Method and sensor system with integrated calibration mechanism

Abstract

The present application relates to a method and a sensor system with integrated calibration mechanism. A system (100) for generating electrical signals based on at least one physical quantity, comprising sensor units (104), each sensor unit generating an individual electrical signal in response to the at least one physical quantity; a selection unit (114) selecting a first number of sensor units (104) from the sensor units (104) and outputting a first combined electrical signal based on the first number of sensor units (104); and a calibration unit (140) determining a second number of sensor units (104) to be selected based on the first combined electrical signal. A method for calibrating a system (100) is also involved.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201880098019.0, entitled "Method and Sensor System with Integrated Calibration Mechanism", filed on September 26, 2018. Technical Field

[0002] This invention relates to sensor systems, and more particularly to sensor systems with integrated calibration mechanisms. Background Technology

[0003] Sensor systems are widely used to sense physical quantities such as force / pressure, temperature, light levels, position, velocity, or sound, and convert them into analog quantities that can be measured electrically (e.g., voltage, capacitance, inductance, or ohmic resistance). A sensor system typically consists of sensor devices mounted on a printed circuit board (PCB) with input and output terminals. However, due to errors caused by various factors (e.g., the electrical connection between the sensor device and the PCB, the package type of the sensor device, the PCB's dimensional characteristics, the sensor device's mounting position on the PCB, and variations in other components within the sensor system (e.g., mass or cantilever)), each sensor system requires calibration before being put into use. Summary of the Invention

[0004] This invention relates to a sensor system that generates an electrical signal based on at least one sensed physical quantity. In one example, a system includes a plurality of sensor units, each sensor unit generating an individual electrical signal in response to at least one sensed physical quantity. The system also includes a selection unit coupled to the plurality of sensor units, the selection unit being configured to select a first number of sensor units from the plurality of sensor units and output a first combination of electrical signals based on the first number of sensor units, and a calibration unit coupled to the selection unit, the calibration unit being configured to determine a second number of sensor units to be selected based on the first combination of electrical signals.

[0005] In another example, the present invention provides a method for calibrating a system having a plurality of sensor units, each sensor unit generating an electrical signal in response to at least one sensed physical quantity, wherein each sensor unit generates a separate electrical signal in response to at least one sensed physical quantity. The method includes: a selection unit performing the selection of a first number of sensor units from the plurality of sensor units; generating a first combination of electrical signals based on the first number of sensor units; and a calibration unit performing the determination of a second number of sensor units. Attached Figure Description

[0006] Figure 1 This is a schematic block diagram of a sensor system with an integrated calibration mechanism according to an embodiment of the present invention.

[0007] Figure 2 According to an embodiment of the present invention Figure 1 A schematic enlarged view of a single sensor unit in a sensor system.

[0008] Figure 3 According to an embodiment of the present invention Figure 1 A schematic block diagram of the calibration unit of the sensor system.

[0009] Figure 4 This is a flowchart of a method for calibrating a sensor system according to another embodiment of the present invention. Detailed Implementation

[0010] In an embodiment of the present invention, a system for generating an electrical signal based on at least one sensed physical quantity is provided. The system includes: a plurality of sensor units, a selection unit coupled to the plurality of sensor units, and a calibration unit coupled to the selection unit. Each sensor unit generates a separate electrical signal in response to at least one sensed physical quantity. The selection unit selects a first number of sensor units from the plurality of sensor units and outputs a first combination of electrical signals based on the first number of sensor units. The calibration unit determines a second number of sensor units to be selected based on the first combination of electrical signals.

[0011] In another embodiment, the present invention provides a method for calibrating a system having a plurality of sensor units that generate electrical signals in response to at least one sensed physical quantity, wherein each sensor unit generates a separate electrical signal in response to at least one sensed physical quantity. The method includes: selecting a first number of sensor units from the plurality of sensor units by a selection unit; generating a first combination of electrical signals based on the first number of sensor units; and determining a second number of sensor units to be selected by a calibration unit based on the first combination of electrical signals.

