A differential current-voltage conversion circuit for an inertial navigation system

Abstract

The present invention provides an inertial navigation system differential current-voltage conversion circuit, which belongs to the technical field related to carrier modulation conversion. The circuit comprises a sensor output current I1, a sensor equivalent internal resistance R8, a current sampling resistor Rs, a first inverting amplifier and a second inverting amplifier connected in series, and a resistor R5 located between the first inverting amplifier and the second inverting amplifier. The first inverting amplifier and the second inverting amplifier are connected in series with the resistor R5 to form a differential amplifier of an input signal I1*Rs. The amplification factor is adjusted by adjusting the resistance value of Rs, and the input impedance is adjusted by adjusting the resistance values ​​of R7 and R6. The signal input mode and the signal conversion circuit are adjusted to achieve high input impedance and high common interference mode suppression capabilities, thereby greatly reducing the system complexity of the signal acquisition circuit, and realizing low output impedance and groundless signal sensor current differential amplification processing, which can better match the back-end acquisition circuit.

Description

Technical Field

[0001] The invention relates to carrier frequency modulation conversion related technologies, and in particular to a differential current-voltage conversion circuit of an inertial navigation system. Background Art

[0002] In order to achieve long-distance transmission of weak signals of inertial navigation systems, the signal output mode of most inertial navigation sensors is current output. In order to convert current signals into digital signals, the commonly used signal acquisition methods are I / F conversion or I / V conversion. Among them, I / F conversion is suitable for high-precision signal acquisition occasions, while I / V is used for most signal acquisition occasions.

[0003] Conventional I / V conversion usually uses the method of current flowing directly into the earth through a sampling resistor. This sampling method has the characteristics of low input impedance and poor common-mode suppression. This characteristic requires that the front-end sensor must have a low output impedance and the transmission path needs to be very clean. However, in actual use, some sensors have high internal resistance and no direct grounding terminal, and it is difficult to guarantee the suppression of common-mode interference in the actual functional application environment. The above phenomenon has brought great troubles to subsequent signal acquisition, increased the difficulty of back-end signal processing circuit design, wasted design resources, and increased product costs; it is not suitable for complex engineering application environments. Summary of the invention

[0004] An embodiment of the present invention provides a differential current-voltage conversion circuit for an inertial navigation system. By adjusting the signal input mode and the signal conversion circuit, high input impedance and high common interference mode suppression capabilities can be achieved, greatly reducing the system complexity of the signal acquisition circuit, and low output impedance and groundless signal sensor current differential amplification processing are achieved, which can better match the back-end acquisition circuit.

[0005] The present invention provides an inertial navigation system differential current-voltage conversion circuit, which includes a sensor output current I1, a sensor equivalent internal resistance R8, a current sampling resistor Rs, a first inverting amplifier and a second inverting amplifier connected in series, and a resistor R5 located between the first inverting amplifier and the second inverting amplifier. The first inverting amplifier includes an operational amplifier U1, a resistor R2, a resistor R6 and a capacitor C2. The second inverting amplifier includes an operational amplifier U2, a resistor R1, a resistor R7 and a capacitor C1. The first inverting amplifier and the second inverting amplifier are connected in series with the resistor R5 to form a differential amplifier of an input signal I1*Rs. The amplification factor is adjusted by adjusting the resistance value of Rs, and the input impedance is adjusted by adjusting the resistance values ​​of R7 and R6.

[0006] Optionally, the sensor output current I1 and the sensor equivalent internal resistance R8 are connected in series and then connected in parallel with the current sampling resistor Rs, and both ends of the current sampling resistor Rs are connected to the resistor R6 and the resistor R7 respectively.

[0007] Optionally, the positive input terminal of the operational amplifier U1 is simultaneously connected to resistor R2, resistor R6 and capacitor C2, the other ends of resistor R2 and capacitor C2 are simultaneously connected to the output terminal of the operational amplifier U1, and the two ends of resistor R5 are respectively connected to the output terminal of the operational amplifier U1 and the positive input terminal of the operational amplifier U2.

[0008] Optionally, the positive input terminal of the operational amplifier U2 is connected to the resistor R7, the resistor R1 and the capacitor C1 at the same time, and the other ends of the resistor R1 and the capacitor C1 are connected to the output terminal of the operational amplifier U2 at the same time.

