A temperature compensation type quartz tuning fork accelerometer control circuit

Abstract

The present invention discloses a control circuit for a temperature-compensated quartz tuning fork accelerometer. The present invention transforms the original internal temperature field of the quartz tuning fork accelerometer collected by a temperature sensor into a temperature compensation voltage. After fusing it with the original acceleration information detected by a multivibrator and an F / V converter through an adder, a frequency signal after temperature compensation is output through a V / F converter. The present invention can achieve comprehensive compensation for the zero offset and scale factor temperature coefficient of the quartz tuning fork accelerometer. The present invention can also adjust the zero offset and scale factor of the quartz tuning fork accelerometer by changing the conversion coefficients of the F / V converter, V / F converter, and adder. The present invention can be widely applied to military and civilian fields such as aircraft autonomous navigation, oil while drilling inclinometer systems, and microgravity field measurement, and has great economic and social benefits. The present invention can be applied to the control of other types of tuning fork accelerometers and has general applicability.

Description

Technical Field

[0001] The present invention belongs to the field of inertial measurement, and particularly relates to a control circuit for a temperature-compensated quartz tuning fork accelerometer. Background Art

[0002] A tuning fork accelerometer is an accelerometer based on the principle of mechanical resonance. It measures acceleration by detecting the frequency change of the tuning fork with the external input acceleration. Usually, the material of the tuning fork arm is quartz or silicon. Due to the more stable and excellent mechanical and temperature characteristics of quartz material itself, currently, high-precision tuning fork accelerometers mainly use quartz tuning fork accelerometers as the mainstream. A typical quartz tuning fork accelerometer is excited and detected based on the quartz piezoelectric effect. Its basic feature is to output a frequency signal, which does not require analog signal processing and digital conversion and can be directly used in the subsequent digital system. It has strong anti-interference ability, large range, and small volume, and can be widely used in national defense and people's livelihood fields such as inertial autonomous navigation of aircraft, geological measurement while drilling, and microgravity field measurement.

[0003] Temperature stress can cause mechanical deformation of structural components, changes in the performance of adhesives, and parameter drift of electronic components, thus affecting the output accuracy of the quartz tuning fork accelerometer. Therefore, improving the output temperature characteristics of the quartz tuning fork accelerometer has practical engineering value for enhancing its performance. Currently, the methods to reduce the influence of temperature stress on the accelerometer output include temperature control and temperature compensation. Temperature control is to use temperature control equipment to monitor and control the temperature, so that the accelerometer works in an environment with a constant temperature. This method will increase the system volume, power consumption, and cost; temperature compensation is to establish a temperature error compensation model for the accelerometer through environmental temperature stress tests, so as to construct an output compensation function for the accelerometer. At present, the mainstream temperature compensation schemes are mainly divided into software compensation and hardware compensation. Software compensation is to use algorithms to compensate the accelerometer output in the digital processing system. However, the digital processing system requires a large number of peripheral electronic components, which greatly increases the compensation cost; the hardware compensation scheme mainly finds the main factors affecting the accelerometer accuracy, adds active or passive compensation components, so as to perform temperature compensation on the accelerometer output. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above deficiencies and provide a control circuit for a temperature-compensated quartz tuning fork accelerometer, which can comprehensively compensate the zero offset, scale factor, etc. of the quartz tuning fork accelerometer. In addition, the present invention can adjust the zero position and scale factor of the accelerometer by changing the conversion coefficients of the F / V converter, V / F converter, and adder.

[0005] To achieve the above object, the present invention includes a multivibrator, which is connected to a quartz meter head. The output end of the multivibrator is connected to a shaping driver, the shaping driver is connected to an F / V converter, one signal input end of the F / V converter is connected to an adder, the other signal input end of the adder is connected to a temperature sensor, the output end of the adder is connected to a V / F converter, and the signal output end of the V / F converter serves as the signal output end of the quartz tuning fork accelerometer.

[0006] The multivibrator includes two lead-out ends provided on the quartz beam arms. One lead-out end is connected to one end of a resistor R1 and the input end of an inverter G1, and the other lead-out end is connected to one end of a resistor R3 and one end of a resistor R4. The other end of the resistor R1 and the output end of the inverter G1 are both connected to one end of a resistor R2. The other end of the resistor R2 is connected to the input end of an inverter G2 and the other end of the resistor R3. A capacitor C1 is connected in parallel with the resistor R3. The output end of the inverter G2 and the other end of the resistor R4 are connected to the shaping driver.

[0007] The shaping driver includes an inverter G3 and an inverter G4 connected in series. The input end of the inverter G3 is connected to the output end of the multivibrator, and the output end of the inverter G4 is connected to the F / V converter.

