An adaptive temperature control device for a relative gravimeter

Abstract

The application provides an adaptive temperature control device for a relative gravimeter. The device comprises a temperature controller, a first PWM drive module, a second PWM drive module, a third PWM drive module and a first temperature sensor, a second temperature sensor and a third temperature sensor connected to the temperature controller, a first heating module, a second heating module and a third heating module connected to the first PWM drive module, the second PWM drive module and the third PWM drive module respectively. The application can ensure a faster heating speed when the difference between the set temperature and the measured temperature is larger and a higher precision when the difference is smaller by adjusting the PID controller parameters according to the difference. The application avoids the interference of the larger amplitude PWM signal directly driving the heating module to the inertial devices such as the fiber optic gyroscope by outputting the smaller amplitude PWM signal to the PWM drive module.

Description

Technical Field

[0001] This invention belongs to the field of temperature control technology, and specifically relates to an adaptive temperature control device for a relative gravimeter. Background Technology

[0002] The Earth's gravitational field is one of the fundamental physical characteristics describing the Earth, and accurate measurement of the Earth's gravitational field is of great significance for surveying, navigation, and guidance. Relative gravimeters, used for measuring gravity anomalies, have become the preferred choice for airborne, marine, and vehicle-mounted gravity measurements due to their advantages such as convenience, small size, light weight, ease of maintenance, high reliability, mature technology, and strong environmental adaptability. A relative gravimeter is an instrument that measures the relative change of a target point relative to an initial gravity reference point based on a high-precision gravity sensor. Its basic principle is based on a high-precision inertial measurement unit (IMU) as its core, utilizing inertial navigation algorithms and acceleration measurement methods to accurately calculate the vertical acceleration caused by the Earth's gravitational field.

[0003] A relative gravimeter mainly consists of an IMU (Insulated Unit), a chassis, and a navigation computer board. Dual-axis or tri-axis platform gravimeters also include inner and outer frame rotation mechanisms, motor control boards, and other components. The IMU primarily comprises an IMU platform, fiber optic gyroscopes, accelerometers, an I / F (Inertial / Four) circuit board, and a temperature control board. The fiber optic gyroscopes, accelerometers, and I / F circuit board are mainly responsible for measuring inertial parameters. Since the vertical accelerometer and I / F circuit board are the most critical components for gravity measurement and are highly sensitive to temperature changes, a temperature control board is needed to maintain the constant temperature of the IMU platform, vertical accelerometers, and I / F circuit board. Current technology typically involves applying a high-amplitude (e.g., 24V) PWM signal to a heating resistor mounted on the temperature-controlled object. Because PWM contains many high-frequency components with large amplitudes, it often generates crosstalk with frequencies close to the intrinsic frequency of the fiber optic gyroscope through power supply channels and spatial radiation, leading to reduced accuracy of the fiber optic gyroscope and consequently affecting the accuracy of attitude measurement during navigation, ultimately causing errors in vertical acceleration calculation. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, the present invention provides an adaptive temperature control device for a relative gravimeter.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] An adaptive temperature control device for a relative gravimeter includes: a temperature controller; a first PWM drive module, a second PWM drive module, and a third PWM drive module connected to the temperature controller; a first temperature sensor, a second temperature sensor, and a third temperature sensor; and a first heating module, a second heating module, and a third heating module connected to the first PWM drive module, the second PWM drive module, and the third PWM drive module, respectively. The first heating module, the second heating module, and the third heating module are used to heat the IMU stage, the vertical accelerometer, and the I / F circuit board, respectively. The first temperature sensor, the second temperature sensor, and the third temperature sensor are used to measure the temperature of the IMU stage, the vertical accelerometer, and the I / F circuit board in real time. The first PWM drive module, the second PWM drive module, and the third PWM drive module are used to output DC voltage signals that are proportional to the duty cycle of the input PWM signals, respectively. The temperature controller outputs three PWM signals to the first PWM drive module, the second PWM drive module, and the third PWM drive module, respectively. The duty cycle of the three PWM signals is obtained by running a PID controller algorithm on the difference between the corresponding set temperature and the measured temperature.

