Method and device for operating a gyroscope

Abstract

Method (800) for operating a gyroscope (DS), wherein the gyroscope (DS) comprises a spring-mounted and electrically chargeable vibrating mass (M) which can be set into oscillation by at least one drive electrode (A1, A2) along a drive axis (x), and wherein the gyroscope (DS) comprises at least one detection electrode (D1, D2), wherein the detection electrode (D1, D2) is configured to detect an oscillation of the vibrating mass (M) which is generated by a rotation of the vibrating mass (M) about a rotation axis (z) extending transversely to the drive axis (x), wherein the detection axis (y) extends transversely to the drive axis (x) and the rotation axis (z) of the vibrating mass (M), wherein the method (800) comprises the following steps: - Applying (810) to the drive electrode (A1, A2) with a drive voltage (510), wherein the drive voltage (510) has a first frequency (1f); - Applying (820) a modulation voltage (200) to at least one drive electrode (A1) and at least one further drive electrode (A2) and / or to at least one detection electrode (D1) and at least one further detection electrode (D2), wherein the modulation voltage (200) has a second frequency (2f) that differs from the first frequency (1f); and - Detecting (830) a deflection (a) of the oscillating mass (M) from the at least one detection electrode (D1, D2) to operate the gyroscope (DS).

Description

State of the art

[0001] The present invention relates to a method for operating a gyroscope, to a corresponding device and to a corresponding computer program product.

[0002] For example, in modern vehicles, a very precise determination of the yaw rate is of considerable importance for safety-relevant and comfort-supporting systems. Accurate determination of the yaw rate enables, for instance, the precise triggering of vehicle safety systems, which would otherwise be impossible or only possible with limited functionality. In state-of-the-art approaches, the Coriolis effect is used to measure the yaw rate signal. This involves calculating the yaw rate of a Coriolis mass m moving at velocity v. c acting Coriolis force F C out of: FC=−2⋅mC⋅Ω×v.

[0003] This means that the Coriolis mass m cThe vehicle accelerates orthogonally to the direction of velocity and the applied rotation rate. This resulting Coriolis force F C A spring force F acts k with spring constant k eff in contrast to FC=Fk→−2⋅mC⋅Ω×v=keff⋅x.

[0004] A gyroscope is typically operated under a high vacuum (approx. 1 mbar). This allows for high sensitivity of the gyroscope signal through increased Q factor with low attenuation. However, using a vacuum is expensive, and therefore alternatives are being sought.

[0005] An approach to measuring the angular rate is disclosed in DE 199 39 998 A1, in which a device for generating a preload for an oscillating angular rate sensor is presented.

[0006] From DE 103 50 037 A1 a gyroscope with force-mediating means is already known, wherein the force effect mediated by these means has a frequency such that the frequency of the mediated force effect is an integer multiple of the frequency of the oscillation of the drive element parallel to the x-axis. Disclosure of the invention

[0007] Against this background, the present invention presents a method for operating a gyroscope, a device that uses this method, and a corresponding computer program product according to the main claims. Advantageous embodiments are described in the respective dependent claims and the following description.

[0008] The approach presented here provides a method for operating a gyroscope, wherein the sensor has a spring-mounted and electrically chargeable vibrating mass which can be set into oscillation by at least one drive electrode along a drive direction, and wherein the sensor has at least one detection electrode, wherein the detection electrode is configured to detect an oscillation of the vibrating mass, which is generated by a rotation of the vibrating mass (A1) about a rotation axis (z) extending transversely to the drive axis (x), along a detection axis (y), wherein the detection axis (y) extends transversely to the drive axis (x) and the rotation axis (z) of the vibrating mass (M), wherein the method comprises the following steps: - Applying a drive voltage to the drive electrodes, wherein the drive voltage has a first frequency; - Applying a modulation voltage to at least one drive electrode and at least one further drive electrode (A2) and / or to at least one detection electrode and at least one further detection electrode (D2), wherein the modulation voltage has a second frequency that differs from the first frequency; and - Detecting a deflection of the oscillating mass from at least one detection electrode in order to operate the gyroscope.

