Papers by Author: Jun Feng Hu

Abstract: The comparative analysis of a parabolic and hyperbolic flexible hinges were presented. The closed-form compliance equations in the working and non-working plane can be derived by using the Castigliano’s second theorem. In order to compare the relative performance of parabolic and hyperbolic flexure hinges, a ratio function between specific compliances of the two hinges is defined. We analyzed the non-dimensional ratios of working plane and non-working plane compliance to show the relative properties of parabolic versus hyperbolic flexure hinges. The analysis results has showed compared to a hyperbolic flexure, a parabolic flexure can produce more desired output and is slightly less sensitive to axial effects under identical loading conditions. Meanwhile, the comparative study on the parabolic and hyperbolic flexure hinges can provide a theoretical basis for choosing them.

Abstract: A discrete sliding mode control based on reaching law is investigated to suppress vibration of high-speed flexible manipulator. The finite element method and experimental modal test is applied to obtain the dynamic model of the system. Due to the influence from uncertain external disturbances and measurement noise, and uncertain parameters, sliding mode control has invariance of the sliding mode. The discrete sliding mode control approach with reaching law is applied to design the vibration controller which enables the system to be zero state as the system states are away from the equilibrium one due to external disturbances. The discrete Kalman filtering technique is employed to construct state estimator because the state variables cannot be directly measured. The first three natural frequencies and damping ratio are obtained by using experimental modal testing. The experimental control system is constructed and experimental validation is carried out using dSPACE real-time simulation system and MATLAB/Simulink. The experimental results showed that the proposed controller can effectively suppress the vibration response of the flexible manipulator.

Abstract: Considering the increasingly wider applications of flexible hinge in the fields of micro-electromechanical and micro-positioning etc., the optimal design method of a parabolic flexible hinge is presented. According to the structure feature and force exerted on the flexible hinge, the closed-form flexibility expressions in the working and non-working plane can be derived by using the Castigliano’s second theorem. Meanwhile, the accuracy analysis of the parabolic flexure hinge is performed. The rotation angle of flexure hinge in the working plane is treated as objective function, and the constraints of optimization model are displacements in the non-working plane and one described the accuracy of hinge, such that the optimization model expressed performance requirements of flexure hinge can be established. Based on the optimization model, the optimization designs of parabolic flexure hinge are accomplished to acquire the optimized structural parameters. In conclusion, the study on the optimization design of the parabolic flexure hinge can provide a theoretical basis for its engineering applications

Abstract: In order to the effects of structural sizes of a hyperbolic on its performance, sensitivity and accuracy analysis are performed in this paper. According to the structure feature and force exerted on the flexible hinge, the closed-form equations are formulated for compliances to characterize both the active rotation and all other in- and out-of-plane parasitic motions by using the Castigliano’s second theorem. Meanwhile, the accuracy equations are obtained using the Castigliano’s second theorem. According to the closed-form flexibility formulas, the effects of the four structural parameters, such as thickness, notch depth, length and width, on the flexibility of flexible hinge are analyzed, respectively. In order to study further the effects of the structural parameters on its flexibility, we derive the sensitivity equations, and the sensitivity analysis is carried out. Meanwhile, the accuracy analysis of the hyperbolic flexure hinge is performed. The analysis results have shown that the parameters have large influence on in-plane compliance, and have small effects on out-of-plane one. And the changes are larger within initial small range of parameters, while be small variation in larger size range. And the length has no effect of sensitivity.