Method for correcting gyro demodulation phase drift

Abstract

Embodiments of the present disclosure relate to a method for correcting a demodulation phase drift of a gyroscope. A gyroscope sensor unit detects a phase drift between a demodulation output signal and a demodulation signal during output of a quadrature test signal. A delay calculator detects the phase drift based on a change in the demodulation output signal during application of the quadrature test signal. A delay compensation circuit compensates for the phase drift by delaying the demodulation signal by a phase drift value.

Description

Technical Field

[0001] This disclosure generally relates to gyroscopes. More particularly, it relates to detecting phase drift during gyroscope demodulation. Background Technology

[0002] Sensing the motion of electronics used in vehicles is often beneficial. For this reason, many vehicles and electronic devices include inertial sensors. Inertial sensors can include accelerometers and gyroscopes. Accelerometers can detect linear motion. Gyroscopes can detect rotational motion.

[0003] Detecting the rotational rate of a vehicle or electronic device using a gyroscope can be quite complex. This is partly due to the fact that using a complex signal to excite the gyroscope's resonant mass is sufficient to sense the rotational motion of the resonant mass block. Accurately extracting the rotational rate from the gyroscope's raw output signal can be quite difficult.

[0004] One particularly complex factor is the quadrature component of the output signal. The raw output of the gyroscope corresponds to the oscillation of the resonant mass in the sensing direction, perpendicular to the excitation direction of the resonant mass. While rotational motion will cause oscillation of the resonant mass in the sensing direction, the quadrature effect will also contribute to this oscillation. However, the quadrature component of the raw output signal is parasitic and does not represent rotational motion.

[0005] The gyroscope utilizes the fact that the quadrature component of the original output signal is usually in phase with the excitation or drive signal, while the rotational component is usually 90° out of phase with the excitation or drive signal. Therefore, the rotational component of the original output signal can be obtained by extracting the component of the original output signal that is 90° out of phase with the excitation or drive signal. However, if a phase drift is associated with the original output signal, extracting the component of the output signal that is 90° out of phase with the drive signal will not accurately represent the rotational rate. Summary of the Invention

[0006] Embodiments of this disclosure provide a sensor unit including a gyroscope. The sensor unit effectively and efficiently identifies the phase drift between the gyroscope's raw output signal and its drive signal. This is achieved by applying a test voltage to an orthogonal compensation electrode adjacent to the gyroscope's resonator mass block and detecting changes in the gyroscope's demodulated output signal while the test voltage is applied. After identifying the phase drift, it can be taken into account when generating the demodulated output signal. The demodulated signal then accurately represents the rotational component of the raw output signal.

[0007] A demodulated signal is generated by demodulating the original output signal using the drive signal. The demodulation process extracts the portion of the original output signal that is 90 degrees out of phase with the drive signal. When phase drift is detected when a test voltage is applied, a delay compensation circuit inserts a delay into the drive signal before demodulation occurs. The added delay compensates for the phase drift, effectively eliminating its negative effects.

[0008] The test signal includes a first phase and a second phase. In the first phase, the test signal has a first polarity. In the second phase, the test signal has a second polarity. The sensor unit detects the difference between the first and second phases of the demodulated output signal. This difference indicates phase drift. Attached Figure Description

[0009] Figure 1 This is a block diagram of an electronic device including a sensor unit with a gyroscope, according to some embodiments.

[0010] Figure 2A and Figure 2B This is a simplified illustration of the resonator mass block of a gyroscope according to some embodiments.

[0011] Figure 3 This is a graph showing the signals associated with a gyroscope according to some embodiments.

[0012] Figure 4 It is a graph representing the demodulation plane associated with the drive and output signals of the gyroscope, according to some embodiments.

[0013] Figure 5A and Figure 5B This is a graph showing the demodulation plane associated with the drive and output signals of the gyroscope during a test cycle of the gyroscope, according to some embodiments.

[0014] Figure 6 This is a graph showing the test signals of a gyroscope according to some embodiments.

[0015] Figure 7 This is a block diagram illustrating various aspects of the output operation of a sensor unit according to some embodiments.

[0016] Figure 8 This is an illustration of a portion of a gyroscope according to some embodiments.

[0017] Figure 9 This is an illustration of a portion of a gyroscope according to some embodiments.

[0018] Figure 10 This is an illustration of a portion of a gyroscope according to some embodiments.

[0019] Figure 11This is a block diagram illustrating a sensor unit including a gyroscope according to some embodiments.

[0020] Figure 12 This is a flowchart of a method for operating a gyroscope according to some embodiments. Detailed Implementation

[0021] In the following description, certain specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments can be practiced without one or more of these specific details or using other methods, components, materials, etc. In other examples, well-known structures and processes associated with gyroscopes and gyroscope signal processing have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments. Furthermore, well-known components and circuitry associated with the gyroscope sensor unit have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0022] Unless the context otherwise requires, throughout the specification and appended claims, the word “comprising” and its variations, such as “including” and “containing”, shall be interpreted as having an open, inclusive meaning, i.e., “including but not limited to”. Furthermore, the terms “first,” “second,” and similar sequence indicators shall be interpreted as interchangeable unless the context clearly specifies otherwise.