[0009] A spring-mounted vibrating mass can be understood as a mass element that, upon deflection, is returned to its initial position by springs. This mass element can be electrically charged or brought to a ground potential, thereby attracting one or more different electrodes. For this purpose, the mass element can have an electrically conductive surface or an electrically conductive material within it (or be made entirely of a conductive material) to enable an electrostatic effect of the electrodes on the mass element. The vibrating mass can be set into oscillation in a first direction along a drive axis by means of at least one drive electrode.For this purpose, the vibrating mass can be brought to a defined electrical potential that differs from the potential of at least one of the drive electrodes, causing the vibrating mass to move towards the drive electrode due to an electrostatic attraction force. The drive axis can, for example, run perpendicularly through the drive electrode and through the vibrating mass, e.g., through the center of gravity of the vibrating mass. The drive axis can also run perpendicularly through two drive electrodes. If the gyroscope is now rotated, the vibrating mass is moved in a second direction different from the drive axis along a detection axis, with the detection axis being, for example, perpendicular to the drive axis. The detection axis can, for example, run perpendicularly through the detection electrode and through the vibrating mass, e.g., through the center of gravity of the vibrating mass.The detection axis can also run perpendicularly through two detection electrodes. The movement of the vibrating mass in the second direction can then be detected by the electrodes, for example, by observing how the potential at the electrodes changes when the distance between the (electrically charged) vibrating mass and at least one of the electrodes changes. In this context, "applying" can be understood as the application of an electrical voltage to the electrodes. "Applying" can also refer to changing the electrical potential at one or more electrodes, where the electrodes may already be charged relative to a reference potential. A modulation voltage can, for example, also be understood as a voltage applied to the electrode in question, relative to a reference potential such as ground potential.This means that the modulation voltage can also be applied to one or more electrodes that are already subjected to another voltage, such as the drive voltage. In this sense, "applying" can be understood as superimposing the modulation voltage or a potential onto the drive voltage. "Detection" can be understood as determining the distance between at least one detection electrode and the vibrating mass, for example, by evaluating a potential at at least one detection electrode.

[0010] The approach presented here is based on the understanding that using different frequencies for the drive voltage and the modulation voltage allows for the adaptation of spring forces acting on the spring-mounted oscillating mass. This adaptation is based, on the one hand, on a mechanical spring force caused by mechanical springs acting on the oscillating mass, and on the other hand, on a force caused by electrostatic attraction. Thus, forces acting on the oscillating mass are superimposed to form a total spring force, caused by different physical principles. The mechanical spring force and the electrostatic attraction force can also have opposite signs. By adapting the spring forces, the oscillation and return phases of the oscillating mass can be advantageously influenced.For example, a low overall spring force can be set when the oscillating mass is displaced from its rest position to achieve the largest possible displacement or travel of the mass from its rest position, thereby enabling very precise detection of rotation. Conversely, a very low overall spring force can be set to move the oscillating mass back from its maximum displacement position to its rest position, thus resetting the gyroscope as quickly as possible and preparing it for a new measurement. To adapt the spring forces, it is therefore possible to apply relative voltages to both the drive electrodes and the detection electrodes to influence the movement of the oscillating mass.

[0011] The approach presented here offers the advantage of significantly increasing the measurement accuracy of the gyroscope through technically simple means. For this, a voltage corresponding to the modulation voltage simply needs to be applied to one or more specific electrodes of a gyroscope that already has the appropriate electrodes. This allows the adaptation of the total spring force to be achieved by superimposing the electrostatic forces between the relevant electrode(s) and the (charged) oscillating mass via the spring forces exerted by the mechanical springs.

[0012] Furthermore, the approach presented here provides a device for operating a gyroscope, wherein the sensor has a spring-mounted vibrating mass which can be set into oscillation by at least one drive electrode along a drive axis, and wherein the sensor has at least one detection electrode, wherein the at least one detection electrode is configured to detect an oscillation of the vibrating mass, which is generated by a rotation of the vibrating mass (A1) about a rotation axis (z) extending transversely to the drive axis (x), along a detection axis (y), wherein the detection axis (y) extends transversely to the drive axis (x) and the rotation axis (z) of the vibrating mass (M), wherein the device has the following features: - a unit for applying a drive voltage or drive potential to the drive electrode, wherein the drive voltage or drive potential has a first frequency; - a unit for applying a modulation voltage to at least one drive electrode and at least one further drive electrode (A2) and / or to at least one detection electrode and at least one further detection electrode, wherein the modulation voltage has a second frequency that differs from the first frequency; and - a unit for detecting a deflection of the oscillating mass from at least one detection electrode in order to operate the gyroscope.

[0013] Thus, the approach presented here introduces a device designed to carry out or implement the steps of a variant of the method presented herein in appropriate facilities. This embodiment of the invention, in the form of a device, also allows the underlying problem to be solved quickly and efficiently.

[0014] In this context, a device can be understood as an electrical device that processes sensor signals and outputs control and / or data signals accordingly. The device may have an interface, which can be implemented in hardware and / or software. In the case of a hardware-based interface, the interfaces can, for example, be part of a so-called system ASIC, which incorporates various functions of the device. However, it is also possible that the interfaces are separate integrated circuits or consist at least partially of discrete components. In the case of a software-based interface, the interfaces can be software modules, which, for example, are present on a microcontroller alongside other software modules.

[0015] It is also advantageous to have a computer program product with program code that can be stored on a machine-readable medium such as semiconductor memory, hard disk memory or optical memory and is used to carry out the method according to one of the embodiments described above, if the program product is executed on a computer or device.

[0016] Furthermore, an embodiment of the present invention is particularly advantageous in which, during the application step, two synchronized modulation voltages are applied to each of the two drive electrodes and / or to each of the two detection electrodes.

