Signal acquisition circuit and signal acquisition method of accelerometer

Abstract

The invention discloses a signal acquisition circuit and a signal acquisition method of an accelerometer, and belongs to the technical field of circuits. The accelerometer generates three-axis acceleration current signals; the signal conditioning module is used for converting the acceleration current signals of the three axes into voltage signals, and conditioning each path of voltage signals by using an operational amplifier and a rail-to-rail amplifier to obtain conditioning signals of the three axes; the signal acquisition module carries out triple redundancy sampling on the conditioning signals of the X axis and the Y axis and carries out double redundancy sampling on the conditioning signals of the Z axis; the controller calculates the dynamic weight of each path of sampling signal of the X axis and the Y axis and calculates optimization signals of the X axis and the Y axis according to each path of sampling signal and the dynamic weight, and the dynamic weight corresponding to each path of sampling signal is related to errors of sampling channels of the other two paths of sampling signals; and calculating an optimized signal of the Z axis for the two paths of sampling signals of the Z axis. According to the invention, the interference of common-mode noise and differential-mode noise can be reduced, and the precision influence caused by zero drift and performance difference between channels can be reduced.

Description

Technical Field

[0001] This application relates to the field of circuit technology, and in particular to a signal acquisition circuit and signal acquisition method for an accelerometer. Background Technology

[0002] High-precision pendulum accelerometers and other sensors typically use current signals as their output, with the magnitude of the current representing the magnitude of acceleration. The current range is from nA to mA. Therefore, high-precision sampling of the accelerometer's current is crucial for obtaining high-precision acceleration information.

[0003] Traditional current sampling methods mainly use current / frequency (I / F) circuits. The principle of I / F circuits is to convert the weak current signal output by the accelerometer into a pulse signal or digital signal of a certain frequency, and then perform digital sampling.

[0004] The advantages of I / F circuits are high precision, low power consumption, and good temperature consistency, but they also have disadvantages such as large size, complex structure, and high cost. Summary of the Invention

[0005] This application provides a signal acquisition circuit and method for an accelerometer, addressing the problems of large size, complex structure, and high cost in existing signal acquisition systems based on I / F circuits. The technical solution is as follows: According to a first aspect of this application, an accelerometer signal acquisition circuit is provided, the signal acquisition circuit including an accelerometer, a signal conditioning module, a signal acquisition module, and a controller; The accelerometer is used to generate acceleration current signals along the X, Y, and Z axes. The signal conditioning module is used to convert the acceleration current signals of the X-axis, Y-axis and Z-axis into corresponding voltage signals, and to condition each voltage signal using an operational amplifier and a rail-to-rail amplifier to obtain the conditioned signals of the X-axis, Y-axis and Z-axis. The signal acquisition module is used to perform triple redundant sampling on the conditioning signals of the X-axis and Y-axis respectively, and double redundant sampling on the conditioning signal of the Z-axis to obtain eight sampling signals. The controller is used to calculate the corresponding dynamic weight for each sampled signal of the X-axis and Y-axis, and to calculate the optimized signal of the X-axis and Y-axis based on each sampled signal and the corresponding dynamic weight. The dynamic weight corresponding to each sampled signal is related to the error of the sampling channels of the other two sampled signals. The controller is also used to calculate the optimized signal of the Z-axis for the two sampled signals of the Z-axis.

[0006] In one possible implementation, the controller is further configured to: For three sampling signals along the X-axis or Y-axis, a channel error coefficient is calculated for every two sampling signals. The channel error coefficient represents the error between the two sampling channels corresponding to the two sampling signals. For each sampled signal, a predetermined algorithm is used to calculate the error coefficients of the three channels to obtain the dynamic weight corresponding to the sampled signal.

[0007] In one possible implementation, the controller is further configured to: When the first and second sampling signals of the X-axis are positive sampling signals and the third sampling signal is a negative sampling signal, the absolute value of the second sampling signal minus the first sampling signal is used as the first channel error coefficient, the negative value of the third sampling signal minus the absolute value of the first sampling signal is used as the second channel error coefficient, and the negative value of the third sampling signal minus the absolute value of the second sampling signal is used as the third channel error coefficient. The error coefficients of the first channel, the second channel, and the third channel are added together to obtain the sum of the first coefficients; Divide the error coefficient of the third channel by the sum of the first coefficients to obtain the first dynamic weight corresponding to the first sampling signal; Divide the second channel error coefficient by the sum of the first coefficients to obtain the second dynamic weight corresponding to the second sampling signal; Divide the first channel error coefficient by the sum of the first coefficients to obtain the third dynamic weight corresponding to the third sampling signal.

[0008] In one possible implementation, the controller is further configured to: Multiply the first sampled signal by the first dynamic weight to obtain the first product; Multiply the second sampled signal by the second dynamic weight to obtain the second product; The third sampled signal is multiplied by the second dynamic weight to obtain the third product; The first product, the second product, and the third product are added together to obtain the optimized signal for the X-axis.

