Dynamic Investigation of Coulomb and Dahl Friction Models Applied to the Multibody Model of a Physical Pendulum

Modern mechanical systems are increasingly becoming the product of the interdisciplinary work of mechanical, control, electrical, and computer engineering. In these systems, models developed to perform complex tasks should reflect reality as much as possible. In this regard, the successful modeling of friction interaction is very important, especially in applications where precise motion control is needed, such as the analysis and synthesis of robotic and articulated mechanical systems. In this study, the classical Coulomb friction force model, which is a “static” friction force model, and the Dahl friction force model, which is a “dynamic” friction force model, are compared in terms of the dynamic responses they produce. To this end, this work considers the physical pendulum, a simple model that can represent robotic manipulators, as a benchmark problem. Equations of motion and state-space representations are presented for both friction force models. Then, a SIMSCAPE MULTIBODY model of the mechanical system is developed to simulate the system response. After validating these simulation results with those obtained from MATLAB, the effect of the contact stiffness parameter used in the Dahl friction force model on the applied friction torque and angular displacement is investigated.