[0017] A further advantageous embodiment of the present invention is one in which a modulation voltage is used during the application step, where the second frequency is twice the first frequency. Such an embodiment of the present invention offers the advantage that, by using a modulation voltage with a second frequency twice that of the first frequency of the drive voltage, it is possible to control the oscillation of the vibrating mass particularly well.

[0018] In particular, this allows the total spring force acting on the oscillating mass to be set very softly during a partial cycle when the oscillating mass is deflected, whereas when the oscillating mass returns to its rest position, the total spring force is increased so that the oscillating mass returns to its rest position very quickly.

[0019] A particularly advantageous embodiment of the present invention is one in which the modulation voltage is superimposed on the drive voltage during the application step. Such an embodiment of the following invention offers the advantage that no modulation voltage needs to be applied to the detection electrodes, which would otherwise have to be taken into account when evaluating the potential of the detection electrode(s).

[0020] A further advantage of an embodiment of the present invention is that, in the detection step, a voltage difference between the detection electrodes is detected, and a rotation rate is determined from this voltage difference, particularly in that the voltage difference is detected using a charge integrator. Such an embodiment of the present invention offers the advantage of particularly precise detection of a voltage difference, whereby common-mode signals are suppressed and thus do not constitute interfering factors for the detection of the voltage difference.

[0021] A further advantageous embodiment of the present invention is one in which the modulation voltage and / or the drive voltage follows the actual current position of the vibrating mass. This allows for a particularly precise and controllable displacement of the vibrating mass, which, due to the large displacement range, also enables a very accurate measurement of the rotation rate. Specifically, according to a particularly advantageous embodiment of the present invention, a measurement of the current displacement of the vibrating mass between the drive electrodes can be performed during the application step, with the modulation voltage being controlled as a function of the displacement of the vibrating mass between the drive electrodes.

[0022] A particularly advantageous embodiment of the present invention is one in which the application of a voltage to the electrodes and the detection of the vibrating mass's position occur at different times. Depending on the vibrating mass's position, a drive voltage can then be regulated, allowing a desired displacement of the vibrating mass to be precisely set by using a variable drive voltage. This makes it possible to use the same electrodes both for precisely measuring the position or displacement of the vibrating mass and for moving the vibrating mass by means of a variable applied voltage.In a particularly advantageous embodiment of the present invention, the deflection of the vibrating mass between the drive electrodes can be controlled in the step of application such that, in a first clock cycle, the deflection of the vibrating mass between the drive electrodes is detected, wherein the drive electrodes are decoupled from the drive voltage, wherein a measuring unit for detecting the current deflection of the vibrating mass between the drive electrodes is coupled to the drive electrodes, and wherein, in a second clock cycle, the drive electrodes are supplied with a drive voltage that depends on the deflection of the vibrating mass between the drive electrodes, wherein the measuring unit for detecting the current deflection of the vibrating mass between the drive electrodes is decoupled from the drive electrodes.Alternatively or additionally, in the application step, the displacement of the vibrating mass between the detection electrodes can be controlled such that in a first clock cycle the displacement of the vibrating mass between the detection electrodes is detected, wherein a measuring unit for detecting the current displacement of the vibrating mass between the detection electrodes is coupled to the detection electrodes, and wherein in a second clock cycle the detection electrodes are subjected to the force feedback voltage dependent on the displacement of the vibrating mass between the detection electrodes by means of a force feedback unit, wherein a measuring unit for detecting the current displacement of the vibrating mass between the detection electrodes is decoupled from the detection electrodes.In parallel to the embodiments in the drive and detection circuits, the modulation voltage can be applied continuously and / or periodically to the respective electrodes in sync.

[0023] Furthermore, an embodiment of the present invention is particularly advantageous as a sensor system with the following features: - a gyroscope comprising a spring-mounted oscillating mass which can be set into oscillation by at least one drive electrode along a drive axis, and wherein the sensor comprises at least one detection electrode, the detection electrode being configured to detect an oscillation of the oscillating mass which is generated by a rotation of the oscillating mass (A1) about a rotation axis (z) extending transversely to the drive axis (x), along a detection axis (y), wherein the detection axis (y) extends transversely to the drive axis (x) and the rotation axis (z) of the oscillating mass (M); and - a device corresponding to a variant presented here, which is coupled to the gyroscope.

[0024] The invention is explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a schematic representation of the structure of a gyroscope; Fig. 2 diagrams to illustrate the parametric amplification approach; Fig. 3 a schematic representation of the construction of a gyroscope for use in an embodiment of the present invention; Fig. 4 a circuit diagram of an evaluation circuit with a feed of the modulation signal to the detection electrodes for use in an embodiment of the present invention; Fig. 5 a circuit diagram of an evaluation circuit with a feed of the modulation signal to the drive electrodes for use in an embodiment of the present invention; Fig. 6 a circuit diagram of an evaluation circuit with a feed of the modulation signal to the drive electrodes for use in an embodiment of the present invention; Fig. 7 a circuit diagram of an evaluation circuit with a feed of the modulation signal to the detection electrodes for use in an embodiment of the present invention; Fig. 8 a flowchart of a method according to an embodiment of the present invention;

[0025] In the following description of preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, without repeating these elements.

