Unmanned aerial vehicle analog image transmission power control method based on heat source temperature detection

Abstract

The present application relates to the technical field of unmanned aerial vehicle, disclose a kind of unmanned aerial vehicle simulation picture transmission power control method based on heat source temperature detection, control method includes the following steps: S1. obtain the temperature control basis related to the heating state of unmanned aerial vehicle simulation picture transmission module;S2. when the temperature control basis reaches alarm temperature, compare current temperature control basis with the temperature control basis of last control cycle, to judge temperature change direction.The unmanned aerial vehicle simulation picture transmission power control method based on heat source temperature detection, by the temperature of unmanned aerial vehicle simulation picture transmission module reaches alarm temperature, according to temperature control basis and its change direction to RF power is gradually adjusted, so that picture transmission module can reduce heat release while, try to avoid the impact on image transmission link caused by RF power one-time substantial decline.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) technology, specifically to a UAV analog image transmission power control method based on heat source temperature detection. Background Technology

[0002] Drone image transmission modules typically need to achieve high-power radio frequency output within a small volume to ensure image transmission distance and image return stability during flight. Due to the compact internal space of the image transmission module, the heat generated by the RF power amplifier, PLL and related RF devices during operation is not easily dissipated in time. When the internal temperature of the module continues to rise, it may lead to a decrease in device performance, attenuation of RF output power, and a shortening of image transmission distance. In severe cases, it may cause video link interruption, affecting the pilot's ability to control the drone to return to base or continue flying based on real-time images.

[0003] In the field of drone-simulated image transmission equipment, there are two common handling methods: one is not to detect the module temperature, which makes it impossible to protect against overheating in time; the other is to quickly and significantly reduce the RF power after detecting that the temperature exceeds the warning line. Although this can reduce the temperature, it may cause the image transmission link to suddenly weaken or even be interrupted during long-distance flight.

[0004] Existing technologies already include solutions for adjusting the transmit power or transmission resources of communication equipment. For example, patent document No. 202011134432.3, which discloses a method and device for scheduling data transmission, discloses that when a terminal device transmits data using a first transmission layer, it performs actions such as reducing the SRS or PUSCH transmit power, shutting down some antenna ports, or sending auxiliary information after meeting preset conditions, and receives scheduling information from the network device, enabling the terminal device to use a lower transmission layer for data transmission, thereby reducing bit errors. This document also states that preset conditions may include the terminal device temperature exceeding a threshold. This solution can adjust transmission-related parameters when the communication terminal's temperature, power consumption, or radio frequency resources are limited, solving some communication stability and power consumption control problems.

[0005] However, the above solutions are mainly aimed at scheduling and control between communication terminals and network devices. They do not address the heat accumulation problem of the drone's simulated image transmission module in high-power, long-distance image transmission scenarios, nor do they solve the problem that if the RF power is reduced significantly at once after the image transmission module temperature exceeds the warning temperature, it may cause the image link to suddenly weaken or even be interrupted. Summary of the Invention

[0006] The purpose of this invention is to provide a method for controlling the simulated image transmission power of a UAV based on heat source temperature detection, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a UAV simulated image transmission power control method based on heat source temperature detection, applied to a UAV simulated image transmission module, wherein the UAV simulated image transmission module includes an NTC temperature sensor, an MCU, and an RF power control section, and the control method includes the following steps: S1. Obtain temperature control data related to the heating status of the drone's simulated image transmission module; S2. When the temperature control basis reaches the warning temperature, compare the current temperature control basis with the temperature control basis of the previous control cycle to determine the direction of temperature change; S3. The MCU selects the corresponding RF power reduction method according to the direction of temperature change, so that the RF power is reduced gradually, rather than being reduced sharply all at once after the warning temperature is reached; S4.MCU sends the adjusted POWER_DATA to the RF power control section to change the RF output power of the drone's simulated image transmission module; S5. After a predetermined control interval, obtain the temperature control data again and repeat the above power control process.

[0008] As a further step, the module temperature is obtained by continuously sampling the NTC temperature sensor multiple times and then averaging the results.

