Unmanned aerial vehicle flight system capable of hovering through foreign object and long-endurance unmanned aerial vehicle

Abstract

The invention relates to the field of unmanned aerial vehicle control application, in particular to an unmanned aerial vehicle flight system capable of hovering through a foreign object and a long-endurance unmanned aerial vehicle. The flight system comprises a PCB object carrying platform, a helium balloon, a propeller, a brushless motor, a sensor group, a remote control module, a flight control module and a power battery; the flight control module receives motion attitude and displacement information from the sensor group and expected displacement information from the remote control module, then calculates voltages which should be distributed by brushless motors of the four propellers, and transmits signals to the corresponding brushless motors respectively, so that air pressure differences are formed by controlling the respective rotating speeds of the four propellers, and the flight control module controls the four propellers to rotate. Lifting and horizontal and circumferential flight of the unmanned aerial vehicle are realized by using the air pressure difference; the flight system is applied to the long-endurance unmanned aerial vehicle. By arranging the helium balloon, the power output of the motor of the unmanned aerial vehicle is remarkably reduced, energy is hardly consumed during hovering, the electric energy consumption of flight of the unmanned aerial vehicle is reduced, and meanwhile, the endurance time is multiplied.

Description

Technical Field

[0001] The present invention relates to the field of unmanned aerial vehicle applications, and particularly to an unmanned aerial vehicle flight system capable of hovering through external objects and a long-endurance unmanned aerial vehicle. Background Art

[0002] Unmanned aerial vehicles (UAVs) are emerging as a new class of mobile computing platforms and are widely used in multiple fields such as aerial mapping, sensing, search and rescue, film production, package delivery, and wireless network deployment. However, their efficient operation is often restricted by two key factors: mobility and endurance time. Although multi-rotor UAVs have become the most popular aerial platforms currently due to their flexibility and low cost, their flight time is severely limited by the battery capacity. Due to physical dynamics limitations, the motors of multi-rotor UAVs must always generate a thrust that is approximately 50% higher than their own weight, and a large amount of energy is consumed just to maintain hovering. This makes the flight time of multi-rotor UAVs typically only dozens of minutes.

[0003] To extend the flight time of UAVs, various improvement schemes have been proposed, including optimizing flight paths, phased battery replacement, wireless charging, and laser energy transmission. However, these methods either require complex ground facilities or increase the complexity of system design, and their application scope is limited. In addition, although alternative platforms such as tethered UAVs and airships can significantly improve the endurance time, their mobility and vertical movement capabilities are poor, and it is difficult to meet the requirements in many application scenarios.

[0004] The patent with the publication number CN214138944U discloses a super-endurance helium balloon UAV, which is characterized by including a frame and four propellers arranged on the frame. A spindle-shaped helium balloon is arranged above the frame, and a power battery, a GPS positioning module, a flight control module, and a remote control receiving device are arranged at the center of the frame. A camera is carried on the front part of the frame through a tiltable self-stabilizing gimbal; a tail fin is installed at the tail of the spindle-shaped helium balloon. This technical solution consumes less power, has a long endurance time, and a high degree of intelligence, and is very suitable for large-area mapping, long-time detection and other fields. However, this technical solution only reduces the power output by means of a helium balloon, and still needs to continuously output power if it is to hover in the air. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies of the prior art and provide an unmanned aerial vehicle flight system capable of hovering through external objects, so that the UAV hardly consumes energy when hovering, further reduces the power output of the UAV, and extends the flight usage time of the UAV.

