Self-adaptive adjustment linear control gravimeter constant temperature system and working method

Abstract

The invention relates to a self-adaptive adjustment linear control gravimeter constant temperature system and a working method, the self-adaptive adjustment linear control gravimeter constant temperature system comprises a precision circuit subsystem, a primary subsystem, a secondary subsystem, a vibration damping pillar and a gravity sensor, and the self-adaptive adjustment linear control gravimeter constant temperature system takes enhancement of constant temperature and uniform temperature effects of a core inertial device as a core and takes temperature excursion and heat dissipation characteristics of an electronic device into consideration. The current control type linear constant temperature control circuit with the current adjustable function is adopted, electromagnetic interference is restrained, and the temperature control reliability is improved. The graphite material with a good soaking effect is adopted to enhance the soaking property of the gravity sensor and is filled with a proper amount of soaking inert gas, and meanwhile, multi-point self-adjusting constant-temperature control is adopted for inertia core parts such as the gravity sensor, so that the global temperature field of the inertia core parts such as the gravity sensor is balanced and stable; the method has strong stability against dynamic disturbance, and is beneficial to improving the resolution and precision of gravity measurement.

Description

Technical Field

[0001] The invention belongs to the technical field of inertial measurement, and in particular to a self-adjusting linear control gravimeter constant temperature system and a working method. Background Art

[0002] In the field of high-precision dynamic gravity measurement, it is necessary to implement high-precision constant temperature control for inertial core parts such as gravity sensors. In the field of portable mobile relative gravimeters, domestic gravimeter equipment is gradually developing, but it is difficult to achieve breakthrough results in small-volume, low-power constant temperature systems. In the existing technical achievements, the structure cannot effectively balance heat dissipation and stability, and the temperature field of the hollow gravity sensor is uneven, resulting in high power consumption, general stability, and difficulty in adapting to extreme high and low temperature environments. In terms of circuit control, a single analog or digital PWM control method is generally used. The former has poor adaptability and is inconvenient to debug. Although the latter has good ergonomics, it has large electromagnetic interference, which is not conducive to high-precision gravity measurement. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and propose an adaptively adjusted linear control gravimeter constant temperature system and working method, with the core of enhancing the constant temperature and temperature equalization effect of the core inertial device, taking into account the temperature drift and heat dissipation characteristics of the electronic device, and adopting a current-controlled linear constant temperature control circuit with an adjustable current function. The constant temperature and temperature equalization effect of the inertial core parts such as the gravity sensor are greatly improved, while suppressing electromagnetic interference and improving the reliability of temperature control, which is conducive to further improving the measurement resolution and accuracy of the inertial gravity sensor.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] A self-adjusting linear control gravimeter constant temperature system and a working method thereof, comprising a precision circuit subsystem, a primary subsystem, a secondary subsystem, a vibration-damping strut and a gravity sensor, wherein the secondary subsystem is provided with vibration-damping struts at the top and the bottom respectively, and the vibration-damping struts are used to reduce the vibration of the constant temperature system of the gravimeter, the primary subsystem and the precision circuit subsystem are arranged inside the secondary subsystem, and the gravity sensor is arranged inside the primary subsystem.

[0006] Moreover, the first-level subsystem includes a first-level upper heating film belt, a first-level side wall heating film belt, a first-level lower heating film belt, a first-level subsystem temperature measuring thermistor and a first-level thermal insulation aerogel. The outer four sides of the gravity sensor are first covered with graphite thermal conductive material. The first-level upper heating film belt, the first-level side wall heating film belt and the first-level lower heating film belt are respectively pasted on the upper end, side wall and lower end of the gravity sensor covered with graphite thermal conductive material. The gravity sensor pasted with the heating film belt is tightly wrapped by the first-level thermal insulation aerogel and arranged inside the second-level subsystem. The first-level subsystem temperature measuring thermistors are respectively arranged at the upper, middle and lower ends of the gravity sensor.

[0007] Moreover, the precision circuit subsystem includes a precision circuit module, a heating circuit module, a heating circuit heating film tape, a heating circuit thermal insulation aerogel, a precision circuit heating film tape and a precision circuit thermal insulation aerogel. After the precision circuit module is pasted with the precision circuit heating film tape and wrapped with the precision circuit thermal insulation aerogel, it is arranged above the primary subsystem. After the heating circuit module is pasted with the heating circuit heating film tape and wrapped with the heating circuit thermal insulation aerogel, it is arranged above the precision circuit module.

