A ground calibration device and calibration method for a UAV fuel level measurement system

Abstract

This invention discloses a ground calibration device and method for an unmanned aerial vehicle (UAV) fuel level measurement system. The device includes a ground calibration host, a connected dual-container fuel tank simulation fixture, and test cables. The fuel tank simulation fixture utilizes the principle of communicating vessels to ensure that the liquid levels in the two containers are equal, simultaneously calibrating two fuel level sensors. Both fuel level sensors are electrically connected to the same airborne fuel level measurement unit, which converts the capacitive signals of the two fuel level sensors into voltage signals. The ground calibration host receives the voltage signals through the test cables, calculates and displays the simulated fuel quantity, allowing the operator to compare it with the actual fuel quantity in the fuel tank simulation fixture. Based on the comparison results, the output characteristics of the measurement unit are adjusted to complete the fuel level measurement system calibration, and the suitability of the fuel level sensors is determined based on the simulated fuel quantity. This invention can significantly save aviation fuel and significantly improve calibration efficiency and accuracy.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle (UAV) fuel system testing technology, and more specifically, relates to a ground calibration device and calibration method for a UAV fuel level measurement system. Background Technology

[0002] The UAV fuel level measurement system is a core component of the UAV fuel management system. It monitors the fuel level in the UAV's fuel tank in real time, providing ground command centers with data for flight range assessment and mission planning. Typically, a UAV fuel level measurement system includes a fuel level sensor (usually a capacitive sensor installed inside the fuel tank, whose capacitance changes linearly with fuel level) and an onboard fuel level measurement unit (electrically connected to the fuel level sensor, used to collect the sensor's capacitance signal and convert it into a voltage signal for output to the flight control system). The accuracy of this measurement system directly affects the ground command center's judgment of the UAV's remaining fuel level. Significant errors can lead to misjudgments of flight range, and in severe cases, can cause the UAV to crash due to low fuel levels. Therefore, ground calibration of the UAV fuel level measurement system is a crucial step in the UAV manufacturing and maintenance process.

[0003] In the design of UAV fuel systems, to improve the reliability and safety of fuel measurement, many medium and large UAVs adopt a dual-sensor redundancy architecture. This involves installing two fuel level sensors in the same fuel tank or at symmetrical locations, both electrically connected to the same onboard fuel level measurement unit. The core purpose of this design is that if one sensor fails, the system can still obtain fuel level information through the other sensor; simultaneously, by comparing the output values ​​of the two sensors, the system can determine in real time whether the sensors are functioning correctly. However, this redundancy architecture places higher demands on ground calibration—the output characteristics of the two sensors must remain highly consistent; otherwise, the flight control system will be unable to determine whether the difference in the outputs of the two sensors stems from actual fuel level changes or inconsistencies within the sensors themselves. Therefore, during calibration, both sensors need to be simultaneously calibrated under identical fuel level conditions to ensure that they output the same voltage signal at the same fuel level, thus guaranteeing the effectiveness of the dual-sensor redundancy architecture.

[0004] Currently, the common ground calibration method for UAV fuel level measurement systems typically involves installing a fuel level sensor on the actual fuel tank of the UAV, injecting fuel into the tank, and then using parameters fed back from the flight control system to verify the measurement accuracy of the fuel level sensor and the onboard fuel level measurement unit. However, this method has the following shortcomings: (1) Serious fuel waste: The amount of fuel required to fill the fuel tank of a large long-endurance UAV can reach hundreds or even thousands of liters (for example, about 1 ton). Each flight requires a large amount of aviation fuel, resulting in significant economic losses.

[0005] (2) Low calibration efficiency: Each calibration requires oil filling and draining operations, which are complicated and time-consuming, making it difficult to meet the needs of mass production or rapid field maintenance.

[0006] (3) Insufficient calibration accuracy: Traditional methods rely on the flight control system to read the fuel quantity value. Due to the influence of the flight control sampling accuracy and environmental factors, the calibration error is difficult to control within the ideal range.

[0007] (4) Difficult to achieve synchronous calibration of dual sensors: Traditional methods usually calibrate individual sensors one by one, and it is impossible to calibrate the two sensors synchronously in the same oil level environment. It is difficult to guarantee the consistency of the output characteristics of the two sensors, thus failing to effectively support the design requirements of the dual sensor redundancy architecture.

[0008] (5) Lack of qualification judgment means: Existing calibration methods usually only complete the sensor output adjustment and do not provide an independent qualification judgment process, making it impossible to quantitatively verify whether the sensor truly meets the accuracy requirements after calibration.

[0009] In addition, some fuel calibration devices are disclosed in the prior art, such as simple tooling that uses a single-cylinder simulated container or relies on manual reading of liquid level height. However, most of them only support single-sensor calibration and cannot achieve dual-sensor synchronous calibration. They also fail to integrate voltage-fuel quantity automatic conversion algorithm and fault diagnosis function, making it difficult to meet the calibration requirements of UAV fuel level measurement system for high efficiency, high precision, high reliability and dual-sensor consistency.

[0010] Therefore, there is an urgent need to provide a ground calibration device and calibration method for a UAV fuel level measurement system that can overcome the above-mentioned defects. Summary of the Invention

[0011] The purpose of this invention is to propose a ground calibration device and method for a UAV fuel level measurement system, which solves the problems of large fuel waste, low efficiency, poor accuracy, inability to simultaneously calibrate dual sensors, and lack of qualification judgment in the ground calibration of existing UAV fuel level measurement systems; and achieves the goals of saving aviation fuel, improving calibration efficiency, enhancing calibration accuracy, ensuring consistency of dual sensor outputs, and quantitatively judging sensor qualification.

[0012] To achieve the above objectives, in a first aspect, the present invention proposes a ground calibration device for an unmanned aerial vehicle (UAV) fuel level measurement system. The UAV fuel level measurement system includes a fuel level sensor and an airborne fuel level measurement unit. The ground calibration device includes: Ground calibration host, connected dual-container oil tank simulation fixture and test cables; The connected dual-container fuel tank simulation fixture is used to keep the fuel level in the two containers consistent during the calibration process, so as to calibrate the two fuel level sensors simultaneously. Both fuel level sensors are electrically connected to the same airborne fuel level measurement unit, which is used to collect the capacitance signal output by the fuel level sensors and convert the capacitance signal into a voltage signal. The ground calibration host is connected to the airborne fuel level measurement unit via the test cable. It receives the voltage signal output by the airborne fuel level measurement unit, calculates and displays the simulated fuel quantity based on the voltage signal, and allows the operator to compare it with the actual fuel quantity of the connected dual-container fuel tank simulation tool. Based on the comparison result, the output characteristics of the airborne fuel level measurement unit are adjusted to complete the calibration of the fuel level measurement system and to perform a qualification judgment on the calibrated fuel level sensor based on the simulated fuel quantity.

