Upcoming SlideShare. Ultrasonic Motor Powerpoint pdf. Embed Size px. Start on. Show related SlideShares at end. WordPress Shortcode. Share Email. Top clipped slide. Education , Technology , Business. Download Now Download Download to read offline. Ultrasonic Motor. Rakesh R Follow. What to Upload to SlideShare. A few thoughts on work life-balance. Is vc still a thing final. The GaryVee Content Model. Mammalian Brain Chemistry Explains Everything. Related Books Free with a 30 day trial from Scribd.
Related Audiobooks Free with a 30 day trial from Scribd. Empath Up! Kuldeep Dwivedi. Padakanti Anil. Srivastava Anamika. Udipta Gogoi. Eliazer Johny. Abhishek Mehta. Santosh Kumar. Amulya Ammu. Show More. Views Total views. Actions Shares. No notes for slide. Motor is a device that converts electrical energy to mechanical energy. An electric motor is a machine that converts electrical energy into mechanical energy for obtaining useful work.
In normal motoring mode, most electric motors operate through the interaction between an electric motor's magnetic field and winding currents to generate force within the motor. Almost all the motor that dominates the present world such as DC motors, induction motors, synchronous motors etc. The energy conversion in such motors involves two stages, where initially electrical energy is converted to magnetic energy and further, the magnetic energy is converted to mechanical energy.
Because of this two-stage energy conversion, the electromagnetic motor suffers from several losses that lead to a rigorous energy wastage. The ultrasonic motors belong to the class of piezoelectric motors.
In this prose, the term USM will be used for denoting the machine. The working principles have been well known for at least 50 years. However they gained widespread interest with the influential work of T Sashida in Before that piezo-ceramic materials with high conversion efficiency and fast electronic power control of ultrasonic vibrations were not available.
Besides that, USMs also offer a high potential for miniaturization. The study deals with the fundamentals of this modern machine such as, principles, parts, working and eventually mentions the pros and cons. The study wraps up with the major applications of this quick response device and the scope for further development. Here emerged the requirement of a better machine.
After years of studies and researches the engineers developed an entirely different kind of motor that directly converted electrical energy to mechanical energy. As technologies improved in course of time, USMs replaced not only the EM motors, but also the servomotors, stepper motors and sycnhros.
The term sonic is applied to ultrasound waves of very high amplitudes. Hyper sound, sometimes called praetor sounds or micro sounds are sound waves of frequencies greater than hertz. At such high frequencies it is very difficult for a sound wave to propagate efficiently; indeed, above a frequency of about 1. An ultrasonic transducer is a device used to convert some other type of energy into an ultrasonic vibration.
There are several basic types, classified by the energy source and by the medium into which the waves are being generated.
Mechanical devices include gas-driven, or pneumatic, transducers such as whistles as well as liquid-driven transducers such as hydrodynamic oscillators and vibrating blades. These devices, limited to low ultrasonic frequencies, have a number of industrial applications, including drying, ultrasonic cleaning, and injection of fuel oil into burners.
Electromechanical transducers are far more versatile and include piezoelectric and magnetostrictive devices. By far, the most popular and versatile type of ultrasonic transducer is the piezoelectric crystal, which converts an oscillating electric field applied to the crystal into a mechanical vibration. Piezoelectric crystals include quartz, Rochelle salt and certain types of ceramics. Piezoelectric transducers are readily employed over the entire frequency range and at all output levels.
Particular shapes can be chosen for particular applications. For example, a disc shape provides a plane ultrasonic wave, while curving the radiating surface in a slightly concave or bowl shape creates an ultrasonic wave that will focus at a specific point. It was found that in certain types of crystals when a pressure is applied across a pair of opposite faces, an equivalent potential difference is developed across the other pair of opposite faces.
Further, if we reverse the direction of application of force, the polarity of the potential difference developed also reverses. In fig 4. If the compressive force is replaced by an elongation force, the polarity reverses i. Fig 4. When a potential difference is applied across the pair of opposite faces, compressions or elongations are obtained across the other pair of opposite faces depending upon the polarity of the applied PD.