[0026] The aforementioned disadvantage of reduced quality and thus loss of sensitivity of the gyroscope due to capping at increased internal pressure can be counteracted by parametric amplification. This principle of parametric amplification can be applied to a gyroscope DS according to the Fig. 1. can be applied. Fig. Figure 1 shows a schematic diagram of a gyroscope DS. The gyroscope DS comprises a (in the Fig. A cubically represented oscillating mass M, which is resiliently mounted on two opposite sides by a drive spring FA1 and FA2, respectively. A drive electrode A1 and A2 are arranged on the sides of the oscillating mass M where a drive spring FA1 or FA2 is located. The oscillating mass M is electrostatically chargeable, for example, by having an electrically conductive surface or by being made of a completely electrically conductive material (such as conductively doped silicon). This allows the oscillating mass to be brought to a defined electrical potential.

[0027] Furthermore, the following are located in the Fig. Figure 1 shows a gyroscope DS with a detection spring FD1 and FD2 on each of two opposite sides where there are no drive springs FA1 and FA2, respectively. These detection springs FD1 and FD2 return the oscillating mass M to its position as shown in the Fig. Figure 1 shows the rest position when the mass has moved during an oscillation between the drive electrodes A1 and A2 and during a rotation of the gyroscope DS in one direction of one of the detection springs FD1 or FD2. The detection electrodes D1 and D2 are aligned along a detection axis (y) that is defined by the mass, while the drive electrodes A1 and A2 are aligned along a drive axis that runs transversely to the detection axis (y), specifically perpendicular to it. Thus, the detection springs FD1 and FD2 serve to return the oscillating mass M to its rest position. Furthermore, the gyroscope DS comprises two detection electrodes, D1 and D2 respectively, and two parametric electrodes, P1 and P2 respectively, located on opposite sides of the oscillating mass M.In this arrangement, a first parametric electrode P1 and a first detection electrode D1 are arranged on a common side of the oscillating mass M like the first detection spring FD1, and a second parametric electrode P2 and a second detection electrode D2 are arranged on a common side of the oscillating mass M like the second detection spring FD2.

[0028] The parametric gain, which is associated with the in the Fig. The method described for the application of the gyroscope DS shown in Figure 1 describes a procedure in which the spring stiffness k eff a oscillating spring-mass system is periodically varied. By varying the spring stiffness k in phase. eff The displacement of an oscillating mass m C increased by increasing the spring stiffness k eff It is reduced during the deflection phase and increased during the rebound phase.

[0029] A variation in spring stiffness can be caused by the "electrostatic spring-softening effect." This occurs with nonlinear changes in capacitance across the electrode spacing, such as in plate capacitances. Here, a mechanical spring stiffness k is involved. mech detection springs FD1 or FD2) are caused by an electrical spring stiffness k acting on the oscillating mass M (caused by applying a voltage to the parametric electrodes P1 or P2). el to an effective spring stiffness k eff extended. The following formula gives the relationship between the mechanical spring stiffness k mech and the electrical spring stiffness k el to the overall spring stiffness k eff (effective spring stiffness) again: keff=kmech+kel kel=−A⋅ε(a0+a)3⋅U2, where a0 is the rest position and a is the displacement from the rest position a 0' designated.

[0030] Here, U describes the parametric excitation voltage applied to plate electrodes (for example, P1 and P2 in Fig. 1) be applied in the detection direction. A DC component U DC The excitation voltage is typically used for resonance tuning in angular rate sensors (positive feedback voltage). It is also important that Û is always smaller than U. DC is, because otherwise the direction of action reverses with negative voltage U due to the quadratic dependence (k el ~ U 2 ). U=UDC+U^⋅sin(2π⋅2fres⋅t+ϕ)

[0031] Since the Coriolis effect only comes into play in a gyroscope when a moving mass M is present, the physical mass m should be c The oscillating mass M is excited in the direction of drive. This is achieved by applying two drive signals with a phase shift of 180° and a frequency of f to the drive electrodes A1 and A2, which is described in the Fig. Figure 1 is shown. When a rotation rate Ω is applied, the mass m c The oscillating mass M is periodically deflected along the detection direction (between the detection electrodes D1 and D2). Such a deflection is based on the Coriolis force FC, which can be determined according to the formula given below: FC=−2⋅mC⋅Ω×v

[0032] This periodic deflection can be amplified by parametric amplification through the phase-correct application of a 2f signal with phase Φ.