[0013] Optionally, the connected dual-container oil tank simulation fixture includes: The interconnected double container consists of two transparent containers of equal diameter and height that are connected at the bottom. The outer walls of the two transparent containers are provided with scales for reading the liquid level. A fuel level sensor mounting plate is fixed to the top of the connected double container. The fuel level sensor mounting plate has two sensor mounting positions for fixing two fuel level sensors respectively, and allowing the two fuel level sensors to extend into the corresponding transparent container. An oil drain valve is located on the bottom side wall of the interconnected double container; A fuel filling funnel is fixed to the top plate of the fuel level sensor, and the bottom of the fuel filling funnel is connected to the filling hole at the top of the connected double container. A leveling device is installed at the bottom of the connected double container to support the connected double container and to adjust the level of the connected double container.

[0014] Optionally, the ground calibration host includes: Portable chassis, including a chassis body and an openable lid; The measuring motherboard is located inside the enclosure; The control panel is located inside the housing. When the housing lid is opened, the control panel is exposed, and when the housing lid is closed, the control panel is covered and protected.

[0015] Optionally, the leveling device includes: A three-point height-adjustable base is used to support the connected double containers and to adjust the level of the connected double containers. A dual-axis electronic level is used to display the horizontal status of the connected dual containers; The bottom of the three-point height-adjustable base is equipped with pulleys, which allows the connected dual-container oil tank simulation fixture to be moved.

[0016] Optionally, the operation panel is provided with: Mains power socket; The power conversion module is electrically connected to the mains power socket; The ground calibration host power switch has its input terminal electrically connected to the first output terminal of the power conversion module, and its output terminal electrically connected to the power input terminal of the measurement motherboard. The power-on indicator light of the ground calibration host is electrically connected to the power-on switch of the ground calibration host; The power-on switch of the airborne oil level measurement unit is electrically connected to the second output terminal of the power conversion module. The power-on indicator light for the airborne fuel level measurement unit is electrically connected to the power-on switch for the airborne fuel level measurement unit. The airborne fuel level measurement unit interface has its input terminal electrically connected to the output terminal of the power switch of the airborne fuel level measurement unit, its output terminal electrically connected to the power input terminal of the airborne fuel level measurement unit, and is communicatively connected to the measurement motherboard. The display screen, which is communicatively connected to the measurement motherboard, is used to receive and display the simulated fuel quantity and the fault status of the fuel level sensor.

[0017] Optionally, the measurement motherboard includes: The high-resistivity analog quantity acquisition module is connected to the airborne fuel level measurement unit interface via the test cable, and then communicates with the measurement motherboard to receive the voltage signal output by the airborne fuel level measurement unit. The calculation module is communicatively connected to the high-resistivity analog quantity acquisition module, and is used to receive the voltage signal and calculate the simulated oil quantity based on the voltage signal using a voltage-to-oil quantity conversion algorithm.

[0018] Optionally, the voltage-to-fuel conversion algorithm preset in the calculation module is as follows: Let V1 represent the voltage signal output by the airborne fuel level measurement unit, in volts; and L1 represent the simulated fuel quantity, in liters. When V1 < 0.2V, it is determined to be an open circuit fault; When 0.2V ≤ V1 < 0.5V, L1 = 0; When 0.5V≤V1<0.643V, L1=20.83916×V1-10.41958; When 0.643V≤V1<1.459V, L1=-26.19758×V1³+94.89053×V1²-54.16953×V1+5.54027; When 1.459V≤V1<1.587V, L1=96.25×V1-93.27875; When 1.587V≤V1≤4.90V, L1=0.77996×V1²+52.12384×V1-24.92382; When V1 > 4.90V, it is determined to be a short circuit fault.

[0019] Optionally, the step of performing a pass / fail determination on the calibrated fuel level sensor based on the simulated fuel quantity includes: After calibration, empty all the fuel in the connected dual-container fuel tank simulation tool, and then refill the connected dual-container fuel tank simulation tool until the fuel level is level with the bottom of the fuel level sensor. At this time, read the current simulated fuel volume displayed on the ground calibration equipment. If the current simulated fuel volume is ≤0.25L, the fuel level sensor is deemed qualified.

[0020] In a second aspect, the present invention proposes a ground calibration method for an unmanned aerial vehicle (UAV) fuel level measurement system, utilizing the ground calibration equipment for an UAV fuel level measurement system as described in any one of the first aspects, the method comprising: Connect the ground calibration host and the airborne fuel level measurement unit via test cables; The airborne fuel level measurement unit is electrically connected to two fuel level sensors installed on a connected dual-container fuel tank simulation fixture. Power on the ground calibration host and power on the airborne fuel level measurement unit; Adjust the connected dual-container oil tank simulation fixture to a horizontal position; Fuel is added to the connected dual-container fuel tank simulation tool at a fuel injection rate of 0.5L / min. When the added fuel is level with the bottom of the fuel level sensor, the simulated fuel volume displayed on the ground calibration host is observed. The simulated fuel volume should be 0L. If it is not 0L, the output parameters of the airborne fuel level measurement unit are adjusted until the simulated fuel volume displayed on the ground calibration host is 0L (corresponding to a fuel level voltage of 0.50V). Fuel is added to the connected dual-container fuel tank simulation fixture at a rate of 3L / min. When the added fuel is about to reach the top of the fuel level sensor, the fuel injection rate is slowed down until the fuel level with the top of the fuel level sensor is reached. Then, the fuel injection is stopped. The simulated fuel volume displayed on the ground calibration host is observed. This simulated fuel volume should be the actual fuel volume of the connected dual-container fuel tank simulation fixture at this fuel level. If the deviation exceeds ±0.25L, the output parameters of the airborne fuel level measurement unit are slightly adjusted until the error between the simulated fuel volume and the actual fuel volume meets the requirements (corresponding to a fuel level voltage of 4.90V).

[0021] Optionally, the method further includes: After calibration, empty all the fuel in the connected dual-container fuel tank simulation tool, and then refill the connected dual-container fuel tank simulation tool until the fuel level is level with the bottom of the fuel level sensor. At this time, read the current simulated fuel volume displayed on the ground calibration equipment. If the current simulated fuel volume is ≤0.25L, the fuel level sensor is deemed qualified.

[0022] The beneficial effects of this invention are as follows: By employing a connected dual-container fuel tank to simulate the fixture, the fuel level in both containers remains consistent, enabling synchronous calibration of the two fuel level sensors under the same fuel level environment. This effectively ensures the consistency of the output characteristics of the two sensors and meets the special requirements of the UAV's dual-sensor redundancy architecture for calibration consistency. Simultaneously, the ground calibration host receives the voltage signal output from the airborne fuel level measurement unit and automatically calculates the simulated fuel volume, allowing operators to compare it with the actual fuel volume of the fixture. This significantly reduces reliance on operator experience during calibration and improves calibration accuracy. Furthermore, the entire calibration process does not require the use of the UAV's actual fuel tank or a large amount of aviation fuel; only a small amount of fuel needs to be added to the small-volume connected dual containers to complete the calibration, significantly saving fuel costs. The ground calibration host also has a pass / fail determination function, enabling quantitative verification of whether the fuel level sensor meets the accuracy requirements after calibration, avoiding the shortcomings of traditional methods that lack an independent judgment step. This invention can significantly save aviation fuel, significantly improve calibration efficiency and accuracy, ensure the consistency of the output characteristics of the two sensors, and achieve quantitative determination of post-calibration pass / fail.

