Method and system for improving and guaranteeing cross-night flight capability of solar-powered unmanned aerial vehicle

Abstract

The present application belongs to the technical field of solar unmanned aerial vehicle energy management, and discloses a solar unmanned aerial vehicle cross-night flight capacity improvement and guarantee method for residual flight time, which uses residual flight time to evaluate the ability of the solar unmanned aerial vehicle to perform flight and payload task only relying on energy storage batteries. Combined with the flight profile of the solar unmanned aerial vehicle, the residual flight time constraint of the solar unmanned aerial vehicle cross-night flight is given. The relationship between the propulsion system power consumption of the solar unmanned aerial vehicle and the cruising speed, and the relationship between the payload power consumption and the task queue are pointed out. Then, the energy self-management strategy is used to gradually reduce the power consumption of the power consumption end to extend the residual flight time, so as to meet the requirements of cross-night flight.

Description

Technical Field

[0001] This invention belongs to the field of solar-powered unmanned aerial vehicle (UAV) energy management technology, and in particular relates to a method for improving and ensuring the overnight flight capability of solar-powered UAVs with remaining flight time. Background Technology

[0002] High-altitude, long-endurance solar-powered unmanned aerial vehicles (UAVs) utilize solar cell arrays as their energy source. During the day, the solar cells absorb solar radiation and convert it into electricity, which powers the propulsion motor, avionics, and payload. Excess energy is used to charge storage batteries, ensuring continuous flight until sunrise the following day, even in darkness. This cycle repeats. Such UAVs can fly for several days to several months, carrying radar and communication payloads to perform tasks such as target search, target tracking, surface SAR imaging, relay communication, and satellite communication. They hold great promise in both military and civilian applications.

[0003] Due to the limited capacity of the energy storage batteries carried by solar-powered drones, it is difficult to meet the requirements for day-and-night flight and payload execution. Currently, there is a four-stage flight profile strategy that allows the drone to climb during the day to store gravitational potential energy and glide to release it at night, improving the ability of solar-powered drones to fly through the night. This strategy alleviates the above contradictions to some extent, but it cannot guarantee the safe overnight flight of the drone.

[0004] The above UAV flight profile strategy mainly uses glide to release gravitational potential energy to increase the remaining flight time after sunset. Based on this flight profile strategy, this invention uses the remaining flight time to evaluate the cross-night flight capability of solar-powered UAVs. By adopting the energy management strategy of this invention, it can be ensured that the remaining flight time meets the cross-night flight constraints, significantly improving the cross-night flight capability of solar-powered UAVs and providing a guarantee for the safe cross-night flight of solar-powered UAVs.

[0005] Based on the above analysis, the problems and shortcomings of the existing technology are as follows: Due to the limited capacity of the energy storage batteries carried by solar-powered drones, it is difficult to meet the requirements for day-and-night flight and payload execution. Currently, there is a four-stage flight profile strategy that allows the drone to climb during the day to store gravitational potential energy and glide to release it at night, improving the ability of solar-powered drones to fly through the night. This strategy alleviates the above contradictions to some extent, but it cannot guarantee the safe overnight flight of the drone.

[0006] Existing technology: Energy management system for traditional solar-powered drones Traditional solar-powered drones typically feature a basic energy management system. This system primarily relies on solar panels to directly power the drone's propulsion system and electronics, while storing additional energy in batteries for use when sunlight is insufficient. Such systems usually charge during daytime flights and utilize the stored energy at night or when sunlight is low. The energy management strategy is relatively simple, relying mainly on a fixed flight profile and preset energy usage patterns.

[0007] Existing technical problems: 1) Inaccurate energy forecasting: Traditional systems typically lack advanced energy forecasting capabilities and cannot effectively predict the efficiency of solar power generation under different weather conditions, which makes it impossible to effectively plan energy use when energy is scarce.

[0008] 2) Rigidity of flight profile: Fixed flight profiles are not adapted to sudden changes in weather or other external conditions, resulting in wasted or insufficient energy.

[0009] 3) Limitations of energy management: Traditional energy management systems often lack flexibility and cannot dynamically adjust energy allocation according to real-time energy demand and supply, especially during long-duration night flights, which can lead to the failure of critical missions.

[0010] 4) Insufficient ability to respond to emergencies: In the event of emergencies such as unexpected weather changes or equipment failures, traditional solar-powered drones cannot effectively adjust their flight strategies to ensure the continuous operation of critical systems. Summary of the Invention

[0011] To address the problems existing in the prior art, this invention provides a method for improving and ensuring the overnight flight capability of solar-powered UAVs with remaining flight time.

[0012] This invention is implemented as follows: A method for improving and ensuring the overnight flight capability of a solar-powered UAV with remaining flight time includes: Step 1: Calculate the remaining flight time of the UAV, indicate the relationship between the remaining flight time and the total power consumption of the onboard power-consuming equipment, and give the remaining flight time constraint for safely passing through the night; Step two: During the gliding phase, a model for the gliding speed decrease of the UAV was established, and the gliding duration of the UAV was calculated using this model. During the nighttime level flight cruise phase, an energy model for the energy storage system was established. Step 3: By combining the energy management system to obtain energy from the energy storage battery, a dynamic model of the UAV was established. Through this model, the relationship between the power consumption of the propulsion system and the cruise speed was obtained. Step 4: Obtain the payload power calculation method through the payload mission queue, obtain the remaining flight time during the level flight cruise phase, and combine it with the gliding phase duration to further obtain the remaining flight time after sunset; Step 5: If the remaining flight time constraint is not met, a method for degrading the propulsion system and payload power is proposed through energy management strategy.