[0012] Now for reference Figure 1A schematic block diagram of a sensor system 100 with an integrated calibration mechanism according to an embodiment of the present invention is shown. The sensor system 100 is configured to generate an electrical signal based on at least one sensed physical quantity. For example, the sensor system 100 is a force or pressure sensor system, and the electrical signal is a voltage signal converted from the force or pressure sensed by the sensor system 100. The sensor system 100 includes a sensor device 102 having a plurality of sensor units 104_a1 to 104_a32 and 104_b1 to 104_b32 (collectively referred to as “sensor units 104”), wherein each sensor unit 104 is configured to generate a separate electrical signal in response to at least one sensed physical quantity. In a preferred embodiment, the sensor device 102 is a lead zirconate titanate (PZT) (or more generally referred to as piezoelectric) strain sensor device comprising a plurality of sensor units 104 arranged in series. Preferably, the number of the plurality of sensor units 104 is 2. n , where n is a natural number greater than 2. In Figure 1 In the example shown, the sensor system 100 has 64 sensor units 104. When calibrating the sensor system 100, a known physical quantity is applied to the sensor system 100, and a first number of sensor units 104 is determined based on the known physical quantity.

[0013] Figure 2 yes Figure 1 A schematic enlarged view of a single sensor unit 104 of the sensor system 100. The sensor unit 104 includes at least one sensor element 106 coupled between a first terminal 108 and a second terminal 110 of the sensor unit 104. In a preferred embodiment, the sensor element 106 is a ferroelectric capacitor (FECAP), and the sensor unit 104 includes a plurality of ferroelectric capacitors 106 arranged in parallel and coupled between the first terminal 108 and the second terminal 110. For example, the number of sensor elements in each sensor unit 104 may be four or eight. When a force or pressure 112 is applied to the sensor unit 104 in a direction from the second terminal 110 to the first terminal 108, in a preferred embodiment, a separate electrical signal corresponding to the amount of force or pressure 112 is generated, which is the voltage difference between the first terminal 108 and the second terminal 110 of the sensor unit 104. However, the sensor system 100 is not limited to a force or pressure sensor system. For example, the sensor system 100 may be a tension sensor system, or a system that generates electrical signals based on a combination of separate signals derived from a physical quantity by multiple sensor elements.

[0014] Return to reference Figure 1The sensor system 100 further includes a selection unit 114 coupled to a plurality of sensor units 104. The selection unit 114 selects a first number of sensor units 104 from the plurality of sensor units 104 and outputs a first combination of electrical signals based on the first number of sensor units 104. In a preferred embodiment, the first number of selected sensor units 104 are N consecutive sensor units cascaded in sequence, where N is a natural number. The first combination of electrical signals is the voltage difference across the N sensor units 104.

[0015] In a preferred embodiment, a plurality of sensor units 104 are divided into a first group 116 and a second group 118, preferably with the same number of sensor units 104 in each group, and the first group 116 and the second group 118 of sensor units 104 are ordered from the connector nodes of the first group 116 and the second group 118, for example, the second terminal 110 of the first sequential sensor unit 104_a1 and the first terminal 108 of the first sequential sensor unit 104_b1 in the first group 116 are connected at the connector node. In a preferred embodiment, the voltage V at the connector node... ref It can be used for zero calibration of sensor system 100.

[0016] In a preferred embodiment, selecting the first number of sensor units 104 includes selecting a third number of sensor units 104 from a first group 116 and a fourth number of sensor units 104 from a second group 118. In a preferred embodiment, both the third and fourth number of sensor units 104 are selected consecutively from the connector node. In a preferred embodiment, the selection unit 114 includes a first selector 120 and a second selector 122 respectively coupled to the first group of sensor units 104 and the second group of sensor units 104. In a preferred embodiment, the first selector 120 is implemented as a plurality of first taps 124 respectively coupled to the first terminals 108 of the sensor units 104 in the first group 116 and a first multiplexer 126 having inputs respectively coupled to the plurality of first taps 124. Similarly, the second selector 122 is implemented as a plurality of second taps 128 respectively coupled to the second terminals 110 of the sensor units 104 in the second group 118 and a second multiplexer 130 having inputs respectively coupled to the plurality of second taps 128. Therefore, a first number of sensor units 104 are selected flexibly through the following steps: a signal is sent to a first multiplexer 126 to select one tap from the first taps 124 based on a third number, and another tap from the second taps 128 based on a fourth number. The outputs of both multiplexers 126 and 130 can be combined to form a first combined electrical signal, where the difference between the two outputs corresponds to the voltage difference across the N selected sensor units 104. In a preferred embodiment, the first number of sensor units 104 are selected uniformly from the first group 116 and the second group 118.

