Novel inertial measurement module

Abstract

The invention discloses a novel inertial measurement module. The novel inertial measurement module comprises an acceleration sensor, a gyroscope array, a digital operation processor, a memory and a wave trap array, wherein the acceleration sensor is electrically connected with the digital operation processor, and the acceleration sensor is used for measuring linear acceleration data of a measured object; the gyroscope array is electrically connected with the digital operation processor, and a gyroscope is used for measuring angular velocity data or rotation rate of a measured object; the memory is electrically connected with the digital operation processor, and the memory is used for storing calibration data of the novel inertial measurement module; the digital operation processor is used for processing the linear acceleration data and the angular velocity data or the rotation rate according to calibration data so as to obtain attitude information of the to-be-measured object; the wave trap arrays are electrically connected with the gyroscope arrays in a one-to-one correspondence manner, and the wave trap arrays are used for filtering power supply signals of a power supply and transmitting the filtered power supply signals to the gyroscope arrays.

Description

Technical Field

[0001] The present application belongs to the technical field of inertial measurement devices, and specifically relates to a novel inertial measurement module. Background Art

[0002] The new inertial measurement module (IMU module), also known as the inertial navigation sensor unit module, is usually installed inside the object being measured. It is an electronic device that uses the data collected by the three-axis acceleration sensor and the three-axis gyroscope sensor to infer and fuse and then output the attitude information of the object being measured. Usually, the new inertial measurement module contains a MEMS (micro-electromechanical system) gyroscope component. When the MEMS gyroscope is working normally, a fixed frequency signal will be generated inside it to drive the internal electromechanical structure to work. If the power supply outside the MEMS gyroscope contains the same frequency component as the internal excitation of the MEMS, it will cause the random walk number noise value of the MEMS gyroscope to increase, resulting in a large deviation in the attitude information after the fusion of the new inertial measurement module. The existing new inertial measurement module power supply only uses ordinary capacitors and magnetic beads to filter the noise of the power supply, and the noise suppression of specific frequencies is limited. In specific power supply working scenarios, the attitude information output by the new inertial measurement module will be insufficiently accurate. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present application is to provide a novel inertial measurement module, which can improve the detection accuracy of the existing inertial measurement module for the posture information of the object to be measured.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] A novel inertial measurement module, comprising: an acceleration sensor, a gyroscope array, a digital operation processor, a memory and a notch filter array; wherein the acceleration sensor is electrically connected to the digital operation processor, and the acceleration sensor is used to measure the linear acceleration data of the object to be measured; the gyroscope array is electrically connected to the digital operation processor, and the gyroscope is used to measure the angular velocity data or the rotation rate of the object to be measured; the memory is electrically connected to the digital operation processor, and the memory is used to store calibration data of the novel inertial measurement module; the digital operation processor is used to process the linear acceleration data and the angular velocity data or the rotation rate of the calibration data to obtain the posture information of the object to be measured; the notch filter array is electrically connected to the gyroscope array in a one-to-one correspondence, and the notch filter array is used to filter the power supply signal of the power supply, and transmit the filtered power supply signal to the gyroscope array.

[0006] Optionally, the trap array includes: a short-circuit module, a filtering module, a current limiting module, and an active amplification and impedance transformation module, wherein the short-circuit module is used to short-circuit a noise signal in a current signal provided by an external power supply to ground; the filtering module is used to filter the noise signal in the current signal provided by the external power supply; the current limiting module is used to control the magnitude of the current signal flowing into the active amplification and impedance transformation module; the active amplification and impedance transformation module is used to amplify and impedance transform the current signal filtered by the filtering module and limited by the current limiting module, so as to obtain an amplified and impedance transformed current signal suitable for the gyroscope array.

[0007] Optionally, the short-circuit module includes: a first equivalent resistor, a first inductor and a first capacitor, wherein the first end of the first equivalent resistor is connected to a power supply, the second end of the first equivalent resistor is connected to the first end of the first capacitor through the first inductor, and the second end of the first capacitor is connected to a first ground terminal.