[0009] In one possible implementation, the controller is further configured to: When the fourth and fifth sampling signals of the Y-axis are positive sampling signals and the sixth sampling signal is a negative sampling signal, the absolute value of the fifth sampling signal minus the fourth sampling signal is used as the error coefficient of the fourth channel, the negative value of the sixth sampling signal minus the absolute value of the fourth sampling signal is used as the error coefficient of the fifth channel, and the negative value of the sixth sampling signal minus the absolute value of the fifth sampling signal is used as the error coefficient of the sixth channel. The error coefficients of the fourth channel, the fifth channel, and the sixth channel are added together to obtain the second sum of coefficients. Divide the error coefficient of the sixth channel by the sum of the second coefficients to obtain the fourth dynamic weight corresponding to the fourth sampling signal; Divide the error coefficient of the fifth channel by the sum of the second coefficients to obtain the fifth dynamic weight corresponding to the fifth sampling signal; Divide the error coefficient of the fourth channel by the sum of the second coefficients to obtain the sixth dynamic weight corresponding to the sixth sampling signal.

[0010] In one possible implementation, the controller is further configured to: Multiply the fourth sampled signal by the fourth dynamic weight to obtain the fourth product; Multiply the fifth sampling signal by the fifth dynamic weight to obtain the fifth product; Multiply the sixth sampled signal by the sixth dynamic weight to obtain the sixth product; The fourth, fifth, and sixth products are added together to obtain the optimized signal for the Y-axis.

[0011] In one possible implementation, the controller is further configured to: When the seventh sampling signal of the Z-axis is a positive sampling signal and the eighth sampling signal is a negative sampling signal, the difference between the seventh sampling signal and the eighth sampling signal is divided by 2 to obtain the optimized signal of the Z-axis.

[0012] In one possible implementation, each conditioning channel in the signal conditioning module includes a sampling resistor, a first operational amplifier input resistor, a second operational amplifier input resistor, an operational amplifier, a first rail-to-rail amplifier input resistor, a second rail-to-rail amplifier input resistor, a rail-to-rail amplifier, and an output resistor. The first end of the sampling resistor is connected to the first end of the first operational amplifier input resistor, serving as the input end of the signal conditioning module; The second terminal of the first operational amplifier input resistor is connected to the positive input terminal of the operational amplifier; The output terminal of the operational amplifier is connected to the first terminal of the input resistor of the first rail-to-rail amplifier. The second terminal of the input resistor of the first rail-to-rail amplifier is connected to the input terminal of the rail-to-rail amplifier; The output terminal of the rail-to-rail amplifier is connected to the first terminal of the output resistor, and the second terminal of the output resistor is connected to the first terminal of the input resistor of the second operational amplifier and the first terminal of the input resistor of the second rail-to-rail amplifier, serving as the output terminal of the signal conditioning module. The second terminal of the second operational amplifier input resistor is connected to the negative input terminal of the operational amplifier; The second terminal of the input resistor of the second rail-to-rail amplifier is connected to the negative input terminal of the rail-to-rail amplifier.

[0013] In one possible implementation, the resistance of the op-amp input resistor is 10 times the resistance of the rail-to-rail amplifier input resistor; The resistance of the op-amp input resistor is 100 times the resistance of the output resistor.

[0014] According to a second aspect of this application, a signal acquisition method for an accelerometer is provided for use in the signal acquisition circuit described above, the method comprising: The accelerometer generates acceleration current signals along the X, Y, and Z axes; The signal conditioning module converts the acceleration current signals of the X-axis, Y-axis and Z-axis into corresponding voltage signals, and uses operational amplifiers and rail-to-rail amplifiers to condition each voltage signal to obtain the conditioned signals of the X-axis, Y-axis and Z-axis. The signal acquisition module performs triple redundant sampling on the conditioning signals of the X-axis and Y-axis, and double redundant sampling on the conditioning signal of the Z-axis, to obtain eight sampling signals. The controller calculates the corresponding dynamic weight for each sampled signal of the X and Y axes, and calculates the optimized signals of the X and Y axes based on each sampled signal and the corresponding dynamic weight. The dynamic weight corresponding to each sampled signal is related to the error of the sampling channels of the other two sampled signals. The controller also calculates the optimized signal of the Z axis for the two sampled signals corresponding to the Z axis.

[0015] The beneficial effects of the technical solution provided in this application include at least the following: The signal conditioning module includes operational amplifiers and rail-to-rail amplifiers. These amplifiers condition each voltage signal, significantly reducing common-mode and differential-mode noise interference. By performing triple-redundant sampling on the X-axis and Y-axis conditioning signals, and calculating the corresponding dynamic weights for each sampled signal in both directions, optimized X-axis and Y-axis signals are calculated based on each sampled signal and its corresponding dynamic weight. Since the dynamic weights for each sampled signal are related to the errors of the sampling channels of the other two signals, the accuracy impact caused by zero-point drift and performance differences between sampling channels can be significantly reduced. Furthermore, compared to signal acquisition circuits based on I / F circuits, this application offers advantages such as simple structure and low cost. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a structural block diagram of the signal acquisition circuit of an accelerometer provided in one embodiment of this application; Figure 2 This is a circuit diagram of a signal conditioning module provided in one embodiment of this application; Figure 3 This is a flowchart of a signal acquisition method for an accelerometer provided in one embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0019] like Figure 1 The diagram shows a structural block diagram of the signal acquisition circuit of an accelerometer according to an embodiment of this application. The signal acquisition circuit of the accelerometer may include an accelerometer 101, a signal conditioning module 102, a signal acquisition module 103, and a controller 104. These four modules will be described below.

