A power prediction and compensation method for a range-extended power system of a UAV in a plateau environment

Abstract

The application discloses a kind of power prediction and compensation method of unmanned aerial vehicle range extending power system under highland environment, comprising the following steps: S1, collect multi-source sensor data, and fusion, obtain air density;S2, based on air density, calculate final highland compensation power demand;S3, final highland compensation power demand is used to complete optimization.The present application uses extended Kalman filter to fuse barometer, temperature sensor and GPS height data, successfully solves the temperature drift and weather interference problem existing in single sensor in highland environment;Air density estimation accuracy is improved, and then provides reliable environmental parameter input for energy management strategy.

Description

Technical Field

[0001] This invention relates to the field of power prediction technology, specifically to a method for power prediction and compensation of an extended-range power system for unmanned aerial vehicles (UAVs) in high-altitude environments. Background Technology

[0002] Currently, with the development of applications such as high-altitude logistics transportation, power line inspection, emergency rescue, and border security, most existing UAVs using extended-range propulsion systems are gradually undertaking long-endurance, high-payload, and complex-environment flight missions. However, in areas above 3000m altitude, due to factors such as reduced air density, drastic wind field changes, and decreased engine and battery pack performance, the power requirements of UAVs exhibit rapid fluctuations. Most existing power management systems for UAVs using extended-range propulsion systems primarily employ feedback control, only adjusting power after the demand has changed. This leads to problems such as engine response lag, increased instantaneous battery discharge current, and decreased energy efficiency. Especially under conditions such as climbing, wind resistance, and heavy-load transport, traditional control strategies are insufficient to meet the power demands of the complex high-altitude environment.

[0003] Most existing UAVs using range-extended propulsion systems are essentially new types of flight platforms combining fuel power and electric propulsion systems. They all use an engine to drive a generator to produce electricity, which is then supplied to the propulsion system by batteries and the generator together, thus combining the advantages of high energy density from fuel and high control precision from electric propulsion. In recent years, with the rapid development of the low-altitude economy, most existing UAVs using range-extended propulsion systems have been widely used in fields such as high-altitude logistics transportation, power line inspection, forest fire prevention, and emergency rescue.

[0004] However, the plateau environment differs significantly from the plains environment. As altitude increases, air density decreases, leading to reduced propeller thrust efficiency. Furthermore, maintaining the same lift requires consuming more energy to increase power. Additionally, the complex wind fields in plateau regions cause frequent adjustments to the UAV's flight attitude, resulting in significant fluctuations in the propulsion system's power requirements. Under these circumstances, the power system needs to possess higher response speeds and stronger environmental adaptability.

[0005] Currently, the main power management modes for unmanned aerial vehicles (UAVs) employ SOC control, PID control, and ECMS energy management strategies. SOC control determines the start and stop of the range extender based on the remaining battery charge; its drawbacks include a simple structure and inability to reflect changes during future flight missions. PID control improves system stability by continuously analyzing and correcting current power errors in real time, but it is essentially feedback control and can only compensate for past power changes. ECMS optimizes power distribution between the engine and battery, improving energy efficiency, but its optimization target is still current power demand; it lacks future power prediction capabilities.

[0006] In recent years, some studies have begun to utilize neural networks, LSTM, and model predictive control methods for power prediction. While these methods can improve prediction accuracy, they generally suffer from problems such as large training data requirements, high model complexity, and heavy real-time computational burden, which are not conducive to real-time deployment on UAVs. Furthermore, most prediction models are still based on plains environmental data, failing to adequately consider factors such as air density variations, thrust attenuation, and wind field disturbances in high-altitude regions, thus leading to significantly increased prediction errors at high altitudes.

[0007] Therefore, there is currently a lack of a power management method that can adapt to high-altitude environments, meet the needs of real-time airborne control, and have the ability to predict future power output. Summary of the Invention

[0008] To address the above problems, this invention proposes a method for predicting and compensating the power of an extended-range power system for unmanned aerial vehicles (UAVs) in high-altitude environments.

[0009] The technical solution of this invention is: a method for power prediction and compensation of an extended-range power system for unmanned aerial vehicles (UAVs) in high-altitude environments, comprising the following steps: S1. Collect data from multiple sensor sources and fuse them to obtain air density; S2. Calculate the final high-altitude compensation power requirement based on air density; S3. Optimization is completed by utilizing the final high-altitude compensation power requirement.

[0010] Furthermore, S1 includes the following sub-steps: S11. Collect barometric altitude, GPS altitude, and ambient temperature; S12. The barometric altitude, GPS altitude, and ambient temperature are fused using the observation equation to obtain the fused altitude; S13. Calculate the air density based on the fusion height.

