Modeling of a Planar Microrobot Using LuGre Friction Model

Microrobots design and manufacturing has been one of interesting fields in robotics in recent years. Various legged designs have been proposed in the literature. All designs rely on friction for locomotion. In this paper the dynamic model of a planar two-legged microrobot is presented using LuGre friction model. LuGre friction model is more realistic model, reducing uncertainties of the microrobot dynamic model, providing a better prediction for both design and control applications. The proposed microrobot is driven by a piezoelectric actuator mounted between centers of two legs. One of important issues in modeling of microrobots is to determine the friction force between robot and environment. The LuGre friction model which is a more realistic and comprehensive model for friction is used to determine the friction force between legs and horizontal surface. The results of the LuGre friction based model are compared with those of the model which uses the Coulomb friction. This comparison shows effectiveness of using the LuGre friction model in predicting the dynamic behavior in these types of robots.