[0008] Moreover, the secondary subsystem includes an outer shell, a secondary subsystem temperature-sensitive resistor, a secondary heating film belt and a secondary thermal insulation aerogel, wherein the outer shell is cylindrical, and is made of lightweight red copper to be processed into a cylindrical barrel with a reserved groove for placing the secondary subsystem temperature-sensitive resistor. A secondary heating belt is pasted on the outer wall of the outer shell, and then the secondary aerogel is used for thermal insulation to tightly wrap it.

[0009] Moreover, the precision circuit module includes the precision circuit of the gravity sensor constant temperature multi-point control self-adjusting circuit and the precision circuit of the secondary and precision circuit board constant temperature measurement circuit, wherein the precision circuit of the gravity sensor constant temperature multi-point control self-adjusting circuit includes: a first operational amplifier circuit, a second operational amplifier circuit, a third operational amplifier circuit, a first single-channel precision instrument operational amplifier, a first 24-bit A / D converter, a dual-channel precision instrument operational amplifier and an ARM, wherein the output end of the second operational amplifier circuit is connected to the input end of the first single-channel precision instrument operational amplifier, the output end of the first single-channel precision instrument operational amplifier is connected to the input end of the first 24-bit A / D converter, the output end of the first 24-bit A / D converter, the output end of the first operational amplifier circuit, the output end of the second operational amplifier circuit and the output end of the third operational amplifier circuit are respectively connected to the input end of the dual-channel precision instrument operational amplifier, and the output end of the dual-channel precision instrument operational amplifier is connected to the ARM.

[0010] Moreover, the precision circuits of the secondary and precision circuit board constant temperature measurement circuits include: a fourth operational amplifier circuit, a fifth operational amplifier circuit, a second single-channel precision instrument operational amplifier, a third single-channel precision instrument operational amplifier, a second 24-bit A / D converter, a third 24-bit A / D converter and ARM, wherein the fourth operational amplifier circuit is connected to ARM in sequence through the second single-channel precision instrument operational amplifier and the second 24-bit A / D converter, and the fifth operational amplifier circuit is connected to ARM in sequence through the third single-channel precision instrument operational amplifier and the third 24-bit A / D converter.

[0011] Moreover, the current-controlled digital real-time adjustable linear temperature control circuit with current adjustable function (this circuit is integrated in the precision circuit module and the heating circuit module and will not be repeated separately. The circuits involved in this article are all embodied in the precision circuit module and the heating circuit module) includes: the PWM control signal output by the ARM processor in real time according to the control algorithm is input to the PAC module after the optocoupler isolator, and the 0% to 100% PWM digital signal is linearly converted into a 4 to 20mA current output, and then the current adjustable circuit constructed by the Darlington tube and the current detection operational amplifier drives the heating plate to work.

[0012] A method for operating a self-adjusting linear control gravimeter constant temperature system comprises the following steps:

[0013] Step 1: Build a two-stage six-way constant temperature system, with the core of enhancing the constant temperature and temperature equalization effect of the core inertial device, taking into account the temperature drift and heat dissipation characteristics of the electronic device, and design the circuit board constant temperature system into a precision circuit module and a heating circuit module. The heating circuit module adopts a switch temperature control mode;

[0014] Step 2: Use a precision voltage reference chip to generate a high-precision reference voltage, and construct a grounded constant current source circuit with a precision instrument operational amplifier and a high-precision metal film resistor to generate a constant current suitable for driving the thermistor, which is beneficial to improve the temperature measurement accuracy and provide a precise temperature measurement basis for high-precision constant temperature control;

[0015] Step 3. The heating film strips on the side wall, upper end and lower end of the cylindrical gravity sensor in the first-level constant temperature subsystem are individually controlled for heating, and the real-time temperature value is fed back by the temperature measuring thermistor of the first-level subsystem to achieve three-point constant temperature control; the thermistor at the center is used as the reference for temperature control, and the temperature-voltage comparison method is adopted. The ARM control strategy is used to correct the upper and lower temperature control values ​​in real time to be consistent with the center temperature value, thereby greatly reducing the axial temperature gradient difference and creating a temperature field that is close to equilibrium.

