Wide-temperature low-power-consumption temperature control system suitable for hemispherical resonator gyroscope inertial measurement unit

Abstract

The invention relates to a wide-temperature low-power-consumption temperature control system suitable for a hemispherical resonator gyroscope inertial measurement unit. The wide-temperature low-power-consumption temperature control system comprises a heat shielding unit and a temperature control unit, the heat shielding unit comprises a heat shielding cover and a heat insulation support; the temperature control unit comprises a PID (Proportion Integration Differentiation) signal processing unit, a power amplification unit, a heating element and a heat sensor; the plurality of heat insulation supports penetrate through the bottom of the heat shielding cover in a sealing manner, the upper ends of the plurality of heat insulation supports are positioned in the heat shielding cover and are arranged at equal height, the upper ends of the plurality of heat insulation supports form an inertial component mounting surface, and the inertial component is fixedly mounted in the heat shielding cover by penetrating screws into inner holes of the heat insulation supports; the PID signal processing unit and the power amplification unit are arranged outside the heat shielding case, and the heating element and the heat sensor are arranged inside the heat shielding case and are fixedly mounted on the inertia assembly; the heating element and the heat sensor are respectively connected with the power amplification and PID signal processing unit through respective signal lines, and the signal lines hermetically penetrate through line passing holes formed in the heat shielding cover.

Description

Technical Field

[0001] This invention relates to the field of inertial measurement technology, and in particular to a wide-temperature, low-power temperature control system suitable for hemispherical resonant gyroscope inertial measurement units. Background Technology

[0002] Compared to temperature compensation technology, temperature control technology for inertial measurement units (IMUs) offers several advantages. First, it reduces the accuracy requirements of inertial instruments (a significant proportion of low-precision gyroscopes or instruments require additional temperature compensation because their accuracy is insufficient after temperature compensation, although their accuracy is not low when operating under constant temperature conditions). This facilitates cost-effective product control. Second, it fully utilizes the accuracy potential of inertial instruments (the same inertial instrument can achieve higher accuracy after temperature compensation). Temperature control technology remains an indispensable technology in the field of inertial measurement for low-cost and high-precision applications.

[0003] However, one of the biggest drawbacks of temperature control systems is their high power consumption, which is even much higher than the power consumption of the inertial measurement loop itself. This also narrows the range of ambient temperature adaptability (the wider the range, the greater the power consumption), which greatly limits the application of temperature control technology. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a wide-temperature, low-power temperature control system suitable for hemispherical resonant gyroscope inertial measurement units.

[0005] The above-mentioned objective of this invention is achieved through the following technical solution: A wide-temperature, low-power temperature control system for a hemispherical resonant gyroscope inertial measurement unit includes a thermal shielding unit and a temperature control unit; the thermal shielding unit includes a thermal shielding cover and a thermal insulation support; the temperature control unit includes a PID signal processing unit, a power amplification unit, a heating element, and a thermal sensor. Multiple thermal insulation supports are sealed and installed at the bottom of the heat shield. The upper ends of the multiple thermal insulation supports are located inside the heat shield and are set at the same height. The upper ends of the multiple thermal insulation supports form the mounting surface of the inertial assembly. The inertial assembly is fixedly installed inside the heat shield by inserting screws through the inner holes of the thermal insulation supports. The PID signal processing unit and power amplification unit are located outside the heat shield, while the heating element and thermal sensor are located inside the heat shield and fixedly mounted on the inertial assembly. The heating element and thermal sensor are connected to the power amplification and PID signal processing units respectively via their respective signal lines. The gyroscope and accelerometer of the inertial assembly are also connected to the digital processing and signal acquisition circuits via their respective signal lines. The signal lines are sealed and pass through the wire holes provided on the heat shield.

[0006] Moreover, the heat shield adopts a three-layer structure, with the middle layer being aerogel felt; the inner and outer layers of the heat shield are made of thin-walled aluminum alloy plates.

[0007] Furthermore, the thermal conductivity of the intermediate layer of the heat shield is 0.015 to 0.025 W / mK.

[0008] Moreover, the surface of the thin-walled aluminum alloy plate is mirror polished and treated with a chromium-free conversion film, resulting in a thermal emissivity and absorptivity as low as 0.04 to 0.06.

[0009] Furthermore, the thermal insulation support adopts a support column structure with a screw through hole in the center, and a flange is provided at the upper end of the support column; the thermal insulation support is made of polyetheretherketone material.

