DE102006046896A1 - Device and method for online position initialization of an actuator, in particular a piezoelectric ring motor - Google Patents

Device and method for online position initialization of an actuator, in particular a piezoelectric ring motor

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Publication number
DE102006046896A1
DE102006046896A1 DE200610046896 DE102006046896A DE102006046896A1 DE 102006046896 A1 DE102006046896 A1 DE 102006046896A1 DE 200610046896 DE200610046896 DE 200610046896 DE 102006046896 A DE102006046896 A DE 102006046896A DE 102006046896 A1 DE102006046896 A1 DE 102006046896A1
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DE
Germany
Prior art keywords
φ
loss torque
actuator
function
device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
DE200610046896
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German (de)
Inventor
Bernhard Dr. Gottlieb
Andreas Dr. Kappel
Juan Manuel Armilla Roldan Gomez
Tim Dr. Schwebel
Carsten Wallenhauer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
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Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Priority to DE200610046896 priority Critical patent/DE102006046896A1/en
Publication of DE102006046896A1 publication Critical patent/DE102006046896A1/en
Withdrawn legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02NELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N2/00Electric machines in general using piezo-electric effect, electrostriction or magnetostriction
    • H02N2/10Electric machines in general using piezo-electric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
    • H02N2/14Drive circuits; Control arrangements or methods
    • H02N2/142Small signal circuits; Means for controlling position or derived quantities, e.g. speed, torque, starting, stopping, reversing
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02NELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N2/00Electric machines in general using piezo-electric effect, electrostriction or magnetostriction
    • H02N2/10Electric machines in general using piezo-electric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
    • H02N2/105Cycloid or wobble motors; Harmonic traction motors

Abstract

The present invention relates to a device for a position initialization in operation of an actuator (1), in particular a piezo ring motor. To correct a displaced by overload on a piezo ring motor starting position of an actuator, a simple and effective device is to be provided. At a piezo ring actuator (1), a calibration loss torque function is detected prior to operation and mathematically compared during operation with an operating loss torque function. By means of the comparison, a shift angle Deltaphi can be determined for the correction of an angular position stored as an initial starting position. For example, a cross-correlation is used for the mathematical comparison. Online position initialization is suitable for all motors where loss torque functions can be detected.