[0011] Furthermore, in S13, the air density The expression is: ; in, This represents the atmospheric pressure at an altitude of h. Indicates the molar mass of air. Represents the universal gas constant. Indicates ambient temperature. Indicates the actual height.

[0012] Furthermore, S2 includes the following sub-steps: S21. Calculate the basic plateau power compensation amount based on air density; S22. Based on the basic plateau power compensation amount, obtain the power demand after air density compensation; S23. Determine the equivalent propeller speed required to maintain the same thrust based on the thrust required for current flight and the original air density; S24. Based on the equivalent propeller speed and power demand after air density compensation required to maintain the same thrust, calculate the high-altitude power demand after thrust remapping. S25. Calculate the additional power caused by the wind field disturbance in the plateau region based on the fused altitude change rate and air velocity. S26. Calculate the final plateau compensation power demand based on the basic plateau power compensation amount, the plateau power demand after thrust remapping, and the additional power caused by plateau wind field disturbance.

[0013] Furthermore, in S21, the basic plateau power compensation amount The expression is: ; in, Indicates air density, Indicates ambient temperature. Indicates the actual height. Indicates the current load power. This represents a coefficient that affects air density. This indicates the density of air at standard sea level.

[0014] Furthermore, in S22, the power demand after air density compensation. The expression is: ; in, This represents the basic plateau power compensation amount. This indicates the current load power.

[0015] Furthermore, in S23, the equivalent propeller speed required to maintain the same thrust is... The expression is: ; in, Indicates ambient temperature. Indicates the actual height. Indicates air density, This indicates the thrust required for the drone to maintain flight. This indicates the propeller's thrust coefficient. This indicates the diameter of the propeller.

[0016] Furthermore, in S24, the high-altitude power requirement after thrust remapping. The expression is: ; in, Indicates the current load power. This indicates the equivalent propeller speed required to maintain the same thrust. This represents the reference rotational speed required to maintain the same thrust under standard sea-level conditions. This indicates the motor efficiency.

[0017] Furthermore, in S25, the additional power caused by plateau wind field disturbance. The expression is: ; in, This represents the wind field disturbance coefficient. Indicates air density, Indicates ambient temperature. Indicates the actual height. Indicates airspeed. Indicates wind speed in the vertical direction. This indicates the area of ​​the propeller disk.

[0018] The absolute value represents the intensity of the rising / falling airflow.

[0019] :m 2 It is calculated from the propeller diameter D.

[0020] Furthermore, in S26, the final high-altitude compensation power requirement... The expression is: ; in, Indicates the current load power. This represents the basic plateau power compensation amount. This indicates the additional power caused by wind field disturbances in the plateau region. This represents the high-altitude power requirement after thrust remapping.

[0021] The beneficial effects of this invention are: (1) This invention uses extended Kalman filtering to fuse barometer, temperature sensor and GPS altitude data, successfully solving the temperature drift and meteorological interference problems of single sensor in plateau environment; after fusion, the altitude error is controlled within ±8m, the air density estimation accuracy is improved, and thus provides reliable environmental parameter input for energy management strategy.

[0022] (2) Based on real-time air density estimation data and combined with the aerodynamic characteristics of the propeller, this invention establishes a plateau power increment model to achieve dynamic compensation of power demand. This mechanism ensures that the ECMS optimized input can present the real plateau flight power demand and prevents the situation of battery over-discharge and shortened range caused by the underestimation of power in traditional strategies. Attached Figure Description

[0023] Figure 1 A flowchart illustrating the power prediction and compensation method for the extended-range propulsion system of unmanned aerial vehicles (UAVs) in high-altitude environments. Detailed Implementation

[0024] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, this invention provides a method for power prediction and compensation of an extended-range power system for unmanned aerial vehicles (UAVs) in high-altitude environments, comprising the following steps: S1. Collect data from multiple sensor sources and fuse them to obtain air density; S2. Calculate the final high-altitude compensation power requirement based on air density; S3. Optimization is completed by utilizing the final high-altitude compensation power requirement.

[0026] Establishing a power demand compensation mechanism for high-altitude areas requires real-time air density estimation and propeller characteristic curves. Based on this information, a power increment model for high-altitude regions can be built, and power allocation decisions must be made based on accurate demand forecasts. This mechanism can effectively compensate for power demand in high-altitude areas according to actual conditions.

[0027] Specifically, this involves acquiring real-time air density data and combining it with relevant information from the propeller characteristic curve to accurately calculate the power increment at high altitudes. In this way, power allocation decisions can be made based on precise demand forecasts, enabling the entire system to operate more stably and efficiently in high-altitude environments, providing reliable power support for relevant equipment or systems, and meeting their operational needs in high-altitude regions.