[0009] As a further step, the continuous multiple sampling includes sampling 6-8 times and averaging the results. The MCU then looks up the module temperature in a table based on the average result.

[0010] Furthermore, the direction of temperature change is determined by the difference between the current temperature control basis and the temperature control basis of the previous control cycle. A positive difference indicates that the temperature continues to rise, a zero difference indicates that the temperature remains unchanged, and a negative difference indicates that the temperature decreases.

[0011] Furthermore, when the temperature control threshold is higher than 85 degrees and the temperature continues to rise, the MCU reduces the RF power by a first reduction margin; when the temperature control threshold is higher than 85 degrees and the temperature remains unchanged, the MCU reduces the RF power by a second reduction margin smaller than the first reduction margin; when the temperature control threshold is higher than 85 degrees and the temperature decreases, the MCU reduces the RF power by a second reduction margin. Specifically, when the temperature control threshold first exceeds 85 degrees, the MCU first reduces the RF power by the second reduction margin and records the current temperature; in subsequent control cycles, the first reduction margin or the second reduction margin is selected based on the difference between the current temperature control threshold and the temperature control threshold of the previous control cycle.

[0012] As a further step, the first reduction corresponds to 1 / 32, the second reduction corresponds to 1 / 64, and the adjusted POWER_DATA is sent to the power attenuator in the RF power control section through the SPI port. 1 / 32 and 1 / 64 are the adjustment steps of POWER_DATA.

[0013] As a further step, the MCU samples the temperature every 100ms and compares the temperature control data obtained from the current detection with the temperature control data of the previous control cycle every 10s. When the temperature control data is below 80 degrees, the MCU maintains the current RF power and does not continue to reduce the RF power. When the temperature control data is above 105 degrees, the MCU immediately reduces the RF power to the second level.

[0014] As a further step, the temperature control basis also includes the virtual heat source temperature and the predicted temperature for the next control cycle. The virtual heat source temperature and the predicted temperature are obtained by adding a virtual heat source temperature calculation module before temperature trend control. The virtual heat source temperature calculation module estimates the core heat source temperature of the power amplifier and the temperature change trend for the next control cycle based on at least some data from RF power attenuation code, PA supply voltage, PA current, operating frequency, and historical temperature changes.

[0015] As a further step, the virtual heat source temperature calculation module determines the PA heat loss based on the PA power supply voltage, PA current, and RF output power estimation value; the RF output power estimation value is obtained by looking up the current POWER_DATA, operating frequency, PA gain table, and attenuator code value; when the UAV simulated image transmission module does not set PA current sampling, the PA heat loss is obtained from the factory calibration table corresponding to the operating frequency, POWER_DATA, attenuator code value, PA power supply voltage, and NTC measured temperature.

[0016] As a further step, the MCU predicts the temperature change of the heat source in the next control cycle for multiple candidate power reduction step sizes, including 0, 1 / 64, 1 / 32 and 1 / 16. The MCU selects the smallest power reduction step size from the multiple candidate power reduction step sizes that ensures the predicted temperature does not continue to rise and tends towards the safe control temperature, and that the image transmission link is not interrupted. When the NTC measures a temperature that has not reached 105 degrees but the predicted temperature will exceed 105 degrees, the MCU enters the second protection level in advance.

[0017] Compared with the prior art, the beneficial effects of the present invention are: the UAV simulated image transmission power control method based on heat source temperature detection gradually adjusts the RF power according to the temperature control basis and its change direction after the temperature of the UAV simulated image transmission module reaches the warning temperature, so that the image transmission module can reduce heat generation while avoiding the impact of a large drop in RF power at one time on the image transmission link.

[0018] 1. When the temperature exceeds the warning temperature, the RF power is not directly reduced to a lower power state. Instead, the RF power is gradually reduced by different amounts depending on whether the temperature continues to rise, remains unchanged, or decreases. This helps to reduce the heat generation of the image transmission module and reduce the risk of video link interruption caused by a sudden drop in RF power.

