High-precision inclination angle measuring circuit

Abstract

The utility model provides a high precision inclination angle measuring circuit, including several sets of inclination angle noise reduction circuit, analog-to-digital converter, microcontroller, inclination angle noise reduction circuit include MEMS inclination angle sensor, signal conditioning circuit and output resistor that are electrically connected in proper order, several output resistor are all electrically connected with analog-to-digital converter, and microcontroller is electrically connected with the analog-to-digital converter. The MEMS tilt angle sensor is used for collecting tilt angle information of the structure and converting the tilt angle information into a differential voltage signal, the signal conditioning circuit is used for receiving the differential voltage signal for noise reduction processing and converting the differential voltage signal after noise reduction processing into a single-end voltage signal, and the output resistor is used for reducing disturbance in the single-end voltage signal output process. The analog-to-digital converter is used for gathering analog signals of output voltages of the multiple groups of inclination angle noise reduction circuits and converting the analog signals into digital signals, and the microcontroller is used for processing the digital signals and sending the processed signals to a remote monitoring terminal. The high-precision inclination angle measuring circuit provided by the utility model is low in noise and low in cost.

Description

Technical Field

[0001] The utility model relates to the technical field of engineering surveying, in particular to a high-precision inclination measurement circuit. Background Art

[0002] At present, inclinometers based on the MEMS (Micro-Electro-Mechanical System) principle are mostly used for inclination measurement of structures and buildings. Many monitoring and detection scenarios have high requirements for the measurement accuracy of inclination. Therefore, when designing sensors for industries and scenarios with high-precision inclination measurement requirements, it is necessary to select an inclination sensor chip with high sensitivity. Merely selecting a suitable MEMS inclination sensor often fails to meet the system requirements, restricting the application of MEMS inclination sensors in the high-precision inclination measurement industry.

[0003] At present, for application scenarios of high-precision inclination measurement, inclination sensors based on the active servo principle are mostly used. They adopt high-precision inertial navigation technology, precisely integrating electromechanical technology and inertial measurement technology, and are applied to various high-end industrial fields or military fields. However, the disadvantages of this type of sensor are high cost and large noise in the internal circuit. Summary of the Utility Model

[0004] Based on this, the purpose of the utility model is to provide a high-precision inclination measurement circuit to solve the problems existing in the prior art.

[0005] The utility model provides a high-precision inclination measurement circuit, including several groups of inclination noise reduction circuits arranged in parallel, an analog-to-digital converter electrically connected to the several groups of inclination noise reduction circuits, and a microcontroller electrically connected to the analog-to-digital converter. The inclination noise reduction circuit includes an MEMS inclination sensor, a signal conditioning circuit, and an output resistor that are electrically connected in sequence. The output resistors of the several groups of inclination noise reduction circuits are all electrically connected to the analog-to-digital converter. The MEMS inclination sensor is used to collect the inclination information of the structure and convert it into a differential voltage signal. The signal conditioning circuit is used to receive the differential voltage signal for noise reduction processing and convert the differential voltage signal after noise reduction processing into a single-ended voltage signal. The output resistor is used to reduce the disturbance during the output process of the single-ended voltage signal. The analog-to-digital converter is used to aggregate the single-ended voltage signals output by the several groups of inclination noise reduction circuits and convert them into digital signals. The microcontroller is used to process the digital signals and send the processed digital signals to a remote monitoring terminal.