[0007] Furthermore, there are two first temperature sensors mounted on the surface of the IMU platform; one second temperature sensor mounted on the surface of the I / F circuit board; and one third temperature sensor mounted around the vertical accelerometer.

[0008] Furthermore, the first heating module consists of six heating resistors mounted on the surface of the IMU platform, the second heating module consists of two heating resistors mounted on the surface of the I / F circuit board, and the third heating module consists of three heating resistors mounted around the vertical accelerometer.

[0009] Furthermore, the linear parameter K of the PID controller P Integral parameter K I and differential parameter K D For: K P =K P0 K I =K I0 K D =K D0 K P0 K I0 K D0 All are constants.

[0010] Furthermore, the linear parameter K of the PID controller P Integral parameter K I and differential parameter K D for:

[0011]

[0012] In the formula, K P0 K I0 K D0 Both are constants; a P a I a D K P K I K D The automatic adjustment coefficients are all greater than 0; T set To set the temperature, T f For measuring temperature.

[0013] Furthermore, the a P a I a D The size was determined through repeated adjustments during experiments.

[0014] Furthermore, when T f <T set At this time, the output of the PID controller is equal to the duty cycle D of the PWM signal. duty D duty The Laplace transform is:

[0015]

[0016] When T f ≥T set At that time, D duty =0.

[0017] Furthermore, each PWM drive module includes a MOSFET, a freewheeling diode, an inductor, and an electrolytic capacitor. The control terminal (G) of the MOSFET serves as the input terminal of the PWM drive module, connected to a 3.3V PWM signal output from the temperature controller. The drain (D) is connected to the positive terminal of the power supply, and the source (S) is connected to the negative terminal of the freewheeling diode and one end of the inductor. The positive terminal of the freewheeling diode and the negative terminal of the electrolytic capacitor are connected to the negative terminal of the power supply (ground). The other end of the inductor is connected to the positive terminal of the electrolytic capacitor, serving as the output terminal of the PWM drive module.

[0018] Furthermore, the DC voltage output by each PWM drive module is:

[0019] U TC =V C ·D duty (3)

[0020] In the formula, U TC The DC voltage output by each PWM drive module, V C The power supply voltage for each PWM drive module.

[0021] Furthermore, the power of the heating resistor is:

[0022]

[0023] In the formula, P is the power of the heating resistor, and R is the resistance of the heating resistor.

[0024] Compared with the prior art, the present invention has the following beneficial effects.

[0025] This invention adjusts the PID controller parameters based on the difference between the set temperature and the measured temperature, ensuring a faster heating speed when the error is large and higher accuracy when the error is small. Furthermore, it improves upon the existing technique of directly applying a large-amplitude (24V) PWM signal to the heating resistor by inputting a smaller-amplitude (3.3V) PWM signal into the PWM drive module, thus avoiding interference from the PWM signal to inertial devices such as fiber optic gyroscopes. Attached Figure Description

[0026] Figure 1 This is a block diagram of an adaptive temperature control device for a relative gravimeter according to an embodiment of the present invention. In the figure, 1-temperature controller, 21-first temperature sensor, 22-second temperature sensor, 23-third temperature sensor, 31-first PWM drive module, 32-second PWM drive module, 33-third PWM drive module, 41-first heating module, 42-second heating module, 43-third heating module.

[0027] Figure 2 This is a schematic diagram of a PID temperature control model.

[0028] Figure 3 A schematic diagram of the improved PID temperature control model.