This is the driving force behind the USMs. Crystals that exhibit the above phenomenon are called piezoelectric materials. The interesting fact is that converse piezoelectric effect was discovered on a later occasion, 2 years after the discovery by the Curie brothers. Almost 80 years, the immense potential of motoring produced by this discovery was unknown to the scientific world, until the V V Lavrinenko modeled the 1st ever USM in the year In short, the Ultrasonic Motors works on the principle of converse piezoelectric effect.
Actuator 2. Stator 3. Rotor 4. Casing 5. It is made up of a piezoelectric material such as Quartz, Barium Titanate, Tourmaline, Rochelle salt etc. Actuator is directly connected to the supply. It is fixed on the stator using thin metal sheets and bearings. It is constructed using a malleable material, usually, steel. It can be of ring, cylindrical or rod shaped. Rotor is made of the same material as that of the stator and does have the same shape.
Rotor and stator are coupled by a certain method called the frictional coupling which is much effective and simpler. The idea of frictional coupling is discussed in Chapter 6. They are made of non- corrosive alloys or fiber. They too can be constructed in any of the desired shape as per requirement. These are devised to make the amplitude of elliptic motion large and to reduce abrasions. Further feature of comb tooth is to amplify vibrations.
The grooves also allow the dust created by friction to escape and thus keep the contact surface dust free. So the USMs are well known for their low speed operation. Torque ratings averaging 10 times greater than a comparably sized electromagnetic motor can be achieved.
Voltage inputs vary piezo-crystal assembly. That is, if the piezo-ring assembly is of a thinner design, the voltage requirements will be less than that of a thicker type piezo-ring assembly. Power requirements for the USM usually rate in the low range. We have seen in the previous chapter that actuator is directly connected to the electrical supply mains. When the supply is switched ON, the actuator starts vibrating owing to converse piezoelectric effect.
As the ultrasonic motor uses ultrasonic vibrations as its driving force, it comprises a stator which is a piezoceramic material with an elastic body attached to it, and a rotor to generate ultrasonic vibrations.
It therefore does not use metal or coil. Therefore there is no problem of magnetic field and interference as in case of electric motor.
An ultrasonic motor is a type of electric motor powered by the ultrasonic vibration of a component, the stator, placed against another component, the rotor or slider depending on the scheme of operation rotation or linear translation.
Ultrasonic motors differ from piezoelectric actuators in several ways, though both typically use some form of piezoelectric material, most often lead zirconate titanate and occasionally lithium niobate or other single-crystal materials.
Ultrasonic motors also offer arbitrarily large rotation or sliding distances, while piezoelectric actuators are limited by the static strain that may be induced in the piezoelectric element.
One common application of ultrasonic motors is in camera lenses where it, as part of the autofocus system, is used to move lens elements. It's replacing the noisier and often slower conventional micro-motor. Piezoelectric ultrasonic motors are a new 9. Electromagnetic motors were invented more than a hundred years ago. While these motors still dominate the industry, a drastic improvement cannot be expected except through new discoveries in magnetic or superconducting materials.
Regarding conventional electromagnetic motors, tiny motors smaller than 1 cm3 are rather difficult to produce with sufficient energy efficiency. Therefore, a new class of motors using high power ultrasonic energy—ultrasonic motors—is gaining widespread attention. Ultrasonic motors made with piezo ceramics whose efficiency is insensitive to size are superior in the mini-motor area.
Fig no. Further, the vibrator is composed of a piezoelectric driving component and an elastic vibratory part, and the slider is composed of an elastic moving part and a friction coat.
By comparison, the propagating-wave type combines two standing waves with a 90 degree phase difference both in time and in space. The ultrasonic motor, invented in , utilizes the piezoelectric effect in the ultrasonic frequency range to provide the motive force.
In conventional electric motors the motive force is electromagnetic. The result is a motor with unusually good low-speed high-torque and power- to-weight characteristics. It has already found applications in camera autofocus mechanisms, medical equipment subject to high magnetic fields, and motorized car accessories.
Its This book is the result of a collaboration between the inventor and an expert in conventional electric motors: the result is an introduction to the general theory presented in a way that links it to conventional motor theory.
It will be invaluable both to motor designers and to those who design with and use electric motors as an introduction to this important new invention.
Ultrasonic motors were invented in by V. V Lavrinko. In general we are aware of the fact that the motive force is given by the electromagnetic field in the conventional motors.
But, here to provide a motive force, these motors utilize the piezoelectric effect in the ultrasonic frequency range, which is from 20 kHz to 10 MHz and is not audible to normal human beings.
