Sensor system, method for operating a sensor system

Abstract

Claims are made regarding a sensor system with a MEMS gyroscope and its operation method, the sensor system comprising at least: a vibrating mass that can be excited to oscillate; a measurement signal for detection; a drive circuit for exciting and maintaining the defined oscillating motion of the vibrating mass; a detection circuit for reading out and demodulating the measurement signal, thereby generating a rotational speed signal and an orthogonal signal phase-shifted relative to the rotational speed signal; and a digital processing circuit for compensating for a shift in the digitized rotational speed signal using the digitized orthogonal signal, wherein the detection circuit and the digital processing circuit include rotational speed circuitry for generating and processing the rotational speed signal and orthogonal circuitry for generating and processing the orthogonal signal and for generating a compensation signal, the compensation signal being used for shift compensation of the digitized rotational speed signal; characterized in that at least a portion of the orthogonal circuitry is capable of operating independently of the operating mode of the rotational speed circuitry in at least one operating mode different from that of the rotational speed circuitry.

Description

Technical Field

[0001] This invention is based on a sensor system with a MEMS gyroscope. Background Technology

[0002] Gyroscopes are well-known for measuring rotational speed and are used, for example, in a wide range of devices and applications as microelectromechanical systems (MEMS).

[0003] In practice, such as in consumer electronics, the defining characteristic parameter of this sensor is its current consumption or energy consumption.

[0004] Although the current consumption of active gyroscopes has been reduced in the past, there is a need for further savings in many applications, such as wearable devices and IoT devices.

[0005] However, the pursuit of reducing power consumption often conflicts with the goal of improving the signal quality of the output sensor signal. Therefore, power optimization usually requires careful trade-offs to achieve both a power-efficient sensor system and the most accurate and lowest-noise rotational speed measurement possible. Summary of the Invention

[0006] The objective of this invention is to provide a power-saving sensor system with a MEMS gyroscope, which preferably still enables rotational speed measurement with relatively high signal quality.

[0007] The sensor system according to the invention includes at least: a vibrating mass capable of being excited to oscillate for detecting a measurement signal; a drive circuit for exciting and maintaining the defined oscillating motion of the vibrating mass; a detection circuit for reading out and demodulating the measurement signal, thereby generating a rotational speed signal and an orthogonal signal phase-shifted relative to the rotational speed signal; and a digital processing circuit for compensating for offsets in the digitized rotational speed signal when using the digitized orthogonal signal; wherein the detection circuit and the digital processing circuit include rotational speed circuitry for generating and processing the rotational speed signal, and include orthogonal circuitry for generating and processing the orthogonal signal and for generating a compensation signal for offset compensation of the digitized rotational speed signal; wherein at least a portion of the orthogonal circuitry is capable of operating independently of the operating mode of the rotational speed circuitry in at least one operating mode different from that of the rotational speed circuitry.

[0008] The sensor system according to the invention has the following advantages over the prior art: at least a portion of the quadrature circuit device can operate independently of the operating mode of the speed circuit device in at least one operating mode different from that of the speed circuit device. Therefore, the quadrature circuit device is preferably capable of operating at least partially in an operating mode in which it has lower power consumption compared to its operation in the speed circuit device's operating mode. This enables individualized reductions in current consumption in a large number of cases, while still being able to output a speed signal with relatively high quality. Therefore, it can be particularly individually matched to the specific requirements of the sensor system in a given application.

[0009] In gyroscope systems, orthogonal signals from the gyroscope are typically used to correct for drift in the rotational speed signal, often in conjunction with temperature information. However, the use of simple duty cycle techniques in gyroscopes is limited by the desired signal quality because the data path for the rotational speed signal must be continuously run to efficiently filter noise and interference caused by external influences (e.g., vibration). According to the invention, it is advantageously possible for at least a portion of the orthogonal circuitry to operate independently of the rotational speed circuitry in at least one different operating mode. The drift in the rotational speed signal caused by orthogonal influences and / or temperature influences advantageously typically occurs at frequencies lower than the output frequency of the rotational speed signal. Therefore, according to the invention, current is saved by operating at least a portion of the orthogonal circuitry in other operating modes without (significantly) negatively affecting the signal quality of the rotational speed signal.