[0033] Fig. Figure 2 shows diagrams depicting the time course of the parametric amplification signals over time t. The upper sub-diagram from Fig. Figure 2 shows the amplitude A of a parametric excitation signal 200 over time t. The parametric excitation signal 200 can be understood here as a corresponding modulation signal. In the middle subdiagram of the Fig. Figure 2 shows a displacement a of the oscillating mass M corresponding to the rotation rate over time t, where the dashed line represents the displacement of a displacement that results from a fundamental oscillation of the oscillating mass M (oscillation excited in response to a drive voltage applied between the drive electrodes A1 and A2), without an excitation signal 200 being applied to the parametric electrodes, so that the total spring stiffness of the rotation rate sensor DS remains constant in this case.

[0034] The excitation signal 200 can be a voltage applied between a given electrode and a reference potential, such as ground potential. The solid curve 220 of the displacement corresponds to a displacement a that results when the excitation signal 200 is applied to the parametric electrodes P1 and P2. It is also evident that the excitation signal 200 has twice the frequency 2f of the two curves 210 and 220 of the displacement a. In the lower subdiagram from Fig. Figure 2 shows a representation of the total spring stiffness of the gyroscope in different time ranges. In the first range B1, where the displacement a of the oscillating mass increases continuously in the positive displacement range, a deflection caused by the detection springs can be observed. Fig. 1 as well as the effect of the electrostatic action of a force applied to the parametric electrodes P1 and P2 Fig. In the first region B2, where the displacement a of the oscillating mass M decreases continuously in the positive displacement region, this schematic spring 230 can be considered a spring with low or small spring stiffness. In the second region B2, where the displacement a of the oscillating mass M decreases continuously in the positive displacement region, this schematic spring 230 can be considered a spring with high or large spring stiffness. In the third region B3, where the displacement a of the oscillating mass M increases absolutely continuously in the negative displacement region, this schematic spring 230 can be considered a spring with low or small spring stiffness. In contrast, in the fourth region B4, where the displacement x of the oscillating mass M decreases absolutely continuously in a negative displacement region, the schematic spring 230 can be considered a spring with high or large spring stiffness.

[0035] By applying the modulation signal 200 to the parametric electrodes P1 and P2, the spring stiffness of a schematic overall spring 230 can be increased or decreased, thus enabling, on the one hand, a large displacement of the oscillating mass M through a low spring stiffness in individual time intervals, and on the other hand, a very fast return of the oscillating mass M through a high spring stiffness in other time intervals. Fig. Figure 2 thus shows a temporal signal profile of the modulation signal with respect to a deflection when using the parametric amplification method.

[0036] In particular, the mass m is measured in area B1. cThe spring is deflected in the positive direction, as represented by the dashed line 210. A softening of the spring stiffness at this point leads to an additional deflection x, as shown by the solid line 220 of the detection deflection. This softening is achieved by applying the positive half-wave in phase, thus increasing the voltage signal U (i.e., the modulation signal 200) at electrodes P1 and P2. In region B2, the mass M is returned to its rest position by the spring stiffness (dashed line 210). An additional increase in the spring stiffness is achieved by applying the negative half-wave in phase, thus reducing the voltage signal U at electrodes P1 and P2. This causes the mass, which was previously deflected further due to the parametric gain, to return to its rest position more quickly (solid line 220).The effect of the parametric gain is analogous to that of area B1 in area B3 and analogous to that of area B2 in area B4, whereby the sign of the detection deflection is inverted in each case.

[0037] The following advantages result from the application of parametric amplification as described above: 1. The internal pressure in the DS yaw rate sensor can be increased. 2. A smaller seismic mass (vibration mass M) of the gyroscope DS can be selected.

[0038] The respective sensitivity losses due to the aforementioned points (1) and (2) can be compensated for by parametric amplification. Costs can be reduced by using a smaller sensor element DS and by eliminating the need for costly vacuum packaging.

[0039] The approach presented below enables further cost reduction when using parametric gain by eliminating the need for additional electrodes for injecting the 2f signal 200 of the parametric gain. By eliminating the additional electrodes P1 and P2, and thus also the corresponding pads for controlling these electrodes P1 and P2, the size of the sensor element DS can be effectively reduced. This is particularly relevant because the area of ​​a sensor element DS is primarily dominated by the pads or electrodes of the gyroscope. To enable future area reductions, it is crucial to minimize the number of pads or electrodes of the gyroscope DS as much as possible.

[0040] Fig. Figure 3 shows a schematic setup of an embodiment of the present invention as a minimal angular rate sensor, wherein a minimal concept for an angular rate sensor is presented here, comprising one drive electrode pair A1 and A2 for excitation and one detection electrode pair D1 and D2 for signal acquisition. The setup corresponds to that described in the Fig. The 3 shown rotation rate sensor DS, except for the parametric electrodes P1 and P2, corresponds to the structure of the one shown in the Fig. Figure 1 shows the gyroscope DS. The 2f signal for the parametric gain is also applied, for example, to the detection electrodes D1 and D2. The application of the modulation signal to the drive electrodes A1 and A2 or the detection electrodes D1 and D2 is carried out by means of a device 300 for operating the gyroscope DS.

