Method for electronically tuning the readout vibration frequency of a coriolis gyroscope

Detailed description of the invention

The present invention relates to a method of electronically tuning the frequency of read vibration to the frequency of excitation vibration by a Coriolis angular velocity meter.

The Coriolis angular velocity meter (also known as a vibrating gyro) is for navigation purposes (zu). Navigationszwecken) It is used more and more widely. The Coriolis angular velocity meter has a vibrating mass system. This vibration (Schwingung) is usually a superposition of multiple individual vibrations. These individual vibrations of the mass system are initially independent of each other and can be collectively regarded as a "resonator". At least two resonators are required to operate the vibrating angular velocity meter. One of these resonators (first resonator) is artificially excited and vibrated. This vibration is referred to as "excited vibration" (Anregungsschwingung) in the following text. The other resonator (second resonator) is excited and vibrated only when the vibration angular velocity meter is moved / rotated. Therefore, at this time, the Coriolis force is generated. These Coriolis forces connect the first resonator to the second resonator, extract energy from the excitation vibration of the first resonator, and transfer this energy to the read vibration of the second resonator. The vibration of the second resonator is referred to as "reading vibration" (Ausleseschwingung) in the following text. To determine the movement (especially rotation) of the Coriolis angular velocity meter, tap off the reading vibration (abgegriffen), examine the corresponding reading vibration (eg, the reading signal tap-off signal), and use the Coriolis angular velocity meter rotation index. Determine if the amplitude of the represented read signal has changed. The Coriolis angular velocity meter can be realized as either an open-loop system (Open-Loop-Systern) or a closed-loop system (Closed-Loop-System). In the closed loop system, the amplitude of the read vibration is continuously reset to a fixed value (preferably 0) via each control circuit.

In order to further clarify the operation method of the Coriolis angular velocity meter, an example of the Coriolis angular velocity meter implemented as a closed loop form will be described below with reference to FIG.

Such a Coriolis angular velocity meter 1 has a vibrable mass point system 2. This mass system is also referred to as a "resonator" in the following text. This designation must be distinguished from the abstract "resonator" described above, which refers to the individual vibrations of a "real" resonator. As mentioned above, the resonator 2 can be regarded as a system including two "resonators" (first resonator 3 and second resonator 4). The first and second resonators 3 and 4, respectively, are connected to a "Kraftgeber" (not shown) and a tap-off system (not shown), respectively. The noise generated by the "power machine" and the tap-off system is outlined here by noise 1 (reference number 5) and noise 2 (reference number 6).

The Coriolis angular velocity meter 1 also has four control circuits.

The first control circuit plays a role of controlling the excitation vibration (that is, the frequency of the first resonator 3) to a fixed frequency (resonance frequency). The first control circuit includes a first demodulator 7, a first low-pass filter (Tiefpass filter) 8, a frequency controller 9, a VCO (Voltage Controlled Oscillator) 10, and a first modulator 11.

The second control circuit plays a role of controlling the excitation vibration to a constant amplitude, and includes a second demodulator 12, a second low-pass filter 13, and an amplitude controller 14.

The third and fourth control circuits play a role in resetting the "Kraefte" that excites the reading vibration. In this case, the third control circuit includes a third demodulator 15, a third low-pass filter 16, an orthogonal controller 17, and a second modulator 18. The fourth control circuit includes a fourth demodulator 19, a fourth low-pass filter 20, a rotation speed controller 21, and a third modulator 22.