[0019] 2. By continuously sampling the NTC temperature sensor multiple times and averaging the results to obtain the module temperature, the impact of single sampling fluctuations on power control judgment is reduced. This allows the MCU to perform RF power adjustment based on more stable temperature data. Every predetermined time interval, the current temperature control data is compared with the temperature control data of the previous control cycle, and the power reduction is determined by combining the direction of temperature change. This allows the RF power control to follow the temperature trend of the image transmission module, rather than being fixed based on a single temperature threshold.

[0020] 3. Once the temperature drops below the warning temperature by a certain margin, the current RF power is maintained, and the RF power is no longer continuously reduced. This helps to form hysteresis control and reduces the frequent adjustment of RF power when the temperature fluctuates near the threshold. Furthermore, by incorporating virtual heat source temperature or predicted temperature for the next control cycle into power control, the MCU can estimate the core heat source status of the power amplifier by combining data such as RF power attenuation code, PA supply voltage, PA current, operating frequency, and historical temperature changes. This helps to reduce the impact of thermal hysteresis between the NTC temperature measurement location and the actual heat source, and allows for early entry into protection control under extreme temperature rise trends. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the UAV simulated image transmission module of the present invention; Figure 2 This is a schematic diagram of the process of calling temperature detection processing in the MCU main program of this invention; Figure 3 This is a flowchart illustrating the RF power control process following temperature detection in this invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figures 1-3 The present invention provides the following technical solution: Example 1: This example provides a method for controlling the power of a drone-simulated image transmission based on heat source temperature detection. This method is applied to a drone-simulated image transmission module, which includes an NTC temperature sensor, an MCU, a PLL, an RF power control section, and RF_OUT. The NTC temperature sensor is used to detect the internal temperature of the image transmission module. The MCU is used for temperature sampling, temperature judgment, POWER_DATA adjustment, and control data output. POWER_DATA is the attenuation code value of the power attenuator. The PLL is used to control the RF operating frequency of the image transmission module. The RF power control section is used to change the RF output power of RF_OUT according to the POWER_DATA output by the MCU.

[0024] like Figure 2 As shown, after the MCU powers on, it first performs initialization data processing. This initialization data includes frequency, power, operating status, and interrupts. In the main program loop, the MCU sequentially checks whether there is a valid button state, whether the data received by the UART interrupt meets the data length requirement, and whether the temperature detection time has elapsed. When the temperature detection time is reached, the MCU enters the temperature detection and corresponding processing procedure. This embeds the temperature control process into the original software main loop of the image transmission module, rather than executing it independently of the image transmission module's operating state. The specific workflow is shown in the following steps: S1. Obtain temperature control data related to the heating status of the drone's simulated image transmission module; S2. When the temperature control basis reaches the warning temperature, compare the current temperature control basis with the temperature control basis of the previous control cycle to determine the direction of temperature change; S3. The MCU selects the corresponding RF power reduction method according to the direction of temperature change, so that the RF power is reduced gradually, rather than being reduced sharply all at once after the warning temperature is reached; S4.MCU sends the adjusted POWER_DATA to the RF power control section to change the RF output power of the drone's simulated image transmission module; S5. After a predetermined control interval, obtain the temperature control data again and repeat the above power control process.

[0025] In this embodiment, the UAV simulated image transmission module may further include a PLL, RF_OUT, power supply, KEY, LED, and UART. An NTC temperature sensor is located inside the image transmission module and is used to detect the internal temperature. The MCU is used to perform temperature sampling, temperature judgment, POWER_DATA adjustment, and control data output. The PLL is used to coordinate with the RF operating frequency control of the image transmission module. The RF power control section is used to change the RF output power of RF_OUT according to the POWER_DATA output by the MCU. POWER_DATA is the power control data output from the MCU to the RF power control section, specifically the attenuation code value of the power attenuator. For more detailed steps, please refer to the following content.