[0020] (1) Accelerometer 101 Accelerometer 101 is used to generate acceleration current signals along the X, Y, and Z axes. Specifically, the X-axis outputs one acceleration current signal. Figure 1 The X-axis current; the Y-axis output is an acceleration current signal, i.e. Figure 1 The Y-axis current; the Z-axis output is one acceleration current signal, i.e. Figure 1 The Z-axis current.

[0021] (2) Signal conditioning module 102 The signal conditioning module 102 is used to convert the acceleration current signals of the X-axis, Y-axis and Z-axis into corresponding voltage signals, and to condition each voltage signal using an operational amplifier and a rail-to-rail amplifier to obtain the conditioned signals of the X-axis, Y-axis and Z-axis.

[0022] In this embodiment, the three conditioning channels in the signal conditioning module 102 are responsible for converting the three acceleration current signals into voltage signals within the input range (e.g., amplitude within ±2.5V) of the signal acquisition module 103. Specifically, the signal conditioning module 102 converts the input X-axis acceleration current signal into a voltage signal Vi_X through one conditioning channel, then conditions the voltage signal Vi_X, and outputs a conditioned signal, i.e. Figure 1 The X-axis voltage Vo_x; the signal conditioning module 102 converts the input Y-axis acceleration current signal into a voltage signal Vi_Y through a conditioning channel, then conditions the voltage signal Vi_Y, and outputs a conditioned signal, i.e. Figure 1 The Y-axis voltage Vo_y; the signal conditioning module 102 converts the input Z-axis acceleration current signal into a voltage signal Vi_Z through a conditioning channel, then conditions the voltage signal Vi_Z, and outputs a conditioned signal, i.e. Figure 1 The Z-axis voltage Vo_z.

[0023] like Figure 2 As shown, each conditioning channel in the signal conditioning module 102 includes a sampling resistor 201, operational amplifier input resistors (including first operational amplifier input resistor 202 and second operational amplifier input resistor 203), operational amplifier 204, rail-to-rail amplifier input resistors (including first rail-to-rail amplifier input resistor 205 and second rail-to-rail amplifier input resistor 206), rail-to-rail amplifier 207, and output resistor 208; wherein, the first end of the sampling resistor 201 is connected to the first end of the first operational amplifier input resistor 202, serving as the input terminal of the signal conditioning module 102; the second end of the first operational amplifier input resistor 202 is connected to the positive input terminal of the operational amplifier 204; the operational amplifier 204... The output terminal is connected to the first terminal of the first rail-to-rail amplifier input resistor 205; the second terminal of the first rail-to-rail amplifier input resistor 205 is connected to the input terminal of the rail-to-rail amplifier 207; the output terminal of the rail-to-rail amplifier 207 is connected to the first terminal of the output resistor 208, and the second terminal of the output resistor 208 is connected to the first terminal of the second operational amplifier input resistor 203 and the first terminal of the second rail-to-rail amplifier input resistor 206, serving as the output terminal of the signal conditioning module 102; the second terminal of the second operational amplifier input resistor 203 is connected to the negative input terminal of the operational amplifier 204; the second terminal of the second rail-to-rail amplifier input resistor 206 is connected to the negative input terminal of the rail-to-rail amplifier 207.

[0024] Specifically, sampling resistor 201 is used to convert the acceleration current signals generated by accelerometer 101 along the X, Y, and Z axes into voltage signals Vi_X, Vi_Y, and Vi_Z. Each voltage signal is then conditioned by a two-stage symmetrical precision amplifier (operational amplifier and rail-to-rail amplifier) ​​to become voltages Vo_X, Vo_Y, and Vo_Z, which are then used by signal acquisition module 103. This design achieves the requirements of high input impedance and low output impedance, eliminates impedance differences between the front and rear stages, and provides circuit isolation, significantly reducing interference from the rear stage circuit to the front stage circuit.

[0025] Taking the voltage signal Vi_X as an example, the voltage signal Vi_X is converted into the conditioning signal Vo_X through the first operational amplifier input resistor 202, operational amplifier 204, first rail-to-rail amplifier input resistor 205, rail-to-rail amplifier 207 and output resistor 208 in the conditioning channel; the conditioning signal Vo_X is fed back to the negative input terminals of operational amplifier 204 and rail-to-rail amplifier 207 through the second operational amplifier input resistor 203 and the second rail-to-rail amplifier input resistor 206.

[0026] To improve reliability, the sampling resistor 201 is composed of a pair of precision resistors with equal resistance connected in parallel.

[0027] The input resistors of the operational amplifiers (including the first operational amplifier input resistor 202 and the second operational amplifier input resistor 203) are 10 times the value of the input resistors of the rail-to-rail amplifiers (including the first rail-to-rail amplifier input resistor 205 and the second rail-to-rail amplifier input resistor 206); the input resistors of the operational amplifiers (including the first operational amplifier input resistor 202 and the second operational amplifier input resistor 203) are 100 times the value of the output resistor 208. This design can effectively suppress electromagnetic noise interference in analog signal transmission from a hardware perspective.

[0028] (3) Signal acquisition module 103 The signal acquisition module 103 is used to perform triple redundant sampling on the conditioning signals of the X-axis and Y-axis respectively, and double redundant sampling on the conditioning signal of the Z-axis to obtain eight sampling signals.

[0029] The signal acquisition module 103 has eight differential sampling channels, which are used to convert three conditioning signals into eight sampling signals (digital signals) and output the eight sampling signals to the controller 104.