[0013] Furthermore, the method for calculating the remaining flight time of the UAV: The remaining flight time of a solar-powered drone is given by the following formula: In the formula, represents the power of the energy storage battery, represents the power consumption of all energy-consuming devices of the solar-powered drone, and the remaining flight time can assess the ability to continue flying and performing payload tasks on its own when there is no external energy source. The longer the remaining flight time, the stronger the ability to continue flying and performing payload tasks at night. This invention combines flight profiles and uses an energy autonomous management strategy to reduce the total power consumption of the solar-powered drone's electrical equipment at night, thereby increasing the remaining flight time to meet the constraints of overnight flight and ensuring the drone's safe passage through the night. A schematic diagram of the energy system structure of a long-endurance solar-powered UAV is shown below. Figure 2 As shown, it mainly consists of three parts: solar cells at the power supply end; propulsion motors, avionics equipment and payloads at the power consumption end; and energy storage batteries at the energy storage end.

[0014] Furthermore, the capacity of the energy storage battery can be obtained by reading the SOC parameter from the power management system. SOC is the state of charge of the battery, with a value ranging from 0 to 1. The two have the following relationship: The energy-consuming end consists of the propulsion motor, avionics equipment, and payload, so the total power consumption is calculated using the following formula: As can be seen from the above formula, it is mainly necessary to reduce the power consumption of the propulsion motor, the power of the payload, and the power of the avionics to extend the remaining flight time. However, since the UAV flies continuously, the power of the avionics does not change much and can be regarded as constant. Therefore, the power consumption of the propulsion motor and the power of the payload are mainly constrained by the energy management system. Based on the mission profile of the UAV's cyclic flight, the following gives the remaining flight time constraints for safely passing through the night flight, the detailed calculation method of the remaining flight time, and the method to improve the remaining flight time. Furthermore, the flight of the aforementioned UAV can be divided into four profiles: daytime climb, daytime level flight cruise, evening gliding, and nighttime level flight cruise. When the solar power generation is high, the UAV climbs to store gravitational potential energy and charge its energy storage battery. Upon reaching its maximum flight altitude, it enters the daytime level flight cruise phase. When the power generation is low or even unable to generate power, the UAV begins to glide to release gravitational potential energy. Upon gliding to its lowest flight altitude, it begins nighttime level flight cruise, during which it is entirely powered by its energy storage battery. The solar cell power generation and flight profile of the high-altitude long-endurance solar-powered UAV over 48 hours are as follows: Figure 3As shown, the solar panels begin generating electricity at time tr each day, and the power output is zero at time ts. Since the power output curve of the solar panels has a 24-hour cycle, the flight profile of the solar-powered aircraft also has a 24-hour cycle, dividing the flight profile within one cycle into four segments: A, B, C, and D. In segment A (t0~t1), the solar-powered drone is in the lowest altitude level flight cruise phase at night and in the morning until the power output of the solar panels exceeds the total power of all power-consuming devices, i.e., time t1. In segment B (t1~t3), the solar-powered drone is in the climb phase, converting excess energy into gravitational potential energy. This phase continues to climb until the maximum flight altitude ends. In segment C (t3~t2), the solar-powered drone is in the highest altitude level flight cruise phase during the day until the power output of the solar panels is less than the total power of all power-consuming devices in the afternoon, i.e., time t2. In segment D (t2~t0+24), the drone is in the gliding phase, releasing gravitational potential energy until the lowest flight altitude. The energy management system for solar-powered drones needs to balance the energy and power supplied and consumed by the system to maintain the drone's long-term day-night operation. The key is to ensure the remaining flight time at night under normal flight conditions, enough to last until sunlight returns the following day. Therefore, this invention focuses on the flight phase after the sun has completely set and the solar cells can no longer generate electricity, until the drone begins its ascent the next day, i.e., the period from time ts to time t1+24. Therefore, the nighttime duration is: In the formula, represents the duration of nighttime. For a solar-powered drone to safely survive the night, the following constraints must be met. In the formula, represents the remaining flight time at time ; during this time period, the UAV is in gliding and minimum altitude level flight cruise attitude; therefore, the remaining flight time of the solar-powered UAV at time can be calculated in two segments, namely the unpowered gliding time of the UAV and the remaining time of minimum altitude level flight cruise.

[0015] Furthermore, the method for calculating the unpowered gliding time of the UAV is as follows: During the unpowered gliding descent phase, the solar-powered drone can obtain its gliding speed and descent angle through its onboard avionics. The descent angle represents the angle between the flight direction and the horizontal line; the formula for the drone's descent speed can be derived as follows: Therefore, the duration of unpowered gliding by the drone from its initial gliding point to its lowest flight altitude is: In the formula, represents the aircraft altitude at time .

[0016] Furthermore, the method for calculating the remaining duration of the minimum altitude level flight cruise is as follows: During the level flight cruise phase, the energy storage battery at the start time of level flight cruise (i.e., t0+24) needs to be obtained through the onboard power management system to obtain the total energy of the energy storage battery, and then the remaining time of level flight cruise at that moment: Therefore, the remaining flight time at each time is as follows: If the constraints of safe nighttime flight and payload execution are met, i.e. If the drone flies normally and performs its payload-related tasks, then energy management will gradually reduce the power consumption of the propulsion motor and the payload during the drone's lowest altitude cruise phase, achieving power downgrading at night and thus increasing remaining flight time.

