillation frequency is obtained from the transverse oscillation equation assuming small and linear vibration. Parametric studies are conducted to evaluate the relationship between the oscillation properties and cable drive parameters.
Authors: Qing Kun Zhou, Zhi Yong Zhang, Da Peng Fan, Hua Jie Hong
Abstract: This paper presents a novel compliant linear guided mechanism (CLGM) to replace traditional spring and translation joint to transfer motion and force with its advanced guiding characteristics. In view of the incompatible relationship between axial stiffness and transverse stiffness of CLGM, eight kinds of CLGMs were developed by using building block approach based on fixed-guided flexure beam. The finite element analysis (FEA) models of eight CLGMs were built to complete numerical analysis on the force-displacement in axis and off-axis direction with same geometric sizes. The FEA results show that the structure configuration of Type 2-Type 8 can achieve a larger axial travel, Type 2 and Type4 have the advanced guiding characteristic with higher ratio of axial/transverse stiffness. Analysis indicates that the building block approach is an efficient method to complete the conceptual synthesis of compliant mechanism and FEA is effective on the structure optimization for the required compliance and stiffness in axial and transverse direction.
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