[0030] In this embodiment, the signal acquisition module 103 performs triple redundant sampling on the X-axis conditioning signal Vo_X through three differential sampling channels to obtain three sampled signals; performs triple redundant sampling on the Y-axis conditioning signal Vo_Y through three differential sampling channels to obtain three sampled signals; and performs double redundant sampling on the Z-axis conditioning signal Vo_Z through two differential sampling channels to obtain two sampled signals; after synthesis, a total of eight sampled signals are obtained.

[0031] like Figure 1 As shown, the X-axis conditioning signal Vo_X is connected to two positive inputs (Ain0p and Ain1p) and one inverting input (Ain2n) of the signal acquisition module 103 via matching resistors. The first analog circuit is connected to two inverting inputs (Ain0n and Ain1n) and one positive input (Ain2p) of the signal acquisition module 103 via matching resistors, and the first analog circuit is used to provide a reference voltage. The Y-axis conditioning signal Vo_Y is connected to two positive inputs (Ain3p and Ain4p) and one inverting input (Ain5n) of the signal acquisition module 103 via matching resistors. The second analog circuit is connected to two inverting inputs (Ain3n and Ain4n) and one positive input (Ain5p) of the signal acquisition module 103 via matching resistors, and the second analog circuit is used to provide a reference voltage. The Z-axis conditioning signal Vo_Z is connected to one positive input (Ain6p) and one inverting input (Ain7n) of the signal acquisition module 103 via a matching resistor. The third analog circuit is connected to one inverting input (Ain6n) and one positive input (Ain7p) of the signal acquisition module 103 via a matching resistor, and the third analog circuit is used to provide a reference voltage.

[0032] (4) Controller 104 The controller 104 calculates the corresponding dynamic weights for each sampled signal along the X and Y axes, and calculates optimized signals for the X and Y axes based on each sampled signal and its corresponding dynamic weight. The dynamic weight for each sampled signal is related to the error of the sampling channels of the other two sampled signals. It also calculates optimized signals for the Z-axis based on the two sampled signals along the Z axis. In simple terms, the larger the error of a sampling channel, the lower its corresponding dynamic weight, thus significantly reducing the accuracy impact caused by zero-point drift and inter-channel performance differences in analog-to-digital conversion (ADC).

[0033] Specifically, the controller 104 is also used to: calculate a channel error coefficient for every two sampling signals for the three sampling signals of the X-axis or Y-axis, the channel error coefficient representing the error of the two sampling channels corresponding to the two sampling signals; and calculate the three channel error coefficients for each sampling signal using a predetermined algorithm to obtain the dynamic weight corresponding to the sampling signal.

[0034] For the three sampling signals along the X-axis, the controller 104 is further configured to: when the first sampling signal Ain0 and the second sampling signal Ain1 along the X-axis are positive sampling signals and the third sampling signal Ain2 is a negative sampling signal, use the absolute value of the second sampling signal Ain1 minus the absolute value of the first sampling signal Ain0 as the first channel error coefficient d10; use the negative value of the third sampling signal Ain2 minus the absolute value of the first sampling signal Ain0 as the second channel error coefficient d20; and use the negative value of the third sampling signal Ain2 minus the absolute value of the second sampling signal Ain1 as... Let d21 be the error coefficient of the third channel; add the error coefficients d10, d20, and d21 of the first channel to obtain the sum of the first coefficients; divide the error coefficient d21 of the third channel by the sum of the first coefficients to obtain the first dynamic weight k0 corresponding to the first sampled signal Ain0; divide the error coefficient d20 of the second channel by the sum of the first coefficients to obtain the second dynamic weight k1 corresponding to the second sampled signal Ain1; divide the error coefficient d10 of the first channel by the sum of the first coefficients to obtain the third dynamic weight k2 corresponding to the third sampled signal Ain2.

[0035] That is, d10=|Ain1-Ain0|, d20=|-Ain2-Ain0|, d21=|-Ain2-Ain1|, k0=d21 / (d10+d20+d21), k1=d20 / (d10+d20+d21), k2=d10 / (d10+d20+d21).

[0036] The controller 104 is also configured to: multiply the first sampled signal Ain0 by the first dynamic weight to obtain the first product; multiply the second sampled signal Ain1 by the second dynamic weight to obtain the second product; multiply the third sampled signal Ain2 by the second dynamic weight to obtain the third product; and add the first product, the second product and the third product to obtain the optimized signal of the X-axis.

[0037] That is, X = k0 × Ain0 + k1 × Ain1 + k2 × Ain2.

[0038] When the sampled signal is large, the offset between sampling channels is small relative to the sampled signal. The differences between the pairwise readings of the three sampling channels mainly come from the sampled signal itself, and the dynamic weights are relatively even. When the sampled signal is near zero (zero crossing), the readings of the first sampling signal Ain0 and the second sampling signal Ain1 are close to the offset, while the reading of the third sampling signal Ain2 is close to the negative offset (-offset). The differences d10, d20, and d21 between them mainly reflect the magnitude of the error. Specifically, the first sampling signal Ain0 and the second sampling signal Ain1 are both positive sampling signals, so d10 represents the offset difference between the first and second sampling channels. The first sampling signal Ain0 and the second sampling signal Ain1 are both positive sampling signals, while the third sampling signal Ain2 is a negative sampling signal. Therefore, d20 represents the sum of the offsets of the third sampling channel and the first sampling channel, and d21 represents the sum of the offsets of the third sampling channel and the second sampling channel. Therefore, the dynamic weights calculated based on d10, d20, and d21 can reflect the errors between sampling channels, thereby significantly reducing the accuracy impact caused by zero drift and performance differences between sampling channels.