[0026] In step S1, the module temperature is obtained by continuously sampling the NTC temperature sensor multiple times and averaging the results. This continuous sampling includes 6-8 consecutive samplings and averaging the results. The MCU then looks up the average result in a table to obtain the module temperature. Specifically, the MCU can perform an AD sampling of the NTC temperature sensor every 100ms. In one temperature detection, the MCU continuously samples 6-8 times and averages the results, preferably 6 times, and then averages the results to obtain the corresponding module temperature from a table. Using continuous multiple sampling and averaging reduces the impact of single-sample fluctuations on temperature judgment, allowing subsequent POWER_DATA adjustments to be based on more stable temperature data.

[0027] In S2, the direction of temperature change is determined by the difference between the current temperature control basis and the temperature control basis of the previous control cycle. A positive difference indicates that the temperature continues to rise, a zero difference indicates that the temperature remains unchanged, and a negative difference indicates that the temperature decreases. In this embodiment, the current temperature control basis is denoted as Hot_current, the temperature control basis of the previous control cycle is denoted as hot_last, and the temperature change difference is denoted as delta_hot, where delta_hot = Hot_current - hot_last. When delta_hot is positive, it indicates that the detected temperature continues to rise relative to the previous control cycle; when delta_hot is zero, it indicates that the detected temperature remains unchanged relative to the previous control cycle; and when delta_hot is negative, it indicates that the detected temperature decreases relative to the previous control cycle.

[0028] In S3, when the temperature control threshold is higher than 85 degrees and the temperature continues to rise, the MCU reduces the RF power by a first reduction margin; when the temperature control threshold is higher than 85 degrees and the temperature remains unchanged, the MCU reduces the RF power by a second reduction margin smaller than the first reduction margin; when the temperature control threshold is higher than 85 degrees and the temperature decreases, the MCU reduces the RF power by a second reduction margin. Specifically, when the temperature control threshold first exceeds 85 degrees, the MCU first reduces the RF power by the second reduction margin and records the current temperature; in subsequent control cycles, the first reduction margin or the second reduction margin is selected based on the difference between the current temperature control threshold and the temperature control threshold of the previous control cycle.

[0029] Specifically, such as Figure 3 As shown, after the MCU completes temperature sampling and obtains Hot_current, it can first determine whether Hot_current is higher than 105 degrees. If Hot_current is higher than 105 degrees, the MCU immediately reduces the RF power to the second level to perform extreme over-temperature protection; if Hot_current is not higher than 105 degrees, the MCU continues to determine whether Hot_current is higher than 85 degrees.

[0030] When Hot_current first exceeds 85°C, the MCU first reduces the RF power by the second reduction increment and records the current temperature as hot_last. This initial reduction uses a smaller second reduction increment to avoid a sudden and significant drop in RF output power just as the temperature exceeds the warning temperature. Subsequently, at predetermined control intervals, when the temperature is checked again, the MCU compares the new Hot_current with the hot_last recorded in the previous control cycle, determines the direction of temperature change based on the positive, zero, or negative value of delta_hot, and selects either the first or second reduction increment accordingly. After each control cycle completes the comparison and power adjustment, the MCU updates the Hot_current of the current cycle to hot_last for use in the next control cycle.

[0031] When Hot_current is above 85 degrees and delta_hot is greater than 0, it indicates that the temperature of the image transmission module continues to rise after the previous control cycle, and the MCU reduces the RF power by the first reduction amount; when Hot_current is above 85 degrees and delta_hot is equal to 0, it indicates that the temperature of the image transmission module has not continued to rise but is still above the warning temperature, and the MCU reduces the RF power by the second reduction amount; when Hot_current is above 85 degrees and delta_hot is less than 0, it indicates that the temperature of the image transmission module has dropped but has not yet left the warning range, and the MCU reduces the RF power by the second reduction amount.