[0041] The implementation of the injection of the modulation signal 200 at the detection electrodes D1 and D2 is shown schematically here using the circuit diagram from Fig. 4 explained. The detection of the rotation rate signal at D1 and D2 is preferably achieved using a charge integrator 400, in particular a fully differential charge integrator. This charge integrator 400 comprises an operational amplifier OV, whose inverting input is coupled to a non-inverting output via a capacitor, and whose non-inverting input is coupled to an inverting output. A source for applying the modulation voltage 200 with frequency 2f is connected between the inverting input and the non-inverting input, thus applying the modulation voltage 200 between the detection electrodes D1 and D2, respectively, and a ground potential. The advantage of fully differential circuits (such as the charge integrator 400) is their insensitivity to common-mode signals.As an alternative to the charge integrator 400, another element such as a transresistance amplifier (with at least one resistor instead of capacitance in the feedback) can be used, which makes it possible to detect and evaluate the position of the vibrating mass in relation to an electrode such as the drive electrode and / or the detection electrode.

[0042] This means that the charge integrator 400 can only process differential signals and produce an output signal U corresponding to such a differential signal. out output. Since the DS gyroscope, as used in the Fig. As shown schematically in Figure 3, when the oscillating mass M moves away from the first detection electrode D1, the capacitance of detection electrode D1 (more precisely, the capacitance between the first detection electrode D1 and the electrically chargeable or charged oscillating mass M) decreases, while the other capacitance of detection electrode D2 (more precisely, the capacitance between the second detection electrode D2 and the electrically chargeable or charged oscillating mass M) increases, and vice versa, the counter-current rotation rate signals are displayed at the output as a voltage U. outof the charge integrator. Common-mode signals, such as those present at the input of the charge integrator 400, are not taken into account. This behavior allows the modulation signal 200 with frequency 2f to be fed in parallel with the detection of the rotation rate signal as a common-mode signal using a modulation signal generator 410 at this point (i.e., directly to the detection electrodes D1 and D2), as described in the Fig. 4 schematically represented. Because the detection electrodes D1 and D2 are implemented as plate electrodes, the spring stiffness of the total spring 230 of the gyroscope, which acts on the oscillating mass M and is formed from the mechanical springs and the electrical "springs", can be periodically modulated via the described "spring-softening effect" and thus the sensor DS can be parametrically amplified.

[0043] The loss of sensitivity, for example due to the lower internal pressure of the gyroscope DS, also affects the drive side. Provided that the drive electrodes A1 and A2 are also implemented as plate electrodes, the parametric gain can also be applied via the drive electrodes A1 and A2 by injecting a 2f signal.

[0044] In the Fig. Figure 5 schematically illustrates how the modulation signal 200 is superimposed on the drive voltage 510, supplied by a drive generator 500, at frequency f. A counter-clockwise drive signal 510 is applied to the drive electrodes A1 and A2. This causes the drive oscillator (i.e., the vibrating mass M) to oscillate at a frequency of 1f. Additionally, a synchronous 2f signal (i.e., the modulation signal 200) is applied for parametric gain and superimposed on the drive signal 510. The 2f signal (i.e., the modulation signal 200) causes a spring stiffness modulation, thus increasing the sensitivity, but does not result in oscillation of the vibrating mass M.

[0045] It can be assumed that controlled concepts are more advantageous than uncontrolled ones. For example, the vibrating mass M should not only be driven by the signal 510 of the drive generator 500, but its position should also be detected, for example, for drive control, in particular the position of the vibrating mass M relative to the drive electrodes A1 and / or A2. To avoid needing additional pads or electrodes for this functionality of monitoring the position of the vibrating mass M of the gyroscope DS, time-division multiplexing can be used.

[0046] In the Fig. Figure 6 shows a circuit diagram of such a monitoring circuit for implementing a time-division multiplexing method with a 2f signal input for the drive electrodes A1 and A2. In this monitoring circuit, the drive electrodes A1 and A2 are connected to a time-division multiplexer 600 in addition to being supplied with the modulation signal 200 by a modulation signal generator 410. Depending on a clock signal 610, the time-division multiplexer 600 connects the drive electrodes A1 and A2 either to the drive signal generator 500 (which can also be referred to as the drive generator) or to a charge integrator 620, which is configured to detect the position of the vibrating mass M by determining the potential of the drive electrodes A1 and A2. For this purpose, the charge integrator 620 can be configured analogously to the charge integrator 400. Fig. 4 be set up so that at its output U out1A differential voltage is output, representing the distance of the vibrating mass M from the drive electrodes A1 and A2. The multiplexer 600 alternately applies either the 1f drive signal 510 to A1 and A2, or the charge integrator 620 reads out the movement of the vibrator or the vibrating mass M. The multiplexer 600 is controlled by a clock signal 610 to switch between the respective drive mode and the detection mode.

