With the development of nanotechnology that contains automatic control, precision machinery and precise measurement, etc., micro/nano manipulation has become a new research direction in recent years. This paper presents the design and analysis procedures of a new high precision XY decoupled compact parallel micromanipulator (DCPM) for micro scale positioning applications. The DCPM is made up of the decoupler, two-stage amplifier and the piezoelectric translator (PZT) actuators, which utilizes the characteristics of flexure hinges. In this paper, firstly, a new two-stage bridge-principle amplifier is proposed by a serial connection of two fundamental bridge amplifiers in order to increase the ratio of amplification. It is pivotal for designing the micromanipulator. Then, the kinematic modeling of the micromanipulator is carried out by resorting to stiffness and compliance analysis via matrix method. Finally, the performance of the micromanipulator is validated by finite-element analysis (FEA) which is preliminary job for fabricating the prototype and designing the control system of the XY stage that is expected to be adopted into micro/nano manipulations.
A new variable exponential discrete-time sliding mode control (DSMC) reaching law is proposed to suppress the chattering phenomenon and accelerate the reaching speed for the switching function. The variable exponential reaching law consists of two-phase different exponential term. The main effect of the first phase exponential reaching law is to reduce reaching steps. The second phase exponential reaching law can decrease the magnitude of quasi-sliding-mode domain (QSMD). Otherwise, the disturbance term is restrained by second order difference function which can also significantly diminish the range of QSMD. The reaching steps of the reaching law to converge to QSMD are derived from this new reaching law. Meanwhile, the dynamic analysis of the DSMC system based on new reaching law is presented. Finally, the mathematical simulations are conducted to preliminarily verify the results of theoretical analysis.
In recent years, cable-driven parallel robots (CDPRs) have drawn more and more attention due to the properties of large workspace, large payload capacity, and ease of reconfiguration. In this paper, we present a kinematic and dynamic modeling and workspace analysis for a novel suspended CDPR which generates Schönflies motions. Firstly, the architecture of the robot is introduced, and the inverse and forward kinematic problems of the robot are solved through a geometrical approach. Then, the dynamic equation of the robot is derived by separately considering the moving platform and the drive trains. Based on the dynamic equation, the dynamic feasible workspace of the robot is determined under different values of accelerations. Finally, experiments are performed on a prototype of the robot to demonstrate the correctness of the derived models and workspace.
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