Hence, it is termed as piezoelectric USM technology. Ultrasonic technology is used by the USMs which utilize the ultrasonic vibration power from a component for their operation. Conversion of electric energy into motion by inverse piezoelectric effect An ultrasonic motor is a type of electric motor powered by the ultrasonic vibration of a component, the stator, placed against another component, the rotor or slider depending on the scheme of operation rotation or linear translation.
One common application of ultrasonic motors is in camera lenses where they are used to move lens elements as part of the auto-focus system. Ultrasonic motors replace the noisier and often slower micro-motor in this application. As the ultrasonic motor uses ultrasonic vibrations as its driving force, it comprises a stator which is a piezo ceramic material with an elastic body attached to it, and a rotor to generate ultrasonic vibrations.
In ultrasonic motor, piezoelectric effect is used and therefore generates little or no magnetic interference. All of us known that motor is a machine which produces or imparts motion, or in detail it is an arrangement of coil and magnets that converts electrical energy to mechanical energy and ultrasonic motors are the next generation motors.
In December 25, The motor is just an Ultrasonic Motor. The name of the production is USR Ultrasonic Motor rotates using modification when voltage is applied to piezo-electric ceramics. The name of an ultrasonic motor was named from the frequency of the voltage that is exceeding people's audible sound region. Over 20kHz. By the result of continuous improvement, USR30 series and USR60 series are adopted in many companies and academic organizations in the world.
An Ultrasonic motor is a type of electric motor formed from the ultrasonic vibration of a component, the stator being placed against another, the rotor depending on the scheme of operation. Conversion of electric energy into motion by inverse piezoelectric effect. This wave rotates the rotor which is in contact with the stator. High holding power of Ultrasonic Motor : High pressure is applied between the rotor and the stator. For this reason, the biggest frictional force at the time of a stop is the holding power of an ultrasonic motor.
Ultrasonic motors, which have superior characteristics like high torque at low The stator of an ultrasonic motor that is excited by piezoelectric elements in.
Ultrasonic motors motor is a newly developed motor, and it has excellent performance and many useful features, e. 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 adaptive control is proposed.
Ultrasonic motor is a type of electric motor powered by the ultrasonic vibration of a component, the stator, placed against another component, the rotor or slider depending on the scheme of operation rotation or linear translation. In ultrasonic motor Dry friction is often used in contact, and the ultrasonic vibration induced in the stator is used both to impart motion to the rotor and to modulate the frictional forces present at the interface.
The friction modulation allows bulk motion of the rotor and without this modulation, ultrasonic motors would fail to operate One of the unique characteristics of the piezoelectric effect is that it is reversible, meaning that materials exhibiting the direct piezoelectric effect the generation of electricity when stress is applied also exhibit the converse piezoelectric effect the generation of stress when an electric field is applied.
When piezoelectric material is placed under mechanical stress, a shifting of the positive and negative charge centers in the material takes place, which then results in an external electrical field.
When reversed, an outer electrical field either stretches or compresses the piezoelectric material. The piezoelectric effect is very useful within many applications that involve the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies.
It is also the basis of a number of scientific instrumental techniques with atomic resolution, such as scanning probe microscopes STM, AFM, etc. The piezoelectric effect also has its use in more mundane applications as well, such as acting as the ignition source for cigarette lighters.
The History of the Piezoelectric Effect: The direct piezoelectric effect was first seen in , and was initiated by the brothers Pierre and Jacques Curie. By combining their knowledge of pyroelectricity with their understanding of crystal structures and behavior, the Curie brothers demonstrated the first piezoelectric effect by using crystals of tourmaline, quartz, topaz, cane sugar, and Rochelle salt.
Their initial demonstration showed that quartz and Rochelle salt exhibited the most piezoelectricity ability at the time. Over the next few decades, piezoelectricity remained in the laboratory, something to be experimented on as more work was undertaken to explore the great potential of the piezoelectric effect.
The breakout of World War I marked the introduction of the first practical application for piezoelectric devices, which was the sonar device. This initial use of piezoelectricity in sonar created intense international developmental interest in piezoelectric devices. Over the next few decades, new piezoelectric materials and new applications for those materials were explored and developed. During World War II, research groups in the US, Russia and Japan discovered a new class of man-made materials, called ferroelectrics, which exhibited piezoelectric constants many times higher than natural piezoelectric materials.