[0010] Furthermore, the thermal conductivity of the thermal insulation support is 0.25 W / (m·K).

[0011] Furthermore, a small blind hole is provided at the center of the bottom of the inertial component, and the thermal sensor is attached to the blind hole near the bottom of the hole to achieve center temperature measurement.

[0012] Moreover, the heating element is a heating plate, and multiple heating plates are symmetrically bonded to the left and right sides or front and back sides of the inertial assembly, and the heating power of the heating plates on both sides is equal.

[0013] The advantages and positive effects of this invention are as follows: 1. This invention places the inertial components with minimal power consumption and heat generation within a thermal shield for constant temperature control, while placing the digital processing and signal acquisition circuits with higher power consumption and heat generation but stable temperature compensation characteristics within a thermal shield, thereby achieving a very significant low power consumption characteristic over a wide temperature range.

[0014] 2. The heat shield of this invention adopts a three-layer structure. The middle layer is made of aerogel felt, which achieves a low thermal conductivity. The inner and outer layers are made of thin-walled aluminum alloy plates that have been mirror polished and treated with chromium-free conversion film, which achieves extremely low thermal radiation emissivity and absorptivity, thereby achieving a better heat shielding effect and significantly reducing the heat dissipation of inertial components, thus helping to reduce power consumption. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the heat shielding unit of the present invention; Figure 2 This is a structural diagram of the temperature control unit of the present invention. Detailed Implementation

[0016] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] This invention proposes a low-power temperature control design for hemispherical resonant gyroscope inertial measurement units, which can significantly reduce temperature control power consumption under mainstream temperature range conditions (i.e., wide temperature range). The key design features are: (1) The wide-temperature, low-power temperature control system of this invention is applied to a hemispherical resonant gyroscope inertial measurement unit. Firstly, because the accuracy performance of a hemispherical resonant gyroscope is not correlated with its size (while high-precision optical gyroscopes are very large), a small-volume hemispherical resonant gyroscope inertial measurement unit can cover application scenarios of high, medium, and low accuracy levels. The small size of the inertial measurement unit is a technical advantage for achieving low power consumption in temperature control. Secondly, hemispherical resonant gyroscopes have extremely low power consumption compared to optical gyroscopes, making them suitable for heat-shielded designs. Thirdly, hemispherical resonant gyroscope inertial measurement is an emerging technology field with broad future application prospects.

[0018] (2) The core of the design of this invention is the use of thermal shielding technology for inertial components (including gyroscope HRG and accelerometer). This is the biggest innovation compared to other temperature control designs. Based on thermal shielding, the heat dissipation of the temperature control object can be greatly reduced, which is the key to achieving low power temperature control.

[0019] (3) Based on the low power consumption characteristics, the temperature control system can achieve wide temperature adaptability. Compared with other temperature-controlled inertial measurement units, the design of this invention can adapt to the temperature conditions of non-temperature-controlled products, such as the lower limit of -20℃.

[0020] This invention applies to a wide-temperature, low-power temperature control system for a hemispherical resonant gyroscope inertial measurement unit. Please refer to [link to relevant documentation]. Figure 1 and Figure 2 It mainly includes a heat shielding unit and a temperature control unit. The heat shielding unit includes a heat shield cover and a heat insulation support 4. The temperature control unit includes a PID signal processing unit, a power amplification unit, a heating element 9, and a thermal sensor 8.

[0021] The PID signal processing unit functions as follows: The microcontroller (any system with computational capabilities, such as a microcontroller, DSP, ARM, FPGA, etc.) compares the temperature signal output by the thermal sensor with the target temperature value to obtain an error value. The error value is then processed by a PID (proportional P-integral I-derivative D) algorithm. P controls the response speed, I controls the steady-state accuracy, and D suppresses control overshoot and fluctuations. Finally, a PWM duty cycle control signal is generated. By optimizing and adjusting the PID parameters, high-precision, fast, and stable temperature control can be achieved.

[0022] Power amplifier unit: Using PWM control signal as input, it controls high-power transistors or MOSFETs to efficiently output power signals to the heating element in switching mode.

[0023] The heating element is used to heat the inertial component 6, and the thermal sensor is used to detect the temperature of the inertial component.

[0024] The gyroscope and accelerometer (including preamplifier circuitry) consume very little power and generate very little heat (<2W). The inertial assembly composed of these components is placed within a thermal shield for constant temperature control. The heating element and thermal sensor are placed inside the shield and fixed to the inertial assembly.

