Real-time self-test method and system for a capacitive accelerometer
By applying a phase-switching excitation signal to the capacitive accelerometer for real-time self-testing, the problem of performance drift of traditional accelerometers in dynamic environments is solved, realizing real-time monitoring and self-correction, and improving the reliability and data accuracy of the system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU GST INFOMATION TECH CO LTD
- Filing Date
- 2026-04-23
- Publication Date
- 2026-06-30
AI Technical Summary
Traditional capacitive accelerometers suffer from performance degradation due to environmental factors during long-term use, making it impossible to identify zero bias and sensitivity drift in real time in dynamic environments, thus affecting measurement accuracy and reliability.
By applying a fixed-phase excitation signal to the upper fixed plate and switching the phase of the excitation signal back and forth between the lower fixed plates, the current signal of the movable sensitive mass block is acquired in real time. Self-testing is performed using phase transformation, and the first and second current signals are analyzed to identify zero bias and sensitivity changes.
It enables real-time self-testing of the accelerometer in complex environments, timely identification of performance drift, improves system robustness and data accuracy, and reduces the risk of failure.
Smart Images
Figure CN122307151A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of accelerometer technology, and in particular to a real-time self-testing method and system for capacitive accelerometers. Background Technology
[0002] A capacitive accelerometer is an inertial sensor based on microelectromechanical systems (MEMS) technology. It detects acceleration by measuring the displacement of an internal mass under inertial forces. Its core structure typically includes a movable mass, fixed electrodes, and detection circuitry, converting mechanical motion into an electrical signal output using changes in capacitance. These sensors are characterized by their small size, low power consumption, and low cost, and are widely used in consumer electronics, industrial control, and automotive safety. However, with prolonged use, environmental factors (such as temperature fluctuations and mechanical stress) can lead to performance degradation, affecting measurement accuracy and reliability.
[0003] MEMS accelerometers play a crucial role in several key areas. For example, they are used for vibration analysis and fault diagnosis in industrial equipment monitoring, ensuring stable operation of mechanical systems; integrated into airbag control units in automotive safety systems, they detect collision signals in real time to trigger protective mechanisms; in consumer electronics products, such as smartphones and wearable devices, they support functions like step counting and posture recognition; and they provide high-precision motion data in aircraft navigation and medical monitoring. These applications place stringent demands on the stability and instantaneous response capabilities of accelerometers; any performance deviation can lead to serious consequences, making precise calibration of accelerometers essential.
[0004] However, traditional accelerometers rely on periodic calibration or offline testing, which cannot cope with sudden failures in dynamic environments. Summary of the Invention
[0005] Therefore, it is necessary to provide a real-time self-testing method and system for capacitive accelerometers to address the aforementioned technical problems.
[0006] In a first aspect, this application provides a real-time self-testing method for a capacitive accelerometer, applicable to a capacitive accelerometer including an upper fixed electrode, a lower fixed electrode, and a movable sensitive mass block, the method comprising:
[0007] A fixed-phase excitation signal is applied to the upper fixed plate;
[0008] An excitation signal is applied to the lower fixed electrode plate, switching back and forth between a first phase state and a second phase state; wherein, in the first phase state, the excitation signal of the lower fixed electrode plate is in the same phase as the excitation signal of the upper fixed electrode plate, and in the second phase state, the excitation signal of the lower fixed electrode plate is in opposite phase to the excitation signal of the upper fixed electrode plate.
[0009] In the first phase state, the first current signal output by the movable sensitive mass block is acquired;
[0010] In the second phase state, the second current signal output by the movable sensitive mass block is acquired;
[0011] The accelerometer performs a self-test based on the first and second current signals.
[0012] In one embodiment, the first current signal is proportional to the static capacitance value, and the second current signal is proportional to the capacitance change.
[0013] The static capacitance value is the capacitance value when no acceleration signal is applied, and the capacitance change is the difference between the capacitance value when an acceleration signal is applied and the static capacitance value.
[0014] In one embodiment, the magnitude of the first current signal is k1C0, where k1 is the first gain coefficient for capacitor-to-current conversion and C0 is the static capacitance value.
[0015] The magnitude of the second current signal is k2. C, where k2 is the second gain coefficient for capacitor-to-current conversion. C represents the change in capacitance caused by the acceleration signal.