[0023] The system of the present invention has other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0024] The above and other objects, features and advantages of the present invention will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0025] Figure 1 A schematic diagram of a ground calibration device for an unmanned aerial vehicle (UAV) fuel level measurement system according to Embodiment 1 of the present invention is shown.

[0026] Figure 2 A front view of a simulated tooling for a connected dual-container oil tank according to Embodiment 1 of the present invention is shown.

[0027] Figure 3 A side view of a simulated tooling for a connected dual-container oil tank according to Embodiment 1 of the present invention is shown.

[0028] Figure 4 A schematic diagram of the operation panel according to Embodiment 1 of the present invention is shown.

[0029] Figure 5 A schematic diagram of the electrical connections of the operation panel according to Embodiment 1 of the present invention is shown. Detailed Implementation

[0030] The invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0031] Example 1

[0032] like Figure 1 As shown, this embodiment provides a ground calibration device for a UAV fuel level measurement system. The UAV fuel level measurement system includes a fuel level sensor and an airborne fuel level measurement unit. The ground calibration device includes: Ground calibration host, connected dual-container oil tank simulation fixture and test cables; The connected dual-container fuel tank simulation fixture is used to keep the fuel level in the two containers consistent during the calibration process, so as to calibrate the two fuel level sensors simultaneously. Both fuel level sensors are electrically connected to the same airborne fuel level measurement unit, which is used to collect the capacitance signal output by the fuel level sensors and convert the capacitance signal into a voltage signal. The ground calibration host is connected to the airborne fuel level measurement unit via a test cable. It receives the voltage signal output by the airborne fuel level measurement unit, calculates and displays the simulated fuel quantity based on the voltage signal, and allows the operator to compare it with the actual fuel quantity of the connected dual-container fuel tank simulation tool. Based on the comparison result, the output characteristics of the airborne fuel level measurement unit are adjusted to complete the calibration of the fuel level measurement system and to perform a pass / fail judgment on the calibrated fuel level sensor based on the simulated fuel quantity.

[0033] Specifically, the ground calibration equipment for the UAV fuel level measurement system is used to perform ground calibration of the fuel level measurement system carried on the UAV. The UAV fuel level measurement system includes a fuel level sensor (usually a capacitive sensor) and an airborne fuel level measurement unit.

[0034] The ground calibration equipment for the UAV fuel level measurement system mainly consists of three parts: the ground calibration host, the connected dual-container fuel tank simulation fixture, and the test cables.

[0035] The interconnected dual-container fuel tank simulation fixture consists of two transparent containers with interconnected bottoms and equal diameters and heights. When fuel is added to the fixture, the fuel level in both containers remains consistent due to the principle of communicating vessels. This fixture is used to simultaneously install two fuel level sensors during calibration, with each sensor extending into one of the two containers, thus enabling synchronous calibration of the two sensors under identical fuel level conditions.

[0036] Both fuel level sensors are electrically connected to the same airborne fuel level measurement unit via cables. This airborne fuel level measurement unit is responsible for collecting the capacitance signal generated by the fuel level sensor due to changes in fuel level and converting it into a corresponding voltage signal for output.

[0037] The ground calibration host connects to the airborne fuel level measurement unit via a test cable to receive the voltage signal output by the airborne fuel level measurement unit. Internally, the ground calibration host uses a preset voltage-to-fuel quantity conversion algorithm to calculate the received voltage signal as a simulated fuel quantity value and displays it on the screen. The operator manually compares the simulated fuel quantity displayed on the ground calibration host with the actual fuel quantity read from the scale on the outer wall of the transparent container of the connected dual-container fuel tank simulation fixture. Based on the comparison result (i.e., the deviation between the simulated and actual fuel quantities), the operator adjusts the output characteristics of the airborne fuel level measurement unit, for example, by adjusting the fuel level voltage output knob on the airborne fuel level measurement unit, until the error between the simulated and actual fuel quantities meets the requirements (e.g., no greater than ±0.25L), thus completing the calibration of the fuel level measurement system.

[0038] In addition, the ground calibration host also has a pass / fail determination function: after calibration, it performs a pass / fail determination on the calibrated fuel level sensor based on the simulated fuel volume. Specifically, the fuel is completely emptied through the drain valve at the bottom of the connected dual-container fuel tank simulation tool, and then fuel is added back into the connected dual-container fuel tank simulation tool until the fuel is level with the bottom of the fuel level sensor. If the simulated fuel volume displayed by the ground calibration host does not exceed the set threshold (such as 0.25L), the fuel level sensor is deemed to be qualified.

[0039] Through the above structure and working process, the ground calibration equipment of the UAV fuel level measurement system can realize the synchronous calibration of dual sensors by using the interconnected dual-container fuel tank simulation tooling. It also integrates functions such as automatic voltage-fuel quantity conversion, manual comparison assistance, and post-calibration qualification judgment, effectively solving the problems of large fuel waste, low efficiency, poor accuracy, and inability to synchronously calibrate dual sensors in traditional calibration methods.

[0040] In this embodiment, as Figure 2 and Figure 3 As shown, the connected dual-container oil tank simulation fixture includes: The interconnected double container consists of two transparent containers of equal diameter and height that are connected at the bottom. The outer walls of the two transparent containers are provided with scales for reading the liquid level. The fuel level sensor mounting plate is fixed to the top of the connected double container. The fuel level sensor mounting plate has two sensor mounting positions for fixing two fuel level sensors respectively, and allowing the two fuel level sensors to extend into the corresponding transparent container. An oil drain valve is located on the bottom side wall of a connected double container. A fuel filling funnel is fixed to the top plate of the fuel level sensor, and the bottom of the fuel filling funnel is connected to the filling hole at the top of the connected double container. A leveling device is installed at the bottom of the connected double container to support the connected double container and to adjust the level of the connected double container.

[0041] Specifically, the interconnected dual-container fuel tank simulation fixture comprises the following components: interconnected dual containers, a fuel level sensor mounting plate, a drain valve, a fuel filling funnel, and a leveling device. The interconnected dual containers consist of two transparent containers of equal diameter and height, interconnected at the bottom. Both containers have scales (typically in millimeters) on their outer walls for reading the fuel level. This interconnected design, utilizing the principle of communicating vessels, ensures that the fuel level in both containers remains consistent, providing an identical calibration environment for the two fuel level sensors. This enables synchronous calibration of the two sensors, effectively guaranteeing the consistency of their output characteristics. This meets the specific requirements of the UAV's dual-sensor redundancy architecture for sensor consistency. Furthermore, operators can directly read the actual fuel level from the scales and convert it to the actual fuel volume, providing an intuitive and reliable benchmark for manual comparison with the simulated fuel volume displayed on the ground calibration host.

