MEMS accelerometer measurement and control and compensation circuit

Abstract

The invention provides an MEMS accelerometer measurement and control and compensation circuit. The circuit comprises an ARM chip, a carrier generation module, a charge amplifier, a pre-amplifier, an A / D conversion module, a demodulation filtering module and a comprehensive compensation module. Wherein the ARM chip is used for controlling the carrier generation module to generate digital synthesis sine waves meeting requirements; the carrier wave generation module acts on the MEMS accelerometer, acceleration information sensed by the accelerometer is modulated on sine carrier waves generated in the carrier wave generation module, signals are converted into voltage signals through the charge amplifier, then the voltage signals are converted into strong signals through pre-amplification, the strong signals are converted into digital signals through the A / D conversion module controlled by the ARM chip, and the digital signals are transmitted to the MEMS accelerometer. And the digital signal passes through the demodulation filtering module and then passes through the comprehensive compensation module to obtain final acceleration output. According to the scheme, various errors can be compensated according to different accelerometer headers, so that the accelerometer can stably output in a certain measuring range.

Description

Technical Field

[0001] The invention belongs to the technical field of digital measurement and control circuits for micro-electromechanical systems accelerometers, and relates to a measurement, control and compensation circuit for a MEMS accelerometer, and in particular to a measurement, control and compensation implementation circuit for a micro-electromechanical systems accelerometer. Background Art

[0002] MEMS accelerometers are the core components of inertial navigation systems and are widely used in the navigation field of automobiles and weapons. For MEMS accelerometers, first of all, their output signals are very weak. The interference and noise in the circuit make the useful output signals completely submerged in the noise. Moreover, the spectrum of the useful output signal overlaps with the spectrum of the low-frequency noise. To extract the useful signal from the noise, the signal-to-noise ratio of the signal in the system bandwidth must be improved. Secondly, affected by the thermal expansion coefficient of its sensitive structural materials and the temperature characteristics of the electrical devices, during the temperature change, the material itself expands and contracts, the temperature characteristics of the electrical devices change, and the internal gas medium changes with the temperature. Under different temperature conditions, its scale factor and the output of the accelerometer will change to a certain extent. These changes will directly lead to inaccurate accelerations sensed by the accelerometer at different temperature points, thereby affecting the output accuracy of the accelerometer. Finally, affected by the structural processing errors and the characteristics of the material itself, the MEMS accelerometer will inevitably be affected by the nonlinearity of the sensitive structure and the nonlinearity of the measurement and control circuit, and the final accelerometer output will show a certain degree of nonlinearity. Affected by the above factors, the output error of the MEMS accelerometer is amplified step by step, which eventually deteriorates the performance of the MEMS accelerometer. In order to avoid this problem, it is necessary to adjust the measurement and control scheme of the MEMS accelerometer, and compensate for various errors one by one to correct the output error of the MEMS accelerometer caused by various factors. Among the current error compensation methods, most of them are for compensation and research on a single factor. Secondly, the compensation is mostly offline, and the output of the meter will not change in real time due to the compensation algorithm, and can only be used as a reference for the output capability of the accelerometer. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] To this end, the present invention provides a MEMS accelerometer measurement, control and compensation circuit. The solution can compensate for various errors according to different accelerometer heads, so that the accelerometer can output stably within a certain range.

[0005] The technical solution of the present invention is as follows: a MEMS accelerometer measurement, control and compensation circuit is provided, which includes an ARM chip, a carrier generation module, a charge amplifier, a preamplifier, an A / D conversion module, a demodulation and filtering module and a comprehensive compensation module; wherein the carrier generation module is controlled by the ARM chip to generate a digital synthetic sine wave that meets the requirements; the carrier generation module acts on the MEMS accelerometer, and the acceleration information sensed by the accelerometer is modulated on the sine carrier generated in the carrier generation module. The signal is converted into a voltage signal through the charge amplifier, and then becomes a strong signal through preamplification. The strong signal is converted into a digital signal by the A / D conversion module controlled by the ARM chip, and the digital signal passes through the demodulation and filtering module and then passes through the comprehensive compensation module to obtain the final acceleration output.

