![]() The resonant frequency was found at 46.95 kHz. They indicate the first longitudinal and second bending mode of the actuator. Two peaks can be seen in the measured impedance graph (Fig. Obtained data was inaccurate, therefore new range was defined from 45 kHz to 49 kHz. Frequency range was set from 45 kHz to 60 kHz during the first step of measurements. 4192A LF Impedance Analyzer (Hewlett Packard) was used. Ball bearing is used with intention to prevent unscrewing of the bolt during actuators operation.įirstly, impedance-frequency measurements were done in order to find resonant frequency of the actuator (Fig. Holder consist of conjunctive bolt, ball bearing bead, ball bearing and retaining ring. Holder of the actuator was designed to support actuator during experiments. 7).Ī prototype of the traveling wave actuator and special holder were made (Fig. Finally, trajectories of the contact point motion were calculated in x y plane at the frequency 55.15 kHz when forward and backward excitation regimes are used (Fig. difference of the resonant frequencies is 141 Hz. Shape of the diagram confirms that the first longitudinal and second flexural modes are close i.e. Impedance – frequency characteristic was calculated (Fig. 4, where maximum displacement amplitude is 2.3 μm at 55.15 kHz. Amplitude – frequency characteristic of the contact point is given in Fig. Amplitude of the voltage was set to 100 V. Four electric sinusoidal signal with the phase shifted by π /2 is applied to each section of piezoelectric ring (Fig. Frequency range from 54 kHz to 59 kHz with step 100 Hz was analyzed. Harmonic response analysis was performed in order to find the trajectories of motion of the contact point at the resonant frequency. Modal shapes of the actuator are given in Fig. The differences between natural frequencies is 1.4 kHz. In this case frequency of the first longitudinal mode is 58.5 kHz while frequency of the second flexural mode is 57.1 kHz. The best coincidence of the first longitudinal and second flexural mode frequencies occurs when ratio is equal to 0.05. Node of vibrations is shifting from the middle point of the waveguide length therefore displacement amplitudes are increased on the top surface of the waveguide. The first longitudinal and second flexural vibration mode is used to obtain traveling wave vibrations on the top surface of the waveguide. Waveguide is a cylinder with conical hole inside. Rotary type traveling wave actuator with a novel waveguide is introduced in this paper. symmetrical and asymmetrical was proposed to generate traveling wave. As for example, two different electrodes patterns for the electrodes excitation i.e. Therefore, various driving principles of the traveling wave motors were proposed. Proper regimes of the motor excitation give significant impact to the performance of the traveling wave motors. However, the complicated structure and driving system of the motor makes it bulky and difficult to use for practical applications. first longitudinal, third bending and the sixth radial flexural vibrations was employed. As for example a cylindrical traveling wave ultrasonic motor was proposed where superposition of three vibration modes i.e. Some authors analyze various hybrid vibrations of the stator to achieve higher performance of the traveling wave actuators. A new interaction type between stator and rotor was analyzed to achieve higher performance of ultrasonic motor. There are reports where authors introduce traveling wave ultrasonic motor of high torque. ![]() Linear type traveling wave actuators feature the same advantages but the development of these actuators is more complex. Rotary type actuators have the following advantages as high torque density at low speed, high holding torque, and quick response. Traveling wave actuators can be classified as rotary type and linear type. These advantages give positive impact to developers so huge number of different design of the traveling wave actuators were proposed and used. Advantages of these motors are high resolution, short response time, and good controllability. These type or motors are widely used for high precision mechanical systems such as positioning devices, manipulating systems, control equipment ant etc. Traveling wave motors are one of the most popular piezoelectric motors used in mechatronic systems during the last few decades.
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