[0042] The fuel level sensor mounting plate is fixed to the top of the connected double container. The mounting plate has two sensor mounting positions for fixing two fuel level sensors respectively, and the two fuel level sensors extend into the corresponding transparent container. This ensures that the two fuel level sensors are in the same fuel level environment during the calibration process, and at the same time ensures that the sensor position is stable and does not shake during the calibration process, thus improving the repeatability and reliability of the calibration.

[0043] The drain valve is located on the bottom side wall of the connected dual container. It is used to drain all the fuel in the connected dual container after calibration or when the fuel needs to be replaced. By installing the drain valve, the fuel can be quickly emptied after calibration, which facilitates the qualification judgment, fuel replacement or repeated calibration operation, and significantly improves the convenience of operation.

[0044] The fuel filling funnel is fixed to the top plate of the fuel level sensor. The bottom of the fuel filling funnel is connected to the filling hole at the top of the connected double container. Operators can add aviation fuel into the connected double container through the fuel filling funnel. By setting the fuel filling funnel in this way, the fuel filling operation is controllable and precise, which can meet the requirements of different filling speeds (such as 0.5L / min and 3L / min) during the calibration process, and avoid the problems of fuel splashing or inaccurate filling volume control.

[0045] The leveling device is located at the bottom of the connected double container. It supports the entire connected double container and can adjust the level of the connected double container to ensure that the fuel level in the two transparent containers accurately reflects the fuel level reading during the calibration process. By setting the leveling device in it, the tooling level can be accurately adjusted to avoid measurement errors caused by tilting, and the calibration accuracy can be further improved.

[0046] With the above structure, this connected dual-container fuel tank simulation tooling can replace the large amount of fuel consumption of traditional real drone fuel tanks with extremely low fuel consumption (only needing to be filled to the top of the sensor), significantly reducing calibration costs while improving calibration efficiency and dual-sensor consistency.

[0047] In this embodiment, the ground calibration host includes: Portable chassis, including a chassis body and an openable lid; The motherboard is located inside the enclosure. The control panel is located inside the enclosure. It is exposed when the enclosure lid is open and covered and protected when the enclosure lid is closed.

[0048] Specifically, the ground calibration host includes: a portable chassis, a measurement motherboard, and an operation panel.

[0049] The portable chassis includes a main body and an openable cover. The measurement mainboard is located inside the chassis, as is the control panel. The control panel is exposed when the cover is open and protected when the cover is closed. By using a portable chassis with an openable cover, the ground calibration main unit can be transported and stored with the cover closed, effectively protecting the control panel from dust, impacts, and moisture, significantly improving the equipment's durability and portability. When calibration is required, simply opening the cover reveals the complete control panel, which is clearly visible and easily accessible, making it very convenient to use.

[0050] The measurement motherboard, as the core processing unit of the ground calibration host, is securely installed inside the enclosure. It is responsible for receiving the voltage signal output from the onboard fuel level measurement unit and executing the voltage-to-fuel conversion algorithm. The operation panel integrates all components related to human-machine interaction, such as power supply control, status indication, signal connection, and data display. Operators can complete the entire calibration process without touching the internal circuitry.

[0051] Through the above structural design, the ground calibration host can ensure high-performance signal processing capabilities while also having good environmental adaptability and ease of operation, and can meet the needs of various application scenarios such as batch calibration on the production line and field maintenance.

[0052] In one specific embodiment, a storage device is provided inside the box cover for storing test cables. This storage device neatly secures the test cables inside the box cover when the equipment is not in use, preventing them from scattering, tangling, or getting lost. When needed, the cables can be easily retrieved and connected by opening the box cover. This design further enhances the portability of the equipment and the convenience of on-site operation.

[0053] In this embodiment, as Figure 2 As shown, the leveling device includes: A three-point height-adjustable base is used to support the connected double containers and to adjust the level of the connected double containers. A dual-axis electronic level is used to display the level status of two connected containers. The three-point height-adjustable base is equipped with casters at the bottom, allowing the connected dual-container oil tank simulation fixture to be moved.

[0054] Specifically, the leveling device includes: a three-point height-adjustable base, a dual-axis electronic level, and pulleys located at the bottom of the base.

[0055] The three-point height-adjustable base is located at the bottom of the connected dual-container oil tank simulation fixture. It supports the entire connected dual-container and can adjust the horizontal state of the connected dual-container by adjusting the height of the three support points.

[0056] The dual-axis electronic level is installed at an appropriate position on the simulated tooling of the connected dual-container oil tank (e.g., on the bottom support or base of the connected dual-container) to display the horizontal status of the connected dual-container in both the X and Y axes in real time. The operator can intuitively adjust the three-point height-adjustable base according to the reading of the dual-axis electronic level until the connected dual-container reaches the horizontal requirement (e.g., the horizontal error between the X and Y axes is ≤ ±0.2°).

[0057] By incorporating a three-point height-adjustable base and a dual-axis electronic level in the leveling device, operators can quickly and accurately level the connected dual containers, ensuring that the fuel level in the two transparent containers accurately reflects the fuel level reading during calibration. This avoids level reading errors caused by tilting, thereby improving calibration accuracy and the reliability of calibration results.

[0058] In addition, the three-point height-adjustable base is equipped with casters at the bottom, which makes the entire connected dual-container oil tank simulation tooling mobile. Operators can easily transfer the tooling between different workstations (such as pushing it from the storage area to the calibration operation area) without the need for forklifts or other handling equipment, which significantly improves the portability of the equipment and the flexibility of on-site operation.

[0059] Meanwhile, the height-adjustable function of the three-point height-adjustable base is not lost due to the addition of pulleys. Operators can still adjust the level by adjusting the adjustable feet on the base (usually the pulleys and feet are interchangeable or the feet are retractable), ensuring that the tooling can be stably supported and easily moved. Through the above structure, the leveling device ensures the horizontal accuracy and calibration accuracy of the tooling while giving it good mobility, meeting the actual needs of batch calibration on the production line and rapid deployment in the field.