[0006] The beneficial effects of the present utility model are as follows: The high-precision inclination measurement circuit provided by this application includes an excitation circuit, an induction coil, and a conversion circuit. The excitation circuit includes an energy storage capacitor, a switching circuit, and an excitation coil. The energy storage capacitor is connected to the excitation coil through the switching circuit. The induction coil is used to sense the excitation output by the excitation coil and output an induction signal. The conversion circuit includes an integration circuit, an ADC conversion circuit, a microprocessor, and an EEPROM memory connected in sequence. The capacitance value difference coefficient is written in the EEPROM memory. In the high-precision inclination measurement circuit provided by this application, the excitation circuit realizes signal excitation and enables the induction coil to generate an induction signal. After being converted by the integration circuit, it is connected to the ADC conversion circuit for quantization acquisition. The capacitance value difference coefficient is written in the EEPROM memory, which can correct the acquisition value of the ADC conversion circuit to ensure the consistency of the acquisition results. The high-precision inclination measurement circuit provided by this application has the functions of sensor excitation, induction signal acquisition, and capacitance difference correction at the same time, ensuring the consistency of the acquisition results and improving the versatility of the acquisition system.

[0007] Preferably, the MEMS inclination sensor includes an inclinometer chip, and the inclinometer chip is used to convert the received inclination signal into a differential voltage signal for output.

[0008] Preferably, the signal conditioning circuit includes a differential filter, a radio frequency filter, and an instrumentation amplifier connected in sequence. The differential filter is used to filter the noise of the differential voltage signal, the radio frequency filter is used to filter the external common-mode radio frequency and radio frequency differential mode of the differential voltage signal, and the instrumentation amplifier is used to convert the filtered differential voltage signal into a single-ended voltage signal.

[0009] Preferably, the differential filter includes two parallel differential resistors, and two differential capacitors are electrically connected between the output ends of the two differential resistors. The two output ends of the inclinometer chip are respectively electrically connected to the input ends of the two differential resistors.

[0010] Preferably, the radio frequency filter includes two parallel radio frequency resistors, and three radio frequency capacitors are electrically connected between the output ends of the two radio frequency resistors. The two radio frequency capacitors are connected in parallel, and the other radio frequency capacitor is connected in parallel with the two series-connected radio frequency capacitors. The input end of the radio frequency resistor is electrically connected to the output end of the differential resistor.

[0011] Preferably, the inclination measurement circuit further includes a voltage follower, and the voltage follower is electrically connected to the instrumentation amplifier.

[0012] Preferably, the resistance value of the output resistor is 45Ω - 55Ω.

[0013] Preferably, the inclination angle measurement circuit further includes a reference source circuit, which is electrically connected to the MEMS inclination angle sensor and the analog-to-digital converter respectively, and is used to supply power to the MEMS inclination angle sensor and the analog-to-digital converter.

[0014] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic flowchart of a high-precision inclination angle measurement circuit provided by the present invention;

[0016] Figure 2 is Figure 1 a schematic structural diagram of the high-precision inclination angle measurement circuit in

[0017] Figure 3 is Figure 2 a partially enlarged schematic structural diagram of the inclination angle noise reduction circuit at point A in

[0018] Figure 4 is Figure 2 a partially enlarged schematic structural diagram of the reference source circuit at point B in

[0019] Figure 5 is Figure 2 a partially enlarged schematic structural diagram of the voltage follower at point C in

[0020] Description of the main component symbols:

[0021] 10. Inclination angle noise reduction circuit; 11. MEMS inclination angle sensor; 12. Signal conditioning circuit; 13. Output resistance; 20. Analog-to-digital converter; 30. Microcontroller.

[0022] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. SPECIFIC EMBODIMENTS

[0023] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this utility model belongs. The terms used in the description of this utility model herein are only for the purpose of describing specific embodiments and are not intended to limit this utility model. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0026] Specifically, as Figure 1 shown, an embodiment of a high-precision inclination measurement circuit of this utility model includes several groups of inclination noise reduction circuits 10 arranged in parallel, an analog-to-digital converter 20 electrically connected to several groups of inclination noise reduction circuits 10, and a microcontroller 30 electrically connected to the analog-to-digital converter 20. The inclination noise reduction circuit 10 includes an MEMS inclination sensor 11, a signal conditioning circuit 12, and an output resistor 13 that are electrically connected in sequence. The output resistors 13 of several groups of inclination noise reduction circuits 10 are all electrically connected to the analog-to-digital converter 20. The MEMS inclination sensor 11 is used to collect the inclination information of the structure and convert it into a differential voltage signal. The signal conditioning circuit 12 is used to receive the differential voltage signal for noise reduction processing and convert the differential voltage signal after noise reduction processing into a single-ended voltage signal. The output resistor 13 is used to reduce the disturbance during the output process of the single-ended voltage signal. The analog-to-digital converter 20 is used to aggregate the analog signals of the output voltages of several groups of inclination noise reduction circuits and convert them into digital signals. The microcontroller 30 is used to process the digital signals and send the processed digital signals to a remote monitoring terminal.