[0006] To solve the above problems, the present invention adopts the following scheme: An unmanned aerial vehicle (UAV) flight system capable of hovering through external objects, comprising a frame, and a PCB carrying platform is provided in the middle of the frame; A helium balloon filled with helium gas, which is installed on the frame and drives the UAV to rise and hover by its buoyancy, and a space is formed between it and the PCB carrying platform; Four propellers, which are arranged on the frame and symmetrically divided into two groups along the center line of the frame. Each group is in an "X" shape and is horizontally arranged outward, and is used to realize the flight of the UAV; Four brushless motors, which are respectively arranged corresponding to the four propellers and are used to drive the propellers to rotate; A sensor group, which is installed on the PCB carrying platform and includes an IMU sensor for obtaining the acceleration and angular velocity of the current UAV; an optical flow sensor for obtaining the translational speed of the current UAV; and a ToF sensor for obtaining the height information of the current UAV; A remote control module, which is installed on the PCB carrying platform and includes a communication part and a remote control part, and is used to communicate with the ground station and receive the expected displacement parameters (movement direction or displacement of movement) issued by the ground communication station; A flight control module, which is installed on the PCB carrying platform and is used to obtain the expected displacement parameters issued by the ground communication station received by the communication module and the movement attitude and displacement information of the current UAV read by the sensor group. After calculating the obtained parameters, the voltages allocated to the brushless motors corresponding to the four propellers are obtained, and the allocated voltage information is transmitted to the corresponding brushless motors; A power battery, which is installed on the PCB carrying platform and is used to provide power for the sensor group, the remote control module, and the flight control module.

[0007] Preferably, the flight control steps of the UAV are as follows: S1: Fill the balloon with helium gas to form a helium balloon so that its buoyancy is balanced with the gravity of the UAV; S2: The flight control module receives the movement attitude and displacement information from the sensor group, and the expected displacement information from the remote control module; S3: The flight control module calculates the voltages that should be allocated to the brushless motors of the four propellers through the information obtained in S2, and transmits the signals to the corresponding brushless motors respectively; S4: The flight control module controls the four brushless motors, and one group of diagonal propellers rotates clockwise, and the other group of diagonal propellers rotates counterclockwise; S5: When vertical ascent is required, the flight control module controls the rotational speeds of the four propellers to rise simultaneously, so that a high-pressure area is formed between the helium balloon and the PCB carrying platform, which is superimposed with the buoyancy of the helium balloon to push the UAV to rise; When vertical descent is required, the flight control module controls the rotational speeds of two propellers diagonally opposite to rise simultaneously, while the other two propellers maintain their original rotational speeds, creating a low-pressure area between the helium balloon and the PCB load platform, weakening the buoyancy of the helium balloon and causing the drone to descend; When horizontal movement is required, the flight control module controls the rotational speed of the propellers on one side to rise by a specific ratio and the rotational speed of the propellers on the other side to decrease by a specific ratio, making the thrust forces on both sides of the drone inconsistent and achieving the horizontal movement of the drone; When circular motion is required, the flight control module controls the rotational speeds of the two sets of diagonal propellers to be asymmetric, generating a horizontal rotational torque to achieve the circular motion of the drone.

[0008] Preferably, the method for the flight control module to distribute the voltages of the four brushless motors is as follows: S1: Use the IMU sensor, optical flow sensor, and ToF sensor to obtain the current attitude of the drone, including the yaw angle, displacements in the X-axis, Y-axis, and Z-axis directions, accelerations in the X-axis, Y-axis, and Z-axis, and after obtaining the desired displacements in the X-axis, Y-axis, and Z-axis of the drone and the desired yaw angle of the drone from the remote control module, transmit the obtained information to the flight control module, and the sensor group continues to sense the attitude of the drone; S2: The flight control module uses a control algorithm to calculate the voltages to be allocated to each brushless motor, specifically: First, with the help of the Euler-Lagrange equation of motion: (1) , Then, with the help of the PID control algorithm, from the desired displacements in the Z, X, and Y axes and the real-time motion attitude and displacements in the Z, X, and Y axes of the drone, we get: Equation (2): , Equation (3): , Calculated from Equation (3) to get and , and further calculate the thrust forces of the brushless motors corresponding to the four propellers according to Equation (4): Equation (4) , where is the thrust torque of each propeller, and the thrust torques of the four propellers are respectively 1 、 2 、 3 、 4 , is the sum of the two thrust torques, = 1 + 3 , = 2 + 4 , , , are aerodynamic coefficients, , , are PID control coefficients, is the mass of the UAV device, are the accelerations in each direction, V is the velocity in each direction, is the desired velocity, is the desired displacement, 、 Similarly. is the yaw angle, is the desired yaw angle, is the desired yaw rate, is the angular acceleration, r is the radius of the helium balloon; S3: Control the input voltage through the PWM signal, record the PWM duty cycle, voltage, and the corresponding propeller thrust value, plot the PWM signal duty cycle, input voltage, and the measured thrust as a curve to obtain an empirical formula, and conclude that the thrust is approximately quadratic with the input voltage. Finally, according to this quadratic relationship and the required thrust of each propeller, control the input voltage of each brushless motor through the PWM signal.