[0016] In one embodiment, the first current signal and the second current signal are output synchronously during the switching period between the first phase and the second phase states.
[0017] In one embodiment, the excitation signal is a square wave signal or a simple harmonic wave.
[0018] Secondly, this application also provides a real-time self-testing system for a capacitive accelerometer, applied to a capacitive accelerometer including an upper fixed electrode, a lower fixed electrode, and a movable sensitive mass block, the system comprising:
[0019] An excitation signal module is used to apply an excitation signal with a fixed phase to the upper fixed electrode plate and to apply an excitation signal that switches back and forth between a first phase state and a second phase state to the lower fixed electrode plate; wherein, in the first phase state, the excitation signal of the lower fixed electrode plate is in the same phase as the excitation signal of the upper fixed electrode plate, and in the second phase state, the excitation signal of the lower fixed electrode plate is in opposite phase to the excitation signal of the upper fixed electrode plate.
[0020] The demodulation module is electrically connected to the movable sensitive mass block and is used to switch synchronously with the first phase state and the second phase state, so as to acquire the first current signal output by the movable sensitive mass block in the first phase state and the second current signal output by the movable sensitive mass block in the second phase state.
[0021] The analysis module is used to perform a self-test on the accelerometer based on the first current signal and the second current signal.
[0022] In one embodiment, an operational amplifier is provided between the movable sensitive mass block and the demodulation module.
[0023] In one embodiment, the movable sensitive mass block is equidistant from the upper and lower fixed plates when not subjected to acceleration.
[0024] The aforementioned real-time self-testing method and system for a capacitive accelerometer applies a fixed-phase excitation signal to the upper fixed electrode and an excitation signal that switches between a first phase state and a second phase state to the lower fixed electrode. In the first phase state, the excitation signal from the lower fixed electrode is in phase with the excitation signal from the upper fixed electrode; in the second phase state, the excitation signal from the lower fixed electrode is in opposite phase with the excitation signal from the upper fixed electrode. In the first phase state, a first current signal output by the movable sensitive mass is acquired; in the second phase state, a second current signal output by the movable sensitive mass is acquired; and the accelerometer is self-tested based on the first and second current signals. Real-time self-testing of the accelerometer is achieved through phase transformation. Attached Figure Description
[0025] Figure 1 This is a schematic diagram illustrating the implementation principle of real-time self-testing for a capacitive accelerometer in one embodiment. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0027] A traditional capacitive accelerometer consists of a movable sensing mass and upper and lower fixed sensing plates. The sensing mass and the upper and lower plates form an equally spaced parallel-plate capacitor, with both the upper and lower capacitors having a capacitance of C0. When acceleration is input, the movable sensing mass moves towards one of the fixed plates under the action of inertial force, thereby changing the distance between the movable sensing mass and the two fixed plates, and thus changing the capacitance, which is C0+. C and C0- C. The subsequent detection circuit calibrates the magnitude of the input acceleration by detecting the change in capacitance.
[0028] Under long-term operation or complex environments (such as high temperature, vibration, and mechanical stress), the zero bias stability and sensitivity of the aforementioned accelerometers are prone to uncontrollable drift, leading to distorted measurement data. However, existing technologies can only perform periodic calibration or offline testing, and cannot identify zero bias changes during operation; or they can only diagnose through external equipment after a failure occurs, increasing the risk of downtime.
[0029] This application provides a real-time self-testing method for capacitive accelerometers, applicable to capacitive accelerometers including an upper fixed electrode, a lower fixed electrode, and a movable sensitive mass block. It can continuously verify zero bias and sensitivity during operation, ensuring data reliability and preventing sudden failures.
[0030] The method includes the following steps:
[0031] S1. Apply a fixed-phase excitation signal to the upper fixed electrode; apply an excitation signal to the lower fixed electrode that switches back and forth between a first phase state and a second phase state; wherein, in the first phase state, the excitation signal of the lower fixed electrode is in the same phase as the excitation signal of the upper fixed electrode, and in the second phase state, the excitation signal of the lower fixed electrode is in the opposite phase to the excitation signal of the upper fixed electrode.
