17-07-2017, 10:04 AM
A piezoelectric motor or piezoelectric motor is a type of electric motor based on the shape change of a piezoelectric material when an electric field is applied. Piezoelectric motors use the inverse piezoelectric effect of piezoelectric sensors, where the deformation or vibration of the piezoelectric material produces an electric charge. An electric circuit makes acoustic or ultrasonic vibrations in the piezoelectric material, which produce linear or rotational motion. In one mechanism, the elongation in a single plane does a series of stretches and positions, similar to the way a caterpillar moves.
One drive technique uses piezoelectric ceramic to push a stator. These piezoelectric motors use three groups of two locking crystals, and one motive that permanently connects to the motor or stator housing (not both). The motive group, interspersed between the other two, provides movement. These piezoelectric motors are essentially stepper motors, each step comprising two or three actions, based on the type of blocking. These engines are also known as aphid engines. Another mechanism uses surface acoustic waves (SAW) to generate linear or rotational motion. A second type of drive, the ripple motor, utilizes piezoelectric elements orthogonally attached to a nut. Its ultrasonic vibrations rotate a central screw. This is a direct drive mechanism.
Working
The piezoelectric effect in piezoceramic converts the electric field into mechanical stress. Under the special electric excitation excitation and ceramic geometry of the Nano-motion motors, the longitudinal extension and transverse oscillation modes are excited at close proximity to frequency. Simultaneous excitation of the longitudinal extension mode and the transverse bending mode creates a small elliptical trajectory of the ceramic edge, thus achieving the dual mode stationary wave motor patented by Nano-motion.
By coupling the ceramic edge to a precision step, a resultant driving force is exerted on the platen, causing movement of the platen. The periodic nature of the driving force at much higher frequencies than the mechanical resonance of the stage allows continuous smooth motion for unlimited travel while maintaining high resolution and positioning accuracy typical of piezoelectric devices. The displacement can be linear or rotary, depending on the coupling mechanism.
The closed-loop servo control can be supplied with standard standard servo controllers or with the Nanomotion servo controller offering full PID control at 20 kHz. In addition, the motors can operate in drive mode.
While the drive voltage is not applied, the ceramic plate is stationary and generates retention torque on the platen. Unlike any other braking device, the retention torque of the Nanomotion motor does not cause any change of position.
Nanomotion motors provide compact but precise motorized mechanical systems. If more power is required, Nanomotion motors are specifically designed to allow cascading - as power requirements increase, simply add another Nanomotion motor to the system.