Experimental Characterization of Dry Friction at Low Velocities on a Developed Tribometer Setup for Macroscopic Measurements

Abstract

This paper presents some experimental evidence of dry friction behavior at low velocities. The experiments are carried out on a tribometer developed by the authors, where the functional requirements of the apparatus (accurate displacement and friction force measurement, normal loading possibility and application of arbitrary displacement signals over a large range) are decoupled as much as possible. The experiments are performed from control engineering viewpoint: e.g., given a certain setup and a certain material combination, what is the friction force for different displacement signals? The tribometer allows to carry out experiments in a large range of displacements/velocities, thus allowing that numerous friction characteristics described in literature, such as break-away force, position-dependent hysteresis characteristics in the pre-sliding regime, time lag in the sliding regime and stick-slip phenomena, occur on one and the same configuration and under dry friction conditions. These experimental results can be used to validate physically motivated friction models or to find or validate empirically motivated friction models, e.g., as used in control applications. This paper shows also the influence of the system dynamics on the friction measurements and reciprocally the influence of friction on the design of a controller for the actuating part.