[0017] Furthermore, the method for calculating the power consumption of the propulsion motor during the cruise phase is as follows: When a drone is cruising in level flight, it needs to satisfy the lift-weight balance and thrust-drag balance formulas: In the formula, is the atmospheric density; is the cruising speed; is the lift coefficient; is the wing area; is the drag coefficient; is the lift; is the gravity; is the drag; is the thrust; the power required by the propulsion motor when the UAV cruises at is:

[0018] In the formula, represents the mass of the drone, is the gravitational acceleration constant with a value of 9.8 N / kg, and is the lift-to-drag ratio; therefore, the power consumed by the propulsion motor when the drone cruises at speed can be obtained as: In the formula, represents the motor propulsion efficiency. Using this formula, the cruising speed constraint can be met ( In the case of ), reduce the cruising speed to reduce the power consumption of the propulsion motor; Furthermore, the method for calculating the effective payload power is as follows: Payloads typically need to complete tasks according to a plan via a task queue. During the nighttime level flight cruise phase, there are n payload tasks W1, W2…Wn, with corresponding powers P1, P2…Pn and corresponding task execution durations T1, T2…Tn, with decreasing task priorities. Therefore, the payload power during the UAV's nighttime level flight cruise phase is: In the formula, represents the nighttime level flight cruise duration; the power consumption of the payload can be reduced by successively discarding low-priority tasks to meet the remaining flight time constraints.

[0019] Another object of the present invention is to provide a system for enhancing and ensuring the overnight flight capability of solar-powered unmanned aerial vehicles, comprising the following modules: 1. Flight time calculation module, used to calculate the remaining flight time of the UAV, based on the total power of the onboard power-consuming equipment and the power of the energy storage battery, to provide remaining flight time constraints for safely passing through the night; 2. Dynamics modeling module, including gliding speed descent model and energy storage system energy model, used to assess duration and energy consumption during the gliding and nighttime level flight cruise phases of the UAV; 3. The energy management module, combining dynamic models and energy storage battery data, obtains the relationship between propulsion system power consumption and cruise speed, and calculates payload power through the payload task queue; 4. Flight time optimization module, used to improve the remaining flight time of the UAV by adjusting the power consumption of the propulsion system and payload when the remaining flight time constraint is not met.

[0020] Another object of the present invention is to provide a system for ensuring the nighttime flight capability of solar-powered drones, comprising the following modules: 1. Energy assessment module, used to calculate the remaining flight time of the UAV based on the SOC parameters of the energy storage battery read from the power management system and the total power of the power consuming equipment; 2. Flight profile management module: Based on the power generation cycle of the solar cells, the flight profile of the UAV is divided into daytime climb, daytime level flight cruise, evening gliding, and nighttime level flight cruise; 3. Unpowered gliding calculation module: Calculates the unpowered gliding duration of the UAV based on gliding speed, descent angle, and flight altitude data; 4. Cruise Phase Management Module: Calculates the remaining time for cruising at the minimum altitude and gradually reduces the power of the propulsion motors and payload when the remaining flight time is insufficient, in order to extend the night flight time.

[0021] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows: First, this invention targets high-altitude long-endurance solar-powered unmanned aerial vehicles (UAVs). Combining the flight profile of long-cycle flight of solar-powered UAVs, this invention uses remaining flight time to evaluate the overnight flight capability of solar-powered UAVs. Based on the energy system structure of high-altitude long-endurance solar-powered UAVs, this invention provides a remaining flight time constraint to meet safe nighttime flight and gives a detailed calculation method for the remaining flight time; further, it provides specific methods to improve the remaining flight time to meet the remaining flight time constraint. This invention solves the problem of lacking a method for evaluating the safe overnight flight capability of solar-powered UAVs and improving their overnight flight capability, providing a solution for overnight flight of high-altitude long-endurance solar-powered UAVs. The technical solution and content protected by this invention bring some inventive technical effects, which are described in detail below: This invention uses remaining flight time to evaluate the ability of solar-powered drones to perform flight and payload missions relying solely on energy storage batteries.

[0022] This invention, combined with the flight profile of a solar-powered UAV, provides the remaining flight time constraints for solar-powered UAVs flying across nighttime.

[0023] This invention points out the relationship between the power consumption of a solar-powered UAV propulsion system and its cruising speed, and the relationship between the power consumption of the payload and the mission queue; and further, through an energy autonomous management strategy, it gradually reduces the power consumption of the power-consuming end to extend the remaining flight time, so as to meet the requirements of cross-night flight.

[0024] Second, this invention uses remaining flight time to evaluate the ability of solar-powered UAVs to perform flight and payload tasks solely relying on energy storage batteries. Based on the flight profile of the solar-powered UAV, it provides constraints on the remaining flight time for overnight flight. It clarifies the relationship between the power consumption of the solar-powered UAV's propulsion system and its cruise speed, and the relationship between the power consumption of the payload and the mission queue. Furthermore, it extends the remaining flight time by gradually degrading the power consumption of energy-consuming equipment through an autonomous energy management strategy to meet the requirements for overnight flight. This solves the problem of lacking a method for evaluating the safe overnight flight capability of solar-powered UAVs and improving their overnight flight capability. Using this invention will enable solar-powered UAVs to achieve long-term continuous flight.

[0025] Third, the expected benefits and commercial value of the technical solution of this invention after its transformation are as follows: After the technical solution of this invention is transformed, the ability of high-altitude solar-powered UAVs to fly day and night can be improved, enabling solar-powered UAVs to remain airborne continuously or even permanently. These UAVs can then be used as payload platforms to carry remote sensing, communication, and other equipment, continuously providing services such as communication relay, meteorological monitoring, agricultural monitoring, and environmental monitoring. For example, in communication relay, it can provide continuous communication coverage in remote areas; in agricultural monitoring, it can be used to monitor crop growth and provide disaster early warnings; and in environmental monitoring, it can be used to monitor air pollution and forest fires. Therefore, the commercial application prospects of the high-altitude long-endurance solar-powered UAVs using this invention are very broad in the future.

