An improved equivalent circuit model of a V-shape single-mode linear ultrasonic motor with new actuation mode

Abstract

Single-mode linear ultrasonic motors (SMLUMs) have the advantages of excellent accuracy, long travel distance, single vibration mode and simple driving scheme, which have been applied in precision positioning and micro/nano manipulation actuators. However, it is still challenging to accurately and efficiently analyze such motors due to their complicated electro-mechanical coupling behaviors under contact-based operating conditions. This paper proposed an improved equivalent circuit model for a single-mode linear ultrasonic motor considering the real contact-based operating conditions, where a new actuation mode of the V-shape transducer is adopted. The electro-mechanical coupling characteristics of the stator under contact-based boundary condition is modeled by a modified admittance-type equivalent circuit, where the variable contact stiffness and loss are characterized between the stator and the mover. The friction drive mechanism is modeled by a thyristor rectifying circuit to characterize the intermittent actuation characteristics, and the nonlinear relationship between the motor characteristics and the contact-based operating conditions is initially characterized from the circuit viewpoint. The merits and the applications of the circuit-based model are exemplified by parameter identification and modification, losses segregation, admittance characteristics analysis and output and control characteristics evaluation for such SMLUMs.