[0060] In this embodiment, as Figure 4 and Figure 5As shown, the control panel is equipped with: Mains power socket; The power conversion module is electrically connected to the AC power socket. The power switch of the ground calibration host is electrically connected to the first output terminal of the power conversion module, and its output terminal is electrically connected to the power input terminal of the measurement main board. The power indicator light on the ground calibration host is electrically connected to the power switch on the ground calibration host. The power switch for the airborne oil level measurement unit is electrically connected to the second output terminal of the power conversion module. The power-on indicator light for the airborne fuel level measurement unit is electrically connected to the power-on switch for the airborne fuel level measurement unit. The airborne fuel level measurement unit interface has its input terminal electrically connected to the output terminal of the power switch of the airborne fuel level measurement unit, its output terminal electrically connected to the power input terminal of the airborne fuel level measurement unit, and is also connected to the measurement main board for communication. The display screen, which communicates with the measurement motherboard, is used to receive and display the fault status of the analog fuel quantity and fuel level sensors.

[0061] Specifically, the control panel is equipped with: a mains power socket, a power conversion module, a ground calibration host power switch, a ground calibration host power indicator light, an airborne fuel level measurement unit power switch, an airborne fuel level measurement unit power indicator light, an airborne fuel level measurement unit interface, and a display screen.

[0062] The AC power socket is used to connect to an external AC220V power source to provide power to the entire ground calibration host. The power conversion module is electrically connected to the AC power socket and is used to convert the AC220V alternating current into the operating voltage (e.g., low DC voltage) required by the various modules inside the equipment.

[0063] The input terminal of the power switch of the ground calibration host is electrically connected to the first output terminal of the power conversion module, and its output terminal is electrically connected to the power input terminal of the measurement main board. The power supply to the measurement main board can be controlled by operating the switch. The power indicator light of the ground calibration host is electrically connected to the power switch of the ground calibration host and is used to visually indicate whether the measurement main board is powered on. When the switch is closed and the indicator light is on, it indicates that the measurement main board is in working condition.

[0064] The input terminal of the power-on switch of the airborne fuel level measurement unit is electrically connected to the second output terminal of the power conversion module to control the on / off supply of power to the external airborne fuel level measurement unit; the power-on indicator light of the airborne fuel level measurement unit is electrically connected to the power-on switch of the airborne fuel level measurement unit to indicate the power supply status of the airborne fuel level measurement unit.

[0065] The input terminal of the airborne fuel level measurement unit interface is electrically connected to the output terminal of the power switch of the airborne fuel level measurement unit, and its output terminal is electrically connected to the power input terminal of the airborne fuel level measurement unit, thereby providing working power to the airborne fuel level measurement unit; at the same time, the airborne fuel level measurement unit interface is also connected to the measurement motherboard to transmit the voltage signal output by the airborne fuel level measurement unit to the measurement motherboard for it to perform simulated fuel quantity calculation.

[0066] The display screen is connected to the measurement motherboard to receive and display the simulated fuel quantity calculated by the measurement motherboard and the fault status of the fuel level sensor (such as open circuit fault or short circuit fault).

[0067] Through the above settings, the operation panel integrates all human-machine interaction functions, including power supply, voltage conversion, multi-channel independent power supply control, status indication, signal connection, and data display. On the one hand, the power supply of the ground calibration host itself (controlled by the power-on switch of the ground calibration host) and the power supply of the external device under test (airborne fuel level measurement unit) (controlled by the power-on switch of the airborne fuel level measurement unit) are designed separately, realizing step-by-step power-on, which can avoid the impact on the host when the external equipment fails and improve the safety of the equipment. On the other hand, operators can quickly determine the power supply status of each part by observing the power-on indicator light. The onboard oil level measurement unit interface realizes a unified interface for signals and power supply. The simulated oil level and fault information can be directly read through the display screen, making the operation interface of the entire calibration process clear, logical, and easy to use, reducing the risk of misoperation.

[0068] In this embodiment, the measurement motherboard includes: The high-resistivity analog quantity acquisition module is connected to the airborne fuel level measurement unit interface via a test cable, and then communicates with the measurement motherboard to receive the voltage signal output by the airborne fuel level measurement unit. The calculation module is connected to the high-resistivity analog quantity acquisition module to receive voltage signals and calculate the simulated oil quantity based on the voltage signals using a voltage-to-oil quantity conversion algorithm.

[0069] Specifically, the measurement motherboard includes a high-resistivity analog quantity acquisition module and a calculation module.

[0070] The high-resistivity analog signal acquisition module connects to the onboard fuel level measurement unit interface on the operation panel via a test cable, thereby establishing a communication connection with the measurement motherboard to receive the dual-channel voltage signal output from the onboard fuel level measurement unit. Since this device is used to simultaneously calibrate two fuel level sensors, each sensor transmits its respective capacitance signal to the same onboard fuel level measurement unit. The onboard fuel level measurement unit converts the two capacitance signals into two voltage signals (i.e., dual-channel voltage signals) before outputting them. Therefore, the high-resistivity analog signal acquisition module needs to simultaneously acquire the voltage signals from both channels to reflect the voltage values ​​corresponding to the fuel level heights of the two fuel level sensors. Due to its high-resistivity design, this acquisition module has extremely high input impedance, which minimizes signal attenuation and external interference, ensuring that the acquired dual-channel voltage signals accurately reflect the output values ​​of the onboard fuel level measurement unit, thus providing high-fidelity raw data for subsequent simulated fuel quantity calculations.

[0071] The calculation module communicates with the high-resistivity analog signal acquisition module to receive the dual-channel voltage signal transmitted from the high-resistivity analog signal acquisition module. Based on a preset voltage-to-fuel quantity conversion algorithm, it calculates the corresponding simulated fuel quantity for each channel's voltage signal in real time. This voltage-to-fuel quantity conversion algorithm is pre-calibrated and stored in the calculation module according to the characteristics of the fuel level sensor and the onboard fuel level measurement unit. It can cover the complete working range of the sensor from empty to full fuel level and automatically identify open-circuit faults (voltage below 0.2V) and short-circuit faults (voltage above 4.90V) for each channel. Through the cooperation of the high-resistivity analog signal acquisition module and the calculation module, the measurement motherboard can independently complete the reception, conditioning, conversion, and calculation of the dual-channel voltage signal without relying on the UAV flight control system or other external equipment, which improves calibration accuracy and simplifies the calibration process.

[0072] Furthermore, the calculation module transmits the two simulated fuel volumes and their respective fault statuses to the display screen via the communication interface of the measurement motherboard for operator reference. This data is then compared with the actual fuel volume of the connected dual-container fuel tank simulation fixture (since the liquid levels in the two containers are identical, the two simulated fuel volumes should be approximately equal). This provides a quantitative basis for manually adjusting the output characteristics of the onboard fuel level measurement unit. Through this structure, the measurement motherboard achieves a complete signal link from dual-channel voltage signal acquisition to dual-channel simulated fuel volume calculation. It possesses advantages such as high precision, anti-interference, strong real-time performance, and dual-channel fault self-diagnosis, providing reliable core computational support for the synchronous calibration of the entire ground calibration equipment using dual sensors.