[0026] The technical solution of this invention solves a technical problem that people have long desired to solve but have never been able to achieve: the technical solution of this invention proposes an evaluation method for the night flight capability of solar-powered drones, establishes a power consumption model for the propulsion system of solar-powered drones and a power consumption model for the payload, proposes a method for calculating the power consumption of airborne power-consuming equipment of solar-powered drones, and solves the problem of the difficulty of solar-powered drones flying across night.

[0027] The technical solution of this invention overcomes technical bias: traditional solar-powered drones mainly address the problem of continuous flight across day and night by focusing on energy storage systems and optimizing the drone's flight path. The technical solution of this invention starts from the power-consuming equipment of the drone itself, strengthens the energy management capability of the solar-powered drone, and provides a new solution to the problem of continuous flight of solar-powered drones.

[0028] Fourth, the significant technological advancements achieved by the method for improving and ensuring the overnight flight capability of solar-powered UAVs provided by this invention mainly include the following points: 1) Precise Calculation and Management of Remaining Flight Time: By introducing a mechanism for calculating and managing remaining flight time, this method can more accurately assess the endurance of solar-powered drones under conditions of no external energy input. This assessment is crucial for ensuring the safety of drones during nighttime flights.

[0029] 2) Innovative Application of Dynamic Models: This method, by establishing a model of the UAV's gliding speed decline and an energy model of the energy storage system, provides more accurate predictions of the UAV's energy requirements and performance at different flight stages (such as gliding and level flight cruise). This model innovation enhances the adaptability and reliability of UAVs under complex flight conditions.

[0030] 3) Optimization of the energy management system: By combining the energy management system to regulate and optimize the energy use of the energy storage battery, not only is the efficient use of energy improved, but the energy supply of the drone is also ensured during critical moments (such as night flight), thereby significantly enhancing the drone's continuous operation capability.

[0031] 4) Synergistic optimization of flight profile and energy consumption: By carefully analyzing and adjusting the flight profile (e.g., daytime climb, daytime level flight cruise, evening gliding and nighttime level flight cruise), and simultaneously optimizing energy consumption (especially the power adjustment of propulsion motors and payload), this method significantly improves the efficiency and feasibility of UAVs in long-duration flight missions.

[0032] 5) Enhanced adaptability and flexibility: This method provides enhanced adaptability and flexibility for UAVs in various environmental and mission conditions, especially at night or in environments with insufficient solar energy, ensuring continuous operation and mission execution capabilities of the UAVs.

[0033] The technological advancements of this invention significantly improve the flight endurance, safety performance, and operational efficiency of solar-powered drones, especially in challenging application scenarios such as overnight flights. Attached Figure Description

[0034] Figure 1 This is a flowchart of a method for improving and ensuring the overnight flight capability of a solar-powered UAV based on remaining flight time, provided in an embodiment of the present invention.

[0035] Figure 2 This is a flowchart provided by an embodiment of the present invention.

[0036] Figure 3 This is a schematic diagram of the energy system structure of a high-altitude long-endurance solar-powered unmanned aerial vehicle provided in an embodiment of the present invention.

[0037] Figure 4This is a schematic diagram of the solar cell power generation curve and flight profile of a high-altitude long-endurance solar-powered UAV provided in an embodiment of the present invention.

[0038] Figure 5 This is a detailed calculation flowchart of the present invention, which combines the flight profile of a UAV. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0040] The following are two specific embodiments and their implementation schemes for improving and ensuring the overnight flight capability of solar-powered drones: Example 1: Solar-Powered Drone with High-Efficiency Energy Management System 1) Energy prediction and flight time calculation: Advanced algorithms are used to predict the power generation efficiency of solar cells under different weather conditions.

[0041] Calculate the remaining flight time of the drone, taking into account the actual flight conditions and the total power consumption of the onboard power equipment.

[0042] 2) Dynamic Energy Management System (DEMS): DEMS dynamically adjusts the usage and charging strategies of energy storage batteries based on predicted energy output and real-time power consumption.

[0043] During the daytime ascent phase, the DEM optimizes its charging strategy to maximize energy storage; at night, the DEM adjusts energy distribution to ensure the operation of critical systems.

[0044] 3) Flight profile optimization: Based on energy forecasts, flight profiles can be adjusted to optimize energy utilization, such as increasing climb altitude to obtain more solar energy during periods of abundant sunlight.

[0045] 4) Power consumption optimization: At night or when energy supplies are tight, the power consumption of non-critical systems (such as some sensors and auxiliary equipment) is automatically reduced to extend flight time.

[0046] Example 2: Solar-Powered Unmanned Aerial Vehicle with Adaptive Flight Profile 1) Adaptive flight control system: The system can automatically adjust flight altitude and speed based on real-time weather conditions and the performance of solar cells.

[0047] When sunlight is strong, the flight altitude is increased to improve the efficiency of the solar cells; at night or in cloudy weather, the flight altitude is decreased to reduce energy consumption.

[0048] 2) Intelligent flight profile planning: Plan flight profiles in advance, including daytime climb, daytime level flight cruise, evening gliding, and nighttime level flight cruise.

[0049] Based on weather forecasts and solar cell performance, the flight profile is automatically adjusted to maximize energy utilization.

[0050] 3) Real-time energy monitoring and optimization: Continuously monitor the energy status of energy storage batteries and the power consumption of power-consuming equipment.