[0023] Throughout this specification, references to "an embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0024] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless otherwise clearly indicated. It should also be noted that the term “or” is generally used in its broadest sense, i.e., as meaning “and / or,” unless otherwise clearly indicated.

[0025] Figure 1 This is a block diagram of an electronic device 100 according to some embodiments. The electronic device 100 includes a sensor unit 101. The sensor unit 101 includes a gyroscope 102. As will be described in more detail below, the sensor unit 101 identifies and compensates for phase drift associated with the output signal of the gyroscope 102 in order to provide an accurate indication of the rotational rate applied to the electronic device 100.

[0026] Electronic device 100 may include a vehicle, such as a car, airplane, ship, or other type of vehicle. Knowing the rate of rotation of the vehicle about one or more axes of rotation is often very useful. In a vehicle, these axes of rotation may correspond to yaw, roll, and pitch. Gyroscope 102 can be used to detect the rate of rotation of the vehicle about one or more of these axes.

[0027] Electronic device 100 may include personal electronic devices such as smartphones, smartwatches, smart glasses, gaming devices, game controllers, tablets, laptops, or other types of personal electronic devices. Gyroscope 102 may be used to detect the rate of rotation of electronic device 100 about one or more axes of rotation. Electronic device 100 may include industrial equipment or other types of devices that can benefit from detecting the rate of rotation.

[0028] The gyroscope 102 may correspond to a microelectromechanical system (MEMS) gyroscope. The MEMS gyroscope 102 may include one or more movable mass blocks defined from and coupled to a silicon substrate via one or more spring-door hinge members. The MEMS gyroscope may also include various electrodes interwoven with the movable mass blocks. The embodiments described herein primarily relate to capacitive MEMS gyroscopes. However, other types of gyroscopes may be used in accordance with the principles of this disclosure without departing from the scope of this disclosure.

[0029] The gyroscope 102 includes a resonator mass 104, a drive electrode 106, and a sensing electrode 108. For example... Figure 1 As shown, the resonator mass block 104, drive electrode 106, and sensing electrode 108 are shown to constitute the gyroscope 102, while other components associated with generating signals, sensing signals, and processing signals are shown external to the gyroscope 102. However, in practice, the gyroscope 102 can be considered to include various other components of the sensor unit 101, which will be described in more detail below and are shown external to the gyroscope 102. The sensor unit 101 can be considered as a whole as the gyroscope.

[0030] The resonator mass block 104 may include a mass block suspended above or otherwise movably coupled to the substrate. The resonator mass block 104 is configured to oscillate in at least two directions. A first oscillation direction is referred to as the driving direction and corresponds to a first axis. A second oscillation direction is referred to as the sensing direction and corresponds to a second axis substantially perpendicular to the first axis. The oscillation of the resonator mass block along the sensing axis or sensing direction indicates rotation of the resonator mass block 104 about a third axis substantially perpendicular to the first and second axes.

[0031] The resonator mass 104 can be coupled to a fixed substrate via a spring member that allows the resonator mass to move back and forth along the drive axis. The resonator mass 104 can also be coupled to a fixed substrate via a spring member that allows the resonator mass to move back and forth along the sensing axis. Although Figure 1 The resonator mass block 104 is shown as a single mass block, but in practice, it may comprise multiple mass blocks. For example, a first mass block may be coupled to a second mass block via a spring member. The first mass block may be driven to oscillate along a drive axis. Rotation of the electronic device 100 about a rotation axis (third axis) may cause the second mass block to oscillate along a sensing axis (second axis). Various configurations of the resonator mass block 104 or multiple resonator mass blocks 104 may be utilized without departing from the scope of this disclosure.

[0032] The driving electrode 106 is used to drive the resonator mass block 104 in a second direction. The driving electrode 106 may correspond to a conductive mass block having a comb-like shape. The comb-shaped fingers may be interleaved with the corresponding comb-shaped fingers of the resonator mass block 104. If a voltage is applied to the resonator mass block 104, applying a periodic voltage to the driving electrode can drive the resonator mass block 104 to oscillate along the driving axis. Various other configurations of the driving electrode 106 may be utilized without departing from the scope of this disclosure.

[0033] Sensing electrode 108 is used to sense the oscillation of resonator mass block 104 along the sensing axis. Sensing electrode 108 may correspond to a comb-shaped conductive mass block. The comb-shaped fingers may be interleaved with the corresponding comb-shaped fingers of resonator mass block 104. Various other configurations of sensing electrode 108 may be utilized without departing from the scope of this disclosure.

[0034] As previously described, if the electronic device 100 and the corresponding resonator mass 104 rotate about a third rotation axis while the resonator mass 104 oscillates along a first axis, the Coriolis force generated by the rotation about the rotation axis and the oscillation along the first axis will force the resonator mass 104 to oscillate along a second axis. Therefore, the oscillation of the resonator mass 104 along the sensing axis indicates the rotation of the resonator mass 104 about the rotation axis.

[0035] Sensor unit 101 includes a drive voltage source 112. The drive voltage source 112 applies a drive voltage to drive electrode 106. The drive voltage can correspond to an AC voltage with a selected amplitude and frequency. The drive voltage can be a sinusoidal voltage, a square wave voltage, a sawtooth voltage, or other types of AC voltage waveforms.