[0008] The F / V converter includes a comparator U1. The positive input end of the comparator U1 is connected to a voltage, the negative input end of the comparator U1 is connected to an input signal, the output end of the comparator U1 is connected to a monostable flip-flop U2, the monostable flip-flop U2 is connected to a switch S2, one end of the switch S2 is connected to a constant current source A1, and the other end is connected to an integrator or an output end.

[0009] The integrator includes an operational amplifier U3. The non-inverting input end of the operational amplifier U3 is grounded, and the inverting input end of the operational amplifier U3 is connected to a switch S1, one end of a capacitor C int1 and one end of a resistor R int1 The other end of the capacitor C int1 and the other end of the resistor R int1 are both connected to the output end of the operational amplifier U3.

[0010] The V / F converter includes an integrator. The integrator is connected to an input end, the integrator is connected to one end of a switch S2, one end of the switch S2 is also connected to the negative input end of a comparator U5, the other end of the switch S2 is connected to a constant current source A2, the input end of the integrator is connected to the negative input end of the comparator U5, the positive input end of the comparator U5 is connected to a voltage, the output end of the comparator U5 is connected to a monostable flip-flop U6, the monostable flip-flop U6 controls the switch S2, and the output end of the monostable flip-flop U6 serves as the output end of the V / F converter.

[0011] The integrator includes an operational amplifier U4. The non-inverting input terminal of the operational amplifier U4 is grounded, and the inverting input terminal of the operational amplifier U4 is connected to one end of a resistor R int2 , one end of a capacitor C int2 , and a switch S2. The other end of the resistor R int2 is connected to the input terminal, and the other end of the capacitor C int2 and the output terminal of the operational amplifier U4 are connected to the inverting input terminal of a comparator U5.

[0012] The resonant frequency of the quartz beam arm oscillation in the quartz meter head is:

[0013] f1 = f0(1 + a in F)

[0014] where f0 is the oscillation frequency of the quartz beam arm when the external acceleration a in is 0, and F is the acceleration frequency conversion coefficient.

[0015] Compared with the prior art, the present invention transforms the original internal temperature field of the quartz tuning fork accelerometer collected by the temperature sensor into a temperature compensation voltage. After fusing with the original acceleration information detected by the multivibrator and the F / V converter through an adder, a temperature-compensated frequency signal is output through the V / F converter. The present invention can realize the comprehensive compensation of the zero bias and scale factor temperature coefficient of the quartz tuning fork accelerometer. The present invention can also adjust the zero bias and scale factor of the quartz tuning fork accelerometer by changing the conversion coefficients of the F / V converter, the V / F converter, and the adder. The present invention can be widely applied to military and civilian fields such as aircraft autonomous navigation, oil logging while drilling systems, and microgravity field measurement, and has great economic and social benefits. The present invention can be applied to the control of other types of tuning fork accelerometers and has general applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the circuit principle block diagram of the present invention;

[0017] Figure 2 is the schematic diagram of the multivibrator and shaping drive in the present invention;

[0018] Figure 3 is the schematic diagram of the F / V converter in the present invention;

[0019] Figure 4 is the schematic diagram of the V / F converter in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] Refer to Figure 1, the present invention includes a multivibrator, which is connected to a quartz meter head. The output end of the multivibrator is connected to a shaping driver, the shaping driver is connected to an F / V converter, one signal input end of the F / V converter is connected to an adder, the other signal input end of the adder is connected to a temperature sensor, the output end of the adder is connected to a V / F converter, and the signal output end of the V / F converter serves as the signal output end of the quartz tuning fork accelerometer.

[0022] When there is an acceleration a along the sensitive axis of the quartz tuning fork accelerometer in the external environment in acting, the detection mass of the quartz meter head converts the input acceleration into a force on the quartz beam arms. The force acting along the single-degree-of-freedom direction of the beam arms causes one quartz beam arm to be in tension, and its natural oscillation frequency increases, while the other beam arm is in compression, and its natural oscillation frequency decreases. The resonant frequency of the oscillation of the quartz beam arms in the quartz meter head is:

[0023] f1 = f0(1 + a in F)

[0024] where, f0 is the oscillation frequency of the quartz beam arms when the external acceleration a in is 0, and F is the acceleration frequency conversion coefficient.

