The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	Dynamic friction measurement, modeling, and compensation for precise motion control
Author:	Cohn, Simon
View Online:	njit-etd1998-005 (xvi, 103 pages ~ 5.4 MB pdf)
Department:	Department of Mechanical Engineering
Degree:	Master of Science
Program:	Mechanical Engineering
Document Type:	Thesis
Advisory Committee:	Harnoy, Avraham (Committee chair) Friedland, Bernard (Committee member) Ji, Zhiming (Committee member)
Date:	1998-01
Keywords:	Friction--Measurement Motion control devices Friction--Measurement models
Availability:	Unrestricted
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.