[0009] Optionally, the negative input terminal of the operational amplifier U1 is grounded through a resistor R4, and the negative input terminal of the operational amplifier U2 is grounded through a resistor R3.

[0010] Optionally, the resistance value of the resistor R2 is the same as that of the resistor R1, the resistance value of the resistor R7 is the same as that of the resistor R6, and the resistance value of the resistor R2 is 1.2 to 2 times the resistance value of the resistor R6.

[0011] Optionally, the resistance value of the resistor R2 is 1.5 times the resistance value of the resistor R6, and the resistance value of the current sampling resistor Rs is 8 KΩ~15 KΩ.

[0012] Optionally, the relationship between the sensor input current I1 and the output voltage Vout of the differential current-to-voltage conversion circuit of the inertial navigation system is Vout=I1*Rs*R2 / R6.

[0013] Optionally, the sensor output current I1 ranges from 8 μA to 100 μA.

[0014] Optionally, the resistance values ​​of the resistor R7 and the resistor R6 are greater than 1 MΩ.

[0015] Beneficial technical effects of the present invention:

[0016] The present invention provides an inertial navigation system differential current-voltage conversion circuit, which includes a sensor output current I1, a sensor equivalent internal resistance R8, a current sampling resistor Rs, a first inverting amplifier and a second inverting amplifier connected in series, and a resistor R5 located between the first inverting amplifier and the second inverting amplifier. The first inverting amplifier includes an operational amplifier U1, a resistor R2, a resistor R6 and a capacitor C2, and the second inverting amplifier includes an operational amplifier U2, a resistor R1, a resistor R7 and a capacitor C1. The first inverting amplifier and the second inverting amplifier are connected in series with the resistor R5 to form a differential amplifier of an input signal I1*Rs. The amplification factor is adjusted by adjusting the resistance value of Rs, and the input impedance is adjusted by adjusting the resistance values ​​of R7 and R6. The signal input mode and the signal conversion circuit are adjusted to achieve high input impedance and high common interference mode suppression capabilities, thereby greatly reducing the system complexity of the signal acquisition circuit, and realizing low output impedance and groundless signal sensor current differential amplification processing, which can better match the back-end acquisition circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic diagram of the structure of a differential current-voltage conversion circuit of an inertial navigation system provided by the present invention;

[0019] Figure 2 A simulation diagram of the voltage conversion effect when adjusting the sensor input current of a differential current-to-voltage conversion circuit of an inertial navigation system provided by the present invention;

[0020] Figure 3 This is a simulation diagram of the voltage conversion effect when adjusting the equivalent internal resistance of a sensor of an inertial navigation system differential current-to-voltage conversion circuit provided by the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be understood that in various embodiments of the present invention, the size of the sequence number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0023] It should be understood that in the present invention, "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0024] It should be understood that in the present invention, "plurality" refers to two or more than two. "And / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "Contains A, B and C", "Contains A, B, C" means that A, B, and C are all included, "Contains A, B or C" means that one of A, B, and C is included, and "Contains A, B and / or C" means that any one, any two, or any three of A, B, and C are included.

[0025] It should be understood that in the present invention, "B corresponding to A", "B corresponding to A", "A corresponds to B" or "B corresponds to A" means that B is associated with A and B can be determined based on A. Determining B based on A does not mean determining B based only on A, but B can also be determined based on A and / or other information. A and B match when the similarity between A and B is greater than or equal to a preset threshold.

[0026] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0027] The current-to-voltage conversion in the prior art usually adopts the method of direct current flow into the earth through the sampling resistor. This sampling method has the characteristics of low input impedance and poor common-mode suppression capability. This characteristic requires that the front-end sensor must have a low output impedance and the transmission path needs to be very clean. However, in actual use, some sensors have a high internal resistance and no direct ground terminal, and it is difficult to guarantee the suppression of common-mode interference in the actual functional application environment. The above phenomenon brings great trouble to the subsequent signal acquisition, increases the difficulty of the back-end signal processing circuit design, wastes design resources, and increases product costs. In order to solve this technical problem, an embodiment of the present invention provides an inertial navigation system differential current-to-voltage conversion circuit, which adjusts the amplification factor by adjusting the resistance value of Rs, adjusts the input impedance by adjusting the resistance values ​​of R7 and R6, and achieves high input impedance and high common-mode interference suppression capabilities by adjusting the signal input method and the signal conversion circuit, greatly reducing the system complexity of the signal acquisition circuit, and realizing low output impedance, groundless signal sensor current differential amplification processing, which can better match the back-end acquisition circuit.

