Dahl Friction Model for Driving Characteristics of V-Shape Linear Ultrasonic Motors

Abstract

The contact process of stator and slider described by the Coulomb friction model is basically in a pure sliding friction state, and a mechanical model based on the Dahl friction theory was proposed to describe the contact process between stator and slider of V-shape linear ultrasonic motor. With consideration for the tangential compliance of stator and slider, the dynamic contact and friction processes of stator and slider were addressed in stages. The simulation results show that the ratio of the friction positive work decreases with the increase of the preload, and the vibration amplitude of the stator increases the proportion of positive work of the friction force. Improving the contact stiffness of the stator and slider is conducive to improving the output performance of the ultrasonic motor. The asymmetry of the left and right performance of the V-shaped vibrator will cause a difference in the left and right running speeds of the ultrasonic motor. The improved Dahl friction-driving model makes up for the discontinuity of tangential contact force calculated by the Coulomb friction model. This study demonstrates that the friction-driving model based on the Dahl theory is reliable and reasonable for linear ultrasonic motors according to the experimental results.

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“…Zhu et.al [ 19 ] investigated the dead zone of the vibration amplitude by simplifying the contact model to static friction. Zhang et.al [ 20 ] developed the Dahl model to avoid discontinuities of contact forces in both left and right directions of motion for V-shape linear ultrasonic motors. In addition, the dead zone [ 21 ], wear of the friction interface [ 22 ], and change of pre-pressure [ 23 ] are also frequently related to contact friction [ 24 ].…”