[0028] Multi-source sensor fusion environmental perception is achieved: Extended Kalman filter (EKF) is used to fuse barometer, temperature sensor, and GPS altitude data, thereby outputting high-precision altitude and air density estimates, providing reliable environmental parameter inputs for energy management strategies.

[0029] In this embodiment of the invention, S1 includes the following sub-steps: S11. Collect barometric altitude, GPS altitude, and ambient temperature; S12. The barometric altitude, GPS altitude, and ambient temperature are fused using the observation equation to obtain the fused altitude; S13. Calculate the air density based on the fusion height.

[0030] During data acquisition, data is collected synchronously at a frequency of at least 10Hz. Specific data collected include ambient air pressure (p, in hPa), ambient temperature (T, in °C), and GPS altitude. Height is measured in meters (m), battery SOC is measured in percentage (%), and there is also the load power requirement. The load power requirement unit is kW. After all data has undergone hardware timestamp alignment, it is transmitted to the ECMS controller. The fused altitude error can be controlled within ±8m, which is more than 6 times more accurate than the ±50m error of a single barometer.

[0031] An extended Kalman filter (EKF) is used to fuse data from the barometer, temperature sensor, and GPS altitude sensors. The state vector is set as follows: , Indicates the actual height. It is the velocity in the vertical direction. This is due to the deviation in air pressure altitude. It is the temperature drift coefficient. The observation equation will affect the air pressure altitude. GPS altitude ,temperature The data from these three observations are fused. The fusion height is then obtained through filtering. Then, this fusion height will be substituted into the ideal gas law to calculate the air density.

[0032] In this embodiment of the invention, in S13, the air density... The expression is: ; in, This represents the atmospheric pressure at an altitude of h. Indicates the molar mass of air. Represents the universal gas constant. Indicates ambient temperature. Indicates the actual height.

[0033] p(h): Pa, measured by a barometer or calculated by the International Standard Atmospheric Model.

[0034] : Take 28.97 g / mol = 0.02897 kg / mol.

[0035] R: Take 8.314 J / (mol·K).

[0036] The physical quantity is the molar mass of air, which is represented by the symbol... The exact value is 28.97 g / mol. There is also another physical constant, the universal gas constant, which is expressed using the symbol... The specific value is 8.314 J / (mol·K).

[0037] In this embodiment of the invention, S2 includes the following sub-steps: S21. Calculate the basic plateau power compensation amount based on air density; S22. Based on the basic plateau power compensation amount, obtain the power demand after air density compensation; S23. Determine the equivalent propeller speed required to maintain the same thrust based on the thrust required for current flight and the original air density; S24. Based on the equivalent propeller speed and power demand after air density compensation required to maintain the same thrust, calculate the high-altitude power demand after thrust remapping. S25. Calculate the additional power caused by the wind field disturbance in the plateau region based on the fused altitude change rate and air velocity. S26. Calculate the final plateau compensation power demand based on the basic plateau power compensation amount, the plateau power demand after thrust remapping, and the additional power caused by plateau wind field disturbance.

[0038] The power demand after air density compensation serves as the baseline input for subsequent thrust remapping calculations. When calculating the additional power demand caused by propeller speed variations in high-altitude environments, it is necessary to base the calculation on the power already accounted for by air density. In other words, subsequent steps do not use the original load power, but rather the power after air density compensation for further calculations. This avoids double-counting or omissions and ensures consistency throughout the entire compensation chain.

[0039] The power demand after air density compensation serves as the initial baseline for the final overall power demand. The final determined total power demand for high-altitude areas is calculated by adding the additional compensation from thrust remapping and the additional power caused by wind field disturbances to the power after air density compensation. In other words, the power after air density compensation already reflects the direct impact of altitude on propeller efficiency; subsequent calculations only require "adding" the additional increments caused by other factors. It is the "basic item" of the final power demand.

[0040] The power demand after air density compensation makes the entire compensation process decomposable and interpretable. Separating the impact of air density compensation from subsequent speed remapping compensation helps engineers understand the degree to which different physical factors affect power demand. For example, during commissioning, it's possible to observe separately "how much air density was compensated separately" and "how much additional compensation was made after increasing speed," facilitating troubleshooting and parameter calibration.

[0041] In this embodiment of the invention, in S21, the basic plateau power compensation amount The expression is: ; in, Indicates air density, Indicates ambient temperature. Indicates the actual height. Indicates the current load power. This represents a coefficient that affects air density. This indicates the density of air at standard sea level.