[0032] The first reduction corresponds to 1 / 32, and the second reduction corresponds to 1 / 64. The adjusted POWER_DATA is sent to the power attenuator in the RF power control section via the SPI port. 1 / 32 and 1 / 64 are the adjustment step sizes of POWER_DATA. In other words, the MCU does not necessarily reduce the RF output power directly by 1 / 32 or 1 / 64 linearly, but rather reduces the RF output power by adjusting POWER_DATA so that the attenuation of the power attenuator changes according to the corresponding step size. In one specific implementation, a 1 / 64 adjustment step size can correspond to a power adjustment of approximately 0.125 dBm, and a 1 / 32 adjustment step size can correspond to a power adjustment of approximately 0.25 dBm.

[0033] In S4, the MCU sends the adjusted POWER_DATA to the power attenuator in the RF power control section via the SPI port. The power attenuator changes the corresponding power attenuation amount according to POWER_DATA, thereby changing the RF output power of RF_OUT. In this way, the MCU can achieve progressive RF power control using the power attenuator without changing the main hardware architecture of the UAV simulated image transmission module.

[0034] In S5, the MCU samples the temperature every 100ms and compares the temperature control data obtained from the current detection with the temperature control data of the previous control cycle every 10s. When the temperature control data is below 80 degrees, the MCU maintains the current RF power and does not continue to reduce the RF power. When the temperature control data is above 105 degrees, the MCU immediately reduces the RF power to the second level, namely LEV2 as shown in the figure.

[0035] Specifically, the MCU can sample the NTC temperature every 100ms, and after reaching a power control cycle every 10s, it compares the Hot_current obtained from the current detection with the hot_last from the previous control cycle. The 10s power control cycle is chosen because after each change in RF power, the heat generated inside the image transmission module needs a certain amount of time to be reflected at the NTC temperature sensor. If the control interval is too short, the temperature may not have stabilized, potentially causing unnecessary frequent adjustments; if the control interval is too long, it is not conducive to timely control of the module's temperature rise.

[0036] When Hot_current is below 80 degrees Celsius, the MCU maintains the current RF power and does not further reduce it. This 80-degree threshold has approximately a 5-degree hysteresis relative to the 85-degree warning temperature, ensuring that once the module temperature is below the warning temperature by a certain margin, the RF power is no longer further reduced, thus minimizing repeated power adjustments when the module temperature fluctuates near the threshold. Here, "maintaining the current RF power" means maintaining the currently adjusted RF power, and does not necessarily mean immediately reverting to the initial power before the power reduction.

[0037] When Hot_current exceeds 105 degrees Celsius, the MCU immediately reduces the RF power to the second level (not a second reduction in magnitude). This second level can be a preset over-temperature protection power level, and its corresponding POWER_DATA can be denoted as LEV2, which represents the RF output power level. This second level is lower than the power level under normal high-power image transmission operation, and is used to prevent the module from burning out due to continued significant temperature increases in extreme conditions such as abnormal heat dissipation, high ambient temperature, or rapid rise in module temperature.

[0038] Using the control method described in Example 1, the drone's simulated image transmission module does not immediately reduce its RF power to a lower level when the temperature exceeds the warning temperature. Instead, it first reduces the RF power by a smaller second reduction magnitude when the temperature first exceeds 85°C. Then, depending on whether the temperature continues to rise, remains unchanged, or decreases, the POWER_DATA is adjusted using either the first or second reduction magnitude within each control cycle. This method allows the image transmission module's temperature to be gradually controlled to a reasonable range after exceeding the warning line, while simultaneously reducing the risk of video communication interruption caused by a sudden drop in RF output power.

[0039] Example 2: Building upon Example 1, this example further provides an enhanced control method based on virtual heat source temperature and predicted temperature. This example can serve as an enhancement to Example 1, or as an alternative control scheme when hardware sampling and calibration conditions are met.

[0040] In this embodiment, the temperature control basis also includes the virtual heat source temperature and the predicted temperature for the next control cycle. The virtual heat source temperature and the predicted temperature are obtained by adding a virtual heat source temperature calculation module before temperature trend control. The virtual heat source temperature calculation module estimates the core heat source temperature of the power amplifier and the temperature change trend for the next control cycle based on at least some data from RF power attenuation code, PA supply voltage, PA current, operating frequency, and historical temperature changes.