Description

  • The The present invention relates to a device according to the preamble of the main claim and a method according to the preamble of the independent claim.
  • The The present invention is basic to all actuators, in particular piezoelectric actuators applicable.
  • The DE 199 52 946 A1 discloses a piezoelectric drive called a piezo ring motor (PRM). This piezo ring motor has a high torque, a high positioning accuracy, a flat design and inherent sensor characteristics. This combination is particularly advantageous compared to conventional actuators. The motor principle causes a high reduction ratio between drive ring and shaft and thus provides a high positioning accuracy. In a positive variant of the engine, in which ring and shaft are subjected to a suitable toothing, the accuracy improved by missing slip again. In this way, the piezo ring motor can start each rotational angle position controlled. All that needs to be initialized is the engine control with an initial position.
  • A Absolute positioning is only possible if the engine electronics once an absolute position is known. After that you can join inactive electronics no longer change the motor position. The The last detected motor position must always be stored non-volatile become. Are these technical requirements not available and should be the approach of absolute angular positions after switching on be executable the drive must be initialized. Initializing drives happens on conventional Way by targeted approach an initialization position. there The rotor of the motor is rotated until the rotor position coincides with an outer angle mark. This can be done automatically by using a zero position encoder and by feedback done on the engine control. Another possibility for a targeted start of a Initialization position is the visual comparison, along with a manual correction of the motor position. In both cases, essential Advantages regarding the relative and absolute positioning accuracy of the piezoring motor not be used immediately.
  • Especially It is advantageous if the drive without external intervention its absolute position can also find after losing the last position. It should be one Procedure for a piezoelectric ring motor are provided with the an online initialization and a recovery of the absolute position executable without external position encoder is.
  • On conventional This is an initial initialization by means of a reference run executed. It fixes the motor and the angular position of the motor shaft measured. The zero position is based on a measured value approached by an external angle sensor or zero position sensor. The engine electronics can be initialized based on the encoder become. This conventional Need procedure disadvantageously a special setup for initialization. Likewise, disadvantageously, a reinitialization must be performed, for the Case that the engine electronics zero position, for example due to an overload or a memory error, loses.
  • It is an object of the present invention, a piezoelectric actuator, in particular a piezo ring according to the DE 199 52 946 A1 in such a way that by means of a motor control device each absolute rotational angular position is directly controllable and any shift or loss of the absolute rotational angular position is correctable by means of a simple and effective online position initialization. Position initialization means that an initial starting position is restored. Online means performing a position initialization during operation of the no-load actuator. It should be on external position sensor, such as external angle sensors or zero-position sensors are omitted.
  • The The object is achieved by a device according to the main claim and a Method according to the independent claim solved.
  • Zero position initialization on an actuator, in particular on a piezoelectric actuator, as preferably a piezoelectric Piezoringmotor according to the DE 199 52 946 A1 is performed on the basis of a measurement of the engine's own loss torque with respect to the angular position. Each drive or motor has a unique, typical for this loss torque function, which is essentially determined by the structure of the motor or actuator. Once such a torque loss function is recorded with respect to the angle of rotation and before it is operated Way produces a calibration loss torque function. This calibration loss torque function can be used at any later time to initialize the motor position. A mathematical comparison is made of the known calibration loss torque function (calibration function) with the operating loss torque function measured during operation. In the mathematical comparison by means of correlation, the measured operating loss torque function is pushed along the rotation angle axis via the known calibration function. At the maximum of the correlation, the angular positions of the measured operating loss torque are most likely to coincide with the positions of the calibration function. The position of the maximum of the correlation function for shifting the rotation angle is used for correcting the rotation angle value stored in a motor control means. In this way, the engine control device and thus the actuator are initialized during operation.
