Physik Instŕumente (pi) Gmbh & Co. Kg

Physik Instrumente Gmbh & Co. Kg

Bülent Delibas

Burhanettin Koc

Disclosed is electromechanical actuator for ultrasonic motor in the shape of an n-sided regular polygon plate with n being equal to or greater than five. The polygon plate has two larger main surfaces and at least five smaller side surfaces connecting the main surfaces with each other. Two electrodes are arranged on one of the main surfaces and are electrically isolated from each other by a linear isolation area. One electrode is arranged on the other of the main surfaces. The polygon plate comprises an electromechanical material that undergoes a deformation when electric voltage is applied to the electrodes. The material of the electromechanical actuator comprises a single or polycrystalline piezoelectric ceramic with piezoelectric charge constant ddiffering from piezoelectric charge constant dboth in sign and in value. The piezoelectric charge constants dand ddefine a first and second main deformation direction of the actuator perpendicular to each other. The orientation of the linear isolation area is parallel to either deformation direction.

Electromechanical actuator, method for electrical excitation of an electromechanical actuator and ultrasonic motor

A method is disclosed for closed-loop motion control of an ultrasonic motor having at least one actuator with an excitation electrode and at least one common electrode, an element to be driven, a controller and at least one electrical generator for generating at least first and second excitation voltages Uand Uto be applied to the electrodes of the actuator for vibration of the actuator. A friction element of the actuator, due to its vibration, intermittently contacts the element to be driven with a driving force. The method includes providing the at least two excitation voltages Uand Uwith different resemblance frequencies, a frequency difference deviating from a servo sampling frequency of the controller by 5 kHz at the most, and simultaneously applying the excitation voltages to the electrodes of the actuator.

Method for closed-loop motion control for an ultrasonic motor

An actuator with a rectangular shape] is made of polarized electromechanical material having two large main surfaces and at least four side surfaces, two of which being longer than the other two side surfaces. At least one friction element is arranged on at least one of the shorter side surfaces. At least two active electrodes are arranged on one of the main surfaces, with one common electrode arranged on the other of the main surfaces The electromechanical material of the actuator is excitable to perform standing wave deformations due to an electric field generated therein for moving the friction element to drive an element. The actuator aspect ratio for its length to its thickness is between 3.9 and 4.1 and an aspect ratio for the length relative to width is between 2 and 5.

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Bülent Delibas