[0008] Optionally, the filtering module includes: a second equivalent resistor, a second inductor and a second capacitor, wherein the second equivalent resistor is connected in series with the second inductor, and the second equivalent resistor, the second inductor and the second capacitor after the series connection are connected, the first end of the second equivalent resistor and the first end of the second capacitor are simultaneously connected to the power supply, and the second end of the second inductor and the second end of the second capacitor are commonly connected to the current limiting module.

[0009] Optionally, the current limiting module includes a current limiting resistor, a first end of the current limiting resistor is connected to the second inductor and the second end of the second capacitor, and a second end of the current limiting resistor is connected to the active amplification and impedance transformation module.

[0010] Optionally, the active amplification and impedance conversion module includes a transistor and a parasitic junction capacitor, wherein the base of the transistor is connected to the second end of the current limiting resistor, the collector of the transistor is connected to the power supply, the emitter of the transistor is connected to the power supply output end, and the parasitic junction capacitor is connected in parallel at both ends of the transistor.

[0011] Compared with the prior art, the beneficial effects brought by the present application are as follows: by adding a notch filter to the existing new inertial measurement module, the present application can effectively filter out the noise frequency in the power supply signal that is equivalent to the gyroscope's own driving frequency, thereby protecting the gyroscope from noise interference, thereby improving the detection accuracy of the new inertial measurement module for the posture information of the object to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a circuit block diagram of a novel inertial measurement module provided by an embodiment of the present application;

[0013] Figure 2 is a schematic diagram of the circuit structure of a wave trap provided by another embodiment of the present application;

[0014] Figure 3 This is a schematic diagram of the change trend of gyroscope random walk noise under different 50KHz noise suppression ratios provided by another embodiment of the present application. DETAILED DESCRIPTION

[0015] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Although the specific embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0016] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the implementation of the present application, but the description is based on the general principles of the specification and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims.

[0017] To facilitate understanding of the embodiments of the present application, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and the various drawings do not constitute a limitation on the embodiments of the present application.

[0018] Figure 1 is a circuit block diagram of a novel inertial measurement module provided by an exemplary embodiment of the present application, such as Figure 1As shown, the novel inertial measurement module includes: an acceleration sensor, a gyroscope array, a digital operation processor (DSP), a memory and a notch filter array; wherein the acceleration sensor is electrically connected to the digital operation processor through a first serial interface SPI1, and the acceleration sensor is used to measure the linear acceleration data of the object to be measured; the gyroscope array is electrically connected to the digital operation processor through a second serial interface SPI2, and the gyroscope is used to measure the angular velocity data or rotation rate of the object to be measured; the memory is electrically connected to the digital operation processor through an I2C bus, and the memory is used to store calibration data of the novel inertial measurement module; the digital operation processor is used to process the linear acceleration data and the angular velocity data or rotation rate of the calibration data to obtain the posture information of the object to be measured; the notch filter array is electrically connected to the gyroscope array in a one-to-one correspondence, and the notch filter array is used to filter the power supply signal of the power supply, and transmit the filtered power supply signal to the gyroscope array.

[0019] In this embodiment, the MEMS (micro-electromechanical system) gyroscope generates a fixed frequency signal to drive its internal structure to vibrate when working. This frequency is fixed for each device and is 50KHz in this embodiment. If the external power supply contains components with the same frequency, these frequency components may cause the random walk number of the gyroscope to increase, resulting in a large deviation in the measurement result. Although traditional capacitors and magnetic beads can filter out part of the noise, the noise suppression effect for specific frequencies is limited. This application introduces a notch array, which can effectively reduce the noise level at the target frequency without changing other frequency components. Since the operating frequency of the gyroscope array is 50KHz, this application also sets the center frequency of the notch to 50KHz. When the current signal from the power supply passes through the notch, any frequency component close to 50KHz will be significantly weakened or even completely removed. Specifically, the notch will create a very high impedance path at 50KHz, making it difficult for the current of this frequency to enter the subsequent circuit, thereby protecting the gyroscope from interference.