[0036] In the example of a constant-rate gyroscope, the oscillation along the sensing axis caused by the Coriolis force will have the same frequency as the oscillation of the drive signal. However, the amplitude of the oscillation along the sensing direction indicates the amplitude of the rotational rate about a third axis. The amplitude of the oscillation is indicated by the voltage generated at the sensing electrode 108 through the capacitance interaction with the resonator mass block 104. However, as previously stated, other sensing configurations can be utilized without departing from the scope of this disclosure.

[0037] The signal output from sensing electrode 108 corresponds to the original output signal of gyroscope 102. However, the original output signal of gyroscope 102 itself may not accurately indicate the rotation rate around the third axis. This is due to the orthogonal effect generated at resonator mass 104. In particular, when resonator mass 104 is driven to oscillate along the first axis by a driving voltage applied to driving electrode 106, resonator mass 104 may also begin to oscillate along the sensing axis, even if there is no rotation around the rotation axis. Therefore, the oscillation caused by the orthogonal effect can be considered a parasitic oscillation, or the component of the original output signal based on the orthogonal effect can be considered a parasitic signal. The original output signal can be a current or a voltage, depending on the selected configuration of gyroscope 102.

[0038] In some cases, the component of the original output signal due to the orthogonal effect may be much larger than the component of the original output signal due to the rotation of the electronic device 100 around its axis of rotation. In fact, the component of the original output signal from the orthogonal effect may be many times larger than the component of the original output signal from the Coriolis force.

[0039] Sensor unit 101 utilizes demodulator 120 to extract the Coriolis component from the raw output signal. Since the raw output signal consists of both quadrature and Coriolis components, if the Coriolis component can be extracted from the raw output signal, a final output signal corresponding only to the Coriolis component of the raw output signal can be generated. Demodulator 120 extracts the Coriolis component from the raw output signal and generates a final output signal indicating the rate of rotation about the axis of rotation. As used herein, the terms "Coriolis component" and "rotational component" are used interchangeably.

[0040] Demodulator 120 utilizes the fact that the Coriolis component of the original output signal is 90° out of phase with the quadrature component of the original output signal to separate the Coriolis component from the quadrature component. Furthermore, since there is no collective phase drift in the original output signal, the quadrature component will be in phase with the drive signal, while the Coriolis component will be 90° out of phase with the drive signal. Therefore, demodulator 120 receives the drive signal and the original output signal and performs demodulation of the original output signal based on the drive signal. In particular, demodulator 120 outputs only the portion of the original output signal that is 90° out of phase with the drive signal. If there is no phase drift between the original output signal and the drive signal, then the output of demodulator 120 will only represent the Coriolis portion of the original output signal.

[0041] However, in some cases, phase drift exists between the drive signal and the original output signal. More specifically, phase drift may occur between the original output signal and the demodulated signal based on the drive signal. The demodulated signal may have the same phase as the drive signal, or it may initially have the same phase as the drive signal. Phase drift corresponds to an angle. Quadrature components and demodulated signals are out of phase Coriolis component will be heterogeneous The value of this value depends on the direction of the phase drift. Even a very small phase drift can cause the demodulator 120 to generate a very inaccurate final output signal. Phase drift can be caused by changes in temperature, mechanical stress, or variations during processing by the sensor unit 101. The demodulated signal is the driving reference signal. As used herein, "demodulated signal" and "driving reference signal" are used interchangeably.

[0042] Sensor unit 101 utilizes quadrature compensation electrode 110, quadrature compensation driver 114, delay calculator 116, and delay compensation circuitry 118 to identify and compensate for phase drift. In one example, quadrature compensation electrode 110 is positioned adjacent to resonator mass block 104. Quadrature compensation electrode 110 can be used for either in-plane sensing axis (yaw) or out-of-plane sensing axis (pitch and roll) based on selected design characteristics. Quadrature compensation electrode 110 can be used to drive resonator mass block 104 along the sensing axis to compensate for or counteract the natural orthogonality resulting from driving resonator mass block 104 along the drive axis. However, the principles of this disclosure provide potentially more efficient ways to utilize quadrature compensation electrode 110 to identify and compensate for phase drift in the raw output signal.

[0043] A quadrature compensation driver 114 is configured to apply a test signal to the quadrature compensation electrode 110. During the test cycle, the quadrature compensation driver 114 applies the test signal, and a delay calculator 116 measures the changes in the output of the demodulator 120 during the test cycle. The delay calculator 116 calculates the phase shift value between the original output signal and the demodulated signal based on the changes in the output of the demodulator 120 during the test cycle.

[0044] In some embodiments, the test cycle has two phases. During the first phase, the test signal has a first polarity. During the second phase, the test signal switches to a second polarity opposite to the first polarity. The change in the output of the demodulator 120 between the two phases of the test cycle indicates phase drift. The magnitude of the delay. The delay calculator 116 calculates the phase drift in part based on the changes in the output of the demodulator 120 between the two phases of the test. The value of phase drift is provided below. Further details of the calculation.

[0045] Delay calculator 116 will calculate the phase delay value. The signal is passed to the delay compensation circuit 118. The delay compensation circuit 118 also receives the demodulated signal based on the drive signal. The delay compensation circuit 118 delays the phase of the demodulated signal. The value. The delay compensation circuit 118 transmits the delay drive signal to the demodulator 120. Although Figure 1 The same signal is shown being passed from the drive voltage source to the delay compensation circuit and the drive electrode, but in reality, the drive voltage source can provide the drive signal to the drive electrode 106 and can provide the demodulated signal based on the drive signal to the delay compensation circuit.