[0006] Furthermore, the comprehensive compensation module includes a data acquisition module, a data normalization processing module, an adaptive compensation module and a calibration factor adjustment module. The data acquisition module is used to collect data output from the accelerometer chip. After data acquisition is completed, the data is normalized by the data normalization processing module, and then the adaptive compensation module is used to adaptively compensate the normalized data. According to the output situation, the corresponding compensation algorithm is selected to obtain the normalized accelerometer compensation output. Finally, the calibration factor adjustment module is used to obtain the standard accelerometer digital output to complete the entire nonlinear error compensation process.

[0007] Furthermore, the data acquisition module, the data normalization module and the adaptive compensation module are all controlled by an ARM chip.

[0008] The above technical solution designs the zero compensation, scale factor compensation, and nonlinear error compensation links of the sensor through the ARM chip in the digital circuit of MEMS, which solves the problem that the previous accelerometer compensation method is single, resulting in limited comprehensive accuracy of the accelerometer. In addition, in each compensation link, the present invention integrates different algorithms, so that the accelerometer can select the appropriate compensation method according to different environmental application requirements, so that the comprehensive accuracy of the accelerometer is optimized. The advantage of this is that the MEMS accelerometer will have better environmental adaptability and acceleration output with smaller errors, reducing the impact of various errors on the MEMS accelerometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0010] Figure 1 It is a schematic diagram of a digital circuit of a MEMS accelerometer;

[0011] Figure 2 It is a schematic diagram of a nonlinear compensation method based on ARM. DETAILED DESCRIPTION

[0012] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0014] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0015] like Figure 1 to Figure 2 As shown, in one embodiment of the present invention, a MEMS accelerometer measurement, control and compensation circuit is provided, the circuit comprising an ARM chip, a carrier generation module, a charge amplifier, a preamplifier, an A / D conversion module, a demodulation filter module and a comprehensive compensation module, wherein:

[0016] The carrier generation module is controlled by the ARM chip to generate a digital synthetic sine wave that meets the requirements. The advantage of this is that the influence of high-order harmonics in the traditional square wave on the circuit is omitted, and the frequency component of the circuit is single, which is convenient for subsequent circuit processing; the carrier generation module acts on the MEMS accelerometer, and the acceleration information sensed by the accelerometer is modulated on the generated sine carrier. The signal is converted into a voltage signal that is easy to process through the charge amplifier, and then becomes a strong signal through preamplification. After passing through 7, the signal is converted into a digital signal by the A / D conversion module controlled by the ARM chip. After the digital signal is processed by the demodulation and filtering module, it passes through the comprehensive compensation module to obtain the final acceleration output;

[0017] The structure of the comprehensive compensation module is mainly divided into four parts: the data acquisition module, the main function of which is to collect the data output of the accelerometer chip, to ensure that the original signal information is retained as much as possible during the acquisition process, and to rely on the data normalization module to normalize the data after the data acquisition is completed. The benefit of data normalization is mainly to match the data with the computer communication, to ensure the compensation accuracy of the subsequent compensation algorithm, and the obtained data will not be too small, nor will it exceed the computer operation limit. After the data normalization is completed, the data preprocessing work is completed; then the normalized data is fitted to the standard centrifugal output to obtain the nonlinear error of each standard acceleration output point. Then, the ARM chip is used to control the adaptive compensation module to perform adaptive compensation on the normalized data, and according to the output situation, a suitable compensation algorithm is selected to obtain the normalized accelerometer compensation output, and finally, after the calibration factor adjustment module, the standard accelerometer digital output is obtained to complete the entire nonlinear error compensation process. The advantage of this compensation method is that the convenience of communication with ARM is taken into account in the algorithm, and the data normalization link is introduced to ensure that the data operation will not exceed the boundary in the entire compensation link, and it can also be convenient to transmit data with the host computer; at the same time, an adaptive compensation algorithm is adopted, and multiple algorithms are integrated inside the ARM chip. The nonlinear compensation algorithm can be adjusted for different MEMS accelerometers according to the results of the standard output. After the algorithm is determined, the acceleration output can be compensated in sections according to the output results, which maximizes the compensation effect and plays a key role in the performance of the entire accelerometer. At the same time, a scale factor adjustment link is introduced in the compensation link, which can reasonably adjust the calibration factor size according to the ADC capability and the maximum digital quantity of the circuit output, relieving the pressure of the preamplifier module in the circuit. The preamplifier can reasonably select the amplification factor according to the actual situation of the circuit, without having to work at a very high amplification factor.