[0041] Specifically, the virtual heat source temperature calculation module is set in the MCU's software control flow and can run before the fixed temperature trend control described in Example 1. This module does not directly determine the power reduction step size solely based on the temperature measured by the NTC, but instead combines the RF power attenuation code, PA supply voltage, PA current, operating frequency, and historical temperature changes to estimate the core heat source temperature of the power amplifier PA and the predicted temperature for the next control cycle. Thus, the controlled object is expanded from simply the temperature measured by the sensor to the predicted temperature of the RF heat source.

[0042] The virtual heat source temperature calculation module determines the PA heat loss based on the PA power supply voltage, PA current, and RF output power estimation values. The RF output power estimation values ​​are obtained by looking up the current POWER_DATA, operating frequency, PA gain table, and attenuator code value. When the UAV simulated image transmission module does not set PA current sampling, the PA heat loss is obtained from the factory calibration table corresponding to the operating frequency, POWER_DATA, attenuator code value, PA power supply voltage, and NTC measured temperature.

[0043] Specifically, the virtual heat source temperature calculation module can determine the PA heat loss power in the kth control cycle according to the following formula: P_loss(k)=V_PA(k)×I_PA(k)-P_RF_est(k) Where P_loss(k) represents the PA heat loss power in the k-th control cycle, V_PA(k) represents the PA supply voltage, I_PA(k) represents the PA operating current, and P_RF_est(k) represents the estimated RF output power. P_RF_est(k) can be obtained by looking up the current POWER_DATA(k), the operating frequency, the PA gain table, and the attenuator code value. If the estimated RF output power obtained from the table is in dBm form, it can be converted to linear power units such as watts or milliwatts before being included in the P_loss(k) calculation to ensure consistency of units for physical quantities in the formula.

[0044] When the drone's simulated image transmission module does not have PA current sampling set, the virtual heat source temperature calculation module can determine the PA heat loss power using the following calibration table: P_loss(k)=F_loss[f(k),POWER_DATA(k),ATT(k),V_PA(k),T_ntc(k)] Where F_loss is the heat loss lookup function obtained from the factory calibration, f(k) is the current operating frequency, ATT(k) is the current attenuator code value, and T_ntc(k) is the temperature measured by the NTC. This method does not require the hardware to set up a PA current sampling circuit, and can estimate the PA heat loss based on the factory calibration table corresponding to the frequency, power level, supply voltage, attenuator code value, and NTC measured temperature.

[0045] After obtaining the PA heat loss power, the virtual heat source temperature calculation module can calculate the core heat source temperature of the power amplifier according to the following formula: T_core_est(k)=T_ntc(k)+K1×dT_ntc(k) / dt+K2×P_loss(k)+K3×ΔP_loss(k) Where T_core_est(k) represents the estimated core heat source temperature of the PA, T_ntc(k) represents the temperature measured by the NTC, dT_ntc(k) / dt represents the NTC temperature rise slope, P_loss(k) represents the current PA heat loss power, ΔP_loss(k) represents the difference between the current and previous RF heat loss power, and K1, K2, and K3 are factory calibration coefficients.

[0046] Furthermore, the virtual heat source temperature calculation module can predict the temperature of the next control cycle based on the following formula: T_pred(k+10s)=T_core_est(k)+A×P_loss_candidate-B×[T_core_est(k)-T_ambient] Where T_pred(k+10s) represents the predicted temperature for the next control cycle, P_loss_candidate represents the PA heat loss power after adopting a certain candidate power reduction step size, T_ambient represents the ambient temperature or the module's low-temperature reference temperature, A represents the coefficient of thermal expansion, and B represents the coefficient of thermal dissipation. T_ambient can be determined by the NTC temperature during the module's low-temperature power-on phase, or obtained from an independent ambient temperature sensor, or given by the factory calibration value. Parameters such as A, B, T_safe, and P_RF_min can be determined through factory calibration, prototype thermal testing, or preset empirical values.