Although quartz crystals were the first commercially exploited piezoelectric material and still used in sonar detection applications, scientists kept searching for higher performance materials.
This intense research resulted in the development of barium titanate and lead zirconate titanate, two materials that had very specific properties suitable for particular applications.
Piezoelectric Materials: There are many materials, both natural and man-made, that exhibit a range of piezoelectric effects. Some naturally piezoelectric occurring materials include Berlinite structurally identical to quartz , cane sugar, quartz, Rochelle salt, topaz, tourmaline, and bone dry bone exhibits some piezoelectric properties due to the apatite crystals, and the piezoelectric effect is generally thought to act as a biological force sensor.
An example of man-made piezoelectric materials includes barium titanate and lead zirconate titanate. In recent years, due to the growing environmental concern regarding toxicity in lead-containing devices and the RoHS directive followed within the European Union, there has been a push to develop lead free piezoelectric materials. To date, this initiative to develop new lead-free piezoelectric materials has resulted in a variety of new piezoelectric materials which are more environmentally safe.
Applications BestSuited for the Piezoelectric Effect: Due to the intrinsic characteristics of piezoelectric materials, there are numerous applications that benefit from their use: High Voltage and Power Sources: An example of applications in this area is the electric cigarette lighter, where pressing a button causes a spring-loaded hammer to hit a piezoelectric crystal, thereby producing a sufficiently high voltage that electric current flows across a small spark gap, heating and igniting the gas.
Most types of gas burners and ranges have a built-in piezo based injection systems. Piezoelectric Motors: Because very high voltages correspond to only tiny changes in the width of the crystal, this crystal width can be manipulated with better-than-micrometer precision, making piezo crystals an important tool for positioning objects with extreme accuracy, making them perfect for use in motors, such as the various motor series offered by Nanomotion.
Regarding piezoelectric motors, the piezoelectric element receives an electrical pulse, and then applies directional force to an opposing ceramic plate, causing it to move in the desired direction. Motion is generated when the piezoelectric element moves against a static platform such as ceramic strips.
The characteristics of piezoelectric materials provided the perfect technology upon which Nanomotion developed our various lines of unique piezoelectric motors. Using patented piezoelectric technology, Nanomotion has designed various series of motors ranging in size from a single element providing 0. USM Prototypes 1. Linear ultrasonic motors I DOF planar pin-type actuator The objective of this project is to design and develop a piezoelectric actuator based on the fundamental operating mechanism of ultrasonic motors.
Two pin-type prototypes with piezoelectric bimorph plate and a contact pin for generating driving force in the X-Y direction were designed and fabricated. A test rig was also constructed for the evaluation of the two prototypes and basic characteristics of the actuators were investigated. The working principle of the actuator was verified and proven during the experiment. Basically, the optimal driving speed of an actuator is dependent on the driving frequency, the input voltage, the contact surface and the friction coefficient between the stator and motor.
An analytical study of the prototypes has been carried out by means of finite element analysis utilizing ANSYS5. With comparison to the experimental results, it was proven that the optimal driving condition occurred at the specific resonant mode depending on the pin vibration. Maximum unloaded driving speed was obtained to be approximately 0.
II Bi-directional linear standing wave USM A standing wave bi-directional linear ultrasonic motor has been fabricated. This linear USM has very simple structure and can be easily mounted onto any commercially available linear guide. A high precision positioning x-y table was built by mounting these individual movable linear guides together. The basic parameters of our linear USM are: moving range Rotary ultrasonic motor The characteristics of the rotary disc type motor will be investigated and theoretical model will be formed to relate the important components on the power of the motor.
The scope includes designing different motor with various dimensions, form ulation of the analytical model, experimental testing and ultimately, setting a standard for practical application of this particular type of USM. This project will lay the foundation of the characteristics and performance of the rotary disc type USMs for future application.
Spherical ultrasonic motor Presently a new type of spherical USM is under investigation. This particular USM consists of a thin square plate, 30x30mm in area.
It can rotate in more than 4 individual directions. Now we are trying to compile rotation in any dirction by using a computer to control the 4 individual directions properly. Equivalent Circuit It is often useful to represent a problem in mechanics by an equivalent circuit.