[0017] In a preferred embodiment, the sensor system 100 includes an amplification unit 132 coupled to the selection unit 114 for improving the sensitivity of the sensor system 100, wherein the amplification unit 132 generates an amplified signal V based on a first combination of electrical signals. amp Amplified signal V amp It is the output of the sensor system 100, which is an electrical signal converted by the sensor system 100 from the sensed physical quantity.

[0018] Amplification unit 132 preferably includes at least one first amplifier 134 having two inputs coupled to the outputs of a first multiplexer 126 and a second multiplexer 130, respectively. In a preferred embodiment, the first amplifier 134 is a low-noise amplifier (LNA) having two outputs that generate a pair of amplified differential signals. Amplification unit 132 further includes a second amplifier 136 that generates an amplified signal V based on the pair of amplified differential signals. ampIn a preferred embodiment, amplification unit 132 further includes one or more amplifiers (e.g., a third amplifier 138) coupled between the first amplifier 134 and the second amplifier 136. In a preferred embodiment, the second amplifier 136 and the third amplifier 138 are analog front-end modules having a gain less than that of the first amplifier 134. For example, the first amplifier 134 has a gain of 10x, and the second amplifier 136 and the third amplifier 138 have a gain of 100x. In an alternative example, the first amplifier 134 may be part of a sensor module (e.g., a motion wake-up (WOM) sensor module that generates a signal based on the detection of its motion). The sensor module also includes sensor device 102 and selection unit 114, wherein the output of the first amplifier 134 is the output of the sensor module.

[0019] The sensor system 100 also includes a calibration unit 140 coupled to the selection unit 132. The calibration unit 140 determines a second number of sensor units 104 to be selected from the plurality of sensor units 104 based on the electrical signals of the first combination, and generates a selection signal 142 to calibrate the sensor system 100. In a preferred embodiment, the amplification unit 132 is coupled between the selection unit 114 and the calibration unit 140, wherein the calibration unit 140 is based on the amplified signal V. amp Determine the second number of sensor units 104, amplified signal V amp The electrical signal based on the first combination is generated by the amplification unit 132. The selection unit 114 receives the selection signal 142 indicating the selection of a second number of sensor units 104, selects the second number of sensor units 104 instead of the first number of sensor units 104, and outputs the electrical signal based on the second number of sensor units 104.

[0020] refer to Figure 3 A schematic block diagram of a calibration unit 200 according to an embodiment of the present invention is shown, the calibration unit 200 being connected to... Figure 1 The calibration unit 200 is the same as the calibration unit 140 in the sensor system 100. The calibration unit 200 includes a comparator 202 and a controller 204 coupled to the comparator 202. The comparator 202 receives an amplified signal V. amp and compare it with the predetermined threshold V th The controller 204 compares and generates a comparison result, and determines a second number of sensor units 104 by increasing or decreasing the first number of sensor units 104 by a predetermined step size based on the comparison result. The controller 204 sends a signal to the selection unit 114 to select the second number of sensor units 104 by generating a selection signal 142 to the selection unit 114.

[0021] Predetermined threshold V thThe predetermined step size is determined based on known physical quantities applied to the sensor system 100, and is configured according to the characteristics of the sensor units 104 and the allowable error limit of the sensor system 100. For example, if the allowable error limit is 3%, the predetermined step size is configured for two sensor units 104. Therefore, the increase is performed by selecting more than two sensor units 104 from at least one of the first group 116 and the second group 118, and the decrease is performed by selecting fewer than two sensor units 104 from at least one of the first group 116 and the second group 118. The controller 204 stops determining the second number of sensor units 104, for example, if the amplified signal V... amp and the predetermined threshold V th If the difference between the two values ​​satisfies the allowable error limit of sensor system 100, then sensor system 100 completes the calibration. Controller 204 may be an on-chip microcontroller (MCU) of sensor system 100. Comparator 202 may also be implemented as part of controller 204.

[0022] refer to Figure 4 A flowchart of a method 300 for calibrating a sensor system according to an embodiment of the present invention is shown. The sensor system generates an electrical signal based on at least one sensed physical quantity, wherein, such as Figure 1 The sensor system 100 shown includes a plurality of sensor units 104, each sensor unit generating a separate electrical signal in response to at least one physical quantity. For example, sensor system 100 is a force or pressure sensor system, and the electrical signal is a voltage signal converted from the force or pressure sensed by sensor system 100. Each sensor unit is a set of ferroelectric capacitors connected in parallel, and the plurality of sensor units 104 are arranged in series to form a lead zirconate titanate (PZT) strain sensor device. However, sensor system 100 is not limited to a force or pressure sensor system. For example, sensor system 100 may be a tension sensor system, or a system that generates an electrical signal based on a combination of separate signals converted from a physical quantity by a plurality of sensor elements. To calibrate sensor system 100, a known physical quantity is applied to sensor system 100, and more specifically, to the plurality of sensor units 104.