[0029] Figure 4 This is a circuit schematic diagram of a PWM drive module. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer and more understandable, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0031] Figure 1This is a block diagram of an adaptive temperature control device for a relative gravimeter according to an embodiment of the present invention. It includes: a temperature controller 1; a first PWM drive module 31, a second PWM drive module 32, and a third PWM drive module 33 connected to the temperature controller 1; a first temperature sensor 21, a second temperature sensor 22, and a third temperature sensor 23; and a first heating module 41, a second heating module 42, and a third heating module 43 respectively connected to the first PWM drive module 31, the second PWM drive module 32, and the third PWM drive module 33. The first heating module 41, the second heating module 42, and the third heating module 43 are respectively used to control the temperature of the IMU platform, the vertical accelerometer, and the IMU sensor. The I / F circuit board is heated; the first temperature sensor 21, the second temperature sensor 22, and the third temperature sensor 23 are used to measure the temperature of the IMU platform, the vertical accelerometer, and the I / F circuit board in real time, respectively; the first PWM drive module 31, the second PWM drive module 32, and the third PWM drive module 33 are used to output DC voltage signals that are proportional to the duty cycle of the input PWM signal, respectively; the temperature controller 1 is used to output three PWM signals to the first PWM drive module 31, the second PWM drive module 32, and the third PWM drive module 33, respectively. The duty cycle of the three PWM signals is obtained by running a PID controller algorithm on the difference between the corresponding set temperature and the measured temperature.

[0032] In this embodiment, the device mainly consists of a temperature controller 1, three temperature sensors, a three-channel PWM drive module, and a three-channel heating module, as shown in the connection diagram. Figure 1 As shown below. Each part will be introduced in detail below.

[0033] The three temperature sensors include a first temperature sensor 22, a second temperature sensor 22, and a third temperature sensor 23 connected to the temperature controller 1. They are mainly used to measure the temperature of the IMU platform, the vertical accelerometer, and the I / F circuit board in real time, and input the measured temperature values ​​to the temperature controller 1.

[0034] The three-channel PWM drive module includes a first PWM drive module 31, a second PWM drive module 32, and a third PWM drive module 33 connected to the temperature controller 1. These modules primarily output the DC voltage signals required by the three heating modules. The input to the PWM drive module is a low-amplitude, adjustable-duty-cycle PWM pulse signal output from the temperature controller 1. The output amplitude is a DC signal proportional to the PWM duty cycle. Because the PWM signal amplitude (3.3V) is low, it can eliminate or significantly reduce interference from the PWM signal on inertial devices such as fiber optic gyroscopes.

[0035] The three-way heating module includes a first heating module 41, a second heating module 42, and a third heating module 43, which are respectively connected to the output terminals of the first PWM drive module 31, the second PWM drive module 32, and the third PWM drive module 33. It is mainly used to heat the IMU stage, the vertical accelerometer, and the I / F circuit board by utilizing the generated Joule heat.

[0036] Temperature controller 1 is the control and processing center of the device, mainly used to coordinate the work of other parts and complete necessary data processing tasks. For example, it collects temperature data output from temperature sensors. The data processing tasks include: calculating the duty cycle of the PWM signal in real time using a PID controller algorithm based on the difference between the set temperature and the real-time measured temperature of the heated object; and outputting a PWM signal with an amplitude of 3.3V to the PWM drive module according to the duty cycle until the measured temperature reaches the set temperature and the temperature of the heated object stabilizes at the set temperature. If the set temperature is higher than the measured temperature of the heated object, for example, the ambient temperature of the IMU platform is typically -40℃ to +60℃, and the set temperature is 65℃. When the measured temperature reaches the set temperature, temperature controller 1 stops outputting the PWM signal, or outputs a PWM signal with a duty cycle of 0, and the heated object cools down naturally through heat conduction, causing the IMU platform temperature to begin to drop. When the measured temperature drops below 65℃, temperature controller 1 starts outputting a PWM signal with a certain duty cycle again to stabilize the IMU platform at 65℃.

[0037] As an optional embodiment, there are two first temperature sensors 21, which are installed on the surface of the IMU platform; one second temperature sensor 22, which is installed on the surface of the I / F circuit board; and one third temperature sensor 23, which is installed around the vertical accelerometer.