[0046] Because the demodulated signal is now delayed by the same amount as the original output signal. Therefore, the Coriolis component of the original output signal is 90° out of phase with the delayed demodulated signal. When the demodulator 120 demodulates the delayed demodulated signal and the original output signal, the demodulator 120 outputs the true Coriolis component of the original output signal. Thus, the demodulator 120 outputs a signal that accurately indicates the rotational rate of the electronic device 100 about its rotation axis.

[0047] Figure 2AThis is a simplified representation of a resonator mass block 104 of a gyroscope 102 according to some embodiments. The resonator mass block is oscillating in the X direction via a spring, denoted as spring Kx. The oscillation of the resonator mass block 104 in the X direction is attenuated by a resistor Rx. The resonator mass block 104 is oscillating in the Y direction via a spring, denoted as spring Ky. The oscillation of the resonator mass block 104 in the Y direction is attenuated by a resistor Ry. In practice, the resonator mass block 104 may include mass blocks coupled together in various configurations.

[0048] The X-axis corresponds to the drive axis of the resonator mass block 104. The Y-axis corresponds to the sensing axis of the resonator mass block 104. The Z-axis corresponds to the rotation axis. Therefore, the motion of the resonator mass block 104 along the sensing axis Y indicates the rotation rate of the resonator mass block about the rotation axis Z.

[0049] exist Figure 2A In the middle, the driving electrode (see Figure 1 The resonator mass block 104 is driven to oscillate in the X direction. Figure 2A In the middle, along Figure 2A There is no oscillation along the y-axis. Therefore, there is no rotational rate around the rotation axis Z and no orthogonal motion along the y-axis. Unfortunately, in reality, whenever there is motion along the drive axis, there is usually an orthogonal component along the sensing axis.

[0050] Figure 2B The motion along the drive axis and the motion along the sensing axis are shown. This is indicated by diagonal arrows with components in both the X and Y directions. Figure 2B In this example, there is no rotational motion around the Z-axis. Therefore, all motion along the Y-axis is orthogonal. Figure 2A and Figure 2B This illustrates the basic concepts of driving motion and orthogonal motion.

[0051] Figure 3 This is a graph 300 illustrating various signals output by the gyroscope 102 according to some embodiments. Graph 300 includes the raw output signal 302 of the gyroscope 102. The raw output signal 302 is essentially a sine curve based on a capacitive output signal generated by the sinusoidal motion of the resonator mass block 104 relative to the sensing electrode 108.

[0052] Figure 3 The quadrature component 304 of the original output signal 302 is also shown. If there is no phase drift between the demodulated signal and the original output signal, the quadrature component 304 of the original output signal 302 will be in phase with the demodulated signal.

[0053] Figure 3The Coriolis component 306 of the raw output signal 302 of the gyroscope 102 is also shown. The Coriolis component 306 is a portion of the raw output signal generated by the Coriolis force of the electronic device 100 rotating about the axis of rotation when the resonator mass block 104 is driven to oscillate along the drive axis. Without phase drift, the Coriolis component 306 would be 90° out of phase with the demodulated signal.

[0054] The original output signal 302 is the sum of the quadrature component 304 and the Coriolis component 306. In fact, the amplitude of the quadrature component 304 can be many times larger than the amplitude of the Coriolis component 306. Therefore, it is very beneficial to use the demodulated signal as a phase reference to effectively demodulate the Coriolis component from the quadrature component.

[0055] Figure 4 This is a graph of the demodulation plane 400 associated with the raw output signal and demodulated signal or drive signal of the gyroscope 102 according to some embodiments. The demodulation plane 400 has two axes. The first axis is... Figure 4 The second axis is a parallel axis extending horizontally and marked with the parallel symbol "=". Figure 4 The vertical axis extends in the vertical direction and is marked with the vertical symbol "┴". In the demodulation plane 400, the parallel (horizontal) axis represents the component of the original output signal that is in phase with the demodulated signal. The vertical (vertical) axis is 90° out of phase with the demodulated signal.

[0056] Figure 4 The diagram shows the quadrature component Q and rotation component Ω of the raw output signal from gyroscope 102. The quadrature component Q and the raw output signal Ω are 90° out of phase with each other. As previously stated, without phase drift, the quadrature component Q will be aligned with the vertical axis. Without phase drift, the rotation component Ω will be aligned with the parallel axis. The demodulator 120 of sensor unit 101 outputs the parallel (horizontal) component of the raw output signal as the final output signal of sensor unit 101. Therefore, without phase drift, the output of the demodulator will correspond exactly to the rotation component of the raw output signal.

[0057] exist Figure 4 In, phase drift exists. like Figure 4 As shown, the orthogonal component Q is offset from the vertical axis by a phase drift angle. The rotational component Ω is offset from the parallel axis by a phase drift angle. In this case, when the demodulator 120 outputs a parallel component, the parallel component will not accurately represent the rotating component Ω. Although Figure 4 The diagram shows that the amplitudes of the quadrature component Q and the rotation component Ω are approximately equal. However, in reality, the amplitude of the quadrature component Q can be many times larger than that of the rotation component Ω. Therefore, even with a small phase drift angle... This will also result in a very inaccurate representation of the rotating or Coriolis component Ω of the original output signal. As used herein, the terms “phase drift” and “phase delay” are used interchangeably.