The first resonator 3 is excited at its resonance frequency ω1. The resulting excitation vibration is tapped off, the phase is demodulated using the first demodulator 7, and the demodulated signal component is supplied to the first low-pass filter 8. The first low-pass filter 8 removes the total frequency from the supplied signal component. The tap-off signal is also referred to as an excitation vibration tap-off signal in the following text. The output signal of the first low-pass filter 8 is input to the frequency controller 9. The frequency controller 9 controls the VCO 10 so that the in-phase component becomes almost 0 according to the signal supplied to the frequency controller 9. Therefore, the VCO 10 inputs a signal to the first modulator 11. The first modulator 11 itself controls the "leader" so that the "excitation force (Anregungskraft)" is input to the first resonator 3. If the in-phase component is 0, the first resonator 3 oscillates at its resonance frequency ω1. All modulators and demodulators are operated based on this resonant frequency ω1.

The excitation vibration tap-off signal is further supplied to the second control circuit and demodulated via the second demodulator 12. The output of the second demodulator 12 passes through the second low-pass filter 13. The output signal of the second low-pass filter 13 is also supplied to the amplitude controller 14. The amplitude controller 14 controls the first modulator 11 according to this signal and the reference amplitude source 23, and vibrates the first resonator 3 with a constant amplitude (that is, makes the excitation vibration a constant amplitude).

As described above, when the Coriolis angular velocity meter 1 moves / rotates, the Coriolis force (indicated by the term FC · cos (ω1 · t) in the figure) is generated. These Coriolis forces connect the first resonator 3 to the second resonator 4, thereby vibrating the second resonator 4. Tap off the resulting read vibration at frequency ω2. As a result, the corresponding read vibration tap-off signal (read signal) is supplied to the third and fourth control circuits. In the third control circuit, this signal is demodulated via the third demodulator 15, the total frequency is removed through the third low-pass filter 16, and the low-pass filtered signal is supplied to the orthogonal controller 17. .. The output signal of the quadrature controller 17 is input to the third modulator 22 so that the quadrature component corresponding to the read vibration is reset. Similarly, in the fourth control circuit, the read vibration tap-off signal is demodulated by the fourth demodulator 19, passed through the fourth low-pass filter 20, and the corresponding low-pass filtered signal is passed through, on the one hand, the rotation speed controller. Enter in 21. The output signal of the rotation speed controller 21 is proportional to the instantaneous rotation speed, and is input to the rotation speed output unit 24 as the rotation speed measurement result. Further, the corresponding low-pass filtered signal is input to the second modulator 18 on the other hand. The second modulator 18 resets the rotational speed component corresponding to the read vibration.

The Coriolis angular velocity meter 1 as described above can be operated as both a double resonance (doppel resonance) and a non-double resonance (nicht doppel resonance). When operating the Coriolis angular velocity meter 1 as a double resonance, the frequency ω2 of the read vibration is approximately equal to the frequency ω1 of the excitation vibration. On the other hand, in the non-double resonance, the frequency ω2 of the reading vibration is different from the frequency ω1 of the excitation vibration. The corresponding information about the rotation speed is contained in the output signal of the 4th low-pass filter 20 in the double resonance, whereas it is the output signal of the 3rd low-pass filter 16 in the non-double resonance. .. A double switch 25 is provided to switch between double and non-double resonance between different operating methods. The double switch 25 selectively connects the output units of the third and fourth low-pass filters 16 and 20 to the rotation speed controller 21 and the orthogonal controller 17.

When it is preferable to operate the Coriolis angular velocity meter 1 as a double resonance, it is necessary to tune the frequency of the reading vibration to the frequency of the excitation vibration as described above. This can be done, for example, by mechanical means (mechanischem Wege). In this mechanical means, the material in the mass system is removed (to the resonator 2). Alternatively, for this purpose, the frequency of the read oscillation can also be set by the electric field. In this electric field, the resonator 2 can vibrate (for example, due to a change in the electric field strength). As a result, the frequency of the read vibration can be electronically tuned to the frequency of the excitation vibration even during the operation of the Coriolis angular velocity meter 1.

An object underlying the present invention is to provide a method of electronically tuning the frequency of read vibration to the frequency of excitation vibration in a Coriolis angular velocity meter.