[0038] This embodiment specifies the number of temperature sensors installed on each heated object. There are two first temperature sensors 21 mounted on the surface of the IMU platform, one second temperature sensor 22 mounted on the surface of the I / F circuit board, and one third temperature sensor 23 mounted around the vertical accelerometer.

[0039] As an optional embodiment, the first heating module 41 consists of 6 heating resistors mounted on the surface of the IMU platform, the second heating module 42 consists of 2 heating resistors mounted on the surface of the I / F circuit board, and the third heating module 43 consists of 3 heating resistors mounted around the vertical accelerometer.

[0040] This embodiment provides a technical solution for the heating module. All three heating modules in this embodiment are heating resistors. Based on the requirement for uniform heating, six heating resistors (first heating module 41) are evenly distributed on the surface of the large IMU platform, two heating resistors (second heating module 42) are distributed on the surface of the I / F circuit board, and three heating resistors (third heating module 43) are evenly distributed around the vertical accelerometer.

[0041] As an optional embodiment, the linear parameter K of the PID controller P Integral parameter K I and differential parameter K D For: K P =K P0 K I =K I0 K D =K D0 K P0 K I0 K D0 All are constants.

[0042] This embodiment presents a technical solution for a PID controller. The PID controller consists of a proportional element, an integral element, and a derivative element. The proportional and derivative elements are used to improve the speed of temperature control, while the integral element is used to eliminate steady-state error. The PID controller in this embodiment is a traditional PID controller, and its linear parameter K... P Integral parameter K I and differential parameter K D All are constants. A schematic diagram of a traditional PID temperature control model is shown below. Figure 2 As shown. When the measured temperature differs significantly from the set temperature, the proportional and derivative elements can quickly eliminate the error, while the integrator in the integral element is more prone to saturation and exceeding its power limit. When the difference between the measured and set temperatures is small, the integral element can eliminate steady-state error and achieve precise control, while the proportional and derivative elements often cause significant overshoot.

[0043] As an optional embodiment, the linear parameter K of the PID controller P Integral parameter K I and differential parameter K D for:

[0044]

[0045] In the formula, K P0 K I0 K D0 Both are constants; a P a I a D K P KI K D The automatic adjustment coefficients are all greater than 0; T set To set the temperature, T f For measuring temperature.

[0046] This embodiment presents an improved PID controller. Compared to a traditional PID controller, K... P K I K D No longer a constant K P0 K I0 K D0 Instead, it's in K P0 K I0 K D0 An adjustment amount is added to the base temperature, and the magnitude of the adjustment amount is related to the set temperature T. set and measuring temperature T f The difference (T) set -T f It is directly proportional to . An automatic adjustment coefficient a is introduced. P a I a D The adjustment amount is equal to (T) set -T f ) and automatic adjustment coefficient a P a I a D The product. To make the three automatic adjustment coefficients a... P a I a D All are positive numbers. A negative sign is added before the adjustment amount in the integral stage, as shown in equation (1). The schematic diagram of the improved PID temperature control model is shown below. Figure 3 As shown. K P0 K I0 K D0 The three parameters are the initial controller parameters, K P0 K D0 Typically, K is a small value. I0 A moderate value is usually chosen. When (T) set -T f When the value is large, a larger power is needed to improve heating efficiency. The main components are the proportional and differential elements. P and a D Under the influence of two parameters, K P and K D With (T) set -T f ) increases and increases, while K I It is significantly smaller than K I0 A smaller value; when (T set -T fWhen the value is relatively small, to avoid overshoot and control error caused by excessive heating power, the integral term should play a major role. Therefore, in -a I Under the influence of K I Gradually approaching a more suitable parameter K I0 The K values ​​of the proportional and differential elements P and K D They will gradually tend towards smaller values ​​K. P0 K D0 .