[0039] For the three sampling signals along the Y-axis, the controller 104 is further configured to: when the fourth sampling signal Ain3 and the fifth sampling signal Ain4 along the Y-axis are positive sampling signals and the sixth sampling signal Ain5 is a negative sampling signal, use the absolute value of the difference between the fifth sampling signal Ain4 and the fourth sampling signal Ain3 as the error coefficient d43 for the fourth channel; use the negative value of the sixth sampling signal Ain5 and the absolute value of the difference between the fourth sampling signal Ain3 and the absolute value of the difference between the negative value of the sixth sampling signal Ain5 and the absolute value of the difference between the negative value of the sixth sampling signal Ain5 and the absolute value of the difference between the fifth sampling signal Ain4 and the absolute value of the difference between the negative value of the sixth sampling signal Ain5 and the absolute value of the difference between the fifth sampling signal Ain4 and the absolute value of the difference between the negative value of the sixth sampling signal Ain5 and the absolute value of the difference between the fifth sampling signal Ain4 and the absolute value of the difference between the negative value of the sixth sampling signal Ain5 and the absolute value of the difference between the fifth sampling signal Ain4 and the absolute value of the difference between the negative value of the sixth sampling signal Ain5 and the absolute value of the difference between the fifth sampling signal Ain4 and the absolute value of the difference between the fifth ... Let d54 be the error coefficient of the sixth channel. Add the error coefficients d43 of the fourth channel, d53 of the fifth channel, and d54 of the sixth channel to get the second sum of coefficients. Divide the error coefficient d54 of the sixth channel by the second sum of coefficients to get the fourth dynamic weight k3 corresponding to the fourth sampled signal Ain3. Divide the error coefficient d53 of the fifth channel by the second sum of coefficients to get the fifth dynamic weight k4 corresponding to the fifth sampled signal Ain4. Divide the error coefficient d43 of the fourth channel by the second sum of coefficients to get the sixth dynamic weight k5 corresponding to the sixth sampled signal Ain5.

[0040] That is, d43=|Ain4-Ain3|, d53=|-Ain5-Ain3|, d54=|-Ain5-Ain4|, k3=d54 / (d43+d53+d54), k4=d53 / (d43+d53+d54), k5=d43 / (d43+d53+d54).

[0041] The controller 104 is also used to: multiply the fourth sampling signal Ain3 by the fourth dynamic weight k3 to obtain the fourth product; multiply the fifth sampling signal Ain4 by the fifth dynamic weight k4 to obtain the fifth product; multiply the sixth sampling signal Ain5 by the sixth dynamic weight k5 to obtain the sixth product; and add the fourth product, the fifth product and the sixth product to obtain the optimized signal of the Y-axis.

[0042] That is, Y = k3 × Ain3 + k4 × Ain4 + k5 × Ain5.

[0043] For the two sampling signals of the Z-axis, the controller 104 is also used to: when the seventh sampling signal Ain6 of the Z-axis is a positive sampling signal and the eighth sampling signal Ain7 is a negative sampling signal, divide the difference between the seventh sampling signal Ain6 and the eighth sampling signal Ain7 by 2 to obtain the optimized signal of the Z-axis.

[0044] That is, Z = (Ain6 - Ain7) / 2.

[0045] In summary, the accelerometer signal acquisition circuit provided in this application embodiment includes an operational amplifier and a rail-to-rail amplifier in its signal conditioning module. By using the operational amplifier and rail-to-rail amplifier to condition each voltage signal, the interference of common-mode noise and differential-mode noise can be significantly reduced. By performing triple redundant sampling on the conditioning signals of the X-axis and Y-axis respectively, and then calculating the corresponding dynamic weight for each sampled signal of the X-axis and Y-axis, the optimized signals of the X-axis and Y-axis are calculated based on each sampled signal and the corresponding dynamic weight. Since the dynamic weight corresponding to each sampled signal is related to the error of the sampling channels of the other two sampled signals, the accuracy impact caused by zero-point drift and performance differences between sampling channels can be significantly reduced. Furthermore, compared with the signal acquisition circuit based on I / F circuit, this application has the advantages of simple structure and low cost.

[0046] like Figure 3 The diagram illustrates a flowchart of a signal acquisition method for an accelerometer according to an embodiment of this application. This signal acquisition method for an accelerometer is used for... Figure 1 The signal acquisition circuit shown includes the following signal acquisition method for the accelerometer: Step 301: The accelerometer generates acceleration current signals along the X, Y, and Z axes.

[0047] Among them, the X-axis outputs one acceleration current signal, namely Figure 1 The X-axis current; the Y-axis output is an acceleration current signal, i.e. Figure 1 The Y-axis current; the Z-axis output is one acceleration current signal, i.e. Figure 1 The Z-axis current.

[0048] Step 302: The signal conditioning module converts the acceleration current signals of the X-axis, Y-axis and Z-axis into corresponding voltage signals, and uses operational amplifiers and rail-to-rail amplifiers to condition each voltage signal to obtain the conditioned signals of the X-axis, Y-axis and Z-axis.