[0073] In this embodiment, the voltage-to-fuel conversion algorithm preset in the calculation module is as follows: Let V1 represent the voltage signal output by the airborne fuel level measurement unit, in volts; and L1 represent the simulated fuel quantity, in liters. When V1 < 0.2V, it is determined to be an open circuit fault; When 0.2V ≤ V1 < 0.5V, L1 = 0; When 0.5V≤V1<0.643V, L1=20.83916×V1-10.41958; When 0.643V≤V1<1.459V, L1=-26.19758×V1³+94.89053×V1²-54.16953×V1+5.54027; When 1.459V≤V1<1.587V, L1=96.25×V1-93.27875; When 1.587V≤V1≤4.90V, L1=0.77996×V1²+52.12384×V1-24.92382; When V1 > 4.90V, it is determined to be a short circuit fault.

[0074] Specifically, the preset voltage-to-fuel conversion algorithm in the calculation module is as follows: Let the voltage signal output by the airborne fuel level measurement unit be V1, with the unit being volts; and let the simulated fuel quantity calculated by the ground calibration host be L1, with the unit being liters.

[0075] The algorithm employs different processing methods depending on the range of the voltage signal V1: When V1 is less than 0.2V, since the fuel level sensor is a capacitive sensor, it is affected by the atmospheric capacitance effect. The voltage after the actual capacitance value is converted should not be less than 0.2V. Therefore, it is determined that there is an open circuit fault in the airborne fuel level measurement system. When V1 is greater than or equal to 0.2V but less than 0.5V, the current oil level is considered to be in the dead zone range that the sensor cannot effectively measure, so the simulated oil volume L1 is set to 0 liters. When V1 is greater than or equal to 0.5V and less than 0.643V, the simulated oil quantity L1 is calculated according to the linear formula L1=20.83916×V1-10.41958; When V1 is greater than or equal to 0.643V and less than 1.459V, the simulated oil quantity L1 is calculated according to the cubic polynomial formula L1=-26.19758×V1³+94.89053×V1²-54.16953×V1+5.54027; When V1 is greater than or equal to 1.459V and less than 1.587V, the simulated oil quantity L1 is calculated according to the linear formula L1=96.25×V1-93.27875; When V1 is greater than or equal to 1.587V and less than or equal to 4.90V, the simulated oil quantity L1 is calculated according to the quadratic polynomial formula L1=0.77996×V1²+52.12384×V1-24.92382; When V1 is greater than 4.90V, it is determined that there is a short circuit fault in the airborne fuel level measurement system.

[0076] The aforementioned segmented algorithm covers the entire operating range from empty to full fuel level. 0.50V corresponds to an empty fuel level when the bottom of the fuel level sensor is level, and 4.90V corresponds to a full fuel level when the top of the fuel level sensor is level. The segmented functions use polynomial fitting to ensure a high-precision mapping between the voltage signal and the simulated fuel quantity. Simultaneously, the automatic open-circuit and short-circuit fault detection function can diagnose the health status of the airborne fuel level measurement system in real time during calibration, providing operators with clear fault indications. Through this voltage-to-fuel-quantity conversion algorithm, the ground calibration host can accurately and quickly convert the acquired raw voltage signal into a simulated fuel quantity value, thus providing operators with a basis for comparison and adjustment with the actual fuel quantity of the connected dual-container fuel tank simulation tool.

[0077] In this embodiment, the pass / fail determination of the calibrated fuel level sensor based on simulated fuel quantity includes: After calibration, empty all the fuel in the connected dual-container fuel tank simulation tool, and then refill the connected dual-container fuel tank simulation tool until the fuel level is level with the bottom of the fuel level sensor. At this time, read the current simulated fuel volume displayed on the ground calibration equipment. If the current simulated fuel volume is ≤0.25L, the fuel level sensor is deemed to be qualified.

[0078] Specifically, the process for determining the pass / fail status of the calibrated fuel level sensor based on simulated fuel quantity is as follows: After completing all calibration operations (i.e., adjusting the output characteristics of the airborne fuel level measurement unit so that the ground calibration host displays 0.50V when the fuel level is empty and 4.90V when the fuel level is full), the aviation fuel in the connected dual-container fuel tank simulation tool is first emptied through the drain valve located on the bottom side wall of the connected dual-container fuel tank simulation tool to ensure that there is no residual fuel inside the tool.

[0079] Then, aviation fuel is refilled into the connected double-container fuel tank simulation tooling through the fuel filling funnel again. The refilling speed can adopt the conventional speed (for example, not greater than 3 L / min) until the height of the refilled fuel liquid level is exactly even with the bottom of the fuel level sensor. At this time, the ground calibration host calculates the current simulated fuel quantity through the voltage-to-fuel quantity conversion algorithm based on the voltage signal output by the airborne fuel level measurement unit collected, and displays this simulated fuel quantity on the display screen. The operator reads the current simulated fuel quantity displayed by the ground calibration equipment. If this simulated fuel quantity is less than or equal to 0.25 liters (i.e., ≤0.25 L), it is determined that the fuel level sensor is qualified; otherwise, if the current simulated fuel quantity is greater than 0.25 liters, it is determined that the fuel level sensor is unqualified, and it is necessary to re-calibrate or check whether there is a fault in the sensor.

[0080] This qualification determination step is independent of the zero point and full-scale adjustment during the calibration process, provides a quantitative verification method for the calibration result, can objectively evaluate the measurement accuracy of the fuel level sensor in the low fuel level area, and ensures that the calibrated sensor meets the strict requirements of the UAV fuel level measurement system for low fuel level alarm and remaining fuel quantity accuracy.

[0081] Through the above qualification determination, the operator can clearly know whether the calibration is truly successful, avoiding the problem of unreliable calibration quality caused by the lack of an independent determination link in the traditional method.

[0082] Embodiment 2

[0083] This embodiment provides a method for ground calibration of a UAV fuel level measurement system, using the ground calibration equipment of the UAV fuel level measurement system in Embodiment 1. This method includes: Connect the ground calibration host and the airborne fuel level measurement unit through the test cable; Electrically connect the airborne fuel level measurement unit to two fuel level sensors installed on the connected double-container fuel tank simulation tooling; Power on the ground calibration host and power on the airborne fuel level measurement unit; Adjust the connected double-container fuel tank simulation tooling to be horizontal; Refill fuel into the connected double-container fuel tank simulation tooling at a refilling speed of 0.5 L / min. When the refilled fuel is even with the bottom of the fuel level sensor, observe the simulated fuel quantity displayed by the ground calibration host. This simulated fuel quantity should be 0 L. If it is not 0 L, adjust the output parameters of the airborne fuel level measurement unit until the simulated fuel quantity displayed by the ground calibration host is 0 L (corresponding to an oil level voltage of 0.50 V); Fuel is added to the connected dual-container fuel tank simulation tool at a rate of 3L / min. When the fuel is about to reach the top of the fuel level sensor, the fuel injection rate is slowed down until the fuel level with the top of the fuel level sensor is reached. Then, the fuel injection is stopped. The simulated fuel volume displayed on the ground calibration host is observed. This simulated fuel volume should be the actual fuel volume of the connected dual-container fuel tank simulation tool at this fuel level. If the deviation exceeds ±0.25L, the output parameters of the airborne fuel level measurement unit are slightly adjusted until the error between the simulated fuel volume and the actual fuel volume meets the requirements (corresponding to a fuel level voltage of 4.90V).

