Two-dimensional dynamics of a quasi-static legged piezoelectric actuator

Abstract

Piezoelectric actuators are becoming a viable alternative to electrodrives in terms of size, speed and stall force characteristics. In this paper, a novel dynamic model of a contemporary linear piezoelectric actuator is presented. The model is based on physically meaningful parameters and macroscopically measured data for the fully assembled state. The model describes the frictional interaction between multiple piezoelectric legs and a ceramic rod. It consists of two orthogonal dynamics which are coupled together by means of preload and frictional forces. Linearity of the model is maintained through most of the modelling stages with a clear indication of nonlinear effects due to hysteresis, friction and impact dynamics of the legs. Unknown model parameters are estimated within a global optimization procedure and bounds on parameter values are indicated. The model presented explains the linear drive frequency/velocity as well as the nonlinear load force/velocity characteristics of the actuator within its full operational range. The insights gained throughout the modelling process indicate the possibilities of design improvements. Moreover, the model can be used to explain the resonance phenomena limiting the range of actuator operation and is used to anticipate an alternative drive strategy.

Piezo LEGS Driving Principle Based on Coordinate Transformation

“…Discussion on the operating principle and dynamic behavior of a Piezo LEGS motor in this study will be concise, including only the information necessary for the reader to understand the proposed method for driving the motor. For a detailed dynamic modeling of the motor, the reader is advised to consider study [25] where developed model is based on the physically meaningful parameters and macroscopically measured data for the fully assembled state of the motor.…”

“…In the study [25], this force is denoted as normal force. The rod moves in the direction of this force when its magnitude becomes larger than the magnitude of F p .…”

“…In the studies where the waveforms of driving voltages were discussed [16], [10], [25], the authors proposed different types of the waveforms. Each has its advantages and disadvantages regarding the motor's speed within one step and the y-direction interaction force (normal force [25]) imposed on the rod by the legs. The motion and the forces could be analyzed once the type is selected, but no clear guidance for selection of the particular waveform has been given in those studies.…”

Control system for high precision positioning applications based on piezo motors

“…For a detailed dynamic modeling of the motor, the reader is advised to consider study [27] where developed model is based on the physically meaningful parameters and macroscopically measured data for the fully assembled state of the motor. Fig.…”

Nanometric positioning of a piezo walker

“…The dynamical model of the piezo legs in x and y dimensions can be approximated by simple mass spring damper system (MSD) [27]. In continuous mode all four legs are in clamping contact with the drive rod therefore all forces exerted by four legs should be considered.…”