Position detection and vibration monitoring system using quad-cell optical beam power distribution

In this paper, we study the accuracy of an optical vibration sensing system using Gaussian beam analysis. The proposed optical system uses a He-Ne laser source whose Gaussian beam impinges on a quad-cell photodetector array. The normalized optical power for each cell is obtained through numerical simulation based on the well-known Gaussian beam optics formulation, as the beam scans the plane of the photodetectors due to vibration. The system detection principle lies upon finding a relationship between the power distribution of the quad-cell and the position of the beam centroid, which allows us to identify the characteristics of the vibration applied, such as direction, frequency and strength. The aspects of practical implementation and experimental limitations on the power distribution accuracy are discussed and the discrepancies with the theoretical results are presented.     

Modeling and control of a piezoelectric actuator driven system with asymmetric hysteresis

This study describes the high-precision positioning control of a system with asymmetric hysteresis. A switching system concept is adopted to describe the Preisach-type hysteresis, and a systematic modeling procedure is established to obtain the parameters of the system. A piezoelectric actuator system driven by a voltage amplifier is used to verify the modeling accuracy. A control structure, comprising a feedforward controller and a PD-type feedback controller, is used to realize the high-precision positioning control of the piezoelectric actuator driven stage. To enhance tracking control, a high-frequency modified term is incorporated into the hysteresis model. The experimental results confirm that the addition of this modified term reduces the tracking error and prevents the controlling energy from being saturated.     

Slip energy recovery of a rotor-side field oriented controlled wound rotor induction motor fed by matrix converter

This paper investigates rotor-side field oriented control of a wound-rotor induction motor using the slip energy recovery principle. The proposed drive system uses a matrix converter to transfer the slip energy from the rotor into the mains instead of using ac-dc-ac converter whilst the stator side is fixed to the grid. Operation at both subsynchronous and supersynchronous regions is possible with the proposed drive system. Simulation studies of the proposed doubly fed induction motor drive system verify the good control performance of the system in transient and steady-state conditions.