[0032] like Figure 1 As shown, a fixed phase excitation signal is always applied to the upper fixed plate, and the lower fixed plate switches back and forth between the excitation signal in the first phase state and the second phase state. At the same time, the demodulated signal switches back and forth synchronously between the first phase state and the second phase state.
[0033] The excitation signal can be a square wave, a sine wave, etc. The excitation signal in the first phase state applied by the lower fixed plate has the same frequency, amplitude, and phase as the excitation signal of the upper fixed plate, and the excitation signal in the second phase state has the same frequency, amplitude, and phase as the excitation signal of the upper fixed plate, but is 180° out of phase.
[0034] S2. In the first phase state, acquire the first current signal output by the movable sensitive mass block; in the second phase state, acquire the second current signal output by the movable sensitive mass block.
[0035] During normal operation, the sensitive mass of the accelerometer responds in real time to the external input acceleration, causing displacement and thus changing the capacitance on both sides. In real-time self-test mode, the excitation signal on the fixed plate is switched back and forth between the first phase state and the second phase state.
[0036] When the circuit synchronously switches to the first phase state, the same phase excitation signal is applied to the fixed plates on both sides. The magnitude of the first current signal output by the movable sensitive mass block in the middle is k1C0, where k1 is the first gain coefficient of capacitor-to-current conversion, which is independent of the structure, and C0 is the output capacitance value, which is related to the zero bias and sensitivity of the accelerometer, but independent of the external input acceleration, and serves as a self-test signal.
[0037] When the circuit synchronously switches to the second phase state, excitation signals of opposite phase are applied to the fixed plates on both sides, and the magnitude of the second current information output by the movable sensitive mass block in the middle is k2. C, where k2 is the second gain coefficient for capacitor-to-current conversion, which is independent of the structure, and C is determined by the external input acceleration, which serves as the acceleration signal.
[0038] S3. Perform a self-test on the accelerometer based on the first current signal and the second current signal.
[0039] When the external acceleration is 0, the movable sensitive mass should be precisely centered between the upper and lower plates, and the second current signal should be 0. If the output of the second current signal is not 0, it indicates a fault in the zero bias. However, if the self-test signal remains unchanged, it indicates that the position of the movable sensitive mass and the sensor structure are normal. Conversely, if the self-test signal fluctuates abnormally and the acceleration signal does not return to zero, it indicates that there is a misalignment in the mechanical structure or the sensitive mass itself.
[0040] When a known and precise standard acceleration is applied to the accelerometer, if the self-test signal changes proportionally, the problem lies in the common circuit section (such as excitation voltage or reference voltage drift), and recalibration is required. If the self-test signal is normal but the acceleration signal is abnormal, the problem lies in the mechanical movement of the sensitive mass (such as jamming or damping changes).
[0041] Therefore, analysis based on the first and second current signals enables real-time acceleration self-checking. This method significantly improves system robustness, adapts to complex conditions such as high temperature and vibration, and overcomes the hysteresis defects of traditional methods.
[0042] Traditional MEMS accelerometers are prone to uncontrollable drift in zero bias and sensitivity during long-term operation or in complex environments (such as high temperature, vibration, and mechanical stress), leading to distorted measurement data. Existing technologies rely on periodic calibration or offline testing, which cannot identify performance degradation in real time, potentially causing false triggering or failure risks in critical applications such as automotive airbags. This invention, through a real-time self-testing mechanism, continuously monitors zero bias and sensitivity during operation, providing immediate warnings and correcting performance drift. It also enhances adaptability to dynamic environments (such as mechanical shock and temperature fluctuations), automatically isolates faults, and switches to backup channels, significantly improving system reliability, data accuracy, and equipment lifespan. This provides a cost-effective proactive preventative solution for automotive safety, industrial control, and consumer electronics.
[0043] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.
[0044] Based on the same inventive concept, this application also provides a real-time self-testing system for a capacitive accelerometer. The solution provided by this system is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the real-time self-testing system for a capacitive accelerometer provided below can be found in the limitations of the real-time self-testing method for a capacitive accelerometer described above, and will not be repeated here.
