04-07-2012, 02:36 PM
Ultra Sonic Motor
Ultra Sonic Motor.doc (Size: 347.52 KB / Downloads: 87)
Abstract
Ultra sonic motor is a newly developed motor, and it has excellent performance and many useful features, e.g.: high-torque density, low speed, compactness in size, no electromagnetic interferences, and so on. USM is a kind of piezo motor. The proposed speed control scheme is assumed for these applications because they require quick and precise speed control of actuators for various load conditions. A speed control method of USM using adaptivecontrolisproposed.
Artificial Neural Network (ANN), which follows the biological neural cells in brain, consists of a number of neurons and weighted links, and it has a good potential for control applications because it can approximate the non-linear input-output mapping of the plant. Accordingly, ANN has been applied widely in the field of power electronics control.
Introduction
Piezoelectric ultrasonic motors (PUMs) have a number of advantages over electromagnetic motors. PUMs can achieve positioning accuracies in the range of several tens of nanometerrs.
They hold their positions even when powered down and thus consume less energy. PUMs can be constructed with significantly fewer parts.
The efficiency of electromagnetic motors falls as their dimensions are reduced, but that of PUMs stays virtually constant [1]. Linear electromagnetic motors are very difficult to design; in contrast linear PUMs are quite simple.
Interest in PUMs is growing, especially for use as miniature drives in mass-produced consumer electronic products.
Miniaturized Piezoelectric Ultrasonic Motors
Physik Instrumente (PI) has been active inpiezoelectric ultrasonic motor R&D for many years.Minature PUMs have also been subject to at PI. Several years ago PI developed a piezoelectric rotary traveling-wave motor with a stator measuring only 3x3 mm [2][3]. That motor uses what is known as the tangential-axial oscillation mode of the piezoelectric hollow cylinder.
A traveling wave is set up in the stator with the help of three electrical signals which are 120° out of phase. In addition to rotary ultrasonic motors, PI is also developing linear ultrasonic motors.
Working Principle and Design of the NewUltrasonic Motor
Fig. 3a shows a CAD model of the newly developed ultrasonic motors [7]. These motors are of very simple design, consisting of two basic parts: the actuator (stator) and the sled (spring bonded to two sliders), the moving part of the motor.
The actuator consists of a rectangular piezo-ceramic plate of size L×W×0.5L polarized in the thickness direction. The two large faces of the plate are covered by electrodes. On one (top, in Fig. 3a) are the two exciter electrodes, each covering half of the surface. The “bottom” surface (not visible) has a single electrode that serves as a common drain
The actuator plate has guide grooves cut in the long edges. The sled has two sliders which are pressed against the ceramic actuator by the integrated spring. The entire motor consists of the piezoceramic plate and the moving sled, guided along the integrated grooves in the plate.
. Measurement with 3D Scanning Vibrometer
Finite Element Method (FEM) programs have proven to be essential tools for the development of ultrasonic motors. All the simulations, calculations and the optimization of ultrasonic motors were done with the help of ANSYS FEM software. Fig. 4a shows an FEM simulation of the stator of a 9 mm motor.
Drive Circuitry for the Motor
Fig. 5a shows the impedance characteristic curve of the motor with and without the sliders. The resonant frequency used was 470 kHz. The fact that the resonant frequency is influenced by external conditions like temperature, makes necessary the development of electronics that automatically adjusts to the motor’s resonant frequency.
Ultra Sonic Motor.doc (Size: 347.52 KB / Downloads: 87)
Abstract
Ultra sonic motor is a newly developed motor, and it has excellent performance and many useful features, e.g.: high-torque density, low speed, compactness in size, no electromagnetic interferences, and so on. USM is a kind of piezo motor. The proposed speed control scheme is assumed for these applications because they require quick and precise speed control of actuators for various load conditions. A speed control method of USM using adaptivecontrolisproposed.
Artificial Neural Network (ANN), which follows the biological neural cells in brain, consists of a number of neurons and weighted links, and it has a good potential for control applications because it can approximate the non-linear input-output mapping of the plant. Accordingly, ANN has been applied widely in the field of power electronics control.
Introduction
Piezoelectric ultrasonic motors (PUMs) have a number of advantages over electromagnetic motors. PUMs can achieve positioning accuracies in the range of several tens of nanometerrs.
They hold their positions even when powered down and thus consume less energy. PUMs can be constructed with significantly fewer parts.
The efficiency of electromagnetic motors falls as their dimensions are reduced, but that of PUMs stays virtually constant [1]. Linear electromagnetic motors are very difficult to design; in contrast linear PUMs are quite simple.
Interest in PUMs is growing, especially for use as miniature drives in mass-produced consumer electronic products.
Miniaturized Piezoelectric Ultrasonic Motors
Physik Instrumente (PI) has been active inpiezoelectric ultrasonic motor R&D for many years.Minature PUMs have also been subject to at PI. Several years ago PI developed a piezoelectric rotary traveling-wave motor with a stator measuring only 3x3 mm [2][3]. That motor uses what is known as the tangential-axial oscillation mode of the piezoelectric hollow cylinder.
A traveling wave is set up in the stator with the help of three electrical signals which are 120° out of phase. In addition to rotary ultrasonic motors, PI is also developing linear ultrasonic motors.
Working Principle and Design of the NewUltrasonic Motor
Fig. 3a shows a CAD model of the newly developed ultrasonic motors [7]. These motors are of very simple design, consisting of two basic parts: the actuator (stator) and the sled (spring bonded to two sliders), the moving part of the motor.
The actuator consists of a rectangular piezo-ceramic plate of size L×W×0.5L polarized in the thickness direction. The two large faces of the plate are covered by electrodes. On one (top, in Fig. 3a) are the two exciter electrodes, each covering half of the surface. The “bottom” surface (not visible) has a single electrode that serves as a common drain
The actuator plate has guide grooves cut in the long edges. The sled has two sliders which are pressed against the ceramic actuator by the integrated spring. The entire motor consists of the piezoceramic plate and the moving sled, guided along the integrated grooves in the plate.
. Measurement with 3D Scanning Vibrometer
Finite Element Method (FEM) programs have proven to be essential tools for the development of ultrasonic motors. All the simulations, calculations and the optimization of ultrasonic motors were done with the help of ANSYS FEM software. Fig. 4a shows an FEM simulation of the stator of a 9 mm motor.
Drive Circuitry for the Motor
Fig. 5a shows the impedance characteristic curve of the motor with and without the sliders. The resonant frequency used was 470 kHz. The fact that the resonant frequency is influenced by external conditions like temperature, makes necessary the development of electronics that automatically adjusts to the motor’s resonant frequency.