The aim of this paper is to define a linear model of a
planar standing wave ultrasonic motor (SWUM). First, the analytical
approach using the variational formulation is presented. An
identification method is deduced to find the parameters of a
vibrating rectangular plate. Non-linearities are also emphasized and
verified by the experimental measurements. Secondly, the mechanical
energy conversion of the actuator is identified, using an average
behavior modelling and a linear approach for the contact
interaction. Finally, a complete modelling of the actuator is
presented, using the Causal Ordering Graph formalism.