Date of Award

Fall 2000

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical Engineering

Committee Director

Oscar R. Gonzalez

Committee Member

W. Steven Gray

Committee Member

Colin P. Britcher

Call Number for Print

Special Collections LD4331.E55 J327

Abstract

This thesis presents studies related to the magnetic suspension and balance system (MSBS) of the Princeton/ONR High Reynolds Number Testing Facility (HRTF). The main motivation for developing the MSBS is to provide interference free aero/hydrodynamic testing of submersible models, which will lead to more accurate measurements. From the controls point of view, the main specification of the MSBS is to robustly control the position of a submersible model in five degrees of freedom (DOF), including three translational as well as pitching and yawing positions. The MSBS should not only regulate the submersible model's position but should also allow for small motions around the specified 5 DOF position in the presence of aerodynamic wind tunnel disturbances. The MSBS consists of ten electromagnets, a cooling system for the coils, power amplifiers, a dSpace real-time controller hardware, and laser sensors. The MSBS software consists of a graphical user interface (GUI) developed using tools from Matlab/Simulink and dSpace control system software. A unique feature of this MSBS is that the electromagnets are placed outside a two inches thick stainless steel pipe. This arrangement, required for economic reasons, imposes limitations on the achievable performance by limiting the magnetic field and introducing eddy currents in the stainless steel pipe. These limitations are included in the design of the controller.

A linear quadratic multiple input multiple output (MIMO) LQ compensator is designed using loop transfer recovery (LTR) techniques to stabilize and regulate the model inside the test section of the HTRF. Procedures for tuning of the MIMO controller are developed. Practical concerns, i.e., amplifier dynamics, eddy current effects, disturbances due to aerodynamic forces and torques, and B-coefficient uncertainties, are taken into account during the design phase of the controller. The stability robustness of the LQG/LTR compensator is validated by time domain analysis of the closed-loop system consisting of the controller and a complete nonlinear model of the MSBS.

An interactive graphical user interface is developed for operation and maintenance of the HTRF-MSBS. Important system components, including hardware interfacing, software workbench, protection interlocking, operational modes, and operational procedures, are defined and implemented.

The design and implementation of a I DOF system that was used to validate the hardware and software is also presented. A classical linear lead-lag controller and a sliding mode controller are designed, analyzed, and implemented for the I DOF magnetic suspension and balance system.

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DOI

10.25777/5r36-jc32

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