[0025] See Figure 2 , the multivibrator includes two lead-out ends arranged on the quartz beam arms. One lead-out end is connected to one end of a resistor R1 and the input end of an inverter G1, and the other lead-out end is connected to one end of a resistor R3 and one end of a resistor R4. The other end of the resistor R1 and the output end of the inverter G1 are both connected to one end of a resistor R2. The other end of the resistor R2 is connected to the input end of an inverter G2 and the other end of the resistor R3. A capacitor C1 is connected in parallel with the resistor R3. The output end of the inverter G2 and the other end of the resistor R4 are connected to the shaping driver. The shaping driver includes a series-connected inverter G3 and inverter G4. The input end of the inverter G3 is connected to the output end of the multivibrator, and the output end of the inverter G4 is connected to the F / V converter. The inverter G1, inverter G2, capacitor C1, resistor R1 to resistor R4 form a positive feedback oscillation circuit. The inverter G1 and inverter G2 form a 360° phase shift to maintain the stable oscillation of the quartz beam arms. The inverter G3 and inverter G4 are used to shape the oscillation waveform and provide sufficient signal driving ability for the subsequent F / V converter at the same time. The low level of the frequency signal output by the shaping driver unit is 0V, and the high level is 5V.

[0026] See Figure 3, the F / V converter includes a comparator U1. The positive input terminal of the comparator U1 is connected to a voltage, the negative input terminal of the comparator U1 is connected to an input signal, and the output terminal of the comparator U1 is connected to a monostable flip-flop U2. The monostable flip-flop U2 is connected to a switch S2. One end of the switch S2 is connected to a constant current source A1, and the other end is connected to an integrator or an output terminal. The integrator includes an operational amplifier U3. The non-inverting input terminal of the operational amplifier U3 is grounded, and the inverting input terminal of the operational amplifier U3 is connected to one end of a switch S1, one end of a capacitor C int1 and one end of a resistor R int1 . The other end of the capacitor C int1 and the other end of the resistor R int1 are both connected to the output terminal of the operational amplifier U3.

[0027] When the input signal f in of the F / V converter is less than 2.5V, the comparator U1 outputs a high level, and the monostable flip-flop U2 is triggered (the trigger time is t on1 ). The analog switch S1 closes to the left, and the constant current source A1 (with a current amplitude of a1) charges the integrator capacitor C int1 , and the charging time is t on1 ; after the trigger time of the monostable flip-flop U2 ends, the analog switch S1 closes to the right, and the constant current source A1 discharges through the resistor R int1 to the integrator capacitor C int1 . Within one cycle (t = 1 / f in ), the charging charge on the capacitor C int1 and the discharging charge from R int1 to C int1 are kept in balance, ensuring the stability of the voltage across the capacitor C int1 . Therefore, the output voltage of the F / V converter is:

[0028] V out = t on ·a1·R int1 ·f in = K FV ·f in (2)

[0029] In the formula, K FV is the conversion coefficient of the F / V converter.

[0030] The temperature sensor converts the collected temperature field information into a voltage V temp = K T ·T, where K T is the conversion coefficient of the temperature sensor. The voltage V temp and the output voltage V out of the F / V converter generate a comprehensive control voltage through an adder:

[0031] Vcon = K p ·(V out + V temp ) = K p ·(V out + K T ·T) (3)

[0032] Where K p is the adder gain.

[0033] See Figure 4 , the V / F converter includes an integrator. The integrator is connected to the input terminal. One end of the integrator is connected to one end of switch S2. One end of switch S2 is also connected to the inverting input terminal of comparator U5. The other end of switch S2 is connected to constant current source A2. The input terminal of the integrator is connected to the inverting input terminal of comparator U5. The non-inverting input terminal of comparator U5 is connected to the voltage. The output terminal of comparator U5 is connected to monostable flip-flop U6. Monostable flip-flop U6 controls switch S2. The output terminal of monostable flip-flop U6 serves as the output terminal of the V / F converter.

[0034] The integrator includes operational amplifier U4. The non-inverting input terminal of operational amplifier U4 is grounded. The inverting input terminal of operational amplifier U4 is connected to one end of resistor R int2 , one end of capacitor C int2 , and switch S2. The other end of resistor R int2 is connected to the input terminal. The other end of capacitor C int2 and the output terminal of operational amplifier U4 are connected to the inverting input terminal of comparator U5.

[0035] At the start of conversion, input voltage V con charges capacitor C int2 through resistor R int2 . The charging current is:[[]]

[0036]

[0037] When the output of operational amplifier U4 drops to -1.0V, the output of comparator U5 is at a high level, and monostable flip-flop U6 is triggered (the trigger time is t on2 ). Analog switch S2 closes to the left. Constant current source A2 (with a current amplitude of a2) and the input voltage act together to discharge integrator capacitor C in with a current of (a2 - I int2 ). The discharge time is t on2 . At this time, the voltage change amount is:[[]]

[0038]

[0039] After the triggering time of the monostable flip-flop U5 ends, the analog switch S2 closes to the left, and the converter starts the next integration cycle, repeatedly forming self-excited oscillation.