[0028] refer to Figure 1 As shown, an inertial navigation system differential current-to-voltage conversion circuit provided by an embodiment of the present invention includes a sensor output current I1, a sensor equivalent internal resistance R8, a current sampling resistor Rs, a first inverting amplifier and a second inverting amplifier connected in series, and a resistor R5 located between the first inverting amplifier and the second inverting amplifier, wherein the resistor R5 is used to adjust the amplification factor, the first inverting amplifier includes an operational amplifier U1, a resistor R2, a resistor R6 and a capacitor C2, the second inverting amplifier includes an operational amplifier U2, a resistor R1, a resistor R7 and a capacitor C1, the first inverting amplifier and the second inverting amplifier are connected in series with the resistor R5 to form a differential amplifier of the input signal I1*Rs, the amplification factor is adjusted by adjusting the resistance value of Rs, and the input impedance is adjusted by adjusting the resistance values ​​of R7 and R6.

[0029] An inertial navigation system differential current-voltage conversion circuit provided by an embodiment of the present invention adopts a differential amplifier circuit composed of a first inverting amplifier consisting of an operational amplifier U1, a resistor R2, a resistor R6 and a capacitor C2, and a second inverting amplifier consisting of an operational amplifier U2, a resistor R1, a resistor R7 and a capacitor C1 to suppress common-mode interference; at the same time, the output signal without a direct grounding terminal is connected to the input terminal of the amplifier circuit. At this time, the input impedance is completely determined by the input resistors R7 and R6 at the front end of the operational amplifier. This resistance can reach the MΩ level, thereby achieving the purpose of accurately collecting sensors with large internal resistance.

[0030] refer to Figure 1As shown, an inertial navigation system differential current-voltage conversion circuit provided by an embodiment of the present invention, wherein the sensor output current I1 and the sensor equivalent internal resistance R8 are connected in series with each other and then connected in parallel with the current sampling resistor Rs, and the two ends of the current sampling resistor Rs are respectively connected to the resistor R6 and the resistor R7. The positive input end of the operational amplifier U1 is simultaneously connected to the resistor R2, the resistor R6 and the capacitor C2, and the other ends of the resistor R2 and the capacitor C2 are simultaneously connected to the output end of the operational amplifier U1, and the two ends of the resistor R5 are respectively connected to the output end of the operational amplifier U1 and the positive input end of the operational amplifier U2. The positive input end of the operational amplifier U2 is simultaneously connected to the resistor R7, the resistor R1 and the capacitor C1, and the other ends of the resistor R1 and the capacitor C1 are simultaneously connected to the output end of the operational amplifier U2. The negative input end of the operational amplifier U1 is grounded through the resistor R4, and the negative input end of the operational amplifier U2 is grounded through the resistor R3, wherein the resistor R3 and the resistor R4 are balancing resistors for eliminating zero drift.

[0031] Resistor R2, resistor R6, capacitor C2 and operational amplifier U1 form a group of inverting amplifiers, resistor R1, resistor R7, capacitor C1 and operational amplifier U2 form a group of inverting amplifiers, and the two together form a differential amplifier of the input signal I1*Rs. The amplification factor can be adjusted by adjusting the resistance of Rs, and the input impedance can be adjusted by adjusting R7 and R6. A differential current-to-voltage conversion circuit of an inertial navigation system provided in an embodiment of the present invention requires that the resistance of resistor R2 is the same as that of resistor R1, the resistance of resistor R7 is the same as that of resistor R6, and the resistance of resistor R2 is 1.2 to 2 times the resistance of resistor R6. Preferably, the resistance of resistor R2 is 1.5 times the resistance of resistor R6, the resistance of current sampling resistor Rs is 8 KΩ to 15 KΩ, the range of sensor output current I1 is 8μA to 100μA, and the resistance of resistor R7 and resistor R6 is greater than 1MΩ. The relationship between the sensor input current I1 and the output voltage Vout of the differential current-to-voltage conversion circuit of an inertial navigation system according to an embodiment of the present invention is Vout=I1*Rs*R2 / R6.