[0016] The advantages and positive effects of the present invention are:

[0017] 1. The present invention constructs an adaptively adjusted linear control gravity meter constant temperature system through a precision circuit subsystem, a primary subsystem, a secondary subsystem, a vibration-damping strut, and a gravity sensor, with the core being to enhance the constant temperature and temperature-averaging effect of the core inertial device, while taking into account the temperature drift and heat dissipation characteristics of the electronic device. The present invention adopts a current-controlled linear constant temperature control circuit with an adjustable current function to suppress electromagnetic interference and improve temperature control reliability. The present invention adopts a graphite material with a good heat-averaging effect to enhance the heat-averaging property of the gravity sensor and fills it with an appropriate amount of heat-averaging inert gas. At the same time, multi-point self-adjusting constant temperature control is adopted in the inertial core parts such as the gravity sensor to achieve a balanced and stable global temperature field in the inertial core area such as the gravity sensor, which has strong stability against dynamic disturbances and is conducive to improving the resolution and accuracy of gravity measurements.

[0018] 2. The present invention constructs a multi-channel and multi-point constant temperature control system, fills a sealed hollow gravity sensor with appropriate helium and lays an appropriate amount of graphite material on the copper structure to create a balanced or nearly balanced temperature field for the gravity sensor. Taking into account the temperature drift and heat dissipation characteristics of electronic devices, it is conducive to the construction of a low-power, high-stability constant temperature system.

[0019] 3. The present invention constructs a linear temperature control circuit with digital real-time adjustment, and proposes a current-controlled linear constant temperature control circuit with current adjustable function, which effectively combines the digital processing circuit and the analog drive circuit, greatly improves the feasibility of circuit implementation and the flexibility of low power consumption and temperature control debugging, and greatly suppresses the electromagnetic interference caused by the traditional switch temperature control mode.

[0020] 4. The present invention constructs a temperature measurement circuit with a load-grounded constant current source driving a thermistor to measure temperature with a constant current commutation driving function, and the circuit design is simple and smart. The load common ground is realized, making the output constant current easier to realize and stable, and avoiding the influence of the ground level on the load and the circuit, and the use of an instrument operational amplifier to output the resistor voltage can effectively suppress the common mode influence.

[0021] 5. The upper, middle and lower constant temperature control of the cylindrical gravity sensor of the present invention adopts an autonomous correction strategy to achieve a balanced and stable state of the global temperature field, designs a three-point temperature comparison circuit, and adopts a one-point-drive-multiple-point self-regulating control strategy for real-time dynamic adaptive correction, thereby optimizing control flexibility and improving control efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the multi-point multi-channel constant temperature control system of the present invention;

[0023] Figure 2 This is a constant temperature multi-point control self-adjusting circuit diagram of the gravity sensor of the present invention;

[0024] Figure 3This is the constant temperature measurement circuit diagram of the secondary and precision circuit board of the present invention;

[0025] Figure 4 This is a digital real-time adjustable linear temperature control circuit diagram of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to the accompanying drawings.

[0027] A self-adjusting linear control gravimeter constant temperature system and working method, such as Figure 1 As shown, it includes a precision circuit subsystem, a primary subsystem, a secondary subsystem, a vibration-damping strut and a gravity sensor (the gravity sensor is cylindrical), wherein the secondary subsystem is provided with vibration-damping struts at the top and bottom respectively, and the vibration-damping struts are used to reduce the vibration of the gravimeter's constant temperature system, the primary subsystem and the precision circuit subsystem are arranged inside the secondary subsystem, and the gravity sensor is arranged inside the primary subsystem.

[0028] The first-level subsystem includes a first-level upper heating film belt, a first-level side wall heating film belt, a first-level lower heating film belt, a first-level subsystem temperature measuring thermistor and a first-level thermal insulation aerogel. The outer four sides of the gravity sensor are first covered with graphite thermal conductive material. The first-level upper heating film belt, the first-level side wall heating film belt and the first-level lower heating film belt are respectively pasted on the upper end, side wall and lower end of the gravity sensor covered with graphite thermal conductive material. The gravity sensor pasted with the heating film belt is tightly wrapped by the first-level thermal insulation aerogel and arranged inside the second-level subsystem. The first-level subsystem temperature measuring thermistors are respectively arranged at the upper, middle and lower ends of the gravity sensor.

[0029] The precision circuit subsystem includes a precision circuit module, a heating circuit module, a heating circuit heating film tape, a heating circuit thermal insulation aerogel, a precision circuit heating film tape and a precision circuit thermal insulation aerogel. The precision circuit module is attached with the precision circuit heating film tape and wrapped with the precision circuit thermal insulation aerogel, and then arranged above the first-level subsystem. The heating circuit module is attached with the heating circuit heating film tape and wrapped with the heating circuit thermal insulation aerogel, and then arranged above the precision circuit module (the heating module is connected to the metal cover through a thermal pad to dissipate heat).

