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This paper presents the design of a new monolithic twoaxis electrostatically actuated MEMS microgripper with integrated capacitive position and force sensors working at the micro-scale level. Each of the two jaws of the microgripper possesses two degrees-of-freedom (DOF) and is capable of positioning in both x-and y-axes. Unlike existing works, where one gripper arm is actuated and other one is sensed, both arms of the proposed microgripper are actuated and sensed independently. A sensing scheme is constructed to provide the position and force signals in the noncontact and contact phases, respectively. By applying a 120V driving voltage, the jaw can provide 70 μm x-axis and 18 μm y-axis displacements with the force of 190 μN. By this design, the real-time position and grasping force information can be obtained in the dual sensing mode. Both analytical calculation and finite-element analysis (FEA) were performed to verify the performance of the proposed design. A scaled-up prototype is designed, fabricated and tested through the experiment to verify the structure design of the microgripper.

A micro-/nanopositioning system with both large motion range and compact size is highly desired in various precision engineering applications. In this paper, the design of a new compliant micropositioning stage with translational motion is proposed based on flexure mechanisms. The stage parameters are optimized by using the genetic algorithm (GA) to achieve a large natural frequency under the constraints on motion range (i.e., over 10 mm) and compact physical dimension along with a high safety factor for the material. Both analytical calculations and simulations based on finite element analysis are performed to validate the stage performances. A physical prototype system which employs a voice coil motor and a laser displacement sensor for actuation and sensing, respectively, is fabricated for experimental tests. Result confirms the long-stroke performance of the developed micropositioning system.

Rectangular section parts created through hydroforming have good application prospects in the automotive industry because of their advantages of simple manufacturing procedure, high forming quality, and greater bending module than circular cross-sectional parts. Forming quality is directly influenced by the formed corner parameters of rectangular section parts. It is also a difficult matter in rectangular section hydroforming. The hydroforming rules of an aluminum alloy circular tube are regarded as the research object in this study to investigate the rules of square cross-sectional parts in the hydroforming process. First, the mechanical parameters of the molding material are obtained through experiments. Second, a hydroforming experimental system is self-designed, and tube hydroforming without axial feed is investigated to determine the key parameters of tube forming. Simulation analysis is then conducted for the entire process of tube hydroforming using the nonlinear finite element software DYNAFORM. The finite element model and the correctness of the calculation method are verified by comparing their results with the experimental results. Thereafter, the influence of internal pressure, friction coefficient, and loading path on pipe forming quality is examined. Necessary references are provided for engineering applications.

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