[0027] Optionally, in this embodiment, by using the averaging effect generated by multiple MEMS inclination sensors, it helps to improve the precision performance of the inclinometer measurement; the high-precision inclination measurement circuit provided by this application can perform an average calculation on the uncorrelated error sources and random noises of multiple MEMS inclination sensors. The total noise of the integrated sensor data can be reduced, the signal-to-noise ratio can be increased, and thus the measurement precision can be improved. The goal of enabling the MEMS sensor to achieve high-precision measurement at a lower cost is realized.

[0028] Generally speaking, various noises usually have no correlation with each other and are independently and identically distributed. For example, electrical noise can be approximated as white noise in most bandwidths. In circuit analysis, especially in the processing of signals and noises, noise is usually regarded as a random signal, and the addition of noises generally adopts the root mean square (RMS) because it follows the statistical characteristics of random variables. The main benefit of using multiple sensors and signal chains in parallel is to eliminate this random white noise by taking the average value method; when summing two uncorrelated signals (such as white noise), they are combined mathematically in the form of "square root of the sum" (RSS). Let Un be the noise output by a sensor signal chain, then the average noise on two channels should be:

[0029]

[0030] Similarly, when summing N noises with equal effective values, the average noise is:

[0031]

[0032] In the formula, N represents the number of parallel sensors and signal chains.

[0033] It can be seen from the above formula that when N is larger, the average noise is smaller. Therefore, the more uncorrelated signals are added, the white noise can be reduced, the signal-to-noise ratio can be indirectly improved, and thus the measurement of high-precision tilt angle data can be realized. And when adding two identical signals with the same correlated signals and calculating the average value, the signal power remains unchanged.

[0034] Assume that the output of the signal chain is:

[0035] Uoi = Ui(t) + Uni

[0036] In the formula, Ui(t) is the voltage signal output by the i-th tilt angle sensor, and Uni is the voltage noise output by the i-th tilt angle sensor;

[0037] Then the total signal expression before entering the analog-to-digital converter is:

[0038]

[0039] Since the same MEMS chip and the same signal chain are adopted for each path, it can be considered that: Ui(t) = U(t), Uni = Un, and the above formula can be simplified to:

[0040]

[0041] Optionally, in this embodiment, the high-precision tilt angle measurement circuit includes four groups of tilt angle noise reduction circuits 10 arranged in parallel, that is, N = 4. At this time:

[0042]

[0043] When four MEMS chips and signal conditioning circuits are connected in parallel, the noise is reduced by half. As N continues to increase, the noise will be further reduced, but it is necessary to balance cost, power consumption and the target, and achieve high-precision inclination measurement by selecting an appropriate N.

[0044] Optionally, in this embodiment, as Figure 2 shown, the structures of the four groups of parallel-connected inclination noise reduction circuits are similar. In this embodiment, one group of inclination noise reduction circuits is described, and the others are similar; optionally, as Figure 3 shown, the inclination noise reduction circuit includes a MEMS inclination sensor 11 which includes an inclinometer chip U1. The inclinometer chip is used to convert the received inclination signal into a differential voltage signal for output. For example, when the MEMS inclination sensor varies within the range of ±10°, the output voltage range of its differential voltage signal is -2.5 to 2.5V.