This object is achieved by a method based on the characteristics of claim 1. Further, the present invention provides a Coriolis angular velocity meter based on claim 11. Preferred embodiments and developments of the concept of the present invention (des Erfindungsgedankens) are described in the dependent claims, respectively.

In the Koriori angular velocity meter, the method of the present invention, in which the frequency of the reading vibration is electronically tuned to the frequency of the excitation vibration, a) basically has no effect on the excitation vibration, and b) the reading representing the reading vibration. A disturbance force (Stoerkraft) that changes the reading vibration so that the signal contains the corresponding disturbance component is input to the resonator of Koriori's angular velocity meter. At this time, the frequency of the read vibration is controlled so that the magnitude of the disturbance component included in the read signal becomes as small as possible.

In the present invention, basically, the smaller the frequency range of the read vibration that matches the frequency of the excitation vibration, the wider the artificial change of the read vibration in the rotational speed channel or the orthogonal channel, and in particular, in particular. On the other hand, it is based on the recognition that it becomes remarkable in the channels orthogonal to each other. The "Durchschlagsstaerke" of such disturbances for a read vibration tap-off signal (especially for orthogonal channels) is an indicator of how exactly the frequency of the read vibration matches the frequency of the excitation vibration. Is. That is, if the frequency of the read vibration is controlled assuming that the breaking intensity is the minimum value (that is, the magnitude of the disturbance component contained in the read vibration tap-off signal is minimized), at the same time, at the same time. The frequency of the read vibration almost matches the frequency of the excitation vibration.

What is important here is that the disturbance force on the resonator changes only the read vibration, not the excitation vibration. With reference to FIG. 2, this means that the disturbance force is input only to the second resonator 4 and not to the first resonator 3.

It is preferable to generate a disturbance force via a disturbance signal. The disturbance signal is supplied to the corresponding "power machine" or added to the signal supplied to the "power machine". In order to generate a disturbance force, for example, in each control / reset signal for controlling / compensating the reading vibration,<u style="single">That is, as a control signal for controlling the read vibration, or as a reset signal for compensating for the read vibration.</u>A disturbance signal may be added.

The disturbance signal is preferably an AC signal (for example, a superposition of a sine or cosine signal). These disturbance signals usually have a fixed disturbance frequency, which allows the disturbance component of the read vibration tap-off signal to be determined by the corresponding demodulation processing performed at the disturbance frequency. Alternatively, band-limited noise is used instead of the AC signal. In this case, the disturbance component of the read signal is modulated by the correlation between the disturbance signal (noise signal) and the read signal (signal including the disturbance component). The bandwidth of the noise in this case depends on the characteristics of the resonator 2 and the control circuit.

The above method can be used for both open-loop Coriolis angular velocity meters and closed-loop Coriolis angular velocity meters. In a closed-loop Coriolis angular velocity meter, it is preferable to add a disturbance signal to each control / reset signal for controlling / compensating the read vibration. For example, the disturbance signal can be added to the output signal of the rotation speed control circuit, and the disturbance component can be determined from the signal applied to the orthogonal controller of the orthogonal control circuit or the signal output from the orthogonal controller. On the contrary, the disturbance signal is added to the output signal of the orthogonal control circuit, and the disturbance signal is obtained from the signal applied to the rotation speed controller of the rotation speed control circuit or the signal output from the rotation speed controller. Can be determined. Alternatively, the disturbance signal can be further added to the output signal of the orthogonal control circuit, and the disturbance signal can be determined from the signal applied to the orthogonal controller of the orthogonal control circuit or the signal output from the orthogonal controller. .. Further, the disturbance signal is added to the output signal of the rotation speed controller, and the disturbance signal is obtained from the signal applied to the rotation speed controller of the rotation speed control circuit or the signal output from the rotation speed controller. Can be decided. The concept of "read signal" includes all the signals cited in this paragraph from which the disturbance component can be determined. Further, the concept of "reading signal" includes a reading vibration tap-off signal.