[0030] The secondary subsystem includes an outer shell, a secondary subsystem temperature-sensitive resistor, a secondary heating film belt and a secondary thermal insulation aerogel. The outer shell is cylindrical in shape, and is made of lightweight copper into a cylindrical cylinder (the upper cover is detachable) with a reserved groove for placing the secondary subsystem temperature-sensitive resistor. The inner diameter of the cylindrical cylinder just matches the primary constant temperature subsystem. The secondary heating belt is pasted on the outer wall of the outer shell (except the upper cover), and then the secondary aerogel is used to insulation it tightly.

[0031] The precision circuit module constant temperature subsystem is placed between the upper end of the first-level constant temperature subsystem and the constant temperature subsystem of the heating circuit module. The first-level constant temperature subsystem adopts a three-point constant temperature control method, which is committed to making the upper, middle and lower temperature fields of the cylindrical gravity sensor tend to zero gradient; the second-level constant temperature subsystem and the precision circuit module both adopt a single-point control method, which are respectively committed to resisting the impact of changes in external environmental temperature and providing a stable temperature environment for the precision circuit module; the heating circuit module adopts a switch control mode. When the external temperature is detected to be higher (higher than a certain set temperature value), the heating circuit module suspends control work to ensure that the heat is dissipated in time; when the external temperature is detected to be lower than a certain set temperature value, the heating circuit module starts control work to provide heat maintenance.

[0032] like Figure 2 As shown, the precision circuit module includes a precision circuit of a gravity sensor constant temperature multi-point control self-adjusting circuit and a precision circuit of a secondary and precision circuit board constant temperature measurement circuit, wherein the precision circuit of the gravity sensor constant temperature multi-point control self-adjusting circuit includes: a first operational amplifier circuit, a second operational amplifier circuit, a third operational amplifier circuit, a first single-channel precision instrument operational amplifier, a first 24-bit A / D converter, a dual-channel precision instrument operational amplifier and an ARM, wherein the output end of the second operational amplifier circuit is connected to the input end of the first single-channel precision instrument operational amplifier, the output end of the first single-channel precision instrument operational amplifier is connected to the input end of the first 24-bit A / D converter, the output end of the first 24-bit A / D converter, the output end of the first operational amplifier circuit, the output end of the second operational amplifier circuit and the output end of the third operational amplifier circuit are respectively connected to the input end of the dual-channel precision instrument operational amplifier, and the output end of the dual-channel precision instrument operational amplifier is connected to the ARM.

[0033] Precision voltage reference chip (temperature coefficient ≤ 20ppm / ℃) provides V ref (V ref =4.096V) high-precision reference voltage. Using load grounding technology, the high-precision V ref Voltage and precision instrumentation operational amplifier LTC2053, thermistor R t (load resistance), precision standard resistance R s (accuracy error ≤ 0.05%), high-precision metal film resistor R s (Constant current resistor, accuracy error ≤ 0.05%) to build a load grounded constant current source circuit. Among them, C1 and C2 are filter capacitors, and the capacitance is set to 0.1μF. Resistors R1 and R2 respectively build filter circuits with C1 and C2, and act as pull-down and pull-up buffers respectively. The calculation relationship of this load grounded constant current source is:

[0034]

[0035] Where I is a constant current, and its value can be determined according to the ideal working current required by the thermistor. ref If it is known, the size of I depends on R s The voltages formed by I flowing through the thermistor and the precision standard resistor are:

[0036]

[0037] Where V t Thermistor R t The reference voltage for the A / D converter LTC2380-24 is directly provided by the same precision voltage reference chip V ref High-precision reference voltage, so the conversion digital quantity D of the A / D converter is:

[0038]

[0039] Where n is the number of bits of the A / D converter (LTC2380-24 is a 24-bit analog-to-digital converter, so n = 24). From the relationship between the converted digital quantity D of the A / D converter, it can be seen that the final digital quantity D is only related to the load thermistor R t And precision standard resistor R d For the guaranteed standard resistance R d High precision, long-term stability and thermistor R t Due to its high sensitivity, high-precision temperature measurement can be achieved.