[0045] The signal conditioning circuit 12 includes a differential filter, a radio frequency filter and an instrumentation amplifier connected in sequence. The differential filter is used to filter out the clock noise output by the differential voltage signal, and its passband cut-off frequency meets the frequency response requirements of the MEMS chip; the radio frequency filter is used to filter out the external common-mode radio frequency and radio frequency differential mode of the differential voltage signal. The passband cut-off frequency of the radio frequency filter is generally more than 100 times higher than the frequency response of the MEMS chip; the instrumentation amplifier is used to convert the filtered differential voltage signal into a single-ended voltage signal. For example, the -2.5 to 2.5V MEMS differential voltage signal is converted into a 0 to 5V single-ended voltage signal.

[0046] Optionally, as Figure 3 shown, the differential filter includes two parallel-connected differential resistors R1, R4. Two differential capacitors C3, C6 are electrically connected between the output ends of the two differential resistors. The two output ends of the inclinometer chip are respectively electrically connected to the input ends of the two differential resistors; the radio frequency filter includes two parallel-connected radio frequency resistors R2, R5. Three radio frequency capacitors C4, C5, C7 are electrically connected between the output ends of the two radio frequency resistors. The two radio frequency capacitors C4, C5 are connected in parallel, and the radio frequency capacitor C7 is connected in parallel with the two series-connected radio frequency capacitors. The input end of the radio frequency resistor is electrically connected to the output end of the differential resistor. The instrumentation amplifier is U2. The output resistor R3 integrates the four-way signals into one way and outputs them to the analog-to-digital converter 20. Optionally, the resistance value of the output resistor is 45Ω - 55Ω; in this embodiment, the resistance value of the output resistor is 50Ω; U5 is a 24-bit high-precision analog-to-digital converter; the microcontroller can further adopt digital signal filtering algorithms such as the Kalman filter inside by continuously reading the data of the analog-to-digital converter to further improve the accuracy of the inclination data.

[0047] Furthermore, as Figure 4As shown, the inclination measurement circuit further includes a reference source circuit, which is electrically connected to the MEMS inclination sensor and the analog-to-digital converter respectively, and is used to supply power to the MEMS inclination sensor and the analog-to-digital converter. The reason for using the reference source for power supply is that the reference source has higher voltage accuracy and temperature drift coefficient compared with traditional voltage regulators. Using the same reference source to supply power to the analog-to-digital converter and the MEMS inclinometer can also eliminate the measurement error caused by voltage fluctuation. Optionally, the reference source needs to use a high-current output model. When the current output of the reference source is insufficient, multiple reference sources can also be used for power supply. In this embodiment, the Vref interface of the reference source circuit is electrically connected to the Vref interface of the MEMS inclination sensor and the Vref interface of the analog-to-digital converter respectively.

[0048] Further, as Figure 5 shown, the inclination measurement circuit further includes a voltage follower. R21, R23, C33, U9, and C31 form a voltage follower, which is used to provide the common-mode voltage VCM for the system. The voltage follower is electrically connected to the instrumentation amplifier. Since this circuit uses a single-power signal chain conditioning, it is necessary to set the common-mode voltage VCM = 1 / 2Vref, R21 = R23, and Vref is the reference voltage, so that the MEMS differential voltage signal of -2.5 to 2.5V can be converted into a single-ended voltage signal of 0 to 5V. In this embodiment, the VCM interface of the voltage follower is electrically connected to the VCM interface of the instrumentation amplifier.

[0049] In summary, the high-precision inclination measurement circuit provided by this application includes several groups of inclination noise reduction circuits arranged in parallel, an analog-to-digital converter electrically connected to the several groups of inclination noise reduction circuits, and a microcontroller electrically connected to the analog-to-digital converter. Through the averaging effect generated by multiple MEMS inclination sensors, the uncorrelated error sources and random noise of multiple MEMS inclination sensors can be averaged and calculated, reducing the output noise and helping to improve the precision performance of the inclinometer measurement. It reduces the total noise of the integrated sensor data, improves the signal-to-noise ratio, and thus improves the measurement accuracy. It realizes the goal that MEMS sensors can achieve high-precision measurement at a lower cost.