The basic idea of the circuit is to determine the static and dynamic behavior in force and velocity transmission of a system where friction plays an essential role. The equivalent circuit expression for a piezoelectric vibrator is very convenient for understanding its operating characteristics and for applying it in practice. Shown in Fig. There are two power transformation involved in the running of a USM: 1 electric energy is transformed into mechanical vibrational energy of the stator by converse piezoelectric effect; 2 vibrational energy of the stator is transformed into continous moving energy of the rotor or moving part due to frictional interaction between the stator and the rotor or moving parts.
Correspondingly, modeling a USM normally includes two aspects: 1 piezoelectric vibration analysis for the stator which is a piezoceramic-metal composite structure; 2 the frictional actuation mechanism between the the vibrator and the rotor. Vibration Analysis An uniformizing method for the vibration analysis of metal-piezoceramic composite thin plates has been proposed. Using this method, piezoelectric composite thin plates with different shapes can be uniformized into equivalent uniform single-layer thin plates which have the same vibrational characteristics as the original piezoelectric composite thin plates.
Hence the vibrational characteristics of metal-piezoceramic composite thin plates can be obtained through calculating the natural frequencies and the vibration modes of the equivalent uniform single- Furthermore mid-plane of piezoelectric composite thin plate can also be obtained, which is significant when designing thin plate type USMs. Contact Mechanism In the existing study on the friction actuation mechanism of USMs, the dynamic normal contact between the stator and the rotor in the ultrasonic range has not been taken into consideration.
In fact this is a vital factor which causes the reduction of the coefficient of friction between the stator and rotor when the motor is in motion. In our research we take a traveling wave USM as an example and model the normal ultrasonic dynamic contact of the stator and rotor using elastic Hertzian contact theory.
Result shows that the rotor is levitated in normal direction by the ultrasonic dynamic contact of the stator. Concurrently, the real area of contact of the stator and rotor decreases. Our contact model can give good explanation for the phenomena of reduction in the coefficient of friction when a USM is in operation. In order to validate the normal dynamic contact model, we also tested the normal levitation of rotor.
Tested results gave good agreement with the theoretical model. Advantages of ultrasonic motor over electromagnetic motor: 1. Little influence by magnetic field: The greatest advantage of ultrasonic motor is that it is neither affected by nor creates a magnetic field.
Regular motors which utilize electromagnetic induction will not perform normally when subjected to strong external magnetic fields. Since a fluctuation in the magnetic field will always create an electric field following the principle of electromagnetic induction , one might think that ultrasonic motors will b affected as well. In practice, however, the effects are negligible. For example, consider a fluctuation in the flux density by, say, 1T which is a considerable amount , at a frequency of 50 Hz , will create an electric field of volts per meter.
This magnitude is below the field strength in the piezoelectric ceramic and hence can be ignored. Low speed, high torque characteristics, compact size and quiet operation: Ultrasonic motors can be made very compact in size.
The motor generates high torques at low speeds and no reduction gears are needed unlike the electromagnetic motors. The motor is also very quiet, since its drive is created by ultrasonic vibrations that are inaudible to humans. The ultrasonic motors hollow structure is necessary for an application in several fields such a robotics etc where it would be very difficult to design a device with an electromagnetic motor and satisfy the required specifications.
Their main advantages over the conventional electromagnetic devices are: 1. Different velocities without gear-mechanisms, 2. High positioning accuracy due to the friction drive, 3. High holding torque braking force without energy supply. Simplicity and flexibility in structural design. No magnetic noise. High output torque at low speed. High force density. Piezoelectric Ultrasonic Motor Technology Simply we can call the ultrasonic technology as inverse of the piezoelectric effect because, in this case, the electric energy is converted into motion.
The piezoelectric material named Lead zirconate titanate and quartz are used very often for USMs and also for piezoelectric actuators even though the piezoelectric actuators are different from the USMs.
The materials like lithium niobate and some other single crystal materials are also used for USMs and piezoelectric technology.
The major difference between the piezoelectric actuators and USMs is stated as the vibration of the stator in contact with the rotor, which can be amplified by using the resonance. The amplitude of the actuator motion is in between 20 to nm.
However, each element is calculated strictly and the following capability is realized. Furthermore, the Non-magnetic Model Motor uses for stator metal and a bearing the material which is not affected at all by the influence of magnetic.