[0051] When energy is insufficient, flight parameters and power allocation are automatically adjusted to ensure the completion of critical missions.

[0052] 4) Emergency Energy Supply Plan: When encountering unexpected situations (such as unexpected weather changes or equipment failures), the drone automatically switches to energy conservation mode to prioritize the operation of critical communication and navigation equipment.

[0053] Both embodiments employ advanced technologies and strategies to enhance the overnight flight capability and overall performance of solar-powered drones. The first embodiment focuses on energy management and prediction, while the second emphasizes adaptability and automated optimization of the flight profile. These solutions can be tailored and optimized to specific application scenarios and requirements.

[0054] like Figure 1 , 2 As shown, the present invention provides a method for improving and ensuring the overnight flight capability of a solar-powered UAV with remaining flight time, comprising the following steps: S101, calculate the remaining flight time of the UAV, indicate the relationship between the remaining flight time and the total power consumption of the onboard power-consuming equipment, and give the remaining flight time constraint for safely passing through the night; S102, during the gliding phase, a model for the decrease in gliding speed of the UAV was established, and the gliding duration of the UAV was calculated using this model. During the nighttime level flight cruise phase, an energy model for the energy storage system was established. S103, combined with the energy management system to obtain energy from the energy storage battery, established a dynamic model of the UAV, and obtained the relationship between the power consumption of the propulsion system and the cruise speed through the model; S104, the payload power calculation method is obtained through the payload mission queue, the remaining flight time during the level flight cruise phase is obtained, and the remaining flight time after sunset is further obtained by combining the gliding phase duration; S105 provides a method for degrading the power of the propulsion system and payload by means of an energy management strategy when the remaining flight time constraint is not met.

[0055] The method for calculating the remaining flight time of a UAV provided by this invention: The remaining flight time of a solar-powered drone is given by the following formula: In the formula, represents the power of the energy storage battery, represents the power consumption of all energy-consuming devices of the solar-powered drone, and the remaining flight time can assess the ability to continue flying and performing payload tasks on its own when there is no external energy source. The longer the remaining flight time, the stronger the ability to continue flying and performing payload tasks at night. This invention combines flight profiles and uses an energy autonomous management strategy to reduce the total power consumption of the solar-powered drone's electrical equipment at night, thereby increasing the remaining flight time to meet the constraints of overnight flight and ensuring the drone's safe passage through the night. A schematic diagram of the energy system structure of a long-endurance solar-powered UAV is shown below. Figure 3 As shown, it mainly consists of three parts: solar cells at the power supply end; propulsion motors, avionics equipment and payloads at the power consumption end; and energy storage batteries at the energy storage end.

[0056] The energy storage battery capacity provided by this invention can be obtained by reading the SOC parameter from the power management system. SOC is the state of charge of the battery, with a value range of 0 to 1. The two have the following relationship: The energy-consuming end consists of the propulsion motor, avionics equipment, and payload, so the total power consumption is calculated using the following formula: As can be seen from the above formula, it is mainly necessary to reduce the power consumption of the propulsion motor, the power of the payload, and the power of the avionics to extend the remaining flight time. However, since the UAV flies continuously, the power of the avionics does not change much and can be regarded as constant. Therefore, the power consumption of the propulsion motor and the power of the payload are mainly constrained by the energy management system. Based on the mission profile of the UAV's cyclic flight, the following gives the remaining flight time constraints for safely passing through the night flight, the detailed calculation method of the remaining flight time, and the method to improve the remaining flight time. The flight of the UAV provided by this invention can be divided into four profiles: daytime climb, daytime level flight cruise, evening gliding, and nighttime level flight cruise. When the solar power generation is high, the UAV climbs to store gravitational potential energy and charge the energy storage battery. Upon reaching the maximum flight altitude, it enters the daytime level flight cruise phase. When the power generation is low or even unable to generate power, the UAV begins to glide to release gravitational potential energy. Upon gliding to the lowest flight altitude, it begins the nighttime level flight cruise, which is entirely powered by the energy storage battery. The solar cell power generation and flight profile of the high-altitude long-endurance solar-powered UAV over 48 hours are as follows: Figure 4As shown, the solar panels begin generating electricity at time tr each day, and the power output is zero at time ts. Since the power output curve of the solar panels has a 24-hour cycle, the flight profile of the solar-powered aircraft also has a 24-hour cycle, dividing the flight profile within one cycle into four segments: A, B, C, and D. In segment A (t0~t1), the solar-powered drone is in the lowest altitude level flight cruise phase at night and in the morning until the power output of the solar panels exceeds the total power of all power-consuming devices, i.e., time t1. In segment B (t1~t3), the solar-powered drone is in the climb phase, converting excess energy into gravitational potential energy. This phase continues to climb until the maximum flight altitude ends. In segment C (t3~t2), the solar-powered drone is in the highest altitude level flight cruise phase during the day until the power output of the solar panels is less than the total power of all power-consuming devices in the afternoon, i.e., time t2. In segment D (t2~t0+24), the drone is in the gliding phase, releasing gravitational potential energy until the lowest flight altitude. The energy management system for solar-powered drones needs to balance the energy and power supplied and consumed by the system to maintain the drone's long-term day-night operation. The key is to ensure the remaining flight time at night under normal flight conditions, enough to last until sunlight returns the following day. Therefore, this invention focuses on the flight phase after the sun has completely set and the solar cells can no longer generate electricity, until the drone begins its ascent the next day, i.e., the period from time ts to time t1+24. Therefore, the nighttime duration is: In the formula, represents the duration of nighttime. For a solar-powered drone to safely survive the night, the following constraints must be met. In the formula, represents the remaining flight time at time ; during this time period, the UAV is in gliding and minimum altitude level flight cruise attitude; therefore, the remaining flight time of the solar-powered UAV at time can be calculated in two segments, namely the unpowered gliding time of the UAV and the remaining time of minimum altitude level flight cruise.