The frequency control of the read vibration, that is, the transmission of the control force required for the frequency control, is performed here by controlling the strength of the electric field in which at least a part of the resonator vibrates. In this case, the electrical attraction between the resonator and the frame-fixed opposite object (Gegenstueck) around the resonator is preferably non-linear.

Further, the present invention provides a device including a rotation speed control circuit and an orthogonal control circuit, which electronically tunes the frequency of read vibration to the frequency of excitation vibration.<u style="single">To have</u>Provided a featured Coriolis angular velocity meter. In this case, the device for electronic tuning is included in the disturbance unit that passes the disturbance signal to the rotation speed control circuit or the orthogonal control circuit, and the reading signal representing the reading vibration, and the disturbance component generated by the disturbance signal. It has a disturbance signal detection unit for determining the above, and a control unit for controlling the frequency of the reading vibration so that the magnitude of the disturbance component contained in the reading signal becomes as small as possible.

The disturbance unit inputs the disturbance signal to the orthogonal control circuit, whereby the disturbance signal detection unit receives the signal applied to the rotation speed controller of the rotation speed control circuit or the signal output from the rotation speed controller. Therefore, it is preferable to determine the disturbance component. On the contrary, the disturbance unit inputs the disturbance signal to the rotation speed control circuit, and the disturbance signal detection unit outputs the signal applied to the orthogonal controller of the orthogonal control circuit or the orthogonal controller. The disturbance component can be determined from the signal. Further, the disturbance unit inputs the disturbance signal to the rotation speed control circuit, and the disturbance signal detection unit applies the signal applied to the rotation speed controller of the rotation speed control circuit or the rotation speed controller thereof. The disturbance component can be determined from the signal. Alternatively, the disturbance signal is input to the orthogonal control circuit via the disturbance unit. In this case, the disturbance signal detection unit determines the disturbance component from the signal applied to the orthogonal controller of the orthogonal control circuit or the signal output from the orthogonal controller.

The disturbance signal is preferably an AC signal having a fixed disturbance frequency. In this case, the device for electronically tuning the read vibration frequency and the excitation vibration frequency preferably includes a demodulation unit. This demodulation unit demodulates the read signal at a fixed disturbance frequency to determine the disturbance component contained in the read signal. In principle, the disturbance signal can be introduced anywhere in the control circuit (rotation speed control circuit and orthogonal control circuit).

Examples of the present invention will be described in detail below with reference to the accompanying figures.

FIG. 1 is a diagram showing a schematic structure of a Coriolis angular velocity meter based on the method of the present invention. FIG. 2 is a diagram showing a schematic structure of a conventional Coriolis angular velocity meter.

First, the method of the present invention will be described in detail with reference to FIG. In this case, the parts or devices corresponding to the parts or devices in FIG. 2 are designated by the same reference numerals and are not described repeatedly.

The Coriolis angular velocity meter 1'includes a demodulation unit 27 and a reading vibration frequency controller 28 in addition to the disturbance unit 26.

The disturbance unit 26 generates an AC signal having a frequency ωmod. This AC signal is added to the output signal of the quadrature controller 21, that is, to the output section of the quadrature control circuit. A cohesive signal (zusammengesetzte) thus obtained Signal) is supplied to the (third) modulator 22. The corresponding output signal of the modulator 22 is input to the "leader" (not shown) and the resonator 2. Unless the frequency of the read vibration is essentially the same as the frequency of the excitation vibration, the AC signal generated by the disturbance modulation unit 26 "passes" through the resonator 2 and then of the disturbance component of the read vibration tap-off signal. Observed in shape. The read vibration tap-off signal is demodulated by the fourth demodulator 19 and supplied to the fourth low-pass filter 20. The output signal of the 4th low-pass filter 20 is input to both the rotation speed controller 21 and the demodulation unit 27. The signal supplied to the demodulation unit 27 is demodulated at a modulation frequency ωmod corresponding to the frequency of the AC signal generated by the disturbance unit 26. In this way, the disturbance component or the signal representing the disturbance is determined. Therefore, the demodulation unit 27 can be regarded as a disturbance signal detection unit in this embodiment. The output signal of the demodulation unit 27 is supplied to the reading vibration frequency controller 28. The reading vibration frequency controller 28 sets the reading vibration frequency so that the output signal of the demodulation unit 27, that is, the intensity of the observed disturbance component is minimized according to the supplied signal. If it is such a minimum value, the frequencies of the excitation vibration and the reading vibration are almost the same. The signal supplied to the demodulation unit 27 may be a signal output by the rotation speed controller 21 instead of the signal supplied to the rotation speed controller 21.