[0020] It should be noted that the acceleration sensor, gyroscope array, digital operation processor (DSP) and memory in the above embodiments are all conventional devices in the prior art, and the present application does not involve any improvement to the internal structure of any of the devices. In addition, the series of processing processes of the DSP for the sensor signal are its own characteristics, and the present application does not make any improvement to its internal algorithm or control method. The innovation of the present application lies in the introduction of a notch filter, and the circuit structure of the notch filter is specially designed by the applicant for the specific device of the new inertial measurement module.

[0021] In another exemplary embodiment, Figure 2 As shown, the trap includes: a short-circuit module 100, a filter module 200, a current limiting module 300, and an active amplification and impedance transformation module 400, wherein the short-circuit module 100 is used to short-circuit the noise signal in the current signal provided by the external power supply to the ground; the filter module 200 is used to filter the noise signal in the current signal provided by the external power supply; the current limiting module 300 is used to control the size of the current signal flowing into the active amplification and impedance transformation module 400; the active amplification and impedance transformation module 400 is used to amplify and impedance transform the current signal filtered by the filter module 200 and limited by the current limiting module 300, so as to obtain the amplified and impedance transformed current signal suitable for the gyroscope array.

[0022] In another exemplary embodiment, the short-circuit module 100 includes: a first equivalent resistor R S0 , the first inductor L 1 and the first capacitor C 1 , wherein the first equivalent resistance R S0 The first end is connected to the power supply, and the first equivalent resistor R S0 The second end of the first inductor L 1 With the first capacitor C 1 The first end of the first capacitor C 1 The second end of the transistor is connected to the first ground end GND1.

[0023] In this embodiment, when the circuit is in a resonant state, the first inductor L 1 and the first capacitor C 1 The impedances cancel each other out, as described by: The first equivalent resistance R S0 , the first inductor L 1 and the first capacitor C 1 The total impedance of the series branch becomes very low. Specifically, at the resonant frequency f 0 At, the first inductor L 1 and the first capacitor C 1 The reactive part satisfies the following relationship:

[0024] X L =X C

[0025] Among them, X L =2πfL, indicating the first inductance L 1 The inductive reactance, Represents the first capacitor C 1 The capacitive reactance.

[0026] At the resonant frequency, the two values ​​are equal but opposite in sign, so they cancel each other out, making the total impedance Z of the series branch close to zero:

[0027] Z=R+j(X L -X C )≈R

[0028] Here R is the first equivalent resistance R S0 The resistance value is usually relatively small.

[0029] Since the total impedance is very low at the resonant frequency, any AC signal present at this frequency will find a very low impedance path to ground (GND1) through this path. This means that the 50KHz noise component in the current signal provided by the power supply will prefer this low impedance path instead of continuing along the power line. Therefore, these noise components are effectively "shorted" to ground and will not affect subsequent circuits, especially the MEMS gyroscope.

[0030] In addition, for a signal of a non-resonant frequency, the first inductor L 1 and the first capacitor C 1 No low impedance path is formed. At this time, the first capacitor L 1 behaves as high impedance, while the first capacitor C 1 It appears as low impedance or vice versa, depending on the location of the frequency. As a result, signals at these non-resonant frequencies are not significantly affected and can be passed normally to subsequent circuits.

[0031] In summary, the short-circuit module 100 utilizes the first inductor L 1 and the first capacitor C 1 The characteristics at a specific frequency achieve effective noise suppression by creating a low impedance path for the target frequency while ensuring that signals at other frequencies can be transmitted without interference.

[0032] In another exemplary embodiment, the filtering module 200 includes: a second equivalent resistor R S1 , the second inductor L 2 and the second capacitor C 2 , wherein the second equivalent resistance R S1 With the second inductor L 2 The second equivalent resistance R S1 With the second inductor L 2 With the second capacitor C 2 In parallel, the second equivalent resistance R S1 The first terminal and the second capacitor C 2 The first end of the second inductor L is connected to the power supply. 2The second end of the second capacitor C 2 The second ends of the two terminals are commonly connected to the current limiting module 300 .