[0047] The MCU predicts the temperature change of the heat source in the next control cycle for multiple candidate power reduction step sizes, including 0, 1 / 64, 1 / 32 and 1 / 16. The MCU selects the smallest power reduction step size from the multiple candidate power reduction step sizes that can ensure the predicted temperature does not continue to rise and tends to the safe control temperature, and can maintain the image transmission link without interruption. When the NTC measures a temperature that has not reached 105 degrees but the predicted temperature will exceed 105 degrees, the MCU enters the second protection level in advance.

[0048] Specifically, the MCU can enumerate candidate power reduction step sizes S = {0, 1 / 64, 1 / 32, 1 / 16}. A candidate power reduction step size of 0 indicates that the RF power will not be further reduced in the current control cycle. The MCU calculates the corresponding P_loss_candidate and T_pred_s(k+10s) for each candidate power reduction step size, and selects the smallest power reduction step size that prevents the predicted temperature from rising further and approaches a safe control temperature, while ensuring that the RF output power is not lower than the minimum sustaining power of the image transmission link. This selection process can be expressed as: s*=min{s∈S | T_pred_s(k+10s)≤T_safe and P_RF_s≥P_RF_min} Where s* represents the final selected power reduction step size, T_pred_s(k+10s) represents the predicted temperature after adopting the candidate power reduction step size s, T_safe represents the safety control temperature, P_RF_s represents the RF output power after adopting the candidate power reduction step size s, and P_RF_min represents the minimum RF power required to maintain the image transmission link without interruption.

[0049] In this embodiment, if the NTC measures a temperature higher than 85°C, but T_pred(k+10s) shows that the heat source temperature is decreasing, the MCU can select a candidate power reduction step size of 0 and not continue to add power reduction. If the NTC measures a temperature lower than 105°C but predicts that the temperature will exceed 105°C, the MCU will enter the second level of protection in advance to avoid the NTC temperature lag causing the protection action to be too late.

[0050] The difference between Example 2 and Example 1 is that Example 1 mainly selects between adjustment step sizes such as 1 / 64 and 1 / 32 based on the temperature measured by the NTC and its direction of change; Example 2 adds a virtual heat source temperature calculation module before temperature trend control and predicts the heat source temperature change in the next control cycle through candidate power reduction step sizes. When Example 2 is enabled, the MCU can use the candidate power reduction step size selection result as the final power adjustment result for this control cycle, so it is not necessary to continue to reduce the RF power if the predicted temperature has already decreased.

[0051] Through the processing in Example 2, the MCU can combine RF heating power, POWER_DATA, attenuator code value, frequency point, temperature hysteresis and the prediction result of the next control cycle to perform predictive power control on the PA of the analog image transmission module, thereby reducing the impact of thermal hysteresis between the NTC placement position and the actual heating point of the PA on the timeliness of power control, and entering the second protection level in advance under extreme temperature rise trend.

[0052] It should be noted that the 85°C warning temperature, 80°C hysteresis temperature, and 105°C protection temperature described in the above embodiments are specific examples. Without departing from the concept of this invention, those skilled in the art can preset or calibrate the corresponding temperature thresholds based on the device temperature resistance, heat dissipation structure, transmission power level, and application environment of different image transmission modules.