  • It Particularly advantageous is the loss torque function of a piezoelectric actuator, in particular a piezoelectric Ring motor, used for online position initialization. basis is the comparison between a once-measured calibration loss torque function (Calibration function) with respect to the angle of rotation of the motor shaft and a measured operating loss torque function. Both functions are mathematical, for example via a Correlation, compared. The position of the maximum of the correlation over a Displacement angle gives the displacement of the measured angular position across from the angular position stored in the engine control unit again. By means of the correction of the stored in the engine control unit Angle of rotation with the displacement angle may be the motor or actuator to be initialized during operation.
  • The detection of the loss torque functions takes place with no-load actuator or motor. The displacement angle Δφ determines the displacement Δφ max of the detected angular position φ with respect to the angular position φ G stored as an initial starting position in a motor control device. By means of the correction, the operating loss torque function M (φ) is again approximated to the original calibration loss torque function (calibration function) M (φ).
  • through the proposed solution can complex Angle sensors are avoided.
  • Further advantageous embodiments can be found in the subclaims.
  • According to one advantageous embodiment converts the device for detection the loss torque functions, that is, the calibration loss torque function and the operating loss torque function, this in torque per proportional voltage functions. In this way, the loss torque functions Can be further processed in an electronic way. For example, you can This way the loss torque functions are stored and mathematical or physically compared.
  • According to a further advantageous embodiment, the mathematical comparison is carried out by means of a cross-correlation (see equation 1). An alternative comparison function can be used, which assumes that the mean values of functions remain unchanged over longer periods of time. This alternative comparison function is, for example, that with Equation 2
    Figure 00050001
    certain. Thus, it is advantageous to use a comparison function which is different from the cross-correlation and which retains the scaling and mean value of the loss torque functions.
  • According to a further advantageous embodiment, the actuator is a piezo ring motor, the at least two electromechanical drive elements, at least one drive ring which can be excited by the stroke of the electromechanical drive elements to a circumferential displacement movement, and a shaft which can be placed on the drive ring, so that through the Displacement movement of the drive ring, the shaft is rotatable, has, and the at least one drive ring is mechanically stiffened connected to the drive elements. This piezo ring motor can also do all in the DE 199 52 946 A1 have disclosed features. The disclosure of this document is the entire content of this patent application.
  • According to a further advantageous embodiment in the form of a form-fitting variant of the engine, while ring and shaft are acted upon with suitable teeth, has at least one tooth tip on the drive ring and at least one associated tooth valley on the shaft and / or at least one tooth valley on the drive ring and at least one associated Denture head on the shaft one of an ideal form ing shaping for generating at least one characteristic pulse in the loss torque function. This is particularly advantageous for improving the noise immunity of the device. This targeted change in the tooth shape improves the immunity to interference of the correlation measurement, in particular the cross-correlation measurement.
  • According to one Further advantageous embodiment, the calibration loss torque function (calibration function) stored in a memory device.
  • According to one further advantageous embodiment performs a switching device, in a first mode, operating loss torque functions of the device for mathematical comparison and in a second operating mode calibration functions the storage device to.
  • According to one Another advantageous embodiment is a multi-channel piezo driver for adjusting the output signals of the engine control unit Piezoelectric actuators of the actuator provided.
  • According to one embodiment of a method according to the invention, the mathematical comparison is carried out by means of a correlation, in particular a cross-correlation (see equation 1). Likewise, an alternative compare function may be used which preserves the scaling and mean of loss torque functions. This can in particular the function
    Figure 00060001
    be.
  • According to one further advantageous embodiment of the method according to the invention is determined by means of a shape deviating from an ideal shape of Drive ring and / or shaft of the actuator at least one characteristic Pulse generated in the loss torque function. On In this way, a characteristic mark can be generated.
  • The The present invention will be described in conjunction with the figures of exemplary embodiments described in more detail. Show it:
  • 1 a representation of an embodiment of a device according to the invention;
  • 2 an illustration of a calibration loss torque function and an operation loss torque function according to the embodiment; and
  • 3 a representation of the mathematical comparison based on a cross-correlation.