[0010] Advantageous configurations and extensions of the present invention can be derived from the following description.

[0011] According to one embodiment of the invention, the rotational speed circuit device includes a demodulation device and / or an analog-to-digital converter as part of the detection circuit, and / or includes at least one digital filter as part of the digital processing circuit, thereby enabling particularly advantageous signal quality for the rotational speed signal. Preferably, in the operating mode of the rotational speed circuit device, the rotational speed signal can be generated, digitized, and filtered by means of the demodulation device, the analog-to-digital converter, and the digital filter to achieve advantageous signal quality and, in particular, a low noise level.

[0012] According to one embodiment of the invention, the quadrature circuit device includes a demodulation device and / or an analog-to-digital converter as part of the detection circuit, and / or includes at least one digital filter as part of the digital processing circuit, thus enabling the advantageous generation and utilization of quadrature signals for the correction of the rotational speed signal offset. It is particularly advantageous to generate or update the quadrature signal and compensation signal for correcting the rotational speed signal at a relatively low data rate, thereby saving power. Since the offset drift of the rotational speed signal corrected by the quadrature signal typically changes more slowly than the rotational speed signal output by the sensor system, this power saving can be achieved in a wide range of applications without affecting the quality of the rotational speed signal offset compensation. It is particularly conceivable that some or all of the following quadrature circuit devices operate in operating modes different from those of the rotational speed circuit device:

[0013] Demodulation device used to generate quadrature signals.

[0014] Analog-to-digital converters used to digitize quadrature signals, and / or

[0015] At least one digital filter for filtering digitized quadrature signals.

[0016] According to one embodiment of the invention, a sensor system includes a temperature sensor for detecting a temperature signal and a temperature circuit for processing the temperature signal and generating a compensation signal. The digital processing circuit is designed to generate the compensation signal based on a digitized quadrature signal and a digitized temperature signal. The temperature circuit is characterized in that at least a portion of the temperature circuit is capable of operating independently of the operating mode of the speed circuit, in at least one operating mode different from that of the speed circuit. This enables a particularly advantageous reduction in the current consumption of the sensor system. Temperature typically changes significantly more slowly than the speed signal output by the sensor system, so high-frequency generation of the temperature signal offers no or at most minimal advantage to the signal quality of the speed signal, while significantly increasing current consumption. Therefore, by operating at least a portion of the temperature circuit in a different operating mode than that of the speed circuit, current can be saved without compromising signal quality.

[0017] According to one embodiment of the invention, the temperature circuit device includes an analog-to-digital converter and / or at least one digital filter and / or at least one adder and / or multiplier, thus enabling the generation of a favorable compensation signal when using a temperature signal, while still saving current by operating at least a portion of the temperature circuit device in a different operating mode than the speed circuit device. In particular, it is conceivable that some or all of the following temperature circuit devices operate in a different operating mode than the speed circuit device:

[0018] Temperature sensor,

[0019] Analog-to-digital converter,

[0020] At least one digital filter,

[0021] At least one adder, and / or

[0022] At least one multiplier.

[0023] According to one embodiment of the present invention, the sensor system includes an operating mode control device for pre-defining the current operating mode for the speed circuit device and / or the quadrature circuit device and / or the temperature circuit device. This enables the setting of different operating modes for the speed circuit device and / or the quadrature circuit device and / or the temperature circuit device, thereby achieving the desired signal quality while still saving power. The operating mode control device is preferably responsible for controlling the respective circuit components of the speed circuit device, the quadrature circuit device, and / or the temperature circuit device according to the corresponding operating mode, and / or configuring the circuit components of the speed circuit device, the quadrature circuit device, and / or the temperature circuit device to be set according to the corresponding operating mode. The operating mode control device is also preferably capable of switching between different operating modes. For example, it is conceivable that the quadrature circuit device and / or the temperature circuit device can selectively operate in different energy-saving modes, such as in a duty cycle mode. These modes are distinguished by the duration of the activation and deactivation time interval of the circuit components of the quadrature circuit device and / or the temperature circuit device, and these modes can be configured, selected, and / or set by means of the operating mode control device.