[0025] The PID signal processing unit and power amplification unit constitute the digital processing and signal acquisition circuit. Since the digital processing and signal acquisition circuit consumes a significant amount of power and generates considerable heat, but its temperature compensation characteristics are stable, it is placed outside the thermal shield and its temperature is not controlled. Instead, its temperature error characteristics are digitally compensated, typically using a second-order model, as shown in the following equation: In the formula, — Output error caused by temperature changes; —Temperature coefficient; --temperature.

[0026] See Figure 1 The heat shield is designed for comprehensive shielding based on three mechanisms of heat transfer, specifically: (1) Air heat conduction and convection prevention design: The heat shield adopts a three-layer structure design. The middle layer 3 is "aerogel felt", which has an extremely low thermal conductivity, which can minimize heat conduction loss. The thermal conductivity is only 0.015~0.025W / (mK), which is better than common polyurethane foam and glass fiber cotton, and is easy to process and mold. Silicone rubber 5 is used to seal the joints and pores of the heat shield, so that the gas inside and outside the shield does not have heat convection loss.

[0027] (2) Heat radiation protection design: The inner layer 2 and outer layer 1 of the heat shield are made of thin-walled aluminum alloy plates. The surface of the thin-walled aluminum alloy plates is mirror polished and treated with a chromium-free conversion film. The heat radiation emissivity and absorptivity can be as low as 0.04 to 0.06, which is better than stainless steel materials. It is also easy to process and low in cost. The process steps of mirror polishing and chromium-free conversion film treatment are described as follows: a) Pre-treatment: Surface cleaning to remove grease and dirt; Surface flattening: preliminary grinding of the surface. If the surface flatness of the board is good, the next step can be carried out directly. b) Mirror polishing: Use a polishing machine to perform rough polishing and fine polishing separately. Fine polishing should be done with a cloth wheel or sponge wheel and high-quality polishing compound with a thickness of less than 1μm. After polishing, use anhydrous ethanol or acetone to remove any residual polishing compound. c) Chromium-free conversion coating treatment: Surface cleaning again; surface activation with acidic solution; zirconium-based / titanium-based conversion coating treatment, immersion or spraying with fluorozirconic acid / fluorotitanic acid treatment solution for 1 to 5 minutes, after treatment, a nano-scale completely transparent inert protective film layer is formed on the surface, which will not reduce the specular reflectivity; sealing and drying, after film formation, a sealing treatment can be performed with deionized water or hot air drying at 60℃ to 80℃ (preferably using a dust-free oven).

[0028] In addition, a wire passage hole is provided on the shielding cover, and a signal wire 10 is sealed and installed in the wire passage hole. This is used to realize the electrical connection between the thermal sensor and heating element inside the shielding cover and the PID signal processing unit and power amplification unit outside the shielding cover, as well as the electrical connection between the gyroscope and the accelerometer and the external digital processing and signal acquisition circuitry. The wire passage hole is located on the edge of the shielding cover and is an open U-shaped hole to facilitate the installation and removal of the shielding cover and the wire passage hole.

[0029] The thermal insulation support adopts a support column structure with a screw through hole in the center, and a flange is provided at the upper end of the support column. Multiple thermal insulation supports are sealed and installed at the bottom of the heat shield, and the upper ends of the multiple thermal insulation supports inside the shield are set at the same height to support the inertial assembly and are fixed by screws 7. The thermal insulation support is made of polyetheretherketone (PEEK) material, which has the advantages of high strength, high rigidity, high temperature resistance, and chemical stability. Its creep resistance is far superior to that of nylon material, which can ensure that the inertial assembly does not deform or shift relative to the whole machine and generate additional inertial measurement errors. Its thermal conductivity is only 0.25W / (m·K), which is about one six-hundredth of that of aluminum, and it has good thermal insulation performance.

[0030] See Figure 2 Temperature control design: The temperature control of this invention is a pure heating type temperature control, which does not require stirring or cooling fans.

[0031] The thermal sensor and the inertial components should maintain good thermal contact to ensure accurate measurement, and temperature measurement at the center can ensure temperature uniformity.