[0033] In this embodiment, the main function of the filter module 200 is to present high impedance at a specific frequency (50KHz), thereby preventing the noise current of this frequency from entering the subsequent circuit. The detailed working principle is described as follows:

[0034] In the parallel resonance state, the second inductor L 2 and the second capacitor C 2 The impedances of the parallel branch cancel each other out, making the total admittance of the entire parallel branch very small. Specifically, at the resonant frequency f 0 At, the second inductor L 2 and the second capacitor C 2 The reactive part satisfies the following relationship:

[0035] X L =X C

[0036] Among them, X L =2πfL, indicating the second inductance L 2 The inductive reactance, Represents the second capacitor C 2 The capacitive reactance.

[0037] At the resonant frequency, these two values ​​are equal but opposite in sign, so they cancel each other, making the total admittance Y of the parallel combination close to zero:

[0038] Y=G+j(B L -B C )≈G

[0039] Here G is the second equivalent resistance R S1 The conductivity is usually relatively small.

[0040] Since the total admittance is very low at the resonant frequency, this parallel branch presents a very high impedance, which means that for AC signals at the resonant frequency (such as 50KHz), this path becomes a high impedance path, preventing these frequency components from passing. The result is that the 50KHz noise current is effectively blocked and does not flow into the transistor Q 1 The base of the MOSFET is thus protected from these harmful frequencies.

[0041] For signals of non-resonant frequencies, the filter module 200 no longer exhibits high impedance. 2 and the second capacitor C 2The impedance characteristics will change according to the frequency, allowing the current of non-resonant frequency to pass normally, thereby ensuring that other working currents except the target frequency can be smoothly transmitted to the subsequent circuits without affecting the normal operation of the system.

[0042] In summary, the filtering module 200 utilizes the second inductor L 2 and the second capacitor C 2 The characteristics at a specific frequency achieve effective noise suppression by creating a high impedance path for the target frequency while ensuring that signals at other frequencies can be transmitted without interference.

[0043] In another exemplary embodiment, the current limiting module 300 includes a current limiting resistor R 1 , the current limiting resistor R 1 The first end of the second inductor L is connected 2 And the second capacitor C 2 The second end of the current limiting resistor R 1 The second end is connected to the active amplification and impedance transformation module 400.

[0044] In this embodiment, the transistor Q 1 If the base current is too large, it may cause the transistor to overheat or be damaged. 1 The presence of ensures that even under abnormal conditions (such as power supply voltage fluctuations or load mutations), the current flowing into the transistor Q 1 The base current will not exceed the maximum rating of the transistor, which helps to extend the transistor Q 1 service life and improve the reliability of the entire circuit.

[0045] In another exemplary embodiment, the active amplification and impedance conversion module 400 includes a transistor Q 1 and parasitic junction capacitance C CE , where the transistor Q 1 The base of the current limiting resistor R 1 The second terminal of the transistor Q 1 The collector of the transistor Q is connected to the power supply. 1 The emitter is connected to the power supply output terminal V CC_G (The power output terminal is used to power the gyroscope), the parasitic junction capacitance C CE Connected in parallel to the transistor Q 1 The parasitic junction capacitance C CE The first end of the transistor Q1 is connected to the collector of the transistor Q1, and the parasitic junction capacitance C CE The second end of is connected to the emitter of the transistor Q1.

[0046] In this embodiment, the current limiting resistor R 1 The current signal with the specific frequency noise component removed is passed to the transistor Q 1 The base of the transistor Q 1 Working as a current amplifier, its collector current I C is the base current I B β times (β is the current gain coefficient of the transistor), that is:

[0047] I C =β·I B

[0048] This means that even if the base current is small, the transistor Q 1 It can also generate a collector current large enough to drive subsequent loads (such as a MEMS gyroscope array).

