Dahl friction modeling

Abstract

The drive behind improved friction models has been better prediction and control of dynamic systems. The earliest model was of classical Coulomb friction; however, the discontinuity during force reversal of the Coulomb friction model has long been a point of contention since such a discontinuity does not accurately portray the behavior of real systems. Other models have been suggested, but variations of the Dahl solid friction model remain some of the simplest yet most useful. Dahl's original theory proposed that friction behaved as a stress acting upon the quantum mechanical bonds at the interface. Thus, the relationship between frictional force and position would be analogous to a stress-strain curve, complete with hysteresis should there be permanent displacement akin to plastic deformation in materials. This project reviews the variations of Dahl friction models popular in the literature and then demonstrates it both analytically via Matlab and Simulink simulations and experimentally by observing the behavior of a limited angle torque motor.