[0057] The present invention provides a method for calculating the unpowered gliding time of unmanned aerial vehicles (UAVs): During the unpowered gliding descent phase, the solar-powered drone can obtain its gliding speed and descent angle through its onboard avionics. The descent angle represents the angle between the flight direction and the horizontal line; the formula for the drone's descent speed can be derived as follows: Therefore, the duration of unpowered gliding by the drone from its initial gliding point to its lowest flight altitude is: In the formula, represents the aircraft altitude at time .

[0058] The method for calculating the remaining time of level flight cruise at the minimum altitude provided by this invention: During the level flight cruise phase, the energy storage battery at the start time of level flight cruise (i.e., t0+24) needs to be obtained through the onboard power management system to obtain the total energy of the energy storage battery, and then the remaining time of level flight cruise at that moment: Therefore, the remaining flight time at each time is as follows: If the constraints of safe nighttime flight and payload execution are met, i.e. If the drone flies normally and performs its payload-related tasks, then energy management will gradually reduce the power consumption of the propulsion motor and the payload during the drone's lowest altitude cruise phase, achieving power downgrading at night and thus increasing remaining flight time.

[0059] The present invention provides a method for calculating the power consumption of the propulsion motor during the cruise phase: When a drone is cruising in level flight, it needs to satisfy the lift-weight balance and thrust-drag balance formulas: In the formula, is the atmospheric density; is the cruising speed; is the lift coefficient; is the wing area; is the drag coefficient; is the lift; is the gravity; is the drag; is the thrust; the power required by the propulsion motor when the UAV cruises at is:

[0060] In the formula, represents the mass of the drone, is the gravitational acceleration constant with a value of 9.8 N / kg, and is the lift-to-drag ratio; therefore, the power consumed by the propulsion motor when the drone cruises at speed can be obtained as: In the formula, represents the motor propulsion efficiency. Using this formula, the cruising speed constraint can be met ( In the case of ), reduce the cruising speed to reduce the power consumption of the propulsion motor; The present invention provides a method for calculating the effective payload power: Payloads typically need to complete tasks according to a plan via a task queue. During the nighttime level flight cruise phase, there are n payload tasks W1, W2…Wn, with corresponding powers P1, P2…Pn and corresponding task execution durations T1, T2…Tn, with decreasing task priorities. Therefore, the payload power during the UAV's nighttime level flight cruise phase is: In the formula, represents the nighttime level flight cruise duration; the power consumption of the payload can be reduced by successively discarding low-priority tasks to meet the remaining flight time constraints.

[0061] To demonstrate the inventiveness and technical value of the technical solution of this invention, this section provides specific product or related technology application examples of the technical solution claimed.

[0062] Step 1: Obtain the solar-powered drone's constant flight altitude, gliding speed, and descent angle using onboard avionics equipment. Figure 4 The figure shows the moment when the sun has completely set and the solar panel's power generation is zero. The flight time from this moment to the lowest altitude is calculated using the following formula: In the formula, the minimum flight altitude for nighttime cruising of the UAV flight profile is represented, such as... Figure 4 The flight profile is shown below; Step 2: Obtain the start time of level flight cruise (i.e., time, e.g., through the airborne power management system) Figure 4 (As shown in the flight profile diagram) The energy storage battery obtains the aircraft's minimum nighttime cruise speed through avionics, acquires mission queue information, and calculates the remaining flight time at the start of level flight using the following formula: Where is the rated capacity of the energy storage battery, is the power consumption of the propulsion motor, is the power consumption of the payload, and is the power consumption of the avionics equipment; the power consumption of the propulsion motor can be calculated by the following formula: In the formula, is the mass of the UAV, is the gravitational acceleration constant with a value of 9.8 N / kg, is the lift-to-drag ratio, and is the motor propulsion efficiency; the power consumption of the payload is given by the following formula: In the formula, represents the nighttime level flight cruise duration, n represents the number of missions of the payload, and represents the power consumption and mission execution duration of the i-th mission of the payload, respectively. The avionics equipment of UAVs generally includes flight control system, navigation system, attitude stabilization control system, etc. As long as the UAV is flying in the sky, these avionics equipment need to work, and basically do not change with mission and time, so the power of avionics equipment can be regarded as a constant. Step 3: Using the sum of the results obtained in Step 1 and Step 2, calculate the remaining flight time at the current time using the following formula: Then, using the calculated remaining flight time at the given time, the following formula is used to determine whether the drone can fly through the night relying solely on its battery storage: Where is the duration of night; if the above constraints are met, the flight and payload-related tasks will be executed normally, and the process will end; otherwise, proceed to step four. Step 4: Determine whether the drone can reduce speed during its lowest altitude cruise period using the following formula: If the above constraints are met, let be the deceleration step size, and then execute step two to recalculate the remaining flight time; otherwise, execute step five. Step 5: During the nighttime level flight cruise phase, there are n payload tasks W1, W2...Wn that need to be executed, with corresponding powers of P1, P2...Pn and corresponding task execution durations of T1, T2...Tn, and corresponding task priorities decreasing in sequence; the energy management system discards low-priority tasks, that is, does not execute task Wn, updates the task queue, returns to step 2, and recalculates the remaining flight time.

