Sensor arrangement and method for operating a sensor arrangement

Abstract

The invention relates to a sensor arrangement, comprising at least: a gyroscope device for detecting a rotational speed sensor signal, the gyroscope device having a MEMS gyroscope with a seismic mass that can be excited to vibrate, a drive circuit for exciting and maintaining the vibrating movement of the seismic mass, and a sensor unit, a control unit for selecting one of at least two different predefined operating modes of the gyroscope device, wherein at least one sensing operating mode and at least one standby operating mode are predefined as operating modes, in which the rotational speed sensor signal is detected and / or preprocessed, and in which the rotational speed sensor signal is not detected and / or preprocessed, and a control unit for detecting the other sensor unit. The drive circuit further comprises a digitized sensor device for sensing a rotational speed sensor signal and a digital data processing unit for the rotational speed sensor signal and the other sensor signals; wherein, corresponding to the different operating modes of the gyroscope device, the drive circuit is operated in different operating modes with different energy consumptions, so that the vibration movement of the seismic mass is maintained in the at least one sensing operating mode and the at least one standby operating mode, wherein the digital data processing unit is designed to provide a digitized rotational speed sensor signal and / or a digitized other sensor signal at an output data rate (ODR) based on the vibration frequency of the seismic mass in the at least one sensing operating mode and the at least one standby operating mode.

Description

Technical Field

[0001] The present invention relates to a sensor arrangement comprising at least:

[0002] A gyroscope device is used to detect the speed sensor signal,

[0003] The gyroscope arrangement has a MEMS gyroscope with a seismic mass which can be excited to vibrate.

[0004] The gyroscopic device has a drive circuit for exciting and maintaining the vibratory motion of the seismic mass, and

[0005] The gyroscopic device has a sensing unit;

[0006] a control unit for selecting one of at least two different predefined operating modes of the gyroscopic device, wherein at least one sensing operating mode and at least one standby operating mode are predefined as operating modes, in which the rotational speed sensor signal is detected and / or preprocessed, and in which the rotational speed sensor signal is not detected and / or preprocessed;

[0007] Other sensor devices for detecting other sensor signals; and

[0008] Digital data processing unit for the speed sensor signal and other sensor signals.

[0009] The invention also relates to a method for operating such a sensor arrangement. Background Art

[0010] Known MEMS rotational speed sensors, hereinafter referred to as gyroscopes, are often used together with acceleration sensors in inertial measurement units, for example to implement applications with augmented reality or navigation in buildings. In this regard, the stability and accuracy of the output data rate (ODR), i.e. the data rate at which the gyroscope and / or acceleration sensor outputs the acquired data, is very important. In some navigation applications, the absolute position is determined based on the measurement signals of the gyroscope and the acceleration sensor. For this purpose, these measurement signals are time-integrated. In this case, an inaccurate output data rate can lead to corresponding inaccuracies in the acquired position.

[0011] Known MEMS sensor arrangements with a gyroscope and an acceleration sensor have an integrated electronic oscillator, which provides a signal or frequency for the output data rate of the acceleration sensor. If the gyroscope is switched on, the output data rate or the corresponding clock signal is derived instead from the resonant frequency of the excitation oscillation of the seismic mass of the MEMS gyroscope, which is excited and maintained by means of a drive circuit. However, this clock signal is only available when the gyroscope is in the active state. At each switchover of the gyroscope between the clock signal generated by the integrated electronic oscillator and the clock signal generated by the drive circuit, a jump or change in the frequency of the output data rate ODR occurs. In addition, compared to the drive circuit, the integrated electronic oscillator has an increased drift due to temperature changes. Summary of the invention

[0012] In one embodiment, the present invention provides a sensor arrangement comprising at least:

[0013] A gyroscope device is used to detect the speed sensor signal,

[0014] It has a MEMS gyroscope with a seismic mass that can be excited to vibrate.

