Two different ways are generally available to control the friction along the stator-rotor contact interface, traveling-wave vibration and standing-wave vibration. Ultrasonic motors differ from other piezoelectric motors in several ways, though both typically use some form of piezoelectric material, The most obvious difference is the use of resonance to amplify the vibration of the stator in contact with the rotor in ultrasonic motors. Common applications of piezoelectric motors include focusing systems in camera lenses as well as precision motion control in specialised applications such as microscopy. The main benefits of piezoelectric motors are the high positioning precision, stability of position while unpowered, and the ability to be fabricated at very small sizes or in unusual shapes such as thin rings. The maximum operating temperature is limited by the Curie temperature of the used piezoelectric ceramic and can exceed +250☌. This extends their usefulness to applications that cannot use traditional electromagnetic motors-such as inside nuclear magnetic resonance antennas. This provides a maximum linear speed of approximately 800 mm per second, or nearly 2.9 km/h.Ī unique capability of piezoelectric motors is their ability to operate in strong magnetic fields. High response rate and fast distortion of the crystals also let the steps happen at very high frequencies-upwards of 5 MHz. Manufacturers claim precision to the nanometer scale. This, combined with the minute scale of the distortions, gives the piezoelectric motor the ability to make very fine steps. The growth and forming of piezoelectric crystals is a well-developed industry, yielding very uniform and consistent distortion for a given applied potential difference. Piezoelectric motors typically use a cyclic stepping motion, which allows the oscillation of the crystals to produce an arbitrarily large motion, as opposed to most other piezoelectric actuators where the range of motion is limited by the static strain that may be induced in the piezoelectric element. Examples of types of piezoelectric motors include inchworm motors, stepper and slip-stick motors as well as ultrasonic motors which can be further categorized into standing wave and travelling wave motors. An electrical circuit makes acoustic or ultrasonic vibrations in the piezoelectric material, most often lead zirconate titanate and occasionally lithium niobate or other single-crystal materials, which can produce linear or rotary motion depending on their mechanism. Ī piezoelectric motor or piezo motor is a type of electric motor based on the change in shape of a piezoelectric material when an electric field is applied, as a consequence of the converse piezoelectric effect. Two piezoelectric crystals are visible that provide the mechanical torque. Insides of a slip-stick piezoelectric motor.
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