[0049] The signal conditioning module converts the input X-axis acceleration current signal into a voltage signal Vi_X through a conditioning channel, then conditions the voltage signal Vi_X to output a conditioned signal. Figure 1 The X-axis voltage Vo_x; the signal conditioning module converts the input Y-axis acceleration current signal into a voltage signal Vi_Y through a conditioning channel, then conditions the voltage signal Vi_Y, and outputs a conditioned signal, i.e. Figure 1 The Y-axis voltage Vo_y; the signal conditioning module converts the input Z-axis acceleration current signal into a voltage signal Vi_Z through a conditioning channel, then conditions the voltage signal Vi_Z, and outputs a conditioned signal, i.e. Figure 1 The Z-axis voltage Vo_z.

[0050] Step 303: The signal acquisition module performs triple redundant sampling on the conditioning signals of the X-axis and Y-axis, and double redundant sampling on the conditioning signal of the Z-axis, to obtain eight sampling signals.

[0051] In this embodiment, the signal acquisition module performs triple-redundant sampling on the X-axis conditioning signal Vo_X through three differential sampling channels to obtain three sampled signals; it also performs triple-redundant sampling on the Y-axis conditioning signal Vo_Y through three differential sampling channels to obtain three sampled signals; and it performs double-redundant sampling on the Z-axis conditioning signal Vo_Z through two differential sampling channels to obtain two sampled signals; after synthesis, a total of eight sampled signals are obtained.

[0052] like Figure 1As shown, the X-axis conditioning signal Vo_X is connected to two positive inputs (Ain0p and Ain1p) and one inverting input (Ain2n) of the signal acquisition module via matching resistors. The first analog circuit is also connected to two inverting inputs (Ain0n and Ain1n) and one positive input (Ain2p) of the signal acquisition module via matching resistors, and the first analog circuit is used to provide a reference voltage. Similarly, the Y-axis conditioning signal Vo_Y is connected to two positive inputs (Ain3p and Ain4p) and one inverting input (Ain5n) of the signal acquisition module via matching resistors. The second analog circuit is also connected to two inverting inputs (Ain3n and Ain4n) and one positive input (Ain5p) of the signal acquisition module via matching resistors, and the second analog circuit is used to provide a reference voltage. The Z-axis conditioning signal Vo_Z is connected to one positive input (Ain6p) and one inverting input (Ain7n) of the signal acquisition module via a matching resistor. The third analog circuit is connected to one inverting input (Ain6n) and one positive input (Ain7p) of the signal acquisition module via a matching resistor, and the third analog circuit is used to provide a reference voltage.

[0053] Step 304: The controller calculates the corresponding dynamic weight for each sampled signal of the X-axis and Y-axis, and calculates the optimized signals of the X-axis and Y-axis based on each sampled signal and the corresponding dynamic weight. The dynamic weight corresponding to each sampled signal is related to the error of the sampling channels of the other two sampled signals. The controller also calculates the optimized signal of the Z-axis for the two sampled signals corresponding to the Z-axis.

[0054] Specifically, for three sampling signals along the X-axis or Y-axis, the controller calculates a channel error coefficient for every two sampling signals. The channel error coefficient represents the error between the two sampling channels corresponding to the two sampling signals. For each sampling signal, the controller uses a predetermined algorithm to calculate the three channel error coefficients to obtain the dynamic weight corresponding to the sampling signal.

[0055] For the three sampling signals along the X-axis, when the first sampling signal Ain0 and the second sampling signal Ain1 are positive sampling signals, and the third sampling signal Ain2 is a negative sampling signal, the controller uses the absolute value of subtracting the first sampling signal Ain0 from the second sampling signal Ain1 as the first channel error coefficient d10, the negative value of subtracting the absolute value of the first sampling signal Ain0 from the third sampling signal Ain2 as the second channel error coefficient d20, and the negative value of subtracting the absolute value of the second sampling signal Ain1 from the third sampling signal Ain2 as the third channel error coefficient d20. The error coefficient d21 of the first channel is calculated; the error coefficients d10, d20, and d21 of the second channel are added together to obtain the first sum of coefficients; the error coefficient d21 of the third channel is divided by the first sum of coefficients to obtain the first dynamic weight k0 corresponding to the first sampled signal Ain0; the error coefficient d20 of the second channel is divided by the first sum of coefficients to obtain the second dynamic weight k1 corresponding to the second sampled signal Ain1; the error coefficient d10 of the first channel is divided by the first sum of coefficients to obtain the third dynamic weight k2 corresponding to the third sampled signal Ain2.

[0056] That is, d10=|Ain1-Ain0|, d20=|-Ain2-Ain0|, d21=|-Ain2-Ain1|, k0=d21 / (d10+d20+d21), k1=d20 / (d10+d20+d21), k2=d10 / (d10+d20+d21).

[0057] The controller multiplies the first sampled signal Ain0 by the first dynamic weight to obtain the first product; multiplies the second sampled signal Ain1 by the second dynamic weight to obtain the second product; multiplies the third sampled signal Ain2 by the second dynamic weight to obtain the third product; and adds the first product, the second product and the third product together to obtain the optimized signal of the X-axis.

[0058] That is, X = k0 × Ain0 + k1 × Ain1 + k2 × Ain2.

