Date of Award

Fall 1997

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering - (M.S.)

Department

Mechanical Engineering

First Advisor

Avraham Harnoy

Second Advisor

Bernard Friedland

Third Advisor

Zhiming Ji

Abstract

In this thesis, measurements of dynamic friction in a hydrodynamic journal bearing were performed for varying sinusoidal velocity excitations, loads, and lubricants. The results indicate that the friction data displays a negative slope in the mixed region of friction vs. velocity (f-v) curves, and also shows that the dynamic friction is not just a function of current velocity, but also a function of velocity history (hysteresis). These results are in agreement with previous experimental investigations by other investigators in lubricated friction.

Secondly, a dynamic friction model is fully explored and partially extended to provide quantitative agreement to measured friction values. A contribution to friction modeling was made by reducing the model from a fourth to a second order equation. Parameters were determined for one lubricant and two non-nal loads, and the model output is compared to experimental data.

Finally, model-based friction compensation was successfully performed. The dynamic friction model is used as a basis for velocity and position control of an apparatus with high friction by incorporating a function to constantly learn two parameters of the model. Results demonstrate the feasibility of using a rich friction model in real time, and its ability to greatly reduce the tracking errors caused by friction.

This thesis was supported by the National Science Foundation under Grant MSS9215636.

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