[0024] Another subject of the present invention is a method for operating a sensor system according to an embodiment of the present invention, characterized in that a rotational speed circuit device is operated in a measurement operation mode in which a rotational speed signal is provided at a first data rate, and an orthogonal circuit device is operated in a first energy-saving mode in which an orthogonal signal is provided at a second data rate, wherein the second data rate is less than the first data rate.

[0025] Therefore, it is advantageous to generate and / or output speed signals at a higher frequency than the frequency at which quadrature signals and / or compensation signals are generated or updated. The offset of the speed signal caused by the quadrature effect typically changes more slowly compared to the generation and output of the speed signal. Thus, energy savings can be achieved through the operation of the quadrature circuit device in the first energy-saving mode, without (significantly) negatively affecting the quality of the offset compensation.

[0026] According to one embodiment of the invention, and more particularly according to one embodiment of the method, at least a portion of the quadrature circuit device is periodically activated and deactivated at predetermined time intervals in a first energy-saving mode, thereby enabling power saving during the operation of the quadrature circuit device in the first energy-saving mode.

[0027] According to one embodiment of the present invention, and particularly according to one embodiment of the method, a sensor system includes at least one temperature sensor and a temperature circuit device, characterized in that the temperature circuit device operates in a second energy-saving mode, in which a temperature signal is provided at a data rate less than a first data rate, thereby enabling power saving during the operation of the temperature circuit device. Similarly, it is conceivable that the temperature sensor operates in the second energy-saving mode.

[0028] According to one embodiment of the invention, and particularly according to an embodiment of the method, the quadrature circuit device and the temperature circuit device operate in the same energy-saving mode, thereby providing the quadrature signal and the temperature signal at the same data rate, thus enabling particularly advantageous power saving. Preferably, the compensation signal can be updated or generated at the same data rate as the quadrature signal and the temperature signal.

[0029] Here, for the method of operating the sensor system, the advantages and configurations already described in conjunction with the sensor system according to the invention or in conjunction with embodiments of the sensor system according to the invention can be applied. For the sensor system, the advantages and configurations already described in conjunction with the method of operating the sensor system according to the invention or in conjunction with embodiments of the method according to the invention can be applied. Attached Figure Description

[0030] Embodiments of the present invention are shown in the accompanying drawings and further described below.

[0031] Figure 1 A schematic diagram of a sensor system according to an embodiment of the present invention is shown. Detailed Implementation

[0032] according to Figure 1 The sensor system 100 of the embodiment includes a MEMS gyroscope 1 having a vibrating mass 21 that can be excited to oscillate. The illustrated MEMS gyroscope 1 is a three-axis gyroscope, which, in addition to mass 21, has two other masses 21' and 21'". Masses 21, 21', and 21' are respectively configured to detect rotational speeds around independent axes. The vibrating masses 21, 21', and 21' can be driven, for example, by a common drive circuit 10 and drive device 11 of the sensor system 100.

[0033] The sensor system 100 is described below with respect to mass 21 and the signal detection and signal processing of mass 21. However, for other masses 21', 21'', corresponding detection circuits and digital processing circuits can be provided respectively, which include corresponding speed circuit devices, quadrature circuit devices and (if necessary) temperature circuit devices.