[0015] It has a drive circuit for exciting and maintaining the vibrating motion of the seismic mass, and

[0016] It has a sensing unit;

[0017] a control unit for selecting one of at least two different predefined operating modes of the gyroscopic device, wherein at least one sensing operating mode and at least one standby operating mode are predefined as operating modes, in which the rotational speed sensor signal is detected and / or preprocessed, and in which the rotational speed sensor signal is not detected and / or preprocessed;

[0018] Other sensor devices for detecting other sensor signals; and

[0019] A digital data processing unit for speed sensor signals and other sensor signals;

[0020] In which, corresponding to different operating modes of the gyroscope device, the drive circuit can be operated in different operating modes with different energy consumption, so that the vibration movement of the seismic mass is maintained in at least one sensing operating mode and in at least one standby operating mode, wherein the digital data processing unit is designed to provide a digitized rotational speed sensor signal and / or a digitized other sensor signal at an output data rate (ODR) based on the vibration frequency of the seismic mass in at least one sensing operating mode and in at least one standby operating mode.

[0021] In another embodiment, a method for operating a sensor arrangement is provided, the method comprising at least:

[0022] A gyroscope device for detecting the speed sensor signal,

[0023] The gyroscope device has a MEMS gyroscope having a seismic mass that can be excited to vibrate.

[0024] The gyroscopic device has a drive circuit for exciting and maintaining the vibratory motion of the seismic mass, and

[0025] The gyroscopic device has a sensing unit;

[0026] a control unit for selecting one of at least two different predefined operating modes of the gyroscopic device, wherein at least one sensing operating mode and at least one standby operating mode are predefined as operating modes, in which the rotational speed sensor signal is detected and / or preprocessed, and in which the rotational speed sensor signal is not detected and / or preprocessed;

[0027] Other sensor devices for detecting other sensor signals; and

[0028] A digital data processing unit for speed sensor signals and other sensor signals;

[0029] wherein the drive circuit is operated in different operating modes with different energy consumption, in particular current consumption, corresponding to different operating modes of the gyroscope component, so that the vibrating movement of the seismic mass is maintained in at least one sensing operating mode and in at least one standby operating mode,

[0030] Therein, in at least one sensing operating mode and in at least one standby operating mode, an output data rate (ODR) of the digitized rotational speed sensor signal and / or of the digitized further sensor signal which is provided by means of the data processing unit is based on the vibration frequency of the seismic mass.

[0031] Therefore, the output data rate ODR of all sensors for the sensor arrangement is based on the vibration movement of the seismic mass of the MEMS gyroscope, which is maintained independently of the operating mode of the MEMS gyroscope, that is, both in the sensing operating mode when the rotational speed signal is detected and in the standby operating mode when the rotational speed measurement signal is not detected. As a result, an additional oscillator can be omitted as a clock generator for the output data rate ODR. The seismic mass of the MEMS gyroscope is usually excited to resonant vibration. This vibration movement is very frequency-stable. In addition, the resonant frequency is largely independent of temperature. As a result, extremely high stability of the output data rate can be achieved not only when the MEMS gyroscope is running, that is, in the sensing mode, but also in all operating states. Frequency jumps in the clock signal and therefore in the output data rate ODR are avoided when switching between operating states. Similarly, temperature drift in the output data rate ODR is also significantly reduced. In addition, the energy consumption for maintaining the vibration movement of the seismic mass of the MEMS gyroscope is kept within limits. In addition, only in the sensing operating mode will the drive circuit operate in a high-performance mode with high energy consumption. In the standby operating mode, a low power mode for the drive circuit proves to be sufficient to maintain the vibrating movement of the seismic mass.

[0032] In other words, by means of the embodiments of the present invention, in particular by providing a drive circuit of the gyroscope device with at least two operating modes with different energy consumption, a simple, flexible, cost-saving and energy-saving sensor arrangement is provided, which has high accuracy and stability of the output data rate.

[0033] Other features, advantages and other embodiments of the present invention will be described below or disclosed thereby.

[0034] According to an advantageous embodiment, the control unit is designed to directly actuate the sensor unit and / or the drive circuit of the gyroscopic device in order to predetermine the operating mode, thereby making it possible to control the sensor unit and / or the drive circuit in a simple and flexible manner.

[0035] According to an advantageous embodiment, the driver circuit is designed to provide a clock signal to a digital data processing unit, which clock signal has information about the vibration frequency of the seismic mass. This has the advantage that the digital data processing unit can provide data to the sensor unit in a particularly accurate and stable manner.