[0084] Specifically, firstly, the ground calibration host and the airborne fuel level measurement unit are connected via test cables to ensure unobstructed signal and power transmission paths; simultaneously, the airborne fuel level measurement unit is electrically connected to two fuel level sensors installed on the connected dual-container fuel tank simulation fixture, enabling the two fuel level sensors to transmit capacitive signals to the airborne fuel level measurement unit, which then converts them into voltage signals for output.

[0085] Then, plug the power cord of the ground calibration host into the AC 220V AC power socket to connect the ground calibration host to an external power source.

[0086] Next, power on the ground calibration host (i.e., close the power switch of the ground calibration host to power on the measurement main board) and power on the airborne fuel level measurement unit (i.e., close the power switch of the airborne fuel level measurement unit to supply power to the airborne fuel level measurement unit through the airborne fuel level measurement unit interface).

[0087] Next, the connected dual-container fuel tank simulation fixture is leveled. The operator observes the X-axis and Y-axis readings of the dual-axis electronic level and adjusts the three-point height-adjustable base until the horizontal error of the X-axis and Y-axis is ≤ ±0.2°, to ensure accurate fuel level readings in the two transparent containers.

[0088] After completing the leveling adjustment, inject aviation fuel into the connected dual-container fuel tank simulation fixture through the fuel filling funnel at a fuel filling rate of 0.5L / min. When the fuel level is exactly level with the bottom of the two fuel level sensors, observe the simulated fuel volume displayed on the ground calibration host. This simulated fuel volume should be 0 liters. If the simulated fuel volume is not 0 liters, adjust the output parameters of the airborne fuel level measurement unit (e.g., rotate its fuel level voltage output knob) until the simulated fuel volume displayed on the ground calibration host is 0 liters. At this time, the fuel level voltage collected by the ground calibration host is 0.50V.

[0089] Finally, continue adding aviation fuel to the connected dual-container fuel tank simulator at a fuel injection rate of 3L / min. When the fuel level is about to reach the top of the two fuel level sensors, slow down the injection rate until the fuel level is level with the top of the fuel level sensors. At this point, observe the simulated fuel volume displayed on the ground calibration host. This simulated fuel volume should be the actual fuel volume of the connected dual-container fuel tank simulator at this level (i.e., the total volume corresponding to the fuel in the two transparent containers of the connected dual-container fuel tank simulator reaching the top of the sensors). If the deviation between the simulated fuel volume and the actual fuel volume exceeds ±0.25 liters, slightly adjust the output parameters of the airborne fuel level measurement unit until the error between the simulated fuel volume and the actual fuel volume meets the requirements (i.e., the deviation is no greater than ±0.25 liters). At this point, the fuel level voltage collected by the ground calibration host corresponds to 4.90V.

[0090] Through the above two steps of adjustment, the zero point (0.50V corresponding to 0L of simulated fuel) and full scale (4.90V corresponding to simulated fuel equal to the actual fuel volume of the tooling and with an error ≤ ±0.25L) of the output characteristics of the airborne fuel level measurement unit were calibrated, thereby ensuring that the simulated fuel volume calculated by the ground calibration host can accurately reflect the actual fuel volume.

[0091] Throughout the calibration process, since the bottoms of the two transparent containers of the connected dual-container fuel tank simulation tool are connected, the liquid level remains consistent. Therefore, the two fuel level sensors are calibrated synchronously under the same fuel level conditions, ensuring the consistency of their output characteristics and meeting the design requirements of the UAV dual-sensor redundancy architecture.

[0092] In this embodiment, the method further includes: After calibration, empty all the fuel in the connected dual-container fuel tank simulation tool, and then refill the connected dual-container fuel tank simulation tool until the fuel level is level with the bottom of the fuel level sensor. At this time, read the current simulated fuel volume displayed on the ground calibration equipment. If the current simulated fuel volume is ≤0.25L, the fuel level sensor is deemed to be qualified.

[0093] Specifically, after calibration, in order to verify the accuracy of the calibration results and the qualification of the fuel level sensor, the following qualification judgment operation needs to be performed: First, the aviation fuel inside the connected dual-container fuel tank simulation tool is completely emptied through the drain valve located on the bottom side wall of the tool, ensuring that there is no residual fuel inside the tool.

[0094] Then, aviation fuel is added again through the fuel filling funnel to the simulated dual-container fuel tank (the filling speed can be a conventional speed, for example, not exceeding 3L / min), until the fuel level is exactly level with the bottom of the fuel level sensor. At this point, the ground calibration equipment calculates the current simulated fuel quantity based on the voltage signal output from the airborne fuel level measurement unit using a preset voltage-to-fuel conversion algorithm, and displays this simulated fuel quantity on the display screen.

[0095] The operator reads the current simulated fuel level displayed on the ground calibration equipment. If the simulated fuel level is less than or equal to 0.25 liters (i.e., ≤0.25L), the fuel level sensor is deemed qualified. Conversely, if the current simulated fuel level is greater than 0.25 liters, the fuel level sensor is deemed unqualified and needs to be recalibrated or checked for faults.

[0096] This pass / fail determination step is independent of the zero-point and full-scale adjustment during the calibration process, providing a quantitative verification method for the calibration results. It can objectively evaluate the measurement accuracy of the fuel level sensor in the low fuel level region, ensuring that the calibrated sensor meets the stringent requirements of the UAV fuel level measurement system for low fuel level alarm and remaining fuel accuracy.

[0097] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A ground calibration device for an unmanned aerial vehicle (UAV) fuel level measurement system, wherein the UAV fuel level measurement system comprises a fuel level sensor and an airborne fuel level measurement unit, characterized in that, The ground calibration equipment includes: Ground calibration host, connected dual-container oil tank simulation fixture and test cables; The connected dual-container fuel tank simulation fixture is used to keep the fuel level in the two containers consistent during the calibration process, so as to calibrate the two fuel level sensors simultaneously. Both fuel level sensors are electrically connected to the same airborne fuel level measurement unit, which is used to collect the capacitance signal output by the fuel level sensors and convert the capacitance signal into a voltage signal. The ground calibration host is connected to the airborne fuel level measurement unit via the test cable. It receives the voltage signal output by the airborne fuel level measurement unit, calculates and displays the simulated fuel quantity based on the voltage signal, and allows the operator to compare it with the actual fuel quantity of the connected dual-container fuel tank simulation tool. Based on the comparison result, the output characteristics of the airborne fuel level measurement unit are adjusted to complete the calibration of the fuel level measurement system and to perform a qualification judgment on the calibrated fuel level sensor based on the simulated fuel quantity.