[0023] Starting at step 302, the selection unit 114 of the sensor system 100 selects a first number of sensor units 104 from a plurality of sensor units 104. In a preferred embodiment, the plurality of sensor units 104 includes a first group of continuously connected sensor units and a second group of continuously connected sensor units, wherein the first group and the second group are connected at a connector node. Selecting the first number of sensor units includes, starting from the connector node, selecting a third number of sensor units 104 from the first group and a fourth number of sensor units 104 from the second group.

[0024] In step 304, in response to a known physical quantity applied to the sensor system 100, and more specifically, a known physical quantity applied to a plurality of sensor units 104, the selection unit 114 generates a first combination of electrical signals based on a first number of sensor units 104. In a preferred embodiment, the first number of sensor units 104 is a series of consecutively connected sensor units 104, wherein an individual electrical signal is the voltage difference between a first terminal and a second terminal of a sensor unit 104, and the first combination of electrical signals is the voltage difference across a series of consecutively connected sensor units 104. In a preferred embodiment, the terminals of the first group of sensor units 104 connected to the connector node are second terminals, and the terminals of the second group of sensor units 104 connected to the connector node are first terminals, wherein generating the first combination of electrical signals includes outputting the voltage difference between the first terminal of the last sensor unit of a third number of sensor units, which is away from the connector node, and the second terminal of the last sensor unit of a fourth number of sensor units, which is away from the connector node.

[0025] Preferably, in step 306, the amplification unit 132 of the sensor system 100 generates an amplified signal to improve the sensitivity of the sensor system 100 based on the first combination of electrical signals. In a preferred embodiment, generating the amplified signal includes generating a pair of amplified differential signals based on the first combination of electrical signals, and generating an amplified signal based on the pair of amplified differential signals.

[0026] In step 308, the calibration unit 140 of the sensor system 100 compares the amplified signal with a predetermined threshold, wherein the predetermined threshold V th It is determined based on known physical quantities applied to sensor system 100. In a preferred embodiment, the comparison result of step 308 is the difference between the amplified signal and a predetermined threshold.

[0027] In step 310, calibration unit 140 determines whether the difference between the amplified signal and a predetermined threshold satisfies the permissible error limit of sensor system 100. If the difference satisfies the permissible error limit, the calibration is complete. Otherwise, in step 312, calibration unit 140 further determines a second number of sensor units 104 to be selected. In a preferred embodiment, the second number of sensor units 104 is determined based on the comparison result by increasing or decreasing the first number of sensor units by a predetermined step size, wherein the predetermined step size is configured according to the characteristics of the sensor units 104 and based on the permissible error limit of sensor system 100. For example, if the permissible error limit is 3%, the predetermined step size is configured to two sensor units 104. Therefore, the increase is performed by selecting more than two sensor units 104 from a plurality of sensor units 104, and the decrease is performed by selecting less than two sensor units 104 from a plurality of sensor units 104. In a preferred embodiment, determining the second number of sensor units 104 includes, starting from the connector node, determining a fifth number of sensor units 104 to be selected from a first group and a sixth number of sensor units 104 to be selected from a second group.

[0028] In step 314, selection unit 114 selects a second number of sensor units 104 from the plurality of sensor units 104, instead of selecting a first number of sensor units 104. In a preferred embodiment, the second number of sensor units 104 are also connected sequentially. Then, returning to step 304, selection unit 114 generates a second combination of electrical signals based on the second number of sensor units 104. This calibration continues until the difference between the amplified signal and a predetermined threshold satisfies the permissible error limit of sensor system 100.

[0029] The detailed description set forth above in conjunction with the accompanying drawings is intended as a description of the presently preferred embodiments of the invention and is not intended to represent the only form in which the invention can be practiced. It should be understood that the same or equivalent functions can be achieved through different embodiments intended to be included within the spirit and scope of the invention. In the drawings, the same reference numerals are consistently used to denote the same elements.