[0047] The same considerations can also be applied to the detection of the position of the detection oscillator (i.e., the oscillating mass M), as exemplified in the circuit diagram from Fig. 7 is recognizable. In contrast to the alternating application of the drive signal to the drive electrodes A1 and A2 or a reading of the position of the vibrating mass M using the drive electrodes A1 and A2, the following is shown in the illustration: Fig. 7. The detection electrodes D1 and D2 are now used, in addition to the imprinting of the modulation signal 200, for the alternating imprinting of a force feedback quantity by means of a force feedback unit 700 (for controlling the displacement of the vibrating mass M) or for detecting the position of the vibrating mass M by the charge integrator 400. Here, the multiplexer is used depending on a clock 610 (which is also controlled by a clock 610 according to the Fig. 6 for controlling the use can be distinguished) of the detection electrodes D1 and D2 either the rotation rate signal is read out by means of the charge integrator 400 or a force feedback is applied to D1 and D2 by means of the force feedback unit 700.

[0048] Any combination of the elements listed in the Fig. Figures 5 to 7 illustrate embodiments for imprinting the modulation voltage 200 onto the detection electrodes D1 or D2 and / or the drive electrodes A1 or A2.

[0049] Furthermore, it should be mentioned that this method is particularly advantageous when the sensor element DS has no additional electrodes, such as Q electrodes for quadrature compensation or T electrodes for frequency adjustment. However, the approach proposed here is also interesting for sensors with Q and / or T electrodes, especially when the D electrodes D1 and D2 are much larger than the Q and T electrodes, and thus the parametric gain effect via these electrodes D1 and D2 is much greater.

[0050] Fig.Figure 8 shows an embodiment of the approach presented here as method 800 for operating a gyroscope, wherein the sensor has a spring-mounted and electrically chargeable vibrating mass which can be set into oscillation by at least one drive electrode, and wherein the sensor has at least one detection electrode, the detection electrode being configured to detect an oscillation of the vibrating mass, which is generated by a rotation of the vibrating mass (M) about a rotation axis (z) extending transversely to the drive axis (x), along a detection axis (y), wherein the detection axis (y) extends transversely to the drive axis (x) and the rotation axis (z) of the vibrating mass (M). Method 800 comprises a step 810 of applying a drive voltage to the drive electrode, wherein the drive voltage has a first frequency.Furthermore, the method 800 comprises a step 820 of applying a modulation voltage to at least each of two drive electrodes and / or each of two detection electrodes, wherein the modulation voltage has a second frequency that differs from the first frequency. Finally, the method 800 comprises a step 830 of detecting a displacement of the vibrating mass from the at least one detection electrode in order to operate the gyroscope.

[0051] The embodiments described and shown in the figures are only examples. Different embodiments can be combined completely or with respect to individual features. An embodiment can also be supplemented by features from another embodiment.

[0052] Furthermore, the process steps according to the invention can be repeated and carried out in a different order than described.

[0053] If an embodiment includes an “and / or” connection between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature, and according to another embodiment either only the first feature or only the second feature.