[0032] In the embodiment of the present invention, Rs is set to a fixed value of 10KΩ, and the resistance ratio of R2 / R6 is set to 1.5, and only the current-to-voltage conversion analysis is performed on the input current of the regulating sensor. Figure 2 As shown, as the sensor input current I1 gradually increases from 10μA to 100μA, the output voltage gradually increases; similarly, adjusting the ratio of R2 / R6 and the ratio of R1 / R7 can also achieve the same effect.

[0033] In the embodiment of the present invention, Rs is set to a fixed value of 10KΩ, the resistance ratio of R2 / R6 is set to 1.5, and the sensor input current I1 is set to 10μA, and only the size of the equivalent internal resistance of the sensor is adjusted. Figure 3 As shown in the figure, as the equivalent internal resistance R8 of the sensor gradually increases from 10KΩ to 100KΩ, the output voltage hardly changes. Figure 2 and Figure 3 Through simulation analysis, it can be found that the differential current-to-voltage conversion circuit of an inertial navigation system provided by an embodiment of the present invention can achieve low output impedance and ground-free signal sensor current differential amplification processing, and can better match the back-end acquisition circuit.

[0034] The present invention provides an inertial navigation system differential current-voltage conversion circuit, which includes a sensor output current I1, a sensor equivalent internal resistance R8, a current sampling resistor Rs, a first inverting amplifier and a second inverting amplifier connected in series, and a resistor R5 located between the first inverting amplifier and the second inverting amplifier. The first inverting amplifier includes an operational amplifier U1, a resistor R2, a resistor R6 and a capacitor C2, and the second inverting amplifier includes an operational amplifier U2, a resistor R1, a resistor R7 and a capacitor C1. The first inverting amplifier and the second inverting amplifier are connected in series with the resistor R5 to form a differential amplifier of an input signal I1*Rs. The amplification factor is adjusted by adjusting the resistance value of Rs, and the input impedance is adjusted by adjusting the resistance values ​​of R7 and R6. The signal input mode and the signal conversion circuit are adjusted to achieve high input impedance and high common interference mode suppression capabilities, thereby greatly reducing the system complexity of the signal acquisition circuit, and realizing low output impedance and groundless signal sensor current differential amplification processing, which can better match the back-end acquisition circuit.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A differential current-voltage conversion circuit for an inertial navigation system, characterized in that: The inertial navigation system differential current-to-voltage conversion circuit includes a sensor output current I1, a sensor equivalent internal resistance R8, a current sampling resistor Rs, a first inverting amplifier and a second inverting amplifier connected in series, and a resistor R5 located between the first inverting amplifier and the second inverting amplifier. The first inverting amplifier includes an operational amplifier U1, a resistor R2, a resistor R6 and a capacitor C2. The second inverting amplifier includes an operational amplifier U2, a resistor R1, a resistor R7 and a capacitor C1. The first inverting amplifier and the second inverting amplifier are connected in series with the resistor R5. The sensor output current I1 and the sensor equivalent internal resistance R8 are connected in series and then connected in parallel with the current sampling resistor Rs. The two ends of the current sampling resistor Rs are connected to the resistor R6 and the resistor R7 respectively. The resistance value of the resistor R2 is the same as that of the resistor R1, the resistance value of the resistor R7 is the same as that of the resistor R6, the resistance value of the resistor R2 is 1.5 times that of the resistor R6, and the resistance value of the current sampling resistor Rs is 8 KΩ~15 KΩ; the relationship between the sensor input current I1 and the output voltage Vout of the differential current-to-voltage conversion circuit of the inertial navigation system is Vout=I1*Rs*R2 / R6; the resistance values ​​of resistors R7 and R6 are greater than 1MΩ; the positive input end of the operational amplifier U1 is simultaneously connected to resistor R2, resistor R6 and capacitor C2, the other ends of resistor R2 and capacitor C2 are simultaneously connected to the output end of the operational amplifier U1, and the two ends of resistor R5 are respectively connected to the output end of the operational amplifier U1 and the positive input end of the operational amplifier U2; the positive input end of the operational amplifier U2 is simultaneously connected to resistor R7, resistor R1 and capacitor C1, the other ends of resistor R1 and capacitor C1 are simultaneously connected to the output end of the operational amplifier U2; the negative input end of the operational amplifier U1 is grounded through resistor R4, and the negative input end of the operational amplifier U2 is grounded through resistor R3.

2. The inertial navigation system differential current-voltage conversion circuit according to claim 1, characterized in that: The sensor output current I1 ranges from 8μA to 100μA.

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