Claims

1. A system for calibration, comprising: Connector terminals; A first set of sensor units coupled in series, wherein the first sensor of the first set of sensor units is coupled to the connector terminal; A second set of sensor units coupled in series, wherein the first sensor of the second set of sensor units is coupled to the connector terminal; A selection unit coupled to the first group of sensor units and the second group of sensor units, wherein the selection unit is configured to: Select a first number of sensor units connected in series from the first group of sensor units and the second group of sensor units; as well as Output signals from the first number of serially connected sensor units; as well as A calibration unit, coupled to the selection unit and configured to: Receive the signal; Compare the signal and the range value; as well as In response to the signal being outside the range value, a selection signal is output to the selection unit, wherein, in response to the selection signal, the selection unit is configured to select a second number of sensor units from the first group of sensor units and the second group of sensor units.

2. The system according to claim 1, wherein, The signal is the differential voltage between the first terminal of the first number of series-connected sensor units and the last terminal of the first number of series-connected sensor units.

3. The system according to claim 1, wherein, The first number of serially connected sensor units includes the same number of sensor units in the first group of sensor units and the second group of sensor units.

4. The system according to claim 1, wherein, The second number of sensor units is determined based on the difference between the signal and the range value.

5. The system according to claim 1, wherein, Each of the first group of sensor units and each of the second group of sensor units includes multiple capacitors arranged in parallel.

6. The system of claim 1 further includes an amplification unit coupled between the selection unit and the calibration unit, wherein the signal is amplified by the amplification unit.

7. The system according to claim 1, wherein: The connector terminals include a reference voltage; and The system is configured to be calibrated based on the reference voltage.

8. The system according to claim 1, wherein: The first group of sensor units is a first group of ferroelectric capacitors connected in parallel and configured as a first lead zirconate titanate (PZT) strain sensor device; and The second set of sensor units is a second set of ferroelectric capacitors connected in parallel and configured as a second PZT strain sensor device.

9. The system according to claim 1, wherein: The first number of serially connected sensor units includes the first sensor in the first group of sensor units and the first sensor in the second group of sensor units; The first sensor in the first group of sensor units includes a second sensor coupled to the first group of sensor units, a first terminal of the selection unit, and a second terminal coupled to the connector terminal; as well as The first sensor in the second group of sensor units includes a first terminal coupled to the connector terminal and a second sensor coupled to the second group of sensor units and the second terminal of the selection unit.

10. A method for calibration, the method comprising: A selection unit coupled to a first group of sensor units and a second group of sensor units selects a first number of sensor units connected in series from the first group of sensor units and the second group of sensor units, wherein the first sensor of the first group of sensor units is coupled to a connector terminal and the first sensor of the second group of sensor units is coupled to the connector terminal; The selection unit outputs a signal from the first number of serially connected sensor units; as well as The signal is received by the calibration unit; The calibration unit compares the signal with the range value; as well as In response to the signal being outside the range value: The calibration unit outputs a selection signal coupled to the selection unit; The selection signal is received by the selection unit; as well as Based on the selection signal, the selection unit selects a second number of sensor units from the first group of sensor units and the second group of sensor units.

11. The method according to claim 10, wherein, The signal is the differential voltage between the first terminal of the first number of series-connected sensor units and the last terminal of the first number of series-connected sensor units.

12. The method according to claim 10, wherein, The first number of serially connected sensor units includes the same number of sensor units in the first group of sensor units and the second group of sensor units.

13. The method according to claim 10, wherein, The second number of sensor units is determined based on the difference between the signal and the range value.

14. The method of claim 10, wherein, Each of the first group of sensor units and each of the second group of sensor units includes multiple capacitors arranged in parallel.

15. The method of claim 10, further comprising amplifying the signal by an amplification unit coupled between the selection unit and the calibration unit.

16. The method of claim 10, wherein, The connector terminals include a reference voltage.

17. The method of claim 10, wherein: The first group of sensor units is a first group of ferroelectric capacitors connected in parallel and configured as a first lead zirconate titanate (PZT) strain sensor device; and The second set of sensor units is a second set of ferroelectric capacitors connected in parallel and configured as a second PZT strain sensor device.

18. The method of claim 10, wherein: The first number of serially connected sensor units includes the first sensor in the first group of sensor units and the first sensor in the second group of sensor units; The first sensor in the first group of sensor units includes a second sensor coupled to the first group of sensor units, a first terminal of the selection unit, and a second terminal coupled to the connector terminal; as well as The first sensor in the second group of sensor units includes a first terminal coupled to the connector terminal and a second sensor coupled to the second group of sensor units and the second terminal of the selection unit.

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