[0042] In this embodiment of the invention, in S22, the basic compensation amount is superimposed with the current load power to obtain the power demand after air density compensation.

[0043] Power requirements after air density compensation The expression is: ; in, This represents the basic plateau power compensation amount. This indicates the current load power.

[0044] In this embodiment of the invention, in S23, the equivalent rotational speed of the propeller required to maintain the same thrust is calculated based on the thrust required for the current flight and the air density at high altitude.

[0045] The equivalent propeller speed required to maintain the same thrust The expression is: ; in, Indicates ambient temperature. Indicates the actual height. Indicates air density, This indicates the thrust required for the drone to maintain flight. This indicates the propeller's thrust coefficient. This indicates the diameter of the propeller.

[0046] In this embodiment of the invention, in S24, the high-altitude power requirement after thrust remapping is calculated based on the cubic relationship between propeller power and rotational speed.

[0047] High-altitude power requirements after thrust remapping The expression is: ; in, Indicates the current load power. This indicates the equivalent propeller speed required to maintain the same thrust. This represents the reference rotational speed required to maintain the same thrust under standard sea-level conditions. This indicates the motor efficiency.

[0048] Unit: rpm, given by the propeller characteristic curve; : Dimensionless, with a value range of 0 to 1, or motor loss coefficient, which can be obtained from bench testing.

[0049] In this embodiment of the invention, in S25, the additional power caused by the plateau wind field disturbance is estimated by using the fused altitude change rate and airspeed.

[0050] Additional power caused by wind field disturbance in the plateau The expression is: ; in, This represents the wind field disturbance coefficient. Indicates air density, Indicates ambient temperature. Indicates the actual height. Indicates airspeed. Indicates wind speed in the vertical direction. This indicates the area of ​​the propeller disk.

[0051] The absolute value represents the intensity of the rising / falling airflow.

[0052] :m 2 It is calculated from the propeller diameter D.

[0053] In this embodiment of the invention, in S26, the final plateau compensation power requirement is obtained by integrating air density compensation, thrust remapping compensation, and wind field disturbance compensation.

[0054] Final high-altitude compensation power requirements The expression is: ; in, Indicates the current load power. This represents the basic plateau power compensation amount. This indicates the additional power caused by wind field disturbances in the plateau region. This represents the high-altitude power requirement after thrust remapping.

[0055] The power compensation for high-altitude environments is calculated based on air density and current load power. When the altitude reaches 4000 meters, the typical compensation ratio is between 30% and 50% of the current load power, thus ensuring that the engine power is adequately distributed.

[0056] Throughout the entire operation, the air density at standard sea level is determined by... This is expressed as a value of 1.225 kg / m³. 3 The coefficients affecting air density are labeled as follows: This coefficient is calibrated through bench testing, with typical values ​​ranging from 1.2 to 1.8. The propeller thrust coefficient and propeller diameter are provided by the propeller manufacturer, and the motor efficiency is obtained through bench testing. The wind field disturbance coefficient is calibrated through high-altitude flight tests, with typical values ​​between 0.15 and 0.35. The power demand obtained after compensation will be used as input information for ECMS optimization.

[0057] This invention utilizes EKF to fuse data from multiple sensors, achieving high-precision estimation of altitude and air density. Based on these estimations, high-altitude power demand compensation is then performed. This compensation enables precise power allocation decisions. Such power allocation decisions prevent battery over-discharge, ultimately extending the effective battery life.

[0058] Traditional strategies result in shorter driving range in high-altitude areas because they don't account for the power increase at high altitudes when calculating relevant data. This leads to insufficient engine power distribution, forcing the battery to discharge deeply. Additionally, the low temperatures at high altitudes can cause a 35% reduction in battery capacity (according to some sources). The combination of these two factors ultimately leads to a significant reduction in effective driving range.

[0059] This invention estimates air density, thereby enabling a relatively accurate calculation of the power increment at high altitudes. At an altitude of 4000 meters, this value represents 30% to 50% of the power output at sea level. Afterwards, the ECMS will allocate power based on the compensated power demand to ensure the engine can output sufficient power. The battery only plays a supporting role in discharging during peak power, maintaining the SOC within a safe range and preventing capacity loss due to over-discharge.

[0060] Quantitative results show that when performing power line inspection tasks at an altitude of 4,000 meters, compared with drone operations without compensation strategies, the present invention can effectively extend the flight time by 35% to 50%, while extending the battery cycle life by more than 20%.

[0061] This invention collects relevant data using devices such as barometers, temperature sensors, and GPS. This data is then processed by the EKF extended Kalman filter algorithm. After temperature drift compensation and meteorological interference suppression, the final output is high-precision altitude and air density information.