[0036] According to another advantageous development, the drive circuit comprises at least two separate drive circuits, by means of which different operating modes of the drive circuit are provided. One of the advantages achieved thereby is that the separate operating modes can be provided in a reliable manner. In other words, each operating mode of the drive circuit can thereby be provided by a separate drive circuit. In essence, at least one second circuit is thus provided in the drive circuit, the aim of which is to maintain the oscillation of the gyroscopic device, more precisely the seismic mass of the gyroscopic device, with a minimum of energy. Therefore, this second circuit is used when the circuit for the normal operation of the gyroscopic device - the sensing operating mode - is switched off, i.e. when no data from the gyroscopic device is required. The clock signal of the drive signal circuit can be provided via a separate interface. The control unit can then be constructed to select the corresponding interface.

[0037] According to another advantageous embodiment, the further sensor device comprises a MEMS acceleration sensor, a magnetometer, a pressure sensor, a gas sensor and / or a humidity sensor. This has the advantage of a simple realization of the sensor device for different applications.

[0038] It goes without saying that the features mentioned above and the features yet to be explained below can be used not only in the respectively stated combination but also in other combinations or alone, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Preferred embodiments and implementations of the present invention are shown in the drawings and will be explained in detail in the following description, wherein the same reference numerals refer to the same, similar or functionally identical components or elements. The drawings show:

[0040] Figure 1 shows a known MEMS sensor arrangement;

[0041] Figure 2 shows a MEMS sensor arrangement according to one embodiment of the present invention;

[0042] Figure 3 A MEMS sensor arrangement according to another embodiment of the invention is shown. DETAILED DESCRIPTION

[0043] Figure 1A known MEMS sensor arrangement 1 is shown, which has a gyroscopic device for detecting a rotational speed sensor signal and has a further sensor device in the form of an acceleration sensor. The gyroscopic device comprises a MEMS gyroscope 2, which has a seismic mass 2a that can be excited to vibrate, and an analog circuit device 7. The analog circuit device 7 comprises a drive circuit 3 for exciting and maintaining the vibrating movement of the seismic mass 2a and a sensor unit 5 for reading a gyroscopic measurement signal 101 and converting the measurement signal 101 into an analog electrical signal 106.

[0044] The movement of the seismic mass 2a is detected in the form of a position signal 100 and is provided to the drive circuit 3. The position signal 100 provides information about the amplitude and frequency of the vibrating movement of the seismic mass 2a. Based on this information, the drive circuit 3 generates a drive signal 103, which is used to drive and maintain a defined vibrating movement of the seismic mass 2a.

[0045] The deflection of the vibrating seismic mass 2a along one or more spatial axes caused by the rotational movement of the gyroscopic device is detected, for example capacitively, by means of a suitable circuit arrangement 2b of the MEMS gyroscope 2. The gyroscope measurement signal 101 is then converted into an analog electrical gyroscope signal 106 by means of the sensor unit 5, for example by means of a capacitive voltage converter.

[0046] The acceleration sensor also comprises a MEMS sensor element 6 having at least one deflectable structural element. The deflection of the structural element along one or more spatial axes caused by the acceleration is detected by means of a suitable circuit arrangement 6 b, for example capacitively or piezoresistively. The acceleration sensor also comprises an analog circuit arrangement 8 having a sensor unit 9 for reading the measurement signal 102 and converting it into an analog electrical acceleration signal 107, for example by means of a capacitive voltage converter.

[0047] The analog circuit arrangements 7 and 8 of the gyro arrangement and the acceleration sensor form the analog part of an electronic readout circuit 20 of the sensor arrangement 1 shown here. The digital part 16 of this readout circuit 20 comprises an energy management unit 11 as a control unit, an output data rate unit 12 for generating an output data rate ODR, signal processing units 13 and 14 for analog electrical gyro signals 106 and acceleration signals 107, respectively, and an interface 15 for outputting sensor data 110.

[0048] Energy management unit 11 predetermines an operating mode of the gyroscopic device, either a sensing operating mode, in which a rotational speed sensor signal is detected, or an inactive operating mode, in which no seismic mass is excited and no rotational speed signal is detected. For the sake of clarity, the signal paths for correspondingly actuating the individual components of the gyroscopic device are omitted here.

