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Macau, China

Macau University of Science and Technology is a university located in Macau, China on the Cotai Strip opposite the Venetian Macau on Taipa Island, next to the Macau International Airport. It is a private institution managed by the MUST Foundation and the first college established after the handover of Macau to the People’s Republic of China. The university offers full-time and part-time programs.The General Studies programs, the School of Graduate Studies and the School of Continuing Studies offer a broad range of programs. MUST is authorized to award Ph.D. degrees, master degrees and bachelor degrees in their residence programs. The university enrolls 5,000 full-time students. MUST recruits students from all over the world as well as 20 provinces and cities in Mainland China for its undergraduate and graduate programs. Wikipedia.

Xu Q.,Macau University of Science and Technology
IEEE Transactions on Robotics | Year: 2013

Delicate interaction control is a crucial issue for automated microsystems dedicated to microobjects handling. This paper proposes a new approach to regulate both position and contact force of a piezoelectric-bimorph microgripper for micromanipulation and microassembly applications. The methodology is developed based on the framework of a discrete-time sliding mode generalized impedance control with adaptive switching gain. One unique feature lies in its easy implementation based on a second-order dynamic model, whereas neither a state observer nor a hysteresis/creep model of the system is required. The stability of the control system is proved in theory, which ensures the tracking performance in the presence of model uncertainties and disturbances. The effectiveness of the scheme is validated by experimental investigations on grasp operation of a microgear. Results show that the approach is capable of accomplishing precision position/force control simultaneously. Moreover, the influences of control gains and target impedance parameters on the tracking performance are addressed, and the achievement of balance between the position and force control accuracy is discussed. © 2004-2012 IEEE.

Xu Q.,Macau University of Science and Technology
IEEE Transactions on Industrial Electronics | Year: 2013

This paper presents a new approach for hysteresis identification and compensation of piezoelectric actuators by resorting to an intelligent hysteresis model. In particular, a least squares support vector machine (LSSVM)-based hysteresis model is developed and used for both purposes of hysteresis identification and hysteresis compensation. By this way, the hysteresis inverse is not needed in the feedforward hysteresis compensator since the hysteresis model is directly used. To establish the LSSVM model, the problem of how to select input variables to convert the multivalued mapping into a single-valued one is addressed. The effectiveness of the presented idea is validated by a series of experimental studies on a piezoactuated system. Results show that the proposed approach is superior to the Bouc-Wen-model-based one in terms of both hysteresis modeling and compensation. The reported method is more computational effective than existing model-based hysteresis compensation approaches, and it is extensible to other smart actuator systems as well. © 1982-2012 IEEE.

Xu Q.,Macau University of Science and Technology
IEEE Transactions on Automation Science and Engineering | Year: 2012

Dual-servo systems (DSSs) are highly desirable in micro-/nanomanipulation when high positioning accuracy, long stroke motion, and high servo bandwidth are required simultaneously. This paper presents the design and development of a new flexure-based dual-stage nanopositioning system. A coarse voice coil motor (VCM) and a fine piezoelectric stack actuator (PSA) are adopted to provide long stroke and quick response, respectively. A new decoupling design is carried out to minimize the interference behavior between the coarse and fine stages by taking into account actuation schemes as well as guiding mechanism implementations. Both analytical results and finite-element model (FEM) results show that the system is capable of over 10 mm traveling, while possessing a compact structure. To verify the decoupling property, a single-input-single- output (SISO) control scheme is realized on a prototype to demonstrate the performance of the DSS without considering the interference behavior. Experimental results not only confirm the superiority of the dual-servo stage over the standalone coarse stage but reveal the effectiveness of the proposed idea of decoupling design. © 2004-2012 IEEE.

Yuen K.-V.,Macau University of Science and Technology
Mechanical Systems and Signal Processing | Year: 2012

The problem of model updating for mechanical or structural systems is addressed by using incomplete modal measurement. The proposed method requires only the modal frequencies and mode shapes at some selected degrees of freedom for a few modes. The method updates the mass and stiffness matrix without imposing any parameterization and it utilizes the information from both the nominal finite-element model and the modal data. The method is computationally efficient as neither iteration nor numerical optimization is required. It does not require computation of the complete set of eigenvalues and eigenvectors of the nominal model. Instead, only the ones corresponding to the observed modes are needed. The method first updates the modal frequencies. Then, an efficient algorithm is presented to construct a transformation matrix. This matrix is used to correct the nominal eigenvectors so that the updated model is compatible with the measurement of the eigenvectors. A twelve-degree-of-freedom truss is used to provide insights of the proposed method. Finally, a 1600-degree-of- freedom spring-mass system is considered to illustrate the efficiency of the proposed method for large structure. © 2011 Elsevier Ltd. All rights reserved.

Li X.,Macau University of Science and Technology
IEEE Transactions on Power Electronics | Year: 2014

In this paper, a high-frequency isolated dual-bridge LLC-type resonant converter is proposed. The steady-state analysis of the proposed converter is performed using a modified fundamental harmonics approximation approach, by which the component stress can be obtained quickly without complicated calculation. Necessary and sufficient conditions for zero-voltage switching of all switches are derived too. To illustrate the usefulness of the FHA analysis for a fast design, a design example of a 100 kHz, 200 V input, 40-48 V output 300 W converter is given. Computer simulation and experiment results are included for the purpose of validation. It is shown that this converter is able to maintain zero-voltage switching operation for a wide load range while keeping high efficiency. © 2013 IEEE.

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