9409413 Messner Friction modeling and friction compensation will be studied for ball bearings operating in regimes of rapid lubrication and friction changes which have not previously been investigated. Specifically addressed will be the conditions where a disk drive actuator bearing is undergoing high frequency/low amplitude oscillations in track-follow mode immediately after rapid deceleration from the high angular velocities associated with the track-seek mode. Adaptive, learning, and nonlinear controllers which incorporate the derived friction models will be designed and tested. ***