[0034] The drive circuit 10 is configured to excite and maintain the defined oscillating motion of the vibrating mass 21. The drive circuit includes a C / V converter 12, by means of which the drive motion of the driven mass is detected to obtain information about the oscillation amplitude. This information about the oscillation amplitude is provided to an amplitude gain controller 14 (AGC), by means of which the mass is driven via a corresponding device 11 to achieve a constant mass oscillation amplitude. The drive circuit 10 also includes a phase-locked loop 13 (PLL), which determines the frequency and phase of the mass oscillation and provides corresponding information about the frequency and phase to the amplitude controller 14 and to the I / Q demodulation of the detection circuit 20. For this purpose, the PLL 13 provides a corresponding signal to the demodulation device 30 of the detection circuit 20 for generating a rotational speed signal 210 from the measurement signal 200, and provides a corresponding phase-shifted signal to the demodulation device 41 for generating a quadrature signal 211 from the measurement signal 200. The Q demodulation of the quadrature signal 211 has the same phase as the demodulation of the amplitude controller 14, and the I demodulation of the speed signal 210 is phase-shifted by 90° relative to the demodulation of the amplitude controller 14.

[0035] The sensor system 100 includes an analog detection circuit 20 and a digital processing circuit 50 for detecting and further processing the measurement signal 200. The measurement signal 200 of the detection channel 21 is generated or provided by a C / V converter 22 in the detection circuit 20. The measurement signal 200 contains rotational speed information based on the Coriolis force, which is about the detected rotational speed. This rotational speed information is obtained from and further processed by rotational speed circuit devices 30, 31, and 32. For this purpose, in addition to a demodulation device 30 for generating a rotational speed signal 210 from the measurement signal 200, the rotational speed circuit devices 30, 31, and 32 also include an analog-to-digital converter 31 for digitizing the rotational speed signal 210 and at least one digital filter 32 for filtering the digitized rotational speed signal. Furthermore, there are orthogonal circuit devices 41, 42, and 43 configured to generate and further process an orthogonal signal 211 from the measurement signal 200. In addition to the demodulation device 41 for generating the quadrature signal 211 from the measurement signal 200, the quadrature circuit devices 41, 42, and 43 also include an analog-to-digital converter 42 for digitizing the quadrature signal 211 and a digital filter 43 for filtering the digitized quadrature signal. The quadrature signal 211 contains information about quadrature effects caused by mechanical deficiencies or errors and included in the gyroscope's measurement signal. Therefore, after digitization and filtering, the quadrature signal can be used in the digital processing circuit 50 to correct the offset of the rotational speed signal 210 induced by the quadrature effect.

[0036] Furthermore, the sensor system includes temperature circuitry 61, 62, 63, 63', 63'". Temperature sensor 60 is configured here for temperature measurement. The temperature signal from temperature sensor 60 is digitized by analog-to-digital converter 61 and filtered by digital filter 62. The thus obtained filtered temperature signal can be weighted using at least one adder 63' and one or more multipliers 63, 63', with coefficients C0, C1, and combined with a digitized and filtered quadrature signal to provide a compensation signal 212 for offset compensation of the rotational speed signal.

[0037] The orthogonal circuit devices and temperature circuit devices 41, 42, 43, 60, 61, 62, 63, 63', and 63" of the sensor system 100 are in... Figure 1 The text is highlighted in a common box 40 for further discussion.

[0038] According to the present invention, it is advantageously possible for at least a portion of the quadrature circuit device and / or temperature circuit device 40 to operate independently of the operating modes of the speed circuit devices 30, 31, 32 in at least one operating mode different from that of the speed circuit devices 30, 31, 32. Here, the quadrature circuit device and / or temperature circuit device 40 preferably represents one or more power domains. This power domain is separate from the speed circuit devices 30, 31, and 32, allowing it to operate independently of the speed circuit devices 30, 31, and 32 in one or more other operating modes. Therefore, it is possible for at least a portion of the quadrature circuit device and / or the temperature circuit device 40 to exhibit a power duty cycle that varies over time, while the speed circuit devices 30, 31, and 32 do not follow the same cycle. It is conceivable that at least a portion of the orthogonal circuit devices 41, 42, 43 and / or temperature circuit devices 61, 62, 63, 63', 63" operate in one or more operating modes in which the orthogonal circuit devices and / or temperature circuit devices have lower power consumption compared to the operating modes in which the speed circuit devices 30, 31, 32 are located. Since in many applications, the speed signal offset induced by the orthogonal effect and the dominant temperature change significantly more slowly than the generated and output speed signal, the orthogonal circuit devices and / or temperature circuit devices 40 can advantageously operate in an operating mode in which the compensation signal 212 is updated at a lower data rate than the output speed signal without a significant deterioration in the quality of the speed signal output by the sensor system 100. This lower update rate of the compensation signal 212 allows the orthogonal circuit devices and / or temperature circuit devices 40 to be periodically activated and deactivated, at least partially or completely, thereby saving power.