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the power of simulated image transmission in a UAV based on heat source temperature detection, applied to a simulated image transmission module in a UAV, the simulated image transmission module including an NTC temperature sensor, an MCU, and an RF power control section, characterized in that: The control method includes the following steps: S1. Obtain temperature control data related to the heating status of the drone's simulated image transmission module; S2. When the temperature control basis reaches the warning temperature, compare the current temperature control basis with the temperature control basis of the previous control cycle to determine the direction of temperature change; S3. The MCU selects the corresponding RF power reduction method according to the direction of temperature change, so that the RF power is reduced gradually, rather than being reduced sharply all at once after the warning temperature is reached; S4.MCU sends the adjusted POWER_DATA to the RF power control section to change the RF output power of the drone's simulated image transmission module; S5. After a predetermined control interval, obtain the temperature control data again and repeat the above power control process; The temperature control basis also includes the virtual heat source temperature and the predicted temperature for the next control cycle. The virtual heat source temperature and the predicted temperature are obtained by adding a virtual heat source temperature calculation module before the temperature trend control. The virtual heat source temperature calculation module estimates the core heat source temperature of the power amplifier and the temperature change trend for the next control cycle based on at least some data from RF power attenuation code, PA supply voltage, PA current, operating frequency and historical temperature changes. The core heat source temperature is the temperature of the core heating area of ​​the power amplifier. The virtual heat source temperature calculation module determines the PA heat loss based on the PA power supply voltage, PA current, and RF output power estimation values. The RF output power estimation values ​​are obtained by looking up the current POWER_DATA, operating frequency, PA gain table, and attenuator code value. When the UAV simulated image transmission module does not set PA current sampling, the PA heat loss is obtained from the factory calibration table corresponding to the operating frequency, POWER_DATA, attenuator code value, PA power supply voltage, and NTC measured temperature.

2. The UAV simulated image transmission power control method based on heat source temperature detection according to claim 1, characterized in that: The module temperature is obtained by taking multiple consecutive samples from the NTC temperature sensor and averaging them.

3. The UAV simulated image transmission power control method based on heat source temperature detection according to claim 2, characterized in that: The continuous multiple sampling includes 6-8 consecutive samplings and averaging them. The MCU obtains the module temperature by looking up the average result in a table.

4. The UAV simulated image transmission power control method based on heat source temperature detection according to claim 1, characterized in that: The direction of temperature change is determined by the difference between the current temperature control basis and the temperature control basis of the previous control cycle. A positive difference indicates that the temperature continues to rise, a zero difference indicates that the temperature remains unchanged, and a negative difference indicates that the temperature decreases.

5. The UAV simulated image transmission power control method based on heat source temperature detection according to claim 4, characterized in that: When the temperature control threshold is higher than 85 degrees and the temperature continues to rise, the MCU reduces the RF power by a first reduction margin. When the temperature control threshold is higher than 85 degrees and the temperature remains unchanged, the MCU reduces the RF power by a second reduction margin, which is less than the first reduction margin. When the temperature control threshold is higher than 85 degrees and the temperature decreases, the MCU reduces the RF power by a second reduction margin. Specifically, when the temperature control threshold first exceeds 85 degrees, the MCU first reduces the RF power by the second reduction margin and records the current temperature. In subsequent control cycles, the first reduction margin or the second reduction margin is selected based on the difference between the current temperature control threshold and the temperature control threshold of the previous control cycle.

6. The UAV simulated image transmission power control method based on heat source temperature detection according to claim 5, characterized in that: The first reduction corresponds to 1 / 32, and the second reduction corresponds to 1 / 64. The adjusted POWER_DATA is sent to the power attenuator in the RF power control section through the SPI port. 1 / 32 and 1 / 64 are the adjustment steps of POWER_DATA.

7. The UAV simulated image transmission power control method based on heat source temperature detection according to claim 1, characterized in that: The MCU samples the temperature every 100ms and compares the temperature control data obtained from the current detection with the temperature control data of the previous control cycle every 10s. When the temperature control data is below 80 degrees, the MCU maintains the current RF power and does not continue to reduce the RF power. When the temperature control data is above 105 degrees, the MCU immediately reduces the RF power to the second level.

8. The UAV simulated image transmission power control method based on heat source temperature detection according to claim 1, characterized in that: The MCU predicts the temperature change of the heat source in the next control cycle for multiple candidate power reduction step sizes, including 0, 1 / 64, 1 / 32 and 1 / 16. The MCU selects the smallest power reduction step size from the multiple candidate power reduction step sizes that can ensure the predicted temperature does not continue to rise and tends to the safe control temperature, and can maintain the image transmission link without interruption. When the NTC measures a temperature that has not reached 105 degrees but the predicted temperature will exceed 105 degrees, the MCU enters the second protection level in advance.

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