[0059] For the three sampling signals along the Y-axis, when the fourth and fifth sampling signals Ain3 and Ain4 are positive sampling signals and the sixth sampling signal Ain5 is a negative sampling signal, the controller uses the absolute value of subtracting the fourth sampling signal Ain3 from the fifth sampling signal Ain4 as the error coefficient d43 for the fourth channel, the negative value of subtracting the absolute value of the fourth sampling signal Ain3 from the negative value of the sixth sampling signal Ain5 as the error coefficient d53 for the fifth channel, and the negative value of subtracting the absolute value of the fifth sampling signal Ain4 from the negative value of the sixth sampling signal Ain5 as the error coefficient d53 for the sixth channel. The error coefficient d54 of the fourth channel is calculated; the error coefficients d43 of the fourth channel, d53 of the fifth channel, and d54 of the sixth channel are added together to obtain the second sum of coefficients. The error coefficient d54 of the sixth channel is divided by the second sum of coefficients to obtain the fourth dynamic weight k3 corresponding to the fourth sampling signal Ain3; the error coefficient d53 of the fifth channel is divided by the second sum of coefficients to obtain the fifth dynamic weight k4 corresponding to the fifth sampling signal Ain4; the error coefficient d43 of the fourth channel is divided by the second sum of coefficients to obtain the sixth dynamic weight k5 corresponding to the sixth sampling signal Ain5.

[0060] That is, d43=|Ain4-Ain3|, d53=|-Ain5-Ain3|, d54=|-Ain5-Ain4|, k3=d54 / (d43+d53+d54), k4=d53 / (d43+d53+d54), k5=d43 / (d43+d53+d54).

[0061] The controller multiplies the fourth sampling signal Ain3 by the fourth dynamic weight k3 to obtain the fourth product; multiplies the fifth sampling signal Ain4 by the fifth dynamic weight k4 to obtain the fifth product; multiplies the sixth sampling signal Ain5 by the sixth dynamic weight k5 to obtain the sixth product; and adds the fourth, fifth and sixth products to obtain the optimized signal for the Y-axis.

[0062] That is, Y = k3 × Ain3 + k4 × Ain4 + k5 × Ain5.

[0063] For the two sampling signals of the Z-axis, when the seventh sampling signal Ain6 of the Z-axis is a positive sampling signal and the eighth sampling signal Ain7 is a negative sampling signal, the controller divides the difference between the seventh sampling signal Ain6 and the eighth sampling signal Ain7 by 2 to obtain the optimized signal of the Z-axis.

[0064] That is, Z = (Ain6 - Ain7) / 2.

[0065] In summary, the accelerometer signal acquisition method provided in this application includes an operational amplifier and a rail-to-rail amplifier in the signal conditioning module. By using the operational amplifier and the rail-to-rail amplifier to condition each voltage signal, the interference of common-mode noise and differential-mode noise can be significantly reduced. By performing triple redundant sampling on the conditioning signals of the X-axis and Y-axis respectively, and then calculating the corresponding dynamic weight for each sampled signal of the X-axis and Y-axis, the optimized signals of the X-axis and Y-axis are calculated based on each sampled signal and the corresponding dynamic weight. Since the dynamic weight corresponding to each sampled signal is related to the error of the sampling channels of the other two sampled signals, the accuracy impact caused by zero drift and performance differences between sampling channels can be significantly reduced. Furthermore, compared with the signal acquisition circuit based on I / F circuit, this application has the advantages of simple structure and low cost.

[0066] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware or by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0067] The above description is not intended to limit the embodiments of this application. Any adjustments, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of the embodiments of this application.

Claims

1. A signal acquisition circuit for an accelerometer, characterized in that, The signal acquisition circuit includes an accelerometer, a signal conditioning module, a signal acquisition module, and a controller; The accelerometer is used to generate acceleration current signals along the X, Y, and Z axes. The signal conditioning module is used to convert the acceleration current signals of the X-axis, Y-axis and Z-axis into corresponding voltage signals, and to condition each voltage signal using an operational amplifier and a rail-to-rail amplifier to obtain the conditioned signals of the X-axis, Y-axis and Z-axis. The signal acquisition module is used to perform triple redundant sampling on the conditioning signals of the X-axis and Y-axis respectively, and double redundant sampling on the conditioning signal of the Z-axis to obtain eight sampling signals. The controller is used to calculate the corresponding dynamic weight for each sampled signal of the X-axis and Y-axis, and to calculate the optimized signal of the X-axis and Y-axis based on each sampled signal and the corresponding dynamic weight. The dynamic weight corresponding to each sampled signal is related to the error of the sampling channels of the other two sampled signals. The controller is also used to calculate the optimized signal of the Z-axis for the two sampled signals of the Z-axis.

2. The signal acquisition circuit of the accelerometer according to claim 1, characterized in that, The controller is also used for: For three sampling signals along the X-axis or Y-axis, a channel error coefficient is calculated for every two sampling signals. The channel error coefficient represents the error between the two sampling channels corresponding to the two sampling signals. For each sampled signal, a predetermined algorithm is used to calculate the error coefficients of the three channels to obtain the dynamic weight corresponding to the sampled signal.

3. The signal acquisition circuit of the accelerometer according to claim 2, characterized in that, The controller is also used for: When the first and second sampling signals of the X-axis are positive sampling signals and the third sampling signal is a negative sampling signal, the absolute value of the second sampling signal minus the first sampling signal is used as the first channel error coefficient, the negative value of the third sampling signal minus the absolute value of the first sampling signal is used as the second channel error coefficient, and the negative value of the third sampling signal minus the absolute value of the second sampling signal is used as the third channel error coefficient. The error coefficients of the first channel, the second channel, and the third channel are added together to obtain the sum of the first coefficients; Divide the error coefficient of the third channel by the sum of the first coefficients to obtain the first dynamic weight corresponding to the first sampling signal; Divide the second channel error coefficient by the sum of the first coefficients to obtain the second dynamic weight corresponding to the second sampling signal; Divide the first channel error coefficient by the sum of the first coefficients to obtain the third dynamic weight corresponding to the third sampling signal.