[0039] This allows the speed circuit devices 30, 31, and 32 to operate in a measurement operation mode, where the speed signal is available at a first data rate, and the quadrature circuit devices 41, 42, and 43 to operate in a first energy-saving mode, where the quadrature signal is available at a second data rate, which is less than the first data rate. At least a portion of the quadrature circuit devices 41, 42, and 43 can be periodically activated and deactivated (duty cycle) at predetermined time intervals in the first energy-saving mode, thereby reducing current consumption relative to the continuous operation of the quadrature circuit devices 41, 42, and 43.

[0040] It is possible to enable the temperature circuit devices 61, 62, 63, 63', 63" and / or the temperature sensor 60 to operate in a second energy-saving mode, wherein the temperature signal is available at a data rate lower than the first data rate, which provides the rotational speed signal at the first data rate in the measurement operation mode. It is particularly advantageous to enable the data rates of the first and second energy-saving modes to be the same, wherein, particularly preferably, the compensation signal 212 is updated at the data rates of the first and second energy-saving modes. However, alternatively, the data rate of the second energy-saving mode may differ from the data rate of the first energy-saving mode.

[0041] For example, it is conceivable that the quadrature circuit device and / or temperature circuit device 40 (fully or partially) is activated for a few milliseconds and supplied with energy to generate an offset compensation value, and then the quadrature circuit device and / or temperature circuit device 40 is completely or partially turned off. This switching on and off, and thus the generation of the offset compensation value, can be repeated, for example, at a rate of 1 Hz. Conversely, the speed circuit devices 30, 31, 32 are in a measurement operation mode, in which these speed circuit devices are continuously supplied with energy (and thus continuously activated), and output a speed signal at a data rate of, for example, 500 Hz.

[0042] The sensor system 100 may further include an operating mode control device for pre-defining the current operating mode for the speed circuit devices 30, 31, 32 and / or the quadrature circuit devices 41, 42, 43 and / or the temperature circuit devices 61, 62, 63, 63', 63"). It is conceivable that the operating mode control device can switch between different operating modes. For example, different energy-saving modes with different data rates can be set for the quadrature circuit devices 41, 42, 43 and / or the temperature circuit devices 61, 62, 63, 63', 63" and can be switched between these different energy-saving modes. It is also conceivable that the operating mode control device can at least temporarily set the quadrature circuit devices 41, 42, 43 and / or the temperature circuit devices 61, 62, 63, 63', 63" to an operating mode having the same data rate as the measurement operating mode system of the speed circuit devices 30, 31, 32.

[0043] For example, by means of an operating mode control device, the user can set the operating mode for the speed circuit devices 30, 31, 32 and / or the quadrature circuit devices 41, 42, 43 and / or the temperature circuit devices 61, 62, 63, 63', 63" . This allows for particularly advantageous matching to specific application conditions and requirements.