As described above, instead of this, the AC signal generated by the disturbance unit 26 may be added to the output signal of the rotation speed controller 21. In this case, the signal supplied to the demodulation unit 27 will be tapped off at the input or output of the orthogonal controller 17.

Further, in principle, the disturbance signal (here, an AC signal, but may be another disturbance signal such as band limiting noise) is sent to the orthogonal control circuit (not just immediately before the third modulator 22). The input can be supplied anywhere, that is, between the tap-off for reading vibration and the third modulator 22. The same applies when the disturbance signal is input and supplied to the rotation speed control circuit.

After switching on the Coriolis angular velocity meter 1', it is advantageous to set the modulation frequency ωmod of the AC signal to a high value. This is to control the frequency of the reading vibration quickly and roughly. You can then switch to a relatively low modulation frequency ωmod. This is to accurately set the resonance of the reading vibration. Furthermore, after a certain period of time has passed after the rotational speed controller 21 or the orthogonal controller 17 has stabilized (nach Einlaufen), the amplitude of the modulation frequency ωmod can be significantly reduced. Since the AC signal of the output unit of the rotation speed control circuit (that is, the third control circuit) is compensated, the rotation speed control circuit generally does not require a cutoff filter (Sperr filter) for the modulation frequency ωmod.

At the same time, the rotation speed controller 21 uses the third demodulator 15 and the fourth demodulator 19 as a "leader" for the rotation speed control circuit (cosine force) and for the orthogonal control circuit (sine force). ]Has the effect of assigning (phasen richtig) to the correct phase. In this method, the rotational speed control circuit (4th control circuit) and the orthogonal control circuit (4th control circuit) and the orthogonal control circuit (4th control circuit), even if a phase shift that may change depending on the temperature occurs in the analog electronic device of the Coriolis angular velocity meter 1'. 3 control circuit) can be separated. In general, orthogonal control circuits are highly biased. If the control circuit and the rotation speed control circuit are not clearly separated from each other, this bias also occurs in the rotation speed control circuit.

The control mechanism can be used to orthogonalize the orthogonal control circuit and the rotational speed control circuit, even if the matching of the excitation vibration, the reading vibration, and the electronic frequency is not desirable. In this case, the controlled magnitude is the reference phase of the third and fourth demodulators 15 and 19, which correspond to the orthogonal component and the rotational speed component of the read oscillation, respectively. This control is preferably performed digitally by a signal processor (DSP). This control prevents the Coriolis angular velocity meter from sensing phase shifts in analog electronics.

In the Koriori angular velocity meter, the second alternative method of electronically tuning the frequency of the reading vibration to the frequency of the excitation vibration has basically no effect on the excitation vibration and b) the reading representing the reading vibration. The disturbance force that changes the reading vibration so that the signal contains the corresponding disturbance component is input to the resonator of Koriori's angular velocity meter. At this time, the frequency of the read vibration is controlled so that the phase shift between the disturbance signal that generates the disturbance force and the disturbance component included in the read signal is as small as possible.

The "resonator" is interpreted here as the overall vibrable mass point system (or part thereof) of the Coriolis angular velocity meter, that is, the part indicated by reference number 2 of the Coriolis angular velocity meter.