[0062] EKF fusion uses a state-space model to simultaneously estimate altitude, vertical velocity, pressure deviation, and temperature drift coefficients. It uses GPS altitude to constrain pressure deviation and temperature measurement to compensate for temperature drift, thereby achieving complementary fusion of multi-source information.

[0063] The error in altitude estimation, which was previously within ±50m, has now been reduced to ±8m, representing a six-fold improvement in accuracy. The error in air density estimation, initially at ±8%, has been reduced to ±3%. These results provide environmental parameter inputs that can be used as a basis for energy management strategies.

[0064] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for power prediction and compensation of an extended-range propulsion system for unmanned aerial vehicles (UAVs) in high-altitude environments, characterized in that, Includes the following steps: S1. Collect data from multiple sensor sources and fuse them to obtain air density; S2. Calculate the final high-altitude compensation power requirement based on air density; S3. Optimization is completed by utilizing the final high-altitude compensation power requirement.

2. The method for power prediction and compensation of UAV range-extended propulsion system in high-altitude environment according to claim 1, characterized in that, S1 includes the following sub-steps: S11. Collect barometric altitude, GPS altitude, and ambient temperature; S12. The barometric altitude, GPS altitude, and ambient temperature are fused using the observation equation to obtain the fused altitude; S13. Calculate the air density based on the fusion height.

3. The method for power prediction and compensation of UAV range-extended propulsion system in high-altitude environment according to claim 2, characterized in that, In S13, the air density The expression is: ； in, This represents the atmospheric pressure at an altitude of h. Indicates the molar mass of air. Represents the universal gas constant. Indicates ambient temperature. Indicates the actual height.

4. The method for power prediction and compensation of UAV range-extended propulsion system in plateau environment according to claim 1, characterized in that, S2 includes the following sub-steps: S21. Calculate the basic plateau power compensation amount based on air density; S22. Based on the basic plateau power compensation amount, obtain the power demand after air density compensation; S23. Determine the equivalent propeller speed required to maintain the same thrust based on the thrust required for current flight and the original air density; S24. Based on the equivalent propeller speed and power demand after air density compensation required to maintain the same thrust, calculate the high-altitude power demand after thrust remapping. S25. Calculate the additional power caused by the wind field disturbance in the plateau region based on the fused altitude change rate and air velocity. S26. Calculate the final plateau compensation power demand based on the basic plateau power compensation amount, the plateau power demand after thrust remapping, and the additional power caused by plateau wind field disturbance.

5. The method for power prediction and compensation of UAV range-extended propulsion system in plateau environment according to claim 4, characterized in that, In S21, the basic plateau power compensation amount The expression is: ； in, Indicates air density, Indicates ambient temperature. Indicates the actual height. Indicates the current load power. This represents a coefficient that affects air density. This indicates the density of air at standard sea level.

6. The method for power prediction and compensation of UAV range-extended propulsion system in plateau environment according to claim 4, characterized in that, In S22, the power demand after air density compensation The expression is: ； in, This represents the basic plateau power compensation amount. This indicates the current load power.

7. The method for power prediction and compensation of UAV range-extended propulsion system in plateau environment according to claim 4, characterized in that, In S23, the equivalent propeller speed required to maintain the same thrust The expression is: ； in, Indicates ambient temperature. Indicates the actual height. Indicates air density, This indicates the thrust required for the drone to maintain flight. This indicates the propeller's thrust coefficient. This indicates the diameter of the propeller.

8. The method for power prediction and compensation of UAV range-extended propulsion system in plateau environment according to claim 4, characterized in that, In S24, the high-altitude power requirement after thrust remapping The expression is: ； in, Indicates the current load power. This indicates the equivalent propeller speed required to maintain the same thrust. This represents the reference rotational speed required to maintain the same thrust under standard sea-level conditions. This indicates the motor efficiency.

9. The method for power prediction and compensation of UAV range-extended propulsion system in plateau environment according to claim 4, characterized in that, In S25, the additional power caused by the plateau wind field disturbance The expression is: ； in, This represents the wind field disturbance coefficient. Indicates air density, Indicates ambient temperature. Indicates the actual height. Indicates airspeed. Indicates wind speed in the vertical direction. This indicates the area of ​​the propeller disk.

10. The method for power prediction and compensation of UAV range-extended propulsion system in plateau environment according to claim 4, characterized in that, In S26, the final high-altitude compensation power requirement The expression is: ； in, Indicates the current load power. This represents the basic plateau power compensation amount. This indicates the additional power caused by wind field disturbances in the plateau region. This represents the high-altitude power requirement after thrust remapping.

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