MECHANISM A key observation in the study of ultrasonic motors is that the peak vibration that may be induced in structures occurs at a relatively constant vibration velocity regardless of frequency.
The vibration velocity is simply the time derivative of the vibration displacement in a structure, and is not directly related to the speed of the wave propagation within a structure.
As the frequency is increased, the displacement decreases, and the acceleration increases. As the vibration becomes inaudible at 20 kHz or so, the vibration displacements are in the tens of micrometers, and motors have been built that operate using 50 MHz surface acoustic wave SAW that have vibrations of only a few nanometers in magnitude.
Such devices require care in construction to meet the necessary precision to make use of these motions within the stator. Dry friction is often used in contact, and the ultrasonic vibration induced in the stator is used both to impart motion to the rotor and to modulate the frictional forces present at the interface.
The friction modulation allows bulk motion of the rotor i. Two different ways are generally available to control the friction along the stator-rotor contact interface, travelling-wave vibration and standing-wave vibration. Some of the earliest versions of practical motors in the s, by Sashida , for example, used standing-wave vibration in combination with fins placed at an angle to the contact surface to form a motor, albeit one that rotated in a single direction.
Later designs by Sashida and researchers at Matsushita, ALPS, and Canon made use of travelling-wave vibration to obtain bi-directional motion, and found that this arrangement offered better efficiency and less contact interface wear. An exceptionally high- torque 'hybrid transducer' ultrasonic motor uses circumferentially-poled and axially-poled piezoelectric elements together to combine axial and torsional vibration along the contact interface, representing a driving technique that lies somewhere between the standing and travelling-wave driving methods.
A key observation in the study of ultrasonic motors is that the peak vibration that may be induced in structures occurs at a relatively constant vibration velocity regardless of frequency.
As the vibration becomes inaudible at 20 kHz or so, the vibration displacements are in the tens of micrometers, and motors have been built[2] that operate using 50 MHz surface acoustic wave SAW that have vibrations of only a few nanometers in magnitude.
More generally, there are two types of motors, contact and non-contact, the latter of which is rare and requires a working fluid to transmit the ultrasonic vibrations of the stator toward the rotor. Most versions use air, such as some of the earliest versions by Hu Junhui. Research in this area continues, particularly in near-field acoustic levitation for this sort of application.
This is different from far-field acoustic levitation, which suspends the object at half to several wavelengths away from the vibrating object. Types of Ultrasonic Motors: The USMs are classified into different types based on different criteria, which are as follows: Classification of USMs based on the type of motor rotation operation o Rotary type motors o Linear type motors Classification of USMs based on the shape of the vibrator o Rod type Unidirectional 2.
Bidirectional Working of the Ultrasonic Motors The vibration is induced into the stator of the motor, and it is used for conveying the motion to the rotor and also to modulate the frictional forces.
The amplification and micro deformations of active material are utilized for generation of the mechanical motion. The macro-motion of the rotor can be achieved by the rectification of the micro-motion using the frictional interface between the stator and the rotor. The ultrasonic motor consists of stator and rotor.
The operation of the USM changes the rotor or linear translator. The stator of the USM consists of piezoelectric ceramics for generating vibration, a metal of the stator for amplifying the generated vibration and a friction material for making contact with the rotor. Whenever voltage is applied, a travelling wave is generated on the surface of the stator metal which causes the rotor to rotate.
As the rotor is in contact with the stator metal, as mentioned So, these can be used even in high magnetic field areas as these are unaffected by the magnetic field. So, they do not generate any noise and their operation is very quiet. Demerits of Ultrasonic Motors o A high-frequency power supply is required. Applications of Ultrasonic Motors o Used for the autofocus of camera lens. Construction Ultrasonic motor construction tends to be simpler than EM type motors.
Fewer assembly parts mean fewer moving parts and consequently less wear. The number of components required to construct an USM is small thereby minimizing the number of potential failure points. As the ultrasonic motor uses ultrasonic vibrations as its driving force,it comprises a stator which is a piezoceramic material with an elastic body attached to it,and a rotor to generate ultrasonic vibrations. It therefore does not use magnets or coils. Therefore there is no problem of magnetic field and interference as in the case of electric motors.
In ultrasonic motors, piezoelectric effect is used and therefore generates little or no magnetic interference.
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