[0018] It can be seen that the embodiment of the present invention uses an ARM chip to control a carrier generator to generate a carrier for modulating acceleration signals, controls ADC to convert output signals, and collects output signals. At the same time, it uses the nonlinear characteristics of the standard acceleration input acquisition circuit itself and the temperature characteristics of the circuit, and cooperates with traditional components such as charge amplifiers and output demodulators that are essential to the accelerometer circuit to form a complete accelerometer measurement and control circuit with various compensation functions. The present invention first adjusts the measurement and control scheme to accurately collect the output signal of the accelerometer, and then compensates and corrects the output of the accelerometer step by step in the order of zero compensation, scale factor compensation, and nonlinear compensation. Finally, according to the acceleration output mode required by each application environment, the final acceleration information is output.

[0019] In the digital circuit of the MEMS designed in the embodiment of the present invention, the zero position compensation, scale factor compensation, and nonlinear error compensation links of the sensor are designed through the ARM chip, which solves the problem that the previous accelerometer compensation method is single, resulting in limited comprehensive accuracy of the accelerometer. In addition, in each compensation link, the present invention integrates different algorithms, so that the accelerometer can select a suitable compensation method according to different environmental application requirements, so that the comprehensive accuracy of the accelerometer is optimized. The advantage of this is that the MEMS accelerometer will have better environmental adaptability and acceleration output with smaller errors, reducing the impact of various errors on the MEMS accelerometer. This solution can compensate for various errors according to different accelerometer headers, so that the accelerometer can output stably within a certain range.

[0020] Features described and / or illustrated above for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or used in place of features in other embodiments.

[0021] It should be emphasized that the term "include / comprises" when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps, components or combinations thereof.

[0022] The above method of the present invention can be implemented by hardware, or by hardware combined with software. The present invention relates to such a computer-readable program, which, when executed by a logic component, enables the logic component to implement the above-mentioned device or component, or enables the logic component to implement the above-mentioned various methods or steps. The present invention also relates to a storage medium for storing the above program, such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, etc.

[0023] The many features and advantages of these embodiments are apparent from this detailed description, and thus the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not intended that the embodiments of the invention be limited to the exact construction and operation illustrated and described, but rather all suitable modifications and equivalents falling within the scope thereof are intended to be covered.

[0024] Parts of the present invention that are not described in detail are well known to those skilled in the art.

Claims

1. A MEMS accelerometer measurement, control and compensation circuit, characterized in that: The circuit includes an ARM chip, a carrier generation module, a charge amplifier, a preamplifier, an A / D conversion module, a demodulation and filtering module, and a comprehensive compensation module; wherein the carrier generation module is controlled by the ARM chip to generate a digital synthetic sine wave that meets the requirements; the carrier generation module acts on the MEMS accelerometer, and the acceleration information sensed by the accelerometer is modulated on the sine carrier generated in the carrier generation module. The signal is converted into a voltage signal through the charge amplifier, and then becomes a strong signal through preamplification. The strong signal is converted into a digital signal by the A / D conversion module controlled by the ARM chip, and the digital signal passes through the demodulation and filtering module and then passes through the comprehensive compensation module to obtain the final acceleration output.

2. A MEMS accelerometer measurement, control and compensation circuit according to claim 1, characterized in that: The comprehensive compensation module includes a data acquisition module, a data normalization processing module, an adaptive compensation module and a calibration factor adjustment module. The data acquisition module is used to acquire data output from the accelerometer chip. After data acquisition is completed, the data is normalized by the data normalization processing module, and then the adaptive compensation module is used to adaptively compensate the normalized data. According to the output situation, the corresponding compensation algorithm is selected to obtain the normalized accelerometer compensation output. Finally, the calibration factor adjustment module is used to obtain the standard accelerometer digital output to complete the entire nonlinear error compensation process.

3. A MEMS accelerometer measurement, control and compensation circuit according to claim 1-2, characterized in that: The data acquisition module, data normalization module and adaptive compensation module are all controlled by an ARM chip.

Images