[0049] Finally, in Figure 1 The readout circuit 20 of the sensor arrangement shown in FIG. 1 further comprises an oscillator 4 which generates a clock signal 104. By means of a switch 120 actuated by the energy management unit 11, the oscillator clock signal 104 or a clock signal 105 generated by the drive circuit 3 of the gyroscopic device based on the position signal 100 can be selectively provided to the output data rate unit 12 and the signal processing units 13, 14. The energy management unit 11 corresponds to the switch position of the operating mode selection switch 120 of the gyroscopic device. In the sensing operating mode, the vibrating seismic mass 2a is used as a clock generator for the sensor arrangement 1. In the inactive operating mode, i.e. when the seismic mass is not excited and therefore cannot act as a clock generator, the oscillator 4 is switched on and then used as a clock generator for the sensor arrangement 1. In both cases, a clock signal 108 is therefore available, which is provided to the signal processing units 13 and 14 and can be used, for example, in the digitization of the analog sensor signals 101, 102. Furthermore, the clock signal 108 is also supplied to the output data rate unit 12. This generates a current output data rate ODR 109 for the interface 15 based on the clock signal 108, so that the output of the sensor data 10 takes place at this output data rate 109. Therefore, fluctuations and instabilities of the clock signal 108 have a direct influence on the output data rate 109 of the sensor arrangement 1.

[0050] Figure 2 FIG. 2 shows a MEMS sensor arrangement 200 according to an embodiment of the present invention. Figure 1Unlike the MEMS sensor arrangement 1 of FIG. 1 , the MEMS sensor arrangement 200 shown here does not have a separate electronic oscillator 4 as a clock generator. The oscillator of the gyroscope device, i.e. the seismic mass 2a, in combination with the drive circuit 3, always serves as a clock generator for all components of the sensor arrangement 200. To this end, the drive circuit maintains the vibration movement of the seismic mass 2a, more precisely, independently of the operating mode of the gyroscope device. According to this embodiment of the invention, the drive circuit 3 of the gyroscope device is designed so that it operates in two operating states 3-1, the energy consumption of which is different, i.e. in a low-energy operating mode for a standby operating mode, no rotation rate signal of the MEMS gyroscope 2 should be detected, and in a high-energy operating mode for a sensing operating mode, a rotation rate signal of the MEMS gyroscope 2 should be detected. In both operating modes, the drive circuit 3 generates a drive signal 103 for driving the seismic mass 2a of the MEMS gyroscope device, which ensures a frequency-stable vibration movement of the seismic mass 2a. Based on the driver signal 103, a clock signal 105 is generated as a system clock or system clock for the sensor arrangement 200. The specification or selection of the operating mode 3-1 of the driver circuit 3 by means of the switch 120 together with the specification of the operating mode 3-1 of the gyro device is again taken over by the energy management unit 11. The change of the operating state 3-1 from the standby operating mode to the sensing operating mode or vice versa has no effect on the clock signal 105 and the output data rate ODR109.

[0051] Figure 3 A MEMS sensor arrangement 201 according to another embodiment of the present invention is shown.

[0052] According to Figure 2 The MEMS sensor arrangement 200 differs according to Figure 3 In the MEMS sensor arrangement 201, instead of a single drive circuit 3 that can be operated in two operating modes, separate drive circuits 3a, 3b are arranged for different operating modes, more precisely a low-energy drive circuit or standby drive circuit 3a and a high-energy drive circuit or sensing drive circuit 3b. Accordingly, the position signal 100 of the MEMS gyroscope 2 must be provided to the two drive circuits 3a, 3b. The drive signals 105a, 105b of the two drive circuits 3a and 3b are provided via separate interfaces 70a, 70b. The selection of the corresponding drive circuit 3a or 3b is carried out together with the presetting of the operating mode 3-1 of the gyroscope device by the energy management unit 11, which accordingly controls the switch 120 connected downstream of the interfaces 70a, 70b.

[0053] In summary, at least one embodiment of the present invention has at least one of the following advantages:

[0054] Lower energy consumption of the read circuit compared to known read circuits;

[0055] Lower complexity of the MEMS overall system;

[0056] High accuracy and stability of output data rate;

[0057] When switching between the additional oscillator as clock generator and the gyroscopic component as clock generator for the entire sensor system, jumps or transient oscillation phases are avoided.