  • 1 shows a representation of an embodiment of a device according to the invention. 1 schematically shows a structure of a motor controller 9 . 6 and 7 for a piezo ring motor 1 with which a method according to the invention for online position initialization can be carried out. The facilities 9 . 6 and 7 are part of the engine control. Facility 9 denotes a user interface, which may be, for example, a digital data bus, a serial interface, and the like. Facility 6 includes a controller for generating the control signals of the actuators, in particular sine and / or cosine functions of the piezo ring motor 1 , In normal operation, ie there is no overload on the piezo ring motor 1 on, this slip-free follows the control signals. By counting the periods, with a known initial rotation angle, the just current rotation angle of the motor shaft can be determined with sufficient accuracy. Facility 7 is a multi-channel piezo driver 7 , which controls the output signals 6 to the piezoelectric actuators of the piezo ring motor 1 adapts. Facility 2 is a converter that evaluates the feedback signals of the actuators and generates a torque-proportional voltage U (φ). Facility 3 is a switching device 3 , which are only used to record the calibration function, ie before the operation of the actuator 1 recorded calibration loss torque function M (φ), is switched to a position a. In operation, the switching device 3 switched to position b. The device 5 is a storage device 5 in which the calibration loss torque function (calibration function) is stored. Is the switching device 3 Switched to position b, the measured operating loss torque function U (φ) to a cross-correlator 4 pass the measured operating loss torque function with that in the memory device 5 stored calibration function u c (φ) compares. The cross-correlation function r (Δφ) represents the value for the similarity of two input functions. This is done by measuring the measured operating loss torque ment function along the X-axis, or the φ-axis, relative to the calibration function. For each position, a correlation coefficient is calculated. If the magnitude of the correlation coefficient r = 1, then both input functions are identical. That is, the output function on the device 4 for mathematically comparing the calibration function u c (φ) with the operating loss torque function u (φ), is a function whose global maximum is found at a displacement angle Δφ at which the calibration function and the measured operating loss torque function are most similar. An institution 8th searches the shift angle Δφ associated with the global maximum of the cross-correlation function r (Δφ) and sends it to the controller 6 out. The control 6 adds the displacement angle Δφ to the instantaneous value of the angle of rotation φ G which the controller controls 6 has saved and thereby compensates for the error in the stored angle of rotation value. In normal operation, the shift should be Δφ = 0, ie ei ne correction by means of an online initialization leads to no change of the moment in the controller 6 stored value for the motor rotation angle. In the case of an overload, ie a too high torque, there may be a change in the motor rotation angle, which in the control 6 currently stored motor rotation angle φ G deviates from the real motor rotation angle value. In this case, a shift Δφ ≠ 0 by the cross-correlator 4 detected. By adding Δφ to the currently stored motor rotation angle φ G , it is corrected and the system is initialized online.
  • The cross-correlation can be calculated according to the following equation:
    Figure 00090001
  • The disadvantage is the compensation of displacements of the input function u c (φ) and u (φ) to each other by subtracting the average values of both functions according to equation 1. This is only necessary if due to the change of the boundary conditions, the mean values of the functions over large Change periods, as is the case with aging, for example. If the boundary conditions are stable, a following Equation 2 leads to better results, since in addition the mean values are included in the similarity analysis:
    Figure 00090002
  • In an experiment, the most important steps using an appropriate software were an online initialization to a piezo ring motor 1 traced. For this purpose, a calibration loss torque function or calibration function was first recorded in 2 is shown. Significantly, a characteristic course can be seen, the fingerprint of the piezo ring motor 1 is comparable. After a few turns of the piezo ring motor 1 The operating loss torque function M (φ) has been measured over an angular range of α = 206 ° 2 dotted is shown. The associated rotation angle was set to start with φ G = 0 ° and should be corrected by an initialization. The aim was to calculate the function of the correlation to the displacement angle Δφ by cross-correlation of the calibration function and the operating loss torque curve.
  • A result of the calculation of the correlation function is according to 3 shown. The position of the maximum of the function with respect to the X-axis gives the shift of the measured operating loss torque function to the calibration function. In the experiment, a shift of Δφ = 241.4 ° was determined. For the correction, ie for the initialization, the shift angle Δφ must be added to the angle φ G originally defining 0 °. As a check, a conventional measurement with a rotary encoder coupled to the motor shaft was carried out in parallel to the described test procedure. The measurement showed a shift of Δφ = 239.9 °. The comparison between the measurement results of the measurement based on the cross correlation and an external rotation angle sensor shows a good agreement with ei ner deviation of only 1.5 °.
  • at use of Equation 2 for similarity comparison becomes a same data set, a deviation between the rotational angle measured value based on the similarity comparison and the measured value of an external rotary encoder of only 0.5 °.