[0040] like Figure 3 As shown, the precision circuit of the secondary and precision circuit board constant temperature measurement circuit includes: a fourth operational amplifier circuit, a fifth operational amplifier circuit, a second single-channel precision instrument operational amplifier, a third single-channel precision instrument operational amplifier, a second 24-bit A / D converter, a third 24-bit A / D converter and ARM, wherein the fourth operational amplifier circuit is connected to ARM via the second single-channel precision instrument operational amplifier and the second 24-bit A / D converter in sequence, and the fifth operational amplifier circuit is connected to ARM via the third single-channel precision instrument operational amplifier and the third 24-bit A / D converter in sequence.

[0041] The heating film strips on the side wall, upper end and lower end of the cylindrical gravity sensor in the primary constant temperature subsystem are individually controlled and heated, respectively, with thermistors R t11 , R t12 and R t13 Thermistor R in the center is used to detect the temperature at the top, middle and bottom ends (three thermistors share a common ground). t12 The detected temperature-voltage value is collected and processed by a 24-bit A / D converter, and the upper and lower thermistors R t11 and R t13 High potential terminal voltage and thermistor R t11The high potential terminal voltage is differentially amplified (precision instrumentation amplifier) ​​and output. t11 , R t13 and R t12 When the voltage difference at the high potential end is 0, the temperature fields at the upper, middle and lower ends of the cylindrical gravity sensor reach an equal equilibrium state; when the thermistor R t11 , R t13 and R t12 When the voltage difference of the high potential end is not equal to 0, the temperature fields at the upper, middle and lower ends of the cylindrical gravity sensor have not reached an equal balance state, and it is necessary to correct the control in the ARM controller to achieve an equal balance state of the temperature field. t12 The constant temperature control value is T 12 , upper R t11 The constant temperature control value is T 11 and the lower end R t13 The constant temperature control value is T 13 , the overall temperature control value is T,R t11 (R t13 ) and R t12 The voltage difference at the high potential end is converted into temperature A, R t13 and R t12 The voltage difference at the high potential end is converted into the temperature value B, and the following correction strategy relationship is obtained:

[0042]

[0043] When A and B are not zero, T is corrected in real time in the ARM controller 11 and T 13 , so as to reach the same 12 When A and B are zero, the temperature field of the cylindrical gravity sensor has reached a state of equal equilibrium. Correction T 11 and T 13 With T 12 Maintaining equality is carried out in real time and synchronously with the constant temperature system control to ensure that the temperature field of the gravity sensor can be kept stable at any time.

[0044] like Figure 4 As shown, the real-time output PWM control signal is input to the PAC module (digital signal to analog signal chip) after the optocoupler isolator, and the 0% to 100% PWM digital signal is linearly converted into a 4 to 20mA current output, and then the current adjustable circuit constructed by the Darlington tube and the current detection operational amplifier drives the heater to work.

[0045] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. An adaptively adjusted linear controlled gravimeter constant temperature system and working method, characterized in that: It includes a precision circuit subsystem, a primary subsystem, a secondary subsystem, vibration-damping struts and a gravity sensor, wherein the secondary subsystem is provided with vibration-damping struts at the top and bottom respectively, and the vibration-damping struts are used to reduce the vibration of the gravimeter's constant temperature system, the primary subsystem and the precision circuit subsystem are arranged inside the secondary subsystem, and the gravity sensor is arranged inside the primary subsystem.

2. The self-adaptive linear control gravimeter constant temperature system according to claim 1, characterized in that: The first-level subsystem includes a first-level upper heating film belt, a first-level side wall heating film belt, a first-level lower heating film belt, a first-level subsystem temperature measuring thermistor and a first-level thermal insulation aerogel. The outer four sides of the gravity sensor are first covered with graphite thermal conductive material. The first-level upper heating film belt, the first-level side wall heating film belt and the first-level lower heating film belt are respectively pasted on the upper end, side wall and lower end of the gravity sensor covered with graphite thermal conductive material. The gravity sensor pasted with the heating film belt is tightly wrapped by the first-level thermal insulation aerogel and arranged inside the second-level subsystem. The first-level subsystem temperature measuring thermistors are respectively arranged at the upper, middle and lower ends of the gravity sensor.

3. The self-adjusting linear control gravimeter constant temperature system according to claim 1, characterized in that: The precision circuit subsystem includes a precision circuit module, a heating circuit module, a heating circuit heating film tape, a heating circuit thermal insulation aerogel, a precision circuit heating film tape and a precision circuit thermal insulation aerogel. After the precision circuit module is affixed with the precision circuit heating film tape and wrapped with the precision circuit thermal insulation aerogel, it is arranged above the primary subsystem. After the heating circuit module is affixed with the heating circuit heating film tape and wrapped with the heating circuit thermal insulation aerogel, it is arranged above the precision circuit module.