Claims

[1] Method (800) for operating a gyroscope (DS), wherein the gyroscope (DS) comprises a spring-mounted and electrically chargeable vibrating mass (M) which can be set into oscillation by at least one drive electrode (A1, A2) along a drive axis (x), and wherein the gyroscope (DS) comprises at least one detection electrode (D1, D2), wherein the detection electrode (D1, D2) is configured to detect an oscillation of the vibrating mass (M) which is generated by a rotation of the vibrating mass (M) about a rotation axis (z) extending transversely to the drive axis (x), wherein the detection axis (y) extends transversely to the drive axis (x) and the rotation axis (z) of the vibrating mass (M), wherein the method (800) comprises the following steps: - Applying (810) to the drive electrode (A1, A2) with a drive voltage (510), wherein the drive voltage (510) has a first frequency (1f); - Applying (820) a modulation voltage (200) to at least one drive electrode (A1) and at least one further drive electrode (A2) and / or to at least one detection electrode (D1) and at least one further detection electrode (D2), wherein the modulation voltage (200) has a second frequency (2f) that differs from the first frequency (1f); and - Detecting (830) a deflection (a) of the oscillating mass (M) from the at least one detection electrode (D1, D2) to operate the gyroscope (DS). [2] Method (800) according to claim 1, characterized by , that in the step of application (820) two synchronously pulsed modulation voltages (200) are applied to each of the two drive electrodes (A1, A2) and / or to each of the two detection electrodes (D1, D2). [3] Method (800) according to any one of the preceding claims, characterized by, that in the step of application (820) a modulation voltage (200) is used in which the second frequency (2f) is twice the first frequency (1f). [4] Method (800) according to any one of the preceding claims, characterized by , that in the step of application (820) the modulation voltage (200) is superimposed on the drive voltage (510). [5] Method (800) according to any one of the preceding claims, characterized by , that in the step of detection (830) a voltage difference (U out ) between the detection electrodes (D1, D2) is detected, whereby the voltage difference (U) is measured. out ) a rotation rate (Ω) is determined, in particular where the voltage difference (U) out ) is detected using a charge integrator (400). [6] Method (800) according to any one of the preceding claims, characterized by, that in the step of application (820) a measurement of a current displacement of the vibrating mass (M) between the drive electrodes (A1, A2) is carried out, wherein the modulation voltage (200) is regulated as a function of the displacement of the vibrating mass (M) between the drive electrodes (A1, A2). and / or wherein in the step of application (820) a measurement of a current displacement (a) of the vibrating mass (M) between the detection electrodes (D1, D2) is carried out, wherein the modulation voltage (200) is controlled as a function of the displacement (a) of the vibrating mass (M) between the detection electrodes (D1, D2). [7] Method (800) according to claim 6, characterized by, that in the step of application (820) the displacement of the vibrating mass (M) between the drive electrodes (A1, A2) is controlled such that in a first clock cycle the displacement of the vibrating mass (M) between the drive electrodes (A1, A2) is detected, wherein the drive electrodes (A1, A2) are decoupled from the drive voltage (510), wherein a measuring unit (620) for detecting the current displacement of the vibrating mass (M) between the drive electrodes (A1, A2) is coupled to the drive electrodes (A1, A2), and wherein in a second clock cycle the drive electrodes (A1, A2) are supplied with a drive voltage (510) that depends on the displacement of the vibrating mass (M) between the drive electrodes (A1, A2), wherein the measuring unit (620) for detecting the current displacement of the vibrating mass (M) between the drive electrodes (A1, A2) is coupled to the drive electrodes (A1, A2). The drive electrodes (A1, A2) are decoupled. and / or wherein in the step of application (820) the displacement (a) of the vibrating mass (M) between the detection electrodes (D1, D2) is controlled such that in a first clock cycle the displacement of the vibrating mass (M) between the detection electrodes (D1, D2) is detected, wherein a measuring unit (400) for detecting the current displacement (a) of the vibrating mass (M) between the detection electrodes (D1, D2) is coupled to detection electrodes (D1, D2), and wherein in a second clock cycle the detection electrodes (D1, D2) are acted upon with the modulation voltage (200) dependent on the displacement of the vibrating mass (M) between the detection electrodes (D1, D2) by means of a force feedback unit (700), wherein the measuring unit (400) for detecting the current displacement (a) of the vibrating mass (M) between the Detection electrodes (D1, D2) are decoupled from detection electrodes (D1, D2). [8] Computer program product with program code for carrying out the method (800) according to any one of claims 1 to 7, when the program product is executed on a device. [9] Device (300) for operating a gyroscope (DS), wherein the gyroscope (DS) comprises a spring-mounted vibrating mass (M) which can be set into oscillation by at least one drive electrode (A1, A2) along a drive axis (x), and wherein the gyroscope (DS) comprises at least one detection electrode (D1, D2), wherein the detection electrode (D1, D2) is configured to detect an oscillation of the vibrating mass (M) which is generated by a rotation of the vibrating mass (M) about a rotation axis (z) extending transversely to the drive axis (x), wherein the detection axis (y) extends transversely to the drive axis (x) and the rotation axis (z) of the vibrating mass (M), wherein the device (300) has the following features: - a unit (500) for applying a drive voltage (510) or a drive potential to the drive electrodes (A1, A2), wherein the drive voltage (510) or the drive potential has a first frequency (1f); - a unit (410) for applying a modulation voltage (200) to at least one drive electrode (A1) and at least one further drive electrode (A2) and / or to at least one detection electrode (D1) and at least one further detection electrode (D2), wherein the modulation voltage (200) has a second frequency (2f) that differs from the first frequency (1f); and - a unit (400) for detecting a deflection (a) of the oscillating mass (M) from the at least one detection electrode (D1, D2) to operate the gyroscope (DS). [10] Sensor system (300, DS) with the following features: - a gyroscope (DS) comprising a spring-mounted vibrating mass (M) which can be set into oscillation by at least one drive electrode (A1, A2) along a drive axis (x) and wherein the gyroscope (DS) comprises at least one detection electrode (D1, D2), wherein the detection electrode (D1, D2) is configured to detect an oscillation of the vibrating mass (M) which is generated by a rotation of the vibrating mass (M) about a rotation axis (z) extending transversely to the drive axis (x), along a detection axis (y), wherein the detection axis (y) extends transversely to the drive axis (x) and the rotation axis (z) of the vibrating mass (M); and - a device (300) according to claim 9, which is coupled to the gyroscope (DS).

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