[0049] In addition, the trap itself has a high output impedance, and directly connecting it to the load may cause voltage drop or fail to provide sufficient current. 1 Here, the role of impedance transformation is played. Specifically, since the transistor Q 1 The base of transistor Q has a high impedance characteristic, which can receive the signal from the second-order passive notch network without causing significant impact on the notch filter. 1 The emitter of the filter presents a low impedance characteristic, which enables it to effectively provide large current to the load while maintaining a low output impedance, thus avoiding the problem of voltage drop. This impedance transformation characteristic is crucial to ensure the quality of power supply, especially when a large current needs to be provided. It allows the filter to power the load without affecting its own performance.

[0050] The parasitic junction capacitance C CE It is usually very small (less than about 10pF) and is mainly used for high-frequency bypass, helping to maintain good transmission characteristics of high-frequency signals while preventing DC bias current from passing through. CE It also helps stabilize the transistor Q 1 operating point, reducing the impact of high frequency noise and ensuring that the transistor Q 1 No additional noise or distortion is introduced during the amplification process.

[0051] Through the above mechanism, the active amplification and impedance conversion module 400 can effectively remove the 50KHz noise component and provide a stable and pure power supply to the gyroscope array, thereby greatly improving the attitude measurement accuracy of the new inertial measurement module.

[0052] It should be noted that VCC_G is the power output terminal dedicated to the gyroscope array.1 The emitter of the MOSFET is connected here, ensuring that the clean power after processing can be directly delivered to the gyroscope. This design helps to isolate noise and other interference factors in the original power supply, protect the sensitive gyroscope from power supply fluctuations, and thus improve the overall performance and reliability of the system.

[0053] Next, the present application tests the performance of the new inertial measurement module after adding a notch filter, as shown in Table 1.

[0054] Table 1

[0055]

[0056]

[0057] Table 1 shows the change of gyroscope random walk noise under different 50KHz noise suppression ratios. Among them, "50KHz noise suppression ratio" refers to the degree of suppression of noise of a specific frequency (here 50KHz) through circuit design (such as using a notch filter array), and the unit is decibel (dB). The higher the value, the more the noise at this frequency is suppressed. "Axis" refers to the direction axis measured by the gyroscope, namely the X-axis, Y-axis and Z-axis, which correspond to three mutually perpendicular spatial directions. In Table 1, each row represents the performance of an axis (X-axis, Y-axis or Z-axis) under different noise suppression conditions. The "↓" after the number indicates the trend of random walk noise reduction under this condition compared with the previous column. Specifically, 0dB means no noise suppression. At this time, the gyroscope random walk noise values ​​of the X-axis, Y-axis and Z-axis are 0.6, 0.62 and 0.098 units respectively. 20dB means that when the 50KHz noise is suppressed by 20dB, the noise on all axes is reduced, the X axis is reduced to 0.51, the Y axis is reduced to 0.55, and the Z axis is reduced to 0.081 units. 40dB means that at a noise suppression ratio of 40dB, the noise on the X axis, Y axis and Z axis is further reduced to 0.44, 0.47 and 0.073 units. 60dB means that at a noise suppression ratio of 60dB, the noise on the X axis, Y axis and Z axis is reduced to 0.38, 0.39 and 0.071 units respectively. 80dB means that at a high suppression ratio of 80dB, the noise on the X axis, Y axis and Z axis all reach the lowest point, which are 0.3, 0.3 and 0.065 units respectively.

[0058] In summary, Table 1 shows that as the 50KHz noise suppression ratio increases, the random walk noise of the gyroscope is significantly reduced, which means that the attitude measurement accuracy of the new inertial measurement module has been improved. In particular, with an 80dB suppression ratio, the random walk noise of all three axes has reached the lowest point, proving the effectiveness of the notch array introduced in the new inertial measurement module.

[0059] In addition, this application also provides Figure 3 , Figure 3 The chart shows the changing trend of the random walk noise of the X-axis, Y-axis and Z-axis gyroscopes in the new inertial measurement module under different 50KHz noise suppression ratios (from 0dB to 80dB). The horizontal axis represents the noise suppression ratio, with an interval of 20dB; the vertical axis represents the random walk noise value of the gyroscope. Figure 3 It can be clearly shown that with the increase of 50KHz noise suppression ratio, the random walk noise of the gyroscope is significantly reduced, which directly reflects the improvement of the attitude measurement accuracy of the new inertial measurement module. In particular, when the noise suppression ratio reaches a high level (such as 80dB), the random walk noise of all three axes reaches the lowest point, proving the effectiveness of the notch array introduced in the new inertial measurement module.