[0047] As an optional embodiment, the a P a I a D The size was determined through repeated adjustments during experiments.

[0048] This embodiment provides a method for determining a. P a I a D One technical solution for size. This embodiment repeatedly adjusts 'a' through experiments. P a I a D The size of K. First, give K... P0 K D0 Choose a smaller value and assign it to K. I0 Choose a suitable value that allows the integrator to function normally under normal conditions. Then, assign a parameter 'a' based on the relationship between the PWM signal duty cycle and the heating power. P and a D To ensure that in (T) set -T f With the goal of achieving higher heating power when the value of 'a' is larger, these two parameters are continuously adjusted. Next, a parameter 'a' is given... I And continuously correct it, so that in (T) set -T f When the temperature is relatively small, the temperature control exhibits high stability.

[0049] As an optional embodiment, when T f <T set At this time, the output of the PID controller is equal to the duty cycle D of the PWM signal. duty D duty The Laplace transform is:

[0050]

[0051] When T f ≥T set At that time, D duty =0.

[0052] This embodiment provides the relationship between the duty cycle of the PWM signal, PID controller parameters, and temperature difference (T).set -T f The relationship is based on... Figure 3 The improved PID temperature control model shown can be used to derive the expression for the PID controller output in terms of Laplace transform, which is the duty cycle D. duty Laplace transform D duty The expression for (s) is shown in equation (2). It is worth noting that equation (2) is for measuring temperature T. f Less than the set temperature T set D at time duty Dangdang T f ≥T set At that time, D duty =0, meaning there is no PWM signal output.

[0053] As an optional embodiment, each PWM drive module includes a MOSFET, a freewheeling diode, an inductor, and an electrolytic capacitor. The control terminal G of the MOSFET serves as the input terminal of the PWM drive module, connected to a 3.3V PWM signal output from the temperature controller 1. The drain D is connected to the positive terminal of the power supply, and the source S is connected to the negative terminal of the freewheeling diode and one end of the inductor. The positive terminal of the freewheeling diode and the negative terminal of the electrolytic capacitor are connected to the negative terminal of the power supply (ground). The other end of the inductor is connected to the positive terminal of the electrolytic capacitor, serving as the output terminal of the PWM drive module.

[0054] This embodiment provides a technical solution for each PWM driver module. Each PWM driver module adopts the same circuit structure, consisting of a MOSFET, a freewheeling diode, an inductor, and an electrolytic capacitor, with the connection relationship as follows: Figure 4 As shown. The difference is that the duty cycle of the PWM signal input to each PWM driver module is different, and of course, the output DC voltage U... TC They are also different. A 3.3V PWM pulse signal input from temperature controller 1 is applied to the control electrode of the MOSFET, controlling the MOSFET's on / off state. The freewheeling diode also functions as a rectifier, conducting when the electrolytic capacitor is charging and disconnecting when it is discharging, causing the electrolytic capacitor to output a DC voltage U proportional to the duty cycle. TC Since the amplitude of the PWM pulse signal is only 3.3V, the interference of the PWM signal on inertial devices such as fiber optic gyroscopes can be significantly reduced.

[0055] As an optional embodiment, the DC voltage output by each PWM drive module is:

[0056] U TC =V C ·D duty (3)

[0057] In the formula, U TCThe DC voltage output by each PWM drive module, V C The power supply voltage for each PWM drive module.

[0058] This embodiment provides a formula for calculating the DC voltage output by each PWM drive module. As mentioned earlier, the DC voltage U output by the PWM drive module... TC Duty cycle D of the PWM signal duty Proportional to, equal to the power supply voltage V of the PWM drive module C With D duty The product is shown in equation (3). When V C When = 24V, U TC =24D duty .

[0059] As an optional embodiment, the power of the heating resistor is:

[0060]

[0061] In the formula, P is the power of the heating resistor, and R is the resistance of the heating resistor.