[0050] It should be noted that the above implementation process is only to illustrate the feasibility of this application, but this does not mean that the high-precision inclination measurement circuit and the magnetic flux engineering measuring instrument of this application have only the above several implementation processes. On the contrary, as long as the high-precision inclination measurement circuit and the magnetic flux engineering measuring instrument of this application can be implemented, they can be included in the feasible implementation schemes of this application.

[0051] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0052] The above-described embodiments merely represent several implementation manners of the present utility model, and their descriptions are relatively specific and detailed, but should not be construed as a limitation on the scope of the patent of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all belong to the protection scope of the present utility model. Therefore, the protection scope of the patent of the present utility model shall be subject to the appended claims.

Claims

1. A high-precision inclination measurement circuit, characterized in that: The invention comprises a plurality of tilt noise reduction circuits arranged in parallel, an analog-to-digital converter electrically connected to the plurality of tilt noise reduction circuits, and a microcontroller electrically connected to the analog-to-digital converter. The tilt noise reduction circuit comprises a MEMS tilt sensor, a signal conditioning circuit and an output resistor electrically connected in sequence. The output resistors of the plurality of tilt noise reduction circuits are electrically connected to the analog-to-digital converter. The MEMS tilt sensor is used to collect the tilt information of the structure and convert it into a differential voltage signal. The signal conditioning circuit is used to receive the differential voltage signal for noise reduction processing and convert the differential voltage signal after the noise reduction processing into a single-ended voltage signal. The output resistor is used to reduce the disturbance in the output process of the single-ended voltage signal. The analog-to-digital converter is used to summarize the single-ended voltage signals output by the plurality of tilt noise reduction circuits and convert them into digital signals. The microcontroller is used to process the digital signal and send the processed digital signal to a remote monitoring terminal.

2. The high-precision inclination angle measurement circuit according to claim 1, characterized in that: The MEMS inclination sensor includes an inclinometer chip, and the inclinometer chip is used to convert a received inclination signal into a differential voltage signal for output.

3. The high-precision inclination angle measurement circuit according to claim 2, characterized in that: The signal conditioning circuit includes a differential filter, a radio frequency filter and an instrument amplifier connected in sequence, the differential filter is used to filter out the noise of the differential voltage signal, the radio frequency filter is used to filter out the external common mode radio frequency and radio frequency differential mode of the differential voltage signal, and the instrument amplifier is used to convert the differential voltage signal after filtering into a single-ended voltage signal.

4. The high-precision inclination angle measurement circuit according to claim 3, characterized in that: The differential filter comprises two differential resistors connected in parallel, two differential capacitors are electrically connected between the output ends of the two differential resistors, and the two output ends of the inclinometer chip are electrically connected to the input ends of the two differential resistors respectively.

5. The high-precision inclination angle measurement circuit according to claim 4, characterized in that: The RF filter includes two RF resistors in parallel, three RF capacitors are electrically connected between the output ends of the two RF resistors, the two RF capacitors are connected in parallel, another RF capacitor is connected in parallel with the two RF capacitors connected in series, and the input end of the RF resistor is electrically connected to the output end of the differential resistor.

6. The high-precision inclination angle measurement circuit according to claim 3, characterized in that: The tilt angle measurement circuit further includes a voltage follower, and the voltage follower is electrically connected to the instrument amplifier.

7. The high-precision inclination angle measurement circuit according to claim 1, characterized in that: The output resistor has a resistance value of 45Ω-55Ω.

8. The high-precision inclination angle measurement circuit according to claim 1, characterized in that: The tilt angle measurement circuit further includes a reference source circuit, which is electrically connected to the MEMS tilt angle sensor and the analog-to-digital converter respectively and is used to provide power to the MEMS tilt angle sensor and the analog-to-digital converter.

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