Claims (11)

  1. Device for operating position initialization of an actuator ( 1 ), in particular a piezoelectric actuator ( 1 ), characterized by - a device ( 2 ) for detecting the angular position φ of the actuator ( 1 ) dependent loss torque function M (φ), before the operation of the actuator ( 1 ) as a calibration loss torque function M (φ) and in operation as an operating loss torque function M (φ), - a device ( 4 ) for mathematically comparing the calibration loss torque function M (φ) with the operating loss torque function M (φ), in particular by means of correlation, 8th ) for determining the position of the maximum of the correlation r (Δφ) over a displacement angle Δφ, - a motor control device ( 6 . 7 . 9 ) for correcting the angular position φ G stored as an initial starting position with the displacement angle Δφ.
  2. Device according to claim 1, characterized in that the device ( 2 ) for detecting the loss torque functions M (φ), converts them into torque-proportional voltage functions U (φ).
  3. Device according to claim 1 or 2, characterized in that the device ( 4 ) is a cross-correlator for mathematical comparison or uses an alternative comparison function.
  4. Device according to one or more of the preceding claims 1 to 3, characterized in that the actuator ( 1 ) a piezo ring motor ( 1 ), and - at least two electromechanical drive elements, - at least one drive ring ( 10 ), which is excitable by a stroke of the electromechanical drive elements to a circumferential displacement movement, - a shaft ( 11 ), which can be placed on the drive ring, so that the shaft is rotatable by the displacement movement of the drive ring has, and the at least one drive ring ( 10 ) is mechanically rigidly connected to the drive elements.
  5. Apparatus according to claim 4, characterized in that in a positive-locking variant of the engine, in the drive ring ( 10 ) and wave ( 11 ) are acted upon with suitable toothing, at least one tooth tip on the drive ring ( 10 ) and at least one associated tooth valley on the shaft ( 11 ) and / or at least one tooth valley on the drive ring ( 10 ) and at least one associated tooth tip on the shaft ( 11 ) have a shape deviating from an ideal shape for generating at least one characteristic pulse in the loss torque functions.
  6. Device according to one or more of the preceding claims 1 to 5, characterized by a memory device ( 5 ) for storing the calibration loss torque function M c (φ).
  7. Device according to one or more of the preceding claims 1 to 6, characterized by a switching device ( 3 ), which in a first mode operating loss torque functions M (φ) of the device ( 4 ) for mathematical comparison and in a second mode, a calibration loss torque function M (φ) of the memory device ( 5 ) feeds.
  8. Device according to one or more of the preceding claims 1 to 7, characterized by a multi-channel piezo driver ( 7 ) for adapting the output signals of the engine control device ( 6 ) to piezoelectric actuators of the actuator ( 1 ).
  9. Method for initializing the position of an actuator in operation ( 1 ), in particular a piezoelectric actuator ( 1 ) or piezo ring motor ( 1 ), characterized by - detecting the of an angular position φ of the actuator ( 1 ) dependent loss torque function M (φ), before the operation of the actuator ( 1 ) as a calibration loss torque function M (φ) and in operation as an operation loss torque function M (φ), Mathematically comparing the calibration loss torque function M (φ) with the operating loss torque function M (φ), in particular by correlation, - determining the position of the maximum of the correlation r (Δφ) over a displacement angle Δφ, - Correcting the initial home position stored in a motor controller angular position φ G , with the displacement angle Δφ.
  10. Method according to claim 9, characterized in that that the correlation is a cross-correlation or an alternative Comparative function is.
  11. A method according to claim 9 or 10, characterized in that by means of a deviating from an ideal shape shaping of drive ring ( 10 ) and / or wave ( 11 ) of the actuator ( 1 ) at least one characteristic pulse is generated in the loss torque functions.
DE200610046896 2006-10-04 2006-10-04 Device and method for online position initialization of an actuator, in particular a piezoelectric ring motor Withdrawn DE102006046896A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE200610046896 DE102006046896A1 (en) 2006-10-04 2006-10-04 Device and method for online position initialization of an actuator, in particular a piezoelectric ring motor

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE200610046896 DE102006046896A1 (en) 2006-10-04 2006-10-04 Device and method for online position initialization of an actuator, in particular a piezoelectric ring motor
PCT/EP2007/060423 WO2008040718A1 (en) 2006-10-04 2007-10-02 Device and method for the online position initialization of an actuating drive, particularly of a piezoelectric ring motor
EP20070820805 EP2070188A1 (en) 2006-10-04 2007-10-02 Device and method for the online position initialization of an actuating drive, particularly of a piezoelectric ring motor

Publications (1)

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DE102006046896A1 true DE102006046896A1 (en) 2008-04-10

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DE200610046896 Withdrawn DE102006046896A1 (en) 2006-10-04 2006-10-04 Device and method for online position initialization of an actuator, in particular a piezoelectric ring motor

Country Status (3)

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EP (1) EP2070188A1 (en)
DE (1) DE102006046896A1 (en)
WO (1) WO2008040718A1 (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19952946A1 (en) 1999-11-03 2001-05-17 Siemens Ag Electromechanical motor
DE10262395B4 (en) * 2001-08-09 2016-03-03 Denso Corporation Rotary pump with higher delivery pressure and brake device having the same
CA2379732A1 (en) 2002-04-02 2003-10-02 Turbocor Inc. System and method for controlling an electric motor

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WO2008040718A1 (en) 2008-04-10

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