Date of Award
Master of Science in Mechanical Engineering - (M.S.)
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.
Cohn, Simon, "Dynamic friction measurement, modeling, and compensation for precise motion control" (1998). Theses. 892.