[0058] Figure 5A and Figure 5B This is a representation of a demodulation plane 500 associated with the original output signal during the application of a test signal, according to some embodiments. Figure 5A and Figure 5B The description will be from the reference Figure 1 start. Figure 5A The demodulation plane is shown during the first phase of the test cycle, in which the test signal is applied to the quadrature compensation electrode 110. Figure 5B The demodulation plane is shown during the second phase of the test cycle, in which the test signal is applied to the quadrature compensation electrode 110.

[0059] During the first phase of the test cycle, the quadrature compensation driver 114 applies a test voltage -Vt, thereby increasing the voltage difference relative to the rotor mass block. During the first phase of the applied test voltage, the quadrature component of the original output signal will have a natural quadrature component Qnat and a negative quadrature test component -Qtest. In effect, this results in a total quadrature component smaller than the natural quadrature component Qnat. Figure 5A The rotational component Ω of the original output signal of the gyroscope 102 is also shown. Figure 5A In this process, there is a phase drift angle for each component of the original output signal. The output I of demodulator 120 in phase 1 of the test cycle PH1 It is the sum of the parallel or horizontal components of the natural orthogonal component Qnat, the negative test orthogonal component Qtest, and the Coriolis component.

[0060] During the second phase of the test cycle, the quadrature compensation driver 114 applies a test voltage Vt, thereby reducing the voltage difference relative to the rotor mass block. During this second phase of test voltage application, the quadrature component of the original output signal will have a natural quadrature Qnat component and a quadrature test component. In effect, this results in a total quadrature component greater than the natural quadrature component Qnat. The output I of the demodulator 120... PH2 The second phase of the testing cycle consists of the natural orthogonal component Qnat, the orthogonal component Qtest, and the parallel or horizontal components of the Coriolis component.

[0061] The delay calculator 116 receives the output of the demodulator 120 and calculates the phase drift angle during the first and second phases of the test cycle. The delay calculator 116 calculates the angle based on the changes in the output of the demodulator 120 between the first and second phases of the test cycle and based on the amplitude of the orthogonal test components. I PH2 Given by the following relationship:

[0062]

[0063] I PH1 Given by the following relationship:

[0064]

[0065] The difference in the demodulator output between the first and second stages is given by the following relationship:

[0066]

[0067] Solve The following is given:

[0068]

[0069] Because of the phase drift angle Very small Therefore, a small angle relationship can be used:

[0070]

[0071] The phase drift angle is generated by incorporating the small-angle approximation into the above equation. The following relationships:

[0072]

[0073] As described above, the phase drift angle can be calculated based on the difference in the output of the demodulator 120 between the first and second phases of the test cycle, and the amplitude of the test component of the quadrature component. Phase drift angle The phase drift angle can vary based on temperature, process, mechanical stress, and other factors. However, the delay calculator 116, together with the quadrature compensation driver 114, can quickly and accurately determine the phase drift angle at any time. The operation of the gyroscope 102 was almost uninterrupted or not interrupted at all.

[0074] Furthermore, a relatively small number of compensation electrodes 110 can be used to identify the phase drift angle. In schemes that utilize compensation electrodes to largely eliminate the quadrature components of the original sensor signal, a very large number of compensation electrodes can be used. However, a relatively small number of compensation electrodes 110 can be used to identify the phase drift angle. This can save a significant amount of space when manufacturing the gyroscope 104.

[0075] In another example, a more accurate estimate of the Qtest amplitude can be obtained by using information on the vertical axis. While the Qtest can generally be quite stable, this estimation can be beneficial in reducing second-order effects. During the first phase of the test cycle, the total signal Q on the vertical axis... PH1 Given by the following formula:

[0076]

[0077] During the second phase of the test cycle, the total signal Q on the vertical axis PH2 Given by the following formula:

[0078]

[0079] From Q PH2 Subtract Q PH1 Given:

[0080]

[0081] because The angle is usually very small, so Qtest can be approximated as follows:

[0082]

[0083] Qtest can then be estimated in the following way:

[0084] Q test =(Q PH2 -Q PH2 ) / 2.

[0085] Figure 6 This is a graph showing the test signal 600 applied to the quadrature compensation electrode 110 by the quadrature compensation driver 114. At time T0, the first phase of the test cycle begins with the application of a test voltage with negative polarity -Vt to the compensation electrode 110. At time T1, the second phase of the test cycle begins by switching the polarity of the test signal 600 to positive polarity Vt. During the first phase, a negative quadrature test voltage -Qtest is inserted into the raw output signal of the gyroscope 102. During the second phase, a quadrature test component Qtest is inserted into the raw output signal of the gyroscope 102. As described above, the delay calculator 116 is able to measure the difference in the demodulator output between the first and second phases of the test and calculate the phase drift angle by dividing this difference by 2*Qtest.