[0063] The flowchart of the specific steps of the execution scheme of this invention is as follows: Figure 5 As shown, the workflow of this invention can be understood by referring to the implementation steps.

[0064] It should be noted that embodiments of the present invention can be implemented in hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuitry such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field-programmable gate arrays, programmable logic devices, etc., or by software executed by various types of processors, or by a combination of the above-described hardware circuitry and software, such as firmware.

[0065] This invention uses remaining flight time to evaluate the ability of solar-powered unmanned aerial vehicles (UAVs) to perform flight and payload tasks solely relying on energy storage batteries. Based on the flight profile of the solar-powered UAV, it presents the remaining flight time constraints for overnight flight. It clarifies the relationship between the power consumption of the solar-powered UAV's propulsion system and its cruise speed, and the relationship between the power consumption of the payload and the mission queue. Furthermore, it proposes an energy autonomous management strategy to gradually reduce power consumption and extend remaining flight time, thereby meeting the requirements for overnight flight and significantly improving the overnight flight capability of solar-powered UAVs, thus ensuring safe overnight flight for these vehicles.

[0066] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for enhancing and ensuring the overnight flight capability of a solar-powered unmanned aerial vehicle (UAV) with remaining flight time, characterized in that, Includes the following steps: Step 1: Calculate the remaining flight time of the UAV, indicate the relationship between the remaining flight time and the total power consumption of the onboard power-consuming equipment, and give the remaining flight time constraint for safely passing through the night; Step two: During the gliding phase, a model for the gliding speed decrease of the UAV was established, and the gliding duration of the UAV was calculated using this model. During the nighttime level flight cruise phase, an energy model for the energy storage system was established. Step 3: By combining the energy management system with the energy storage battery, a dynamic model of the UAV was established, and the relationship between the power consumption of the propulsion system and the cruise speed was obtained through this model; Step 4: Obtain the payload power calculation method through the payload mission queue, obtain the remaining flight time during the level flight cruise phase, and combine it with the gliding phase duration to further obtain the remaining flight time after sunset; Step 5: If the remaining flight time constraint is not met, provide a method for power degradation of the propulsion system and payload through energy management strategy; The flight of the drone can be divided into four profiles: daytime climb, daytime level flight cruise, evening gliding, and nighttime level flight cruise. When the solar power generation is high, the drone climbs to store gravitational potential energy and charge its energy storage battery. Upon reaching its maximum flight altitude, it enters the daytime level flight cruise phase. When the power generation is low or even nonexistent, the drone begins to glide to release gravitational potential energy. Upon gliding to its lowest flight altitude, it begins nighttime level flight cruise, which is entirely powered by the energy storage battery. The solar cell power generation and flight profile of the high-altitude long-endurance solar-powered drone over 48 hours, and the daily solar cell capacity (t / kg) are also included. r Power generation begins immediately, t s At any given moment, the power generation is zero. Since the power generation curve of the solar cell has a 24-hour cycle, the flight profile of the solar-powered aircraft also has a 24-hour cycle, dividing the flight profile within one cycle into four segments: A, B, C, and D. In segment A, t0~t1, the solar-powered drone is at its lowest altitude during the night and morning. During the level flight cruise phase, the solar-powered drone continues to climb until the solar panel's power output exceeds the total power of all power-consuming devices, i.e., at time t1. In segment B, from t1 to t3, the solar-powered drone is in its climb phase, converting excess energy into gravitational potential energy. This phase continues as it climbs to its maximum flight altitude. End; During segment C, t3~t2, the solar-powered drone was at its highest daytime altitude. During the level flight cruise phase, the solar panel power output will be less than the total power output of all power-consuming devices until time t2 in the afternoon; during segment D, from t2 to t0+24, the UAV is in the gliding phase, during which it releases gravitational potential energy until it reaches its lowest flight altitude. ; The energy management system for solar-powered drones needs to balance the energy and power supplied and consumed by the system to maintain the drone's long-term day-night operation. The key is to ensure the remaining flight time at night under normal flight conditions, enough to last until sunlight returns the following day. Therefore, the flight phase of concern is the period after the sun has completely set and the solar panels can no longer generate electricity, until the drone begins its ascent the next day, i.e., t. s The time period from time t1 to time t24 is therefore the length of nighttime: In the formula For the duration of nighttime, the solar-powered drone must safely navigate the night while meeting the following constraints. In the formula for The remaining flight time at the given moment; during this period, the drone is in a gliding and minimum altitude level flight cruise attitude; therefore The remaining flight time of a solar-powered drone can be calculated in two segments: the unpowered gliding time of the drone and the remaining time of level flight at the lowest altitude. The method for calculating the remaining time of the minimum altitude level flight cruise: During the level flight cruise phase, the onboard power management system needs to obtain the start time of level flight cruise, i.e., t0+24, from the energy storage battery. The total energy of the energy storage battery is obtained, and then the remaining time of level flight cruise at that moment is obtained: so Remaining flight time at the time as follows: If the constraints of safe overnight flight and payload execution are met, i.e. In the formula for At a given moment, the drone will fly normally and perform its payload-related tasks; otherwise, energy management will gradually reduce the power consumption of the propulsion motors during the drone's lowest altitude cruise phase. and payload power This allows for nighttime power downgrading, thereby increasing remaining flight time.