2. The ground calibration equipment for the UAV fuel level measurement system according to claim 1, characterized in that, The interconnected dual-container oil tank simulation fixture includes: The interconnected double container consists of two transparent containers of equal diameter and height that are connected at the bottom. The outer walls of the two transparent containers are provided with scales for reading the liquid level. A fuel level sensor mounting plate is fixed to the top of the connected double container. The fuel level sensor mounting plate has two sensor mounting positions for fixing two fuel level sensors respectively, and allowing the two fuel level sensors to extend into the corresponding transparent container. An oil drain valve is located on the bottom side wall of the interconnected double container; A fuel filling funnel is fixed to the top plate of the fuel level sensor, and the bottom of the fuel filling funnel is connected to the filling hole at the top of the connected double container. A leveling device is installed at the bottom of the connected double container to support the connected double container and to adjust the level of the connected double container.

3. The ground calibration equipment for the UAV fuel level measurement system according to claim 1, characterized in that, The ground calibration host includes: Portable chassis, including a chassis body and an openable lid; The measuring motherboard is located inside the enclosure; The control panel is located inside the housing. When the housing lid is opened, the control panel is exposed, and when the housing lid is closed, the control panel is covered and protected.

4. The ground calibration equipment for the UAV fuel level measurement system according to claim 2, characterized in that, The horizontal adjustment device includes: A three-point height-adjustable base is used to support the connected double containers and to adjust the level of the connected double containers. A dual-axis electronic level is used to display the horizontal status of the connected dual containers; The bottom of the three-point height-adjustable base is equipped with pulleys, which allows the connected dual-container oil tank simulation fixture to be moved.

5. The ground calibration equipment for the UAV fuel level measurement system according to claim 3, characterized in that, The operation panel is equipped with: Mains power socket; The power conversion module is electrically connected to the mains power socket; The ground calibration host power switch has its input terminal electrically connected to the first output terminal of the power conversion module, and its output terminal electrically connected to the power input terminal of the measurement motherboard. The power-on indicator light of the ground calibration host is electrically connected to the power-on switch of the ground calibration host; The power-on switch of the airborne oil level measurement unit is electrically connected to the second output terminal of the power conversion module. The power-on indicator light for the airborne fuel level measurement unit is electrically connected to the power-on switch for the airborne fuel level measurement unit. The airborne fuel level measurement unit interface has its input terminal electrically connected to the output terminal of the power switch of the airborne fuel level measurement unit, and its output terminal electrically connected to the power input terminal of the airborne fuel level measurement unit. and a communication connection with the measurement motherboard; The display screen, which is communicatively connected to the measurement motherboard, is used to receive and display the simulated fuel quantity and the fault status of the fuel level sensor.

6. The ground calibration equipment for the UAV fuel level measurement system according to claim 5, characterized in that, The measurement motherboard includes: The high-resistivity analog quantity acquisition module is connected to the airborne fuel level measurement unit interface via the test cable, and then communicates with the measurement motherboard to receive the voltage signal output by the airborne fuel level measurement unit. The calculation module is communicatively connected to the high-resistivity analog quantity acquisition module, and is used to receive the voltage signal and calculate the simulated oil quantity based on the voltage signal using a voltage-to-oil quantity conversion algorithm.

7. The ground calibration equipment for the UAV fuel level measurement system according to claim 6, characterized in that, The preset voltage-to-fuel conversion algorithm in the calculation module is as follows: Let V1 represent the voltage signal output by the airborne fuel level measurement unit, in volts; and L1 represent the simulated fuel quantity, in liters. When V1 < 0.2V, it is determined to be an open circuit fault; When 0.2V ≤ V1 < 0.5V, L1 = 0; When 0.5V≤V1<0.643V, L1=20.83916×V1-10.41958; When 0.643V≤V1<1.459V, L1=-26.19758×V1³+94.89053×V1²-54.16953×V1+5.54027; When 1.459V≤V1<1.587V, L1=96.25×V1-93.27875; When 1.587V≤V1≤4.90V, L1=0.77996×V1²+52.12384×V1-24.92382; When V1 > 4.90V, it is determined to be a short circuit fault.

8. The ground calibration equipment for the UAV fuel level measurement system according to claim 1, characterized in that, The process of determining the pass / fail status of the fuel level sensor after calibration based on the simulated fuel quantity includes: After calibration, empty all the fuel in the connected dual-container fuel tank simulation tool, and then refill the connected dual-container fuel tank simulation tool until the fuel level is level with the bottom of the fuel level sensor. At this time, read the current simulated fuel volume displayed on the ground calibration equipment. If the current simulated fuel volume is ≤0.25L, the fuel level sensor is deemed qualified.

9. A ground calibration method for an unmanned aerial vehicle (UAV) fuel level measurement system, utilizing the ground calibration equipment for an UAV fuel level measurement system as described in any one of claims 1-8, characterized in that, The method includes: Connect the ground calibration host and the airborne fuel level measurement unit via test cables; The airborne fuel level measurement unit is electrically connected to two fuel level sensors installed on a connected dual-container fuel tank simulation fixture. Power on the ground calibration host and power on the airborne fuel level measurement unit; Adjust the connected dual-container oil tank simulation fixture to a horizontal position; Fuel is added to the connected dual-container fuel tank simulation tool at a fuel injection rate of 0.5L / min. When the added fuel is level with the bottom of the fuel level sensor, the simulated fuel volume displayed on the ground calibration host is observed. The simulated fuel volume should be 0L. If it is not 0L, the output parameters of the airborne fuel level measurement unit are adjusted until the simulated fuel volume displayed on the ground calibration host is 0L (corresponding to a fuel level voltage of 0.50V). Fuel is added to the connected dual-container fuel tank simulation fixture at a rate of 3L / min. When the added fuel is about to reach the top of the fuel level sensor, the fuel injection rate is slowed down until the fuel level with the top of the fuel level sensor is reached. Then, the fuel injection is stopped. The simulated fuel volume displayed on the ground calibration host is observed. This simulated fuel volume should be the actual fuel volume of the connected dual-container fuel tank simulation fixture at this fuel level. If the deviation exceeds ±0.25L, the output parameters of the airborne fuel level measurement unit are slightly adjusted until the error between the simulated fuel volume and the actual fuel volume meets the requirements (corresponding to a fuel level voltage of 4.90V).

10. The ground calibration method for the UAV fuel level measurement system according to claim 9, characterized in that, The method further includes: After calibration, empty all the fuel in the connected dual-container fuel tank simulation tool, and then refill the connected dual-container fuel tank simulation tool until the fuel level is level with the bottom of the fuel level sensor. At this time, read the current simulated fuel volume displayed on the ground calibration equipment. If the current simulated fuel volume is ≤0.25L, the fuel level sensor is deemed qualified.

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