[0086] Figure 7This is a block diagram of a portion of a sensor unit 101 according to some embodiments. The sensor unit 101 includes a demodulator 120. The demodulator 120 receives a raw output signal from a gyroscope 102. The demodulator 120 also receives a demodulated signal from a delay compensation circuit 118. The demodulated signal may correspond to a drive signal. The demodulator 120 provides the demodulated signal to an output block 124. The output block may perform some signal processing on the demodulated signal. The output block provides the demodulated signal to a delay calculator 116. The delay calculator 116 calculates the phase drift angle in the manner described above. Delay calculator 116 will calculate the phase drift angle value. Provided to delay compensation circuit 118. Delay compensation circuit 118 receives the demodulated signal and adds an amount equal to the phase drift angle value. The phase delay is applied, and the delayed demodulated signal is provided to demodulator 120. The output of demodulator 120 now corresponds to the Coriolis component of the original output signal.

[0087] Figure 8 This is a diagram of a portion of the resonator mass block 104 of a gyroscope 102 according to some embodiments. Figure 8 Compensation electrodes 110a and 110b are also shown positioned within a gap in the resonator mass block 104. The compensation electrodes 110a and 110b are fixed in place. The resonator mass block 104 is movable.

[0088] exist Figure 8 In the example, the resonator mass block 104 is composed of adjacent to Figure 8 Another portion of the resonator mass block 104 (not shown) is driven by a drive electrode 106 (not shown) to oscillate along the X-axis. The resonator mass block 104 has a thicker portion closer to the compensation electrodes 110a and 110b and a thinner portion further away from the quadrature compensation electrodes 110a and 110b. As the resonator mass block 104 moves back and forth along the X-axis, the area of ​​the thicker portion of the resonator mass block 104, directly between the two quadrature compensation electrodes 110a and 110b, also changes. When the resonator mass block moves to the left along the X-axis, the area of ​​the thicker portion facing the quadrature compensation electrodes 110a and 110b decreases. When the resonator mass block moves to the right along the X-axis, the area of ​​the thicker portion facing the quadrature compensation electrodes 110a and 110b increases.

[0089] A quadrature compensation force is generated by applying a voltage to the resonator mass block 104 and then applying a voltage between each pair of electrodes 110a and 110b. In one example, the resonator mass block 104 receives a voltage of 10V. During the first phase of the test, electrode 110a receives 4V and electrode 110b receives 6V. Because there is a higher voltage difference between the mass block and electrode 110a than between the mass block 104 and electrode 110b, a net electrostatic force is applied to the mass block 104 in the positive Y direction. During the second phase of the test cycle, the polarity between electrodes 110a and 110b is switched, such that electrode 110a receives 6V and electrode 110b receives 4V. As a result, a net electrostatic force is applied to the mass block 104 in the negative Y direction. It should be noted that because the quadrature test force depends on the horizontal position of the resonator mass block 104, the quadrature test force is in phase with the drive signal. Other voltage schemes can be applied to generate the quadrature test force without departing from the scope of this disclosure.

[0090] Figure 9 This is a top view of a portion of the resonator mass block 104 of a gyroscope 102 according to some embodiments. Figure 9 Compensation electrodes 110a and 110b are also shown positioned within a gap in the resonator mass block 104. The compensation electrodes 110a and 110b are fixed in place. The resonator mass block 104 is movable. Figure 9 Examples of in-plane orthogonal compensation electrodes 110a and 110b are shown.

[0091] exist Figure 9 In the example, the resonator mass block 104 is composed of adjacent to Figure 9 Another portion of the resonator mass block 104 (not shown) is driven by a driving electrode 106 (not shown) to oscillate along the driving axis. An orthogonal compensating force is generated by applying a voltage to the resonator mass block 104 and then applying a voltage between electrode groups 110a and 110b. In one example, the resonator mass block 104 receives a voltage of 10V. During the first phase of the test, electrode 110a receives 4V and electrode 110b receives 6V. During the second phase of the test cycle, the polarity between electrodes 110a and 110b is switched, such that electrode 110a receives 6V and electrode 110b receives 4V. Based on the geometry of the resonator mass block relative to the test electrodes, a net electrostatic force is generated in different directions during the two test phases. Other voltage schemes can be applied to generate orthogonal test forces without departing from the scope of this disclosure.

[0092] Figure 10 This is a cross-sectional view of a portion of a gyroscope 102 according to some embodiments. Figure 10Compensation electrodes 110a and 110b are also shown below the resonator mass block on substrate 149. Compensation electrodes 110a and 110b are fixed in place. The resonator mass block 104 is movable. Figure 10 Examples of out-of-plane orthogonal compensation electrodes 110a and 110b are shown.

[0093] exist Figure 10 In the example, the resonator mass block 104 is composed of adjacent to Figure 10 Another portion of the resonator mass block 104 (not shown) is driven by a driving electrode 106 to oscillate along the driving axis. An orthogonal compensating force is generated by applying a voltage to the resonator mass block 104 and then a voltage between electrode groups 110a and 110b. In one example, the resonator mass block 104 receives a voltage of 10V. During the first phase of the test, electrode 110a receives 4V and electrode 110b receives 6V. During the second phase of the test cycle, the polarity between electrodes 110a and 110b is switched such that electrode 110a receives 6V and electrode 110b receives 4V. Based on the placement of the test electrodes 110a and 110b relative to the shape of the resonator mass block 104, a net electrostatic force is generated in different directions during the two test phases. Other voltage schemes can be applied to generate orthogonal test forces without departing from the scope of this disclosure.

