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The development of a chopstick-like two-fingered micromanipulator based on a hybrid mechanism is presented. The microhand consists of two 3-prismatic-revolute-spherical (PRS) parallel modules connected serially in a mirror image style. Each module has a long glass pipette as an end effector. The development process consists of three phases. In the first phase, analysis and mathematical modeling, a novel solution of the inverse kinematics problem (IKP) of a 3-revolute-prismatic-spherical (RPS) parallel module, is derived and applied with proper modification to the case of 3-PRS of the proposed mechanism. The solution is extended to the two-fingered hybrid mechanism of the microhand. In the optimization and design phase, the optimization of the chosen design parameters of a theoretical 3-PRS parallel module is carried out using two approaches: discretization method and genetic algorithms. Based on the optimal design parameters, a CAD model of the 3-PRS finger module is built, and a complementary optimization step using the ANSYS Workbench program is carried out to determine suitable characteristics of the pin flexure hinge. Finally, the total CAD model of the two-fingered hand is built. In the realization and implementation phase, the description of the hardware system of the two-fingered microhand prototype is presented. The program description, calibration method, practical Jacobian matrices, practical workspace, and error analysis of the prototype are discussed.
Date of Publication: April 2009