Digital Commons Network^™

Investigation And Implementation Of A Robust Temperature Control Algorithm For Friction Stir Welding, Kenneth A. Ross

Theses and Dissertations

In friction stir welding, the temperature of the process zone affects the properties of the resulting weld and has a dramatic effect on tool life in PCBN (polycrystalline cubic boron nitride) tools. Therefore an active control system that changes process parameters to control weld temperature is desirable. Mayfield and Sorensen proposed a two-stage control model that contains an inner loop that controls the spindle speed to keep power constant and an outer loop for setting the desired power based on weld temperature. This work contains the analysis and implementation of a temperature control method based on their work. This research …

Development Of A Particle Flow Test For Rotational Molding, Russell B. Whatcott

Theses and Dissertations

One of the current testing method (the Dry Flow test) to qualify resin for use in production in the rotomolding process has been shown to have many flaws in both equipment and procedure. Research was done here to investigate a possible alternative that could eliminate some of these testing deficiencies. By reducing equipment and operator errors, the testing of materials becomes more valuable of an exercise. The Angular Flow test developed in this research can increase repeatability. By coming to understand the rotational molding process better, an evaluation that can give more valid information was devised.

Active Minimization Of Acoustic Energy Density To Attenuate Radiated Noise From A Diesel Generator, Andrew J. Boone

Theses and Dissertations

The focus of this thesis was to use active noise control (ANC) to globally minimize the tonal and broadband noise radiating from a diesel generator enclosure. The major goal of this research was to show that minimizing the noise within the enclosure can lead to an overall sound pressure level (SPL) reduction of radiated noise. The target levels for overall SPL reduction were at least 2 dBA. The control algorithms used in this research were based on a filtered-x LMS adaptive algorithm, which minimizes energy density (ED). Both feedforward and feedback control approaches were investigated. The noise spectrum produced by …

Settling-Time Improvements In Positioning Machines Subject To Nonlinear Friction Using Adaptive Impulse Control, Tim Hakala

Theses and Dissertations

A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These …

An Open Architecture For Versatile Machine And Actuator Control, Michael Scott Baxter

Theses and Dissertations

Automatic control technology increases usability, reliability and productivity in manufacturing, transportation, and climate control. There are many additional areas of modern life that could benefit through automatic control; however, current automation components are too expensive or aren't sufficiently flexible. For example, the cost of current commercial motion control components precludes their use in an average home. This thesis describes an automatic control methodology that is low cost and is flexible enough for a wide variety of control applications. Typical applications could include:

- Home lighting, security and appliances

- Commercial building heating, ventilation and air conditioning

- Industrial machine tool …