[0032] The heating elements should maintain good thermal contact with the inertial assembly and be kept away from the thermal sensor. If multiple heating elements are required, they should be spatially symmetrical with the thermal sensor as the center to ensure uniform heating. In this system, a small blind hole is drilled from the center of the bottom of the inertial assembly towards the center. The thermal sensor is then attached to the end of the blind hole, thus achieving temperature measurement at the center. Heating elements (heating plates) are symmetrically attached to the left and right sides or front and back sides of the inertial assembly, achieving spatial symmetry with the heating plates away from the thermal sensor and centered on the sensor. Since the inertial assembly is equipped with a gyroscope and accelerometer, the two sides on which the sensor can be attached may have different sizes and shapes. The heating plates should be attached to the corresponding sides with larger free planes, ensuring that the resistance of the heating plates is equal (i.e., equal heating power). Thermally conductive silicone is used for attachment, with a temperature range of -60℃ to 250℃, which fully meets the requirements of this system.

[0033] Example: The inertial component of a certain type of hemispherical resonant gyroscope inertial measurement unit has a volume of 10 cm³, a support mounting surface of 1 cm² × 3, and is installed inside a 14 cm³ aluminum casing of the inertial measurement unit instrument. It was tested in a temperature chamber simulating an ambient temperature of -20℃, and the inertial component was heated to a constant temperature of 55℃ (these conditions are for comparison purposes only and are not part of the design specifications). After thermal stabilization, the following results were obtained through testing: The design without thermal shielding results in a total heat dissipation of no less than 115W, of which 82W is conducted through the mounting surface and 33W is transmitted through radiation and convection. However, the wide-temperature, low-power temperature control system of this invention has a total heat dissipation of no more than 10W.

[0034] The comparison results show that this design has a very significant low power consumption characteristic over a wide temperature range.

[0035] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A wide-temperature, low-power temperature control system suitable for a hemispherical resonant gyroscope inertial measurement unit, characterized in that: It includes a heat shielding unit and a temperature control unit; the heat shielding unit includes a heat shield cover and a heat insulation support; the temperature control unit includes a PID signal processing unit, a power amplification unit, a heating element, and a thermal sensor; Multiple thermal insulation supports are sealed and installed at the bottom of the heat shield. The upper ends of the multiple thermal insulation supports are located inside the heat shield and are set at the same height. The upper ends of the multiple thermal insulation supports form the mounting surface of the inertial assembly. The inertial assembly is fixedly installed inside the heat shield by inserting screws through the inner holes of the thermal insulation supports. The PID signal processing unit and the power amplification unit are located outside the heat shield, while the heating element and the thermal sensor are located inside the heat shield and are fixedly mounted on the inertial assembly. The heating element and the thermal sensor are connected to the power amplification unit and the PID signal processing unit respectively through their respective signal lines, and the signal lines are sealed and pass through the wire holes provided on the heat shield.

2. The wide-temperature, low-power temperature control system for a hemispherical resonant gyroscope inertial measurement unit according to claim 1, characterized in that: The heat shield has a three-layer structure, with the middle layer being aerogel felt and the inner and outer layers being thin-walled aluminum alloy plates.

3. The wide-temperature, low-power temperature control system for a hemispherical resonant gyroscope inertial measurement unit according to claim 2, characterized in that: The thermal conductivity of the middle layer of the heat shield is 0.015 to 0.025 W / mK.

4. The wide-temperature, low-power temperature control system for a hemispherical resonant gyroscope inertial measurement unit according to claim 2, characterized in that: The surface of the thin-walled aluminum alloy plate is mirror polished and treated with a chromium-free conversion film, resulting in a thermal emissivity and absorptivity as low as 0.04 to 0.

06.

5. The wide-temperature, low-power temperature control system for a hemispherical resonant gyroscope inertial measurement unit according to claim 1, characterized in that: The thermal insulation support adopts a support column structure with a screw through hole in the center, and a flange is provided at the upper end of the support column; the thermal insulation support is made of polyetheretherketone material.

6. The wide-temperature, low-power temperature control system for a hemispherical resonant gyroscope inertial measurement unit according to claim 5, characterized in that: The thermal conductivity of the thermal insulation support is 0.25 W / (m·K).

7. The wide-temperature, low-power temperature control system for a hemispherical resonant gyroscope inertial measurement unit according to claim 1, characterized in that: A small blind hole is provided at the center of the bottom of the inertial component, and the thermal sensor is attached to the blind hole near the bottom of the hole to achieve center temperature measurement.

8. The wide-temperature, low-power temperature control system for a hemispherical resonant gyroscope inertial measurement unit according to claim 7, characterized in that: The heating element is a heating plate, and multiple heating plates are symmetrically bonded to the left and right sides or front and back sides of the inertial assembly, and the heating power of the heating plates on both sides is equal.

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