[0060] In another exemplary embodiment, the digital operation processor is further connected to an external interface.

[0061] In this embodiment, the digital operation processor is also connected to an external interface through a third serial interface SPI3 and an asynchronous receiver-transmitter UART1, wherein the third serial interface SPI3 is used for high-speed data transmission, and the asynchronous receiver-transmitter UART1 is used for feedback of control instructions or states. It should be noted that if the novel inertial measurement module requires more sensor data input (such as a magnetometer, a barometer, etc.), or needs to connect other types of peripherals (such as a wireless communication module, an additional data storage device, etc.), it can be accessed through this interface. Or the interface can also be used to connect a spare gyroscope array, so as to switch to use when the existing gyroscope array fails.

[0062] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A new inertial measurement module, characterized in that: The novel inertial measurement module includes: Accelerometer, gyroscope array, digital operation processor, memory and notch filter array; in, The acceleration sensor is electrically connected to the digital operation processor, and the acceleration sensor is used to measure the linear acceleration data of the object under test; The gyroscope array is electrically connected to the digital operation processor, and the gyroscope is used to measure the angular velocity data or rotation rate of the object being measured; The memory is electrically connected to the digital operation processor, and the memory is used to store calibration data of the novel inertial measurement module; The digital operation processor is used to process the calibration data, the linear acceleration data and the angular velocity data or the rotation rate to obtain the posture information of the object to be measured; The trap array is electrically connected to the gyroscope array in a one-to-one correspondence, and the trap array is used to filter the power supply signal of the power supply and transmit the filtered power supply signal to the gyroscope array.

2. A novel inertial measurement module according to claim 1, characterized in that: The notch filter array comprises: Short-circuit module, filter module, current limiting module, active amplification and impedance transformation module, among which, The short-circuit module is used to short-circuit the noise signal in the current signal provided by the external power supply to the ground; The filtering module is used to filter the noise signal in the current signal provided by the external power supply; The current limiting module is used to control the magnitude of the current signal flowing into the active amplification and impedance conversion module; The active amplification and impedance transformation module is used to amplify and perform impedance transformation on the current signal filtered by the filtering module and limited by the current limiting module, so as to obtain the amplified and impedance transformed current signal suitable for the gyroscope array.

3. A novel inertial measurement module according to claim 2, characterized in that: The short circuit module comprises: a first equivalent resistance, a first inductance and a first capacitance, wherein, A first end of the first equivalent resistor is connected to a power supply, a second end of the first equivalent resistor is connected to a first end of the first capacitor via the first inductor, and a second end of the first capacitor is connected to a first ground terminal.

4. The novel inertial measurement module according to claim 2, characterized in that: The filtering module comprises: a second equivalent resistance, a second inductance, and a second capacitance, wherein: The second equivalent resistor is connected in series with the second inductor, and the second equivalent resistor, the second inductor and the second capacitor are connected in series. The first end of the second equivalent resistor and the first end of the second capacitor are simultaneously connected to the power supply, and the second end of the second inductor and the second end of the second capacitor are commonly connected to the current limiting module.

5. The novel inertial measurement module according to claim 4 is characterized in that: The current limiting module comprises: Current limiting resistor, The first end of the current limiting resistor is connected to the second end of the second inductor and the second end of the second capacitor, and the second end of the current limiting resistor is connected to the active amplification and impedance transformation module.

6. The novel inertial measurement module according to claim 5, characterized in that: The active amplification and impedance conversion module comprises: transistor and parasitic junction capacitance, where The base of the transistor is connected to the second end of the current limiting resistor, the collector of the transistor is connected to the power supply, the emitter of the transistor is connected to the power output end, and the parasitic junction capacitor is connected in parallel to both ends of the transistor.

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