[0040] According to formulas (4) and (5), the capacitor charging time is

[0041]

[0042] In summary, the output frequency of the V / F converter is:

[0043]

[0044] where K VF is the conversion coefficient of the V / F converter.

[0045] Combining formulas (1), (2), (3), and (7), we have:

[0046] f out = K VF K p [K FV f0(1 + a in F) + K T T] (8)

[0047] f out = K VF K p K FV f0 + (K VF K p K FV f0F)a in + K VF K p K T T (9)

[0048] f out = f os + K SF a in + K TF T (10)

[0049] where f os = K VF K p K FV f0 is the zero offset of the vibrating beam accelerometer output; K SF = K VF K p K FV f0F is the scale factor of the vibrating beam accelerometer; K TF = K VF K p K T is the temperature-frequency conversion coefficient of the vibrating beam accelerometer.

[0050] In summary, the frequency output of the temperature compensation type quartz tuning fork accelerometer control circuit of the present invention includes external output acceleration and internal temperature field information, and at the same time adjusts the zero bias and scale factor of the accelerometer by changing the conversion coefficients of the F / V converter, V / F converter and adder.

Claims

1. A temperature compensation type quartz tuning fork accelerometer control circuit, characterized in that, It includes a multivibrator, which is connected to a quartz meter head. The output end of the multivibrator is connected to a shaping driver, the shaping driver is connected to an F / V converter, the F / V converter is connected to one signal input end of an adder, the other signal input end of the adder is connected to a temperature sensor, the output end of the adder is connected to a V / F converter, and the signal output end of the V / F converter serves as the signal output end of the quartz tuning fork accelerometer; The shaping driver includes an inverter G3 and an inverter G4 connected in series. The input end of the inverter G3 is connected to the output end of the multivibrator, and the output end of the inverter G4 is connected to the F / V converter; The F / V converter includes a comparator U1. The positive input end of the comparator U1 is connected to a voltage, the negative input end of the comparator U1 is connected to an input signal, the output end of the comparator U1 is connected to a monostable flip-flop U2, the monostable flip-flop U2 is connected to a switch S2, one end of the switch S2 is connected to a constant current source A1, and the other end is connected to an integrator or an output end; The integrator includes an operational amplifier U3. The non-inverting input terminal of the operational amplifier U3 is grounded, and the inverting input terminal of the operational amplifier U3 is connected to one end of a switch S1, one end of a capacitor C, and one end of a resistor R. int1 int1 The other end of the capacitor C int1 and the other end of the resistor R int1 are both connected to the output terminal of the operational amplifier U3. The V / F converter includes an integrator. The integrator is connected to an input end, the integrator is connected to one end of the switch S2, one end of the switch S2 is also connected to the negative input end of a comparator U5, the other end of the switch S2 is connected to a constant current source A2, the input end of the integrator is connected to the negative input end of the comparator U5, the positive input end of the comparator U5 is connected to a voltage, the output end of the comparator U5 is connected to a monostable flip-flop U6, the monostable flip-flop U6 controls the switch S2, and the output end of the monostable flip-flop U6 serves as the output end of the V / F converter; The integrator includes an operational amplifier U4. The non-inverting input terminal of the operational amplifier U4 is grounded, and the inverting input terminal of the operational amplifier U4 is connected to one end of a resistor R int2 , one end of a capacitor C int2 , and a switch S2. The other end of the resistor R int2 is connected to the input terminal. The other end of the capacitor C int2 and the output terminal of the operational amplifier U4 are connected to the inverting input terminal of a comparator U5; The control circuit adjusts the zero bias and scale factor of the quartz tuning fork accelerometer by changing the conversion coefficients of the F / V converter, the V / F converter and the adder.

2. The temperature compensation type quartz tuning fork accelerometer control circuit according to claim 1, wherein The multivibrator includes two lead-out ends arranged on the quartz beam arm. One lead-out end is connected to one end of a resistor R1 and the input end of an inverter G1, the other lead-out end is connected to one end of a resistor R3 and one end of a resistor R4. The other end of the resistor R1 and the output end of the inverter G1 are both connected to one end of a resistor R2. The other end of the resistor R2 is connected to the input end of an inverter G2 and the other end of the resistor R3. A capacitor C1 is connected in parallel with the resistor R3. The output end of the inverter G2 and the other end of the resistor R4 are connected to the shaping driver.

3. A temperature compensation type quartz tuning fork accelerometer control circuit according to claim 1, characterized in that The resonant frequency of the oscillation of the quartz beam arm in the quartz meter head is: where f0 is the external acceleration a in is the oscillation frequency of the quartz beam arm when it is 0, and F is the acceleration frequency conversion coefficient.

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