The second alternative is the "time" (ie, after the disturbance acts on the resonator) that the disturbance (ie, the artificial modification of the read vibration by inputting a corresponding disturbance force into the resonator) "passes" through the resonator. , The elapsed time until the disturbance is tapped off as part of the read signal) is based on the recognition that it depends on the frequency of the read vibration. Therefore, the shift between the phase of the disturbance signal and the phase of the disturbance component signal included in the read signal is an index with respect to the frequency of the read vibration. If the frequency of the read oscillation is approximately the same as the frequency of the excitation oscillation, the phase shift can be considered to be the minimum value. Therefore, if the frequency of the read vibration is controlled assuming that the phase shift is the minimum value, at the same time, the frequency of the read vibration substantially matches the frequency of the excitation vibration.

In the Koriori angular velocity meter, the third alternative method of electronically tuning the frequency of the reading vibration to the frequency of the excitation vibration has basically no effect on the excitation vibration and b) the reading representing the reading vibration. The disturbance force that changes the reading vibration so that the signal contains the corresponding disturbance component is input to the resonator of Koriori's angular velocity meter. However, the disturbance force is defined as the force caused by the signal noise in the read signal. At this time, the frequency of the read vibration is controlled so that the magnitude of the disturbance component included in the read signal (that is, the noise component) becomes as small as possible.

The "resonator" is interpreted here as the overall vibrable mass point system (or part thereof) of the Coriolis angular velocity meter, that is, the part indicated by reference number 2 of the Coriolis angular velocity meter. What is important here is that the disturbance force on the resonator changes only the read vibration, not the excitation vibration. With reference to FIG. 2, this means that the disturbance force is input only to the second resonator 4 and not to the first resonator 3.

The third alternative is that the smaller the frequency range of the read vibration that matches the frequency of the excitation vibration, the more directly in the read vibration tap-off signal or at the input of the control circuit (rotation speed control circuit / orthogonal control circuit). It is based on the basic perception that a disturbance signal in the form of the resulting signal noise is widely observed in the read vibration tap-off signal after "passing" through the control circuit and resonator. Random walk of reading vibration tap-off electronic device or Coriolis angular velocity meter The signal noise, which is the signal noise of walk), is input to the "leading machine" after "passing" through the control circuit, and generates a corresponding disturbance force. It should be noted that this corresponding disturbance force is input to the resonator and causes an artificial change in the reading vibration. The "destructive force" of such disturbances to the read vibration tap-off signal is an indicator of how exactly the frequency of the read vibration matches the frequency of the excitation vibration. That is, if the frequency of the reading vibration is controlled so that the breaking intensity is the minimum value (that is, the magnitude of the disturbance component (that is, the noise component) contained in the reading vibration tap-off signal is minimized), At the same time, the frequency of the read vibration matches the frequency of the excitation vibration.

The method of the present invention for electronically tuning the reading vibration frequency described first can be optionally combined with the second and / or third alternative method. For example, at the beginning of the Coriolis angular velocity meter operation, use the method described first (quick stabilization characteristics (schnelles Einschwingverhalten)), followed by a third alternative method (slow control process) during stable operation ) Can be used. Specific technical embodiments of this method, as well as other details, will be described by those skilled in the art in the patent application "Verfahren zur elektronischen Abstimmung der" of the same applicant. Ausleseschwingungsfrequenz eines Coriolis skreisels) "Can be recognized from LTF-191-DE and LTF-192-DE. Each of these patent documents describes a second alternative method or a third alternative method. The entire contents of the patent application LTF-191-DE / LTF-192-DE are included herein.

<figref num="1">It is a figure which shows the schematic structure of the Coriolis angular velocity meter based on the method of this invention.</figref><figref num="2">It is a figure which shows the schematic structure of the conventional Coriolis angular velocity meter.</figref>