[0009] The present invention also provides a long-endurance UAV, which applies the above-mentioned UAV flight system.

[0010] Preferably, two power batteries are installed, and the two power batteries are symmetrically placed on the PCB carrier platform.

[0011] Preferably, a vision camera is further installed on the front side of the frame, and the vision camera is connected to the flight control module.

[0012] Preferably, the frame is further provided with a tripod for convenient and stable parking.

[0013] Preferably, four mounting rods are further provided at the upper end of the frame, and the four mounting rods form a mounting position for conveniently mounting the helium balloon.

[0014] Preferably, the helium balloon is installed above the PCB carrier platform and is 2.5 cm away from the PCB carrier platform.

[0015] The beneficial effects of the present invention are as follows: (1) By setting up helium balloons, the present invention significantly reduces the power output of the drone motors by utilizing their buoyancy, enabling hovering with almost no energy consumption. It can achieve omnidirectional control without the need for additional vertical thrusters, simplifies the design while retaining the ability for omnidirectional movement, reduces the power consumption of the drone during flight, and doubles the flight duration, ensuring that the drone can work for a long time and greatly improving the work efficiency in applications such as forest fire monitoring and establishing communication base stations in disaster areas.

[0016] (2) The present invention can rely on helium balloons to achieve hovering in the air. Therefore, even if the motors fail, the platform can still remain stable and land safely.

[0017] (3) In the present invention, the buoyancy of the helium balloons and the low motor operation requirements make the drone very quiet during operation. Its quiet and stable operation characteristics enable it to be used for tasks in crowded areas without disturbing the environment or people.

[0018] (4) The present invention adopts a modular design and uses off-the-shelf commercial components, with low manufacturing costs and easy assembly, facilitating wide application in the fields of sensing and the Internet of Things. Description of the Drawings

[0019] Figure 1 is a three-dimensional structural schematic diagram of the drone in the embodiment of the present invention; Figure 2 is a structural schematic diagram of the drone without helium balloons in the embodiment of the present invention; Figure 3 is a bottom schematic diagram of the drone in the embodiment of the present invention; Figure 4 is a flowchart of the flight control device of the drone in the embodiment of the present invention; Figure 5 is a flowchart for calculating the voltage distribution of each brushless motor of the drone in the embodiment of the present invention.

[0020] Description of the Reference Numerals: Frame 10, PCB carrier platform 11, tripod 12, mounting rod 13, helium balloon 20, propeller 30, Propeller I 31, Propeller II 32, Propeller III 33, Propeller IV 34, brushless motor 40, IMU sensor 51, optical flow sensor 52, ToF sensor 53, remote control module 60, flight control module 70, power battery 80, visual camera 90. Detailed Embodiments

[0021] The following describes the implementation manners of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0022] It should be noted that the diagrams provided in the following embodiments only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the figures, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0023] Embodiment 1: Refer to Figures 1 - 5 , a drone flight system capable of hovering through external objects, including a frame 10, and a PCB loading platform 11 is provided in the middle of the frame 10; A helium balloon 20 filled with helium gas is installed on the frame 10, and its buoyancy is used to drive the drone to rise and achieve hovering. It is 2.5 cm away from the PCB loading platform 11 to form a narrow space, which is convenient to form high pressure or low pressure in this area; Four propellers 30, namely propeller I 31, propeller II 32, propeller III 33, and propeller IV 34, are arranged on the frame 10 and symmetrically divided into two groups along the center line of the frame 10. Each group is in an "X" shape and horizontally arranged outward, and is used to realize the flight of the drone; Four brushless motors 40 are respectively arranged corresponding to the four propellers 30, and are used to drive the corresponding propellers 30 to rotate; A sensor group is installed on the PCB loading platform 11, including an IMU sensor 51, which is used to obtain the acceleration and angular velocity of the current drone; an optical flow sensor 52, which is used to obtain the translational speed of the current drone; a ToF sensor 53, which is used to obtain the height information of the current drone; A