[0045] In one embodiment, such as Figure 1 As shown, a real-time self-testing system for a capacitive accelerometer is provided, applicable to a capacitive accelerometer including an upper fixed electrode, a lower fixed electrode, and a movable sensitive mass block, comprising:
[0046] An excitation signal module is used to apply an excitation signal with a fixed phase to the upper fixed electrode plate and to apply an excitation signal that switches back and forth between a first phase state and a second phase state to the lower fixed electrode plate; wherein, in the first phase state, the excitation signal of the lower fixed electrode plate is in the same phase as the excitation signal of the upper fixed electrode plate, and in the second phase state, the excitation signal of the lower fixed electrode plate is in opposite phase to the excitation signal of the upper fixed electrode plate.
[0047] The demodulation module is electrically connected to the movable sensitive mass block and is used to switch synchronously with the first phase state and the second phase state, so as to acquire the first current signal output by the movable sensitive mass block in the first phase state and the second current signal output by the movable sensitive mass block in the second phase state.
[0048] The analysis module is used to perform a self-test on the accelerometer based on the first current signal and the second current signal.
[0049] In one embodiment, an operational amplifier is provided between the movable sensitive mass block and the demodulation module.
[0050] In one embodiment, the movable sensitive mass block is equidistant from the upper and lower fixed plates when not subjected to acceleration.
[0051] The modules in the aforementioned real-time self-test system for capacitive accelerometers can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module.
[0052] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.
[0053] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0054] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.
Claims
1. A real-time self-testing method for a capacitive accelerometer, characterized in that, The method, applied to a capacitive accelerometer comprising an upper fixed electrode, a lower fixed electrode, and a movable sensitive mass, includes: A fixed-phase excitation signal is applied to the upper fixed electrode plate; An excitation signal that switches back and forth between a first phase state and a second phase state is applied to the lower fixed electrode; wherein, in the first phase state, the excitation signal of the lower fixed electrode is in the same phase as the excitation signal of the upper fixed electrode, and in the second phase state, the excitation signal of the lower fixed electrode is in the opposite phase to the excitation signal of the upper fixed electrode. In the first phase state, the first current signal output by the movable sensitive mass block is acquired; In the second phase state, the second current signal output by the movable sensitive mass block is acquired; The accelerometer performs a self-test based on the first current signal and the second current signal.
2. The method according to claim 1, characterized in that: The first current signal is proportional to the static capacitance value, and the second current signal is proportional to the capacitance change. The static capacitance value is the capacitance value when no acceleration signal is applied, and the capacitance change is the difference between the capacitance value when an acceleration signal is applied and the static capacitance value.
3. The method according to claim 2, characterized in that: The magnitude of the first current signal is k1C0, where k1 is the first gain coefficient for capacitor-to-current conversion and C0 is the static capacitance value. The magnitude of the second current signal is k2 C, where k2 is the second gain coefficient for capacitor-to-current conversion. C represents the change in capacitance caused by the acceleration signal.
4. The method according to claim 1, characterized in that: The first current signal and the second current signal are output synchronously during the switching cycle of the first phase and the second phase state.
5. The method according to claim 1, characterized in that: The excitation signal is a square wave signal or a simple harmonic wave.
6. A real-time self-testing system for a capacitive accelerometer, characterized in that, The system, applicable to a capacitive accelerometer comprising an upper fixed electrode, a lower fixed electrode, and a movable sensitive mass, includes: An excitation signal module is used to apply an excitation signal with a fixed phase to the upper fixed electrode plate and to apply an excitation signal that switches back and forth between a first phase state and a second phase state to the lower fixed electrode plate; wherein, in the first phase state, the excitation signal of the lower fixed electrode plate is in the same phase as the excitation signal of the upper fixed electrode plate, and in the second phase state, the excitation signal of the lower fixed electrode plate is in opposite phase to the excitation signal of the upper fixed electrode plate. The demodulation module is electrically connected to the movable sensitive mass block and is used to switch synchronously with the first phase state and the second phase state, so as to acquire the first current signal output by the movable sensitive mass block in the first phase state and the second current signal output by the movable sensitive mass block in the second phase state. The analysis module is used to perform a self-test on the accelerometer based on the first current signal and the second current signal.
7. The system according to claim 6, characterized in that: An operational amplifier is provided between the movable sensitive mass block and the demodulation module.
8. The system according to claim 6, characterized in that: When the movable sensitive mass block is not subjected to acceleration, the distance between it and the upper fixed electrode plate and the lower fixed electrode plate is equal.