Claims

1. A sensor system (100) having a MEMS gyroscope (1), said sensor system comprising at least: A vibrational mass (21) that can be excited to oscillate for use in detecting measurement signals (200). The drive circuit (10) is used to excite and maintain the defined oscillating motion of the vibrating mass (21). A detection circuit (20) is used to read out the measurement signal (200) and demodulate the measurement signal (200), thereby generating a rotational speed signal (210) and an orthogonal signal (211) phase-shifted relative to the rotational speed signal (210). Digital processing circuitry (50) is used to compensate for the offset of the digitized rotational speed signal when using digitized quadrature signals. The detection circuit (20) and the digital processing circuit (50) include a rotational speed circuit device (30, 31, 32) for generating and processing the rotational speed signal, and an orthogonal circuit device (41, 42, 43) for generating and processing the orthogonal signal and for generating a compensation signal (212), the compensation signal being used for offset compensation of the digitized rotational speed signal; The characteristic feature is that at least a portion of the orthogonal circuit devices (41, 42, 43) is capable of operating independently of the operating mode of the speed circuit devices (30, 31, 32) in at least one operating mode different from that of the speed circuit devices (30, 31, 32). The rotational speed circuit (30, 31, 32) operates in a measurement operation mode, in which the rotational speed signal is provided at a first data rate, and the quadrature circuit (41, 42, 43) operates in a first energy-saving mode, in which the quadrature signal is provided at a second data rate, wherein the second data rate is less than the first data rate.

2. The sensor system (100) according to claim 1, characterized in that, The speed circuit device includes a demodulation device (30) and / or an analog-to-digital converter (31) as part of the detection circuit (20), and / or includes at least one digital filter (32) as part of the digital processing circuit (50).

3. The sensor system (100) according to any one of claims 1 or 2, characterized in that, The orthogonal circuit device includes a demodulation device (41) and / or an analog-to-digital converter (42) as part of the detection circuit (20), and / or includes at least one digital filter (43) as part of the digital processing circuit (50).

4. The sensor system (100) according to any one of claims 1 to 3, wherein the sensor system has at least one temperature sensor (60) for detecting a temperature signal, and has temperature circuitry (61, 62, 63, 63', 63'') for processing the temperature signal and for generating the compensation signal, wherein, The digital processing circuit (50) is designed to generate the compensation signal based on the digitized quadrature signal and the digitized temperature signal, characterized in that at least a portion of the temperature circuit devices (61, 62, 63, 63', 63'') is capable of operating independently of the operating mode of the speed circuit devices (30, 31, 32) in at least one operating mode different from that of the speed circuit devices (30, 31, 32).

5. The sensor system (100) according to claim 4, characterized in that, The temperature circuit device includes an analog-to-digital converter (61) and / or at least one digital filter (62) and / or at least one adder (63') and / or multiplier (63, 63'').

6. The sensor system (100) according to any one of claims 1 to 5, characterized in that... An operating mode control device is used to predefine the current operating mode for the speed circuit device (30, 31, 32) and / or for the quadrature circuit device (41, 42, 43) and / or for the temperature circuit device (61, 62, 63, 63', 63'').

7. A method for operating a sensor system (100) according to any one of the preceding claims, characterized in that, The rotational speed circuit (30, 31, 32) is operated in a measurement operation mode, in which the rotational speed signal is provided at a first data rate, and the quadrature circuit (41, 42, 43) is operated in a first energy-saving mode, in which the quadrature signal is provided at a second data rate, wherein the second data rate is less than the first data rate.

8. The method according to claim 7, characterized in that, In the first energy-saving mode, at least a portion of the orthogonal circuit devices (41, 42, 43) are periodically activated and disabled at predetermined time intervals.

9. The method according to any one of claims 7 or 8, wherein, The sensor system (100) includes at least one temperature sensor (60) and a temperature circuit device (61, 62, 63, 63', 63''), characterized in that the temperature circuit device (61, 62, 63, 63', 63'') operates in a second energy-saving mode, in which the temperature signal is provided at a data rate less than the first data rate.

10. The method according to claim 9, characterized in that, The orthogonal circuit devices (41, 42, 43) and the temperature circuit devices (61, 62, 63, 63', 63'') are operated in the same energy-saving mode, thereby providing the orthogonal signal and the temperature signal at the same data rate.

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