[0094] Figure 11 This is a schematic diagram of a sensor unit 101 according to some embodiments. The sensor unit 101 includes a driving MEMS / ASIC 150 and a sensing MEMS / ASIC 152. The MEMS / ASIC 150 includes a driving voltage source 112. The driving voltage source 112 applies a driving signal to the driving electrode 106. The driving voltage source 112 may include a phase-locked loop for controlling the phase of the driving signal. The driving voltage source 112 may also include adaptive gain control for controlling the amplitude of the driving signal. The driving power supply voltage also provides a demodulated signal to a delay compensation circuit 118. The demodulated signal is a signal with the same phase as the driving signal, unless drift occurs.

[0095] The driving electrode 106 receives a driving signal from the driving voltage source 112 and applies an electrostatic driving force to the resonator mass block 104. The electrostatic driving force drives the resonator mass block 104 to oscillate along the driving axis. The resonator mass block 104 oscillates according to the mechanical transfer function.

[0096] The driving MEMS / ASIC 150 includes a driving sensing electrode 156 that converts the motion of the resonator mass block 104 into a capacitance signal. The capacitance signal is passed to a converter that converts the capacitance signal into a voltage signal. The voltage signal is fed back to the driving voltage source 112 in a feedback loop configuration, allowing the phase-locked loop and adaptive gain control loop to control the phase and amplitude of the driving signal.

[0097] Displacement in the driving direction affects the sensing MEMS / ASIC 152. The driving displacement and rotational rate Ω interact to generate a Coriolis force based on the driving displacement velocity of the resonator mass 104 and the rotational rate Ω about the rotation axis. The displacement of the resonator mass 104 also interacts via spring coupling Kxy 164 to generate an orthogonal force in the sensing direction. The displacement of the resonator mass 104 also interacts with the orthogonal compensation electrode 110 while generating the orthogonal compensation force. The orthogonal compensation driver 114 applies an orthogonal test signal to the orthogonal compensation electrode 110.

[0098] Conceptual block 168 represents the sum of all forces acting on the sensing resonator mass block 160 in the sensing direction. Coriolis force, orthogonal force, and orthogonal compensation force all affect the motion of the sensing resonator mass block 160 along the sensing axis. The sensing resonator mass block is coupled to the resonator mass block 104 via a spring. Although in Figure 11 The mass blocks are shown as separate mass blocks, but in some cases, the sensing resonator mass block 160 and the resonator mass block 140 are a single mass block, or can effectively serve as a single spring-coupled mass block.

[0099] Sensing electrode 108 senses the motion of resonator mass 160 along the sensing axis. Sensing electrode 108 generates a capacitance signal indicating the motion of resonator mass 160 along the sensing axis. The capacitance signal is converted into a sensing voltage signal corresponding to the original output signal of gyroscope 102 in block 170. The original output signal is provided to demodulator 120.

[0100] Drive voltage source 112 provides the demodulated signal to delay compensation block 118. The demodulated signal corresponds to the drive reference signal. Initially, delay compensation block 118 may not add any delay to the demodulated signal. Delay compensation block 118 simply passes the demodulated signal to demodulator 120. During the test phase, quadrature compensation driver 114 applies a test signal to the quadrature compensation electrodes, switching polarity between the first and second phases as previously described. Demodulator 120 demodulates the demodulated signal and the original output signal and generates a demodulated signal. Output block 124 may perform some additional processing on the demodulated signal. Output block 124 provides the demodulated signal to delay calculator 116. Delay calculator 116 calculates the phase drift as previously described. The phase drift angle value is then provided to the delay compensation circuit 118. The delay compensation circuit delays the demodulated signal. The value of Ω is then used. The demodulator 120 then outputs a demodulated signal that precisely corresponds to the rotation rate Ω.

[0101] Figure 12 This is a flowchart of a method 1200 for operating a gyroscope according to some embodiments. At 1202, method 1200 includes driving a resonator mass block of the gyroscope in a first direction by applying a drive signal to drive electrodes. At 1204, method 1200 includes applying a test voltage to orthogonal compensation electrodes adjacent to the resonator mass block. At 1206, method 1200 includes determining a phase difference between a first drive reference signal and the output signal of the gyroscope based on changes in the output signal during the application of the test voltage. At 1208, method 1200 includes compensating for the phase difference between the demodulated signal and the output signal of the gyroscope.

[0102] In some embodiments, a method includes driving a resonator mass of a gyroscope in a first direction by applying a first drive signal to a drive electrode and applying a test voltage to an orthogonal compensation electrode adjacent to the resonator mass. The method includes determining a phase difference between a first drive reference signal and the output signal of the gyroscope, and a phase difference between a drive signal and the output signal of the gyroscope to compensate for the phase difference, based on changes in the output signal during the application of the test voltage.

[0103] In some embodiments, an apparatus includes a gyroscope and a demodulator, the demodulator having a first input, a second input, and an output coupled to the gyroscope. The apparatus includes a delay calculator coupled to the output of the demodulator and delay compensation circuitry coupled to the delay calculator and the second input of the demodulator.