[0062] This embodiment provides a formula for calculating the power of each heating resistor. According to electrical engineering principles, the power of a resistor is equal to the ratio of the square of the voltage across it to the resistance. The voltage across the resistor is equal to U... TC Substituting equation (3) into equation (4) yields the power calculation formula shown in equation (4).

[0063] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An adaptive temperature control device for a relative gravimeter, characterized in that, include: The system includes a temperature controller, a first PWM drive module, a second PWM drive module, a third PWM drive module, and a first temperature sensor, a second temperature sensor, and a third temperature sensor connected to the temperature controller; and a first heating module, a second heating module, and a third heating module connected to the first PWM drive module, the second PWM drive module, and the third PWM drive module, respectively. The first heating module, the second heating module, and the third heating module are used to heat the IMU platform, the I / F circuit board, and the vertical accelerometer, respectively. The first temperature sensor, the second temperature sensor, and the third temperature sensor are used to measure the temperature of the IMU platform, the I / F circuit board, and the vertical accelerometer in real time. The first PWM drive module, the second PWM drive module, and the third PWM drive module are used to output DC voltage signals that are proportional to the duty cycle of the input PWM signals. The temperature controller outputs three PWM signals to the first PWM drive module, the second PWM drive module, and the third PWM drive module, respectively. The duty cycle of the three PWM signals is obtained by running a PID controller algorithm on the difference between the corresponding set temperature and the measured temperature. in: The linear parameter K of the PID controller P Integral parameter K I and differential parameter K D The initial parameter is: K P =K P0 K I =K I0 K D =K D0 K P0 K I0 K D0 Both are constants; The linear parameter K of the PID controller P Integral parameter K I and differential parameter K D for: （1） In the formula, K P0 K I0 K D0 Both are constants; a P a I a D K P K I K D The automatic adjustment coefficients are all greater than 0; T set To set the temperature, T f For measuring temperature; When T f <T set At this time, the output of the PID controller is equal to the duty cycle D of the PWM signal. duty D duty The Laplace transform is: （2） When T f ≥T set At that time, D duty =0.

2. The adaptive temperature control device for a relative gravimeter according to claim 1, characterized in that, There are two first temperature sensors, mounted on the surface of the IMU platform; one second temperature sensor, mounted on the surface of the I / F circuit board; and one third temperature sensor, mounted around the vertical accelerometer.

3. The adaptive temperature control device for a relative gravimeter according to claim 1, characterized in that, The first heating module consists of six heating resistors mounted on the surface of the IMU platform, the second heating module consists of two heating resistors mounted on the surface of the I / F circuit board, and the third heating module consists of three heating resistors mounted around the vertical accelerometer.

4. The adaptive temperature control device for a relative gravimeter according to claim 1, characterized in that, The a P a I a D The size was determined through repeated adjustments during experiments.

5. The adaptive temperature control device for a relative gravimeter according to claim 1, characterized in that, Each PWM drive module includes a MOSFET, a freewheeling diode, an inductor, and an electrolytic capacitor. The control terminal (G) of the MOSFET serves as the input terminal of the PWM drive module, connected to a 3.3V PWM signal output from the temperature controller. The drain (D) is connected to the positive terminal of the power supply, and the source (S) is connected to the negative terminal of the freewheeling diode and one end of the inductor. The positive terminal of the freewheeling diode and the negative terminal of the electrolytic capacitor are connected to the negative terminal of the power supply (ground). The other end of the inductor is connected to the positive terminal of the electrolytic capacitor, serving as the output terminal of the PWM drive module.

6. The adaptive temperature control device for a relative gravimeter according to claim 5, characterized in that, The DC voltage output by each PWM drive module is: （3） In the formula, U TC The DC voltage output by each PWM drive module, V C The power supply voltage for each PWM drive module.

7. The adaptive temperature control device for a relative gravimeter according to claim 6, characterized in that, The power of the heating resistor is: （4） In the formula, P is the power of the heating resistor, and R is the resistance of the heating resistor.

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