[0058] Although the present invention has been described based on preferred exemplary embodiments, the present invention is not limited thereto but can be modified in many different ways.

Claims

1. A sensor arrangement (200, 201), the sensor arrangement comprising at least: A gyroscope device, the gyroscope device is used to detect a rotation speed sensor signal, The gyroscope device has a MEMS gyroscope (2) having a seismic mass (2a) which can be excited to vibrate. The gyroscopic device has a drive circuit (3, 3a, 3b) for exciting and maintaining the vibrating motion of the seismic mass (2a), and The gyroscopic device has a sensor unit (5); A control unit (11) for selecting one of at least two different predefined operating modes (3-1) of the gyroscope device, wherein at least one sensing operating mode and at least one standby operating mode are predefined as operating modes, in which the rotation speed sensor signal (101) is detected and / or preprocessed, and in which the rotation speed sensor signal (101) is not detected and / or preprocessed; Other sensor devices (6) for detecting other sensor signals (102); and A digital data processing unit (16), the digital data processing unit being used for the rotation speed sensor signal and the other sensor signals; The invention is characterized in that, corresponding to different operating modes (3-1) of the gyroscope device, the drive circuit (3, 3a, 3b) can be operated in different operating modes with different energy consumption, so that the vibration movement of the seismic mass (2a) is maintained in the at least one sensing operating mode and in the at least one standby operating mode, and The digital data processing unit (16) is designed to provide a digitized rotational speed sensor signal and / or a digitized other sensor signal at an output data rate (ODR) based on the vibration frequency of the seismic mass (2a) in the at least one sensing operating mode and in the at least one standby operating mode.

2. The sensor arrangement according to claim 1, wherein The control unit (11) is designed to directly actuate a sensor unit (5) of the gyroscopic device and / or a drive circuit (3, 3a, 3b) of the gyroscopic device in order to predetermine an operating mode.

3. A sensor arrangement according to claim 1 or 2, wherein: The drive circuit (3, 3a, 3b) is designed to provide the digital data processing unit (16) with a clock signal that contains information about a vibration frequency of the seismic mass.

4. A sensor arrangement according to claim 1 or 2, wherein: The drive circuit (3, 3a, 3b) comprises at least two separate drive loops (3a, 3b), by means of which different operating modes of the drive circuit (3) are provided.

5. A sensor arrangement according to claim 1 or 2, wherein: The other sensor devices include a MEMS acceleration sensor (6), a magnetometer, a pressure sensor, a gas sensor and / or a humidity sensor.

6. A method for operating a sensor arrangement (200, 201), wherein: The sensor arrangement comprises: a gyroscope device for detecting a first sensor signal in the form of a rotation speed sensor signal, The gyroscope device has a MEMS gyroscope (2) having a seismic mass (2a) which can be excited to vibrate. The gyroscopic device has a drive circuit (3, 3a, 3b) for exciting and maintaining the vibrating motion of the seismic mass (2a), and The gyroscopic device has a sensing unit; A control unit (11), the control unit being used to select one of at least two different predefined operating modes of the gyro device, wherein at least one sensing operating mode and at least one standby operating mode are predefined as operating modes, in which the rotation speed sensor signal is detected and / or preprocessed, and in which the rotation speed sensor signal is not detected and / or preprocessed; a second sensor device (6) for detecting further sensor signals, and A digital data processing unit (16), the digital data processing unit being used for the rotation speed sensor signal and the other sensor signals; Characterized in that the drive circuit (3, 3a, 3b) is operated in different operating modes with different energy consumptions corresponding to different operating modes of the gyroscopic device, so that the vibration movement of the seismic mass (2a) is maintained in at least one sensing operating mode and in at least one standby operating mode, and The following output data rate (ODR) of the digitized rotational speed sensor signal and / or the digitized other sensor signal in the at least one sensing operating mode and in the at least one standby operating mode is based on the vibration frequency of the seismic mass (2a): the output data rate is provided by means of a data processing unit (16).

7. The method according to claim 6, wherein: The drive circuit (3, 3a, 3b) is operated in different operating modes with different current consumptions corresponding to different operating modes of the gyroscopic device, so that the vibration movement of the seismic mass (2a) is maintained in at least one sensing operating mode and in at least one standby operating mode.

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