[0104] In some embodiments, the gyroscope sensor unit includes an orthogonal driver configured to output an orthogonal test signal and sensor electrodes configured to generate a raw output signal. The gyroscope sensor unit includes a demodulator configured to receive the raw output signal and a drive reference signal, and to generate a demodulated signal based on the drive reference signal and the raw output signal. The gyroscope sensor unit includes a delay calculator configured to calculate a phase drift value between the demodulated signal and the drive reference signal based on changes in the demodulated signal during the output of the orthogonal test signal.

[0105] The various embodiments described above can be combined to provide further embodiments. Based on the detailed description above, these and other changes can be made to the embodiments. Generally, the terminology used in the appended claims should not be construed as limiting the claims to the specific embodiments disclosed in the specification and claims, but should be interpreted to include all possible embodiments and the full scope of equivalents granted by these claims. Therefore, the claims are not limited to this disclosure.

Claims

1. A method for correcting demodulation phase drift in a gyroscope, comprising: The resonator mass block of the gyroscope is driven in a first direction by applying a first driving signal to the driving electrode; A test voltage is applied to an orthogonal compensation electrode adjacent to the resonator mass block by an orthogonal compensation driver, wherein the test voltage includes a first test voltage and a second test voltage with opposite polarity to the first test voltage during the test cycle; Based on the changes in the gyroscope's output signal during the application of the first test voltage and during the application of the second test voltage, the phase difference between the first drive reference signal and the gyroscope's output signal is determined; and The phase difference between the first drive reference signal and the output signal of the gyroscope is compensated.

2. The method according to claim 1, further comprising: The original output signal is generated from the gyroscope; and The output signal is generated by performing coherent demodulation between the original output signal and the second drive reference signal based on the first drive reference signal.

3. The method according to claim 2, wherein, Compensating for the phase difference includes generating the second drive reference signal by delaying the first drive reference signal by the phase difference.

4. The method according to claim 1, wherein, Determining the phase difference includes: Determine the test component of the quadrature component of the output signal; The change in the output signal is determined after the polarity of the test voltage is reversed; and Divide the change by twice the test component.

5. The method according to claim 4, wherein, The test component corresponds to a portion of the orthogonal component generated from the test voltage.

6. The method according to claim 2, wherein, The original output signal represents the oscillation of the resonator mass block in a second direction transverse to the first direction.

7. The method according to claim 6, wherein, The output signal corresponds to a component of the original output signal, which represents the rotation of the resonator mass block about a third direction transverse to the first and second directions.

8. A device for correcting demodulation phase drift of a gyroscope, comprising: Gyroscope, including orthogonal compensation electrodes; A driving voltage source is coupled to the gyroscope and the delay compensation circuit; An orthogonal compensation driver is coupled to the gyroscope and configured to output a test voltage to the orthogonal compensation electrode, wherein the test voltage includes a first test voltage and a second test voltage with opposite polarity to the first test voltage during a test cycle; Demodulator, having: The first input coupled to the gyroscope; Second input; as well as Output; A delay calculator, coupled to the output of the demodulator; as well as A delay compensation circuit is coupled to the second input of the delay calculator and the demodulator.

9. The apparatus according to claim 8, wherein, The quadrature compensation driver is configured to apply a test voltage to the gyroscope, the drive power supply voltage is configured to provide a first drive voltage to the gyroscope and a drive reference signal to the delay compensation circuit, the delay compensation circuit is configured to provide the drive reference signal to the second input of the demodulator, and the delay calculator is configured to calculate the phase difference between the output signal of the demodulator and the drive reference signal during the period when the test voltage is applied to the gyroscope.

10. The apparatus according to claim 9, wherein, The delay compensation circuit is configured to delay the drive reference signal by the phase difference to generate the drive reference signal.

11. The apparatus according to claim 10, wherein, The gyroscope includes sensing electrodes configured to generate a raw output signal.

12. The apparatus according to claim 10, wherein, The test voltage includes a first phase with a first polarity and a second phase with a second polarity, wherein the delay calculator calculates the phase difference based on the difference in the output signal of the demodulator between the first phase and the second phase.

13. The apparatus according to claim 10, wherein, The first phase of the test voltage having a first polarity has an amplitude, and the second phase of the test voltage having a second polarity has the amplitude.

14. A gyroscope sensor unit, comprising: A quadrature driver is configured to output a test voltage, wherein the test voltage includes a first test voltage and a second test voltage with opposite polarity to the first test voltage during a test cycle; The sensor electrodes are configured to generate a raw output signal; A demodulator is configured to receive the original output signal and the drive reference signal, and to generate a demodulated signal based on the drive reference signal and the original output signal; A delay calculator is configured to calculate the phase drift value between the demodulated signal and the drive reference signal based on changes in the demodulated signal during the output of the test voltage; as well as A delay compensation circuit is configured to provide the drive reference signal to the demodulator, wherein the delay calculator is configured to pass the phase drift value to the delay compensation circuit.

15. The gyroscope sensor unit according to claim 14, further comprising: Resonator mass block; Drive electrode; as well as A driving voltage source is configured to provide a driving signal to the driving electrode to drive the oscillation of the resonator mass block.

16. The gyroscope sensor unit according to claim 15, wherein, The drive voltage source is configured to provide the drive signal to the delay compensation circuit, wherein the delay compensation circuit is configured to delay the drive signal by the phase drift value to generate the drive reference signal.

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