4. The self-adaptive linear control gravimeter constant temperature system according to claim 1, characterized in that: The secondary subsystem includes an outer shell, a secondary subsystem temperature-sensitive resistor, a secondary heating film belt and a secondary thermal insulation aerogel, wherein the outer shell is cylindrical, made of lightweight copper processed into a cylindrical barrel and a groove is reserved to place the secondary subsystem temperature-sensitive resistor, a secondary heating belt is pasted on the outer wall of the outer shell, and then the secondary aerogel is used for thermal insulation to tightly wrap it.

5. The self-adjusting linear control gravimeter constant temperature system according to claim 3, characterized in that: The precision circuit module includes a precision circuit of a gravity sensor constant temperature multi-point control self-adjusting circuit and a precision circuit of a secondary and precision circuit board constant temperature measurement circuit, wherein the precision circuit of the gravity sensor constant temperature multi-point control self-adjusting circuit includes: a first operational amplifier circuit, a second operational amplifier circuit, a third operational amplifier circuit, a first single-channel precision instrument operational amplifier, a first 24-bit A / D converter, a dual-channel precision instrument operational amplifier and an ARM, wherein the output end of the second operational amplifier circuit is connected to the input end of the first single-channel precision instrument operational amplifier, the output end of the first single-channel precision instrument operational amplifier is connected to the input end of the first 24-bit A / D converter, the output end of the first 24-bit A / D converter, the output end of the first operational amplifier circuit, the output end of the second operational amplifier circuit and the output end of the third operational amplifier circuit are respectively connected to the input end of the dual-channel precision instrument operational amplifier, and the output end of the dual-channel precision instrument operational amplifier is connected to the ARM.

6. The self-adjusting linear control gravimeter constant temperature system according to claim 5, characterized in that: The precision circuits of the secondary and precision circuit board constant temperature measurement circuits include: a fourth operational amplifier circuit, a fifth operational amplifier circuit, a second single-channel precision instrument operational amplifier, a third single-channel precision instrument operational amplifier, a second 24-bit A / D converter, a third 24-bit A / D converter and an ARM, wherein the fourth operational amplifier circuit is connected to the ARM in sequence through the second single-channel precision instrument operational amplifier and the second 24-bit A / D converter, and the fifth operational amplifier circuit is connected to the ARM in sequence through the third single-channel precision instrument operational amplifier and the third 24-bit A / D converter.

7. The self-adjusting linear control gravimeter constant temperature system according to claim 1, characterized in that: The current-controlled digital real-time adjustable linear temperature control circuit with current adjustable function comprises: a PWM control signal output by an ARM processor in real time according to a control algorithm is input into a PAC module through an optocoupler isolator, and a 0% to 100% PWM digital signal is linearly converted into a 4 to 20 mA current output, and then a current adjustable circuit constructed by a Darlington tube and a current detection operational amplifier drives the heating plate to work.

8. A method for operating the temperature-controlled system of a self-adjusting linear control gravimeter according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Build a two-stage six-way constant temperature system, with the core of enhancing the constant temperature and temperature equalization effect of the core inertial device, taking into account the temperature drift and heat dissipation characteristics of the electronic device, and design the circuit board constant temperature system into a precision circuit module and a heating circuit module. The heating circuit module adopts a switch temperature control mode; Step 2: Use a precision voltage reference chip to generate a high-precision reference voltage, and construct a grounded constant current source circuit with a precision instrument operational amplifier and a high-precision metal film resistor to generate a constant current suitable for driving the thermistor, which is beneficial to improve the temperature measurement accuracy and provide a precise temperature measurement basis for high-precision constant temperature control; Step 3. The heating film strips on the side wall, upper end and lower end of the cylindrical gravity sensor in the first-level constant temperature subsystem are individually controlled for heating, and the real-time temperature value is fed back by the temperature measuring thermistor of the first-level subsystem to achieve three-point constant temperature control; the thermistor at the center is used as the reference for temperature control, and the temperature-voltage comparison method is adopted. The ARM control strategy is used to correct the upper and lower temperature control values ​​in real time to be consistent with the center temperature value, thereby greatly reducing the axial temperature gradient difference and creating a temperature field that is close to equilibrium.

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