4. The signal acquisition circuit of the accelerometer according to claim 3, characterized in that, The controller is also used for: Multiply the first sampled signal by the first dynamic weight to obtain the first product; Multiply the second sampled signal by the second dynamic weight to obtain the second product; The third sampled signal is multiplied by the second dynamic weight to obtain the third product; The first product, the second product, and the third product are added together to obtain the optimized signal for the X-axis.

5. The signal acquisition circuit of the accelerometer according to claim 2, characterized in that, The controller is also used for: When the fourth and fifth sampling signals of the Y-axis are positive sampling signals and the sixth sampling signal is a negative sampling signal, the absolute value of the fifth sampling signal minus the fourth sampling signal is used as the error coefficient of the fourth channel, the negative value of the sixth sampling signal minus the absolute value of the fourth sampling signal is used as the error coefficient of the fifth channel, and the negative value of the sixth sampling signal minus the absolute value of the fifth sampling signal is used as the error coefficient of the sixth channel. The error coefficients of the fourth channel, the fifth channel, and the sixth channel are added together to obtain the second sum of coefficients. Divide the error coefficient of the sixth channel by the sum of the second coefficients to obtain the fourth dynamic weight corresponding to the fourth sampling signal; Divide the error coefficient of the fifth channel by the sum of the second coefficients to obtain the fifth dynamic weight corresponding to the fifth sampling signal; Divide the error coefficient of the fourth channel by the sum of the second coefficients to obtain the sixth dynamic weight corresponding to the sixth sampling signal.

6. The signal acquisition circuit of the accelerometer according to claim 5, characterized in that, The controller is also used for: Multiply the fourth sampled signal by the fourth dynamic weight to obtain the fourth product; Multiply the fifth sampling signal by the fifth dynamic weight to obtain the fifth product; Multiply the sixth sampled signal by the sixth dynamic weight to obtain the sixth product; The fourth, fifth, and sixth products are added together to obtain the optimized signal for the Y-axis.

7. The signal acquisition circuit of the accelerometer according to claim 1, characterized in that, The controller is also used for: When the seventh sampling signal of the Z-axis is a positive sampling signal and the eighth sampling signal is a negative sampling signal, the difference between the seventh sampling signal and the eighth sampling signal is divided by 2 to obtain the optimized signal of the Z-axis.

8. The signal acquisition circuit of the accelerometer according to any one of claims 1 to 7, characterized in that, Each conditioning channel in the signal conditioning module includes a sampling resistor, a first operational amplifier input resistor, a second operational amplifier input resistor, an operational amplifier, a first rail-to-rail amplifier input resistor, a second rail-to-rail amplifier input resistor, a rail-to-rail amplifier, and an output resistor; The first end of the sampling resistor is connected to the first end of the first operational amplifier input resistor, serving as the input end of the signal conditioning module; The second terminal of the first operational amplifier input resistor is connected to the positive input terminal of the operational amplifier; The output terminal of the operational amplifier is connected to the first terminal of the input resistor of the first rail-to-rail amplifier. The second terminal of the input resistor of the first rail-to-rail amplifier is connected to the input terminal of the rail-to-rail amplifier; The output terminal of the rail-to-rail amplifier is connected to the first terminal of the output resistor, and the second terminal of the output resistor is connected to the first terminal of the input resistor of the second operational amplifier and the first terminal of the input resistor of the second rail-to-rail amplifier, serving as the output terminal of the signal conditioning module. The second terminal of the second operational amplifier input resistor is connected to the negative input terminal of the operational amplifier; The second terminal of the input resistor of the second rail-to-rail amplifier is connected to the negative input terminal of the rail-to-rail amplifier.

9. The signal acquisition circuit of the accelerometer according to claim 8, characterized in that, The resistance value of the operational amplifier input resistor is 10 times the resistance value of the rail-to-rail amplifier input resistor; The resistance of the op-amp input resistor is 100 times the resistance of the output resistor.

10. A signal acquisition method for an accelerometer, characterized in that, Used in a signal acquisition circuit as described in any one of claims 1 to 9, the method comprises: The accelerometer generates acceleration current signals along the X, Y, and Z axes; The signal conditioning module converts the acceleration current signals of the X-axis, Y-axis and Z-axis into corresponding voltage signals, and uses operational amplifiers and rail-to-rail amplifiers to condition each voltage signal to obtain the conditioned signals of the X-axis, Y-axis and Z-axis. The signal acquisition module performs triple redundant sampling on the conditioning signals of the X-axis and Y-axis, and double redundant sampling on the conditioning signal of the Z-axis, to obtain eight sampling signals. The controller calculates the corresponding dynamic weight for each sampled signal of the X and Y axes, and calculates the optimized signals of the X and Y axes based on each sampled signal and the corresponding dynamic weight. The dynamic weight corresponding to each sampled signal is related to the error of the sampling channels of the other two sampled signals. The controller also calculates the optimized signal of the Z axis for the two sampled signals corresponding to the Z axis.

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