2. The method for enhancing and ensuring the overnight flight capability of solar-powered UAVs based on remaining flight time as described in claim 1, characterized in that, The method for calculating the remaining flight time of the UAV: The remaining flight time of a solar-powered drone is given by the following formula: In the formula, The amount of electricity stored in the battery. The power consumption of all energy-consuming devices of the solar-powered drone; the remaining flight time is an assessment of the ability to continue flying and performing payloads on its own when there is no external energy source. The longer the remaining flight time, the stronger the ability to continue flying and performing payloads at night. By combining flight profiles, an energy autonomous management strategy is used to reduce the total power consumption of solar-powered drones' electrical equipment at night. To increase remaining flight time This ensures that the drone meets the constraints for overnight flight and guarantees its safe passage through the night. The energy system structure of a long-endurance solar-powered UAV consists of three parts: solar cells at the power supply end; propulsion motors, avionics, and payload at the power consumption end; Energy storage batteries at the energy storage end.

3. The method for enhancing and ensuring the overnight flight capability of solar-powered UAVs based on remaining flight time as described in claim 2, characterized in that, The energy storage battery capacity at the energy storage end The SOC parameter is obtained by reading it from the power management system. SOC is the state of charge of the battery, with a value ranging from 0 to 1. The two have the following relationship: The energy-consuming end consists of the propulsion motor, avionics equipment, and payload, so the total power consumption is calculated using the following formula: As can be seen from the above formula, it is necessary to reduce the power consumption of the propulsion motor, the power of the payload, and the power of the avionics equipment to extend the remaining flight time. However, since the UAV flies continuously, the power of the avionics equipment does not change much and can be regarded as a constant. Therefore, the power consumption of the propulsion motor and the power of the payload are mainly constrained by the energy management system. Based on the mission profile of the UAV's cyclic flight, the following gives the remaining flight time constraints for safely passing through the night flight, the detailed calculation method of the remaining flight time, and the method to improve the remaining flight time.

4. The method for enhancing and ensuring the overnight flight capability of solar-powered UAVs based on remaining flight time as described in claim 1, characterized in that, The method for calculating the unpowered gliding time of the UAV: During the unpowered gliding descent phase, the solar-powered drone obtains gliding speed through its onboard avionics. and descent angle The descent angle represents the angle between the flight direction and the horizontal line; the formula for the descent speed of the UAV is obtained as follows: Therefore, drones from Glide to the lowest possible flight altitude at all times; duration of unpowered gliding for the drone. : In the formula for The aircraft's altitude at that moment.

5. The method for enhancing and ensuring the overnight flight capability of solar-powered UAVs based on remaining flight time as described in claim 1, characterized in that, The power consumed by the propulsion motor during the cruise phase Calculation method: When a drone is cruising in level flight, it needs to satisfy the lift-weight balance and thrust-drag balance formulas: In the formula, Atmospheric density; For cruising speed, The lift coefficient, For wing area, The drag coefficient, For lift, For gravity, As resistance, For thrust; the drone uses speed The power required by the propulsion motor during cruise is: In the formula For the quality of drones, The acceleration due to gravity is constant, with a value of 9.8 N / kg. The lift-to-drag ratio is given; therefore, the speed of the UAV is obtained. The power consumed by the propulsion motor during cruise is: In the formula To determine the motor propulsion efficiency, this formula is used while satisfying the cruise speed constraint. In this case, reduce the cruising speed to reduce the power consumption of the propulsion motor.

6. The method for enhancing and ensuring the overnight flight capability of solar-powered UAVs based on remaining flight time as described in claim 1, characterized in that, The effective payload power Calculation method: Payloads typically need to complete their missions according to a plan through a mission queue. During the nighttime level flight cruise phase, there are n payload missions W1, W2…W n The corresponding powers are P1, P2…P n The corresponding task execution times are T1, T2…T n The corresponding task priorities decrease sequentially, so the effective payload power of the UAV during the nighttime level flight cruise phase is: In the formula The duration of level flight cruise at night; by autonomously deciding in turn not to execute low-priority tasks, the power of the payload is degraded to meet the remaining flight time constraints.

7. A system for enhancing and ensuring the overnight flight capability of a solar-powered UAV, applying the method for enhancing and ensuring the overnight flight capability of a solar-powered UAV based on remaining flight time as described in claim 1, characterized in that, Includes the following modules: The flight time calculation module is used to calculate the remaining flight time of the UAV, based on the total power of the onboard power-consuming equipment and the power of the energy storage battery, to provide remaining flight time constraints for safely getting through the night; The dynamics modeling module, including the gliding speed decline model and the energy storage system energy model, is used to assess the duration and energy consumption of the UAV during the gliding and nighttime level flight cruise phases. The energy management module combines dynamic models and energy storage battery data to obtain the relationship between propulsion system power consumption and cruise speed, and calculates payload power through the payload task queue; The flight time optimization module is used to improve the remaining flight time of the UAV by adjusting the power consumption of the propulsion system and payload when the remaining flight time constraint is not met.

8. A system for ensuring the nighttime flight capability of solar-powered UAVs by applying the method for enhancing and ensuring the nighttime flight capability of solar-powered UAVs based on remaining flight time as described in claim 1, characterized in that, Includes the following modules: The energy assessment module is used to calculate the remaining flight time of the drone based on the SOC parameters of the energy storage battery and the total power of the power-consuming equipment read by the power management system. The flight profile management module divides the UAV's flight profile into daytime climb, daytime level flight cruise, evening gliding, and nighttime level flight cruise based on the solar cell's power generation cycle. The unpowered gliding calculation module calculates the duration of unpowered gliding for the UAV based on gliding speed, descent angle, and flight altitude data. The cruise phase management module calculates the remaining time for cruising at the minimum altitude and gradually reduces the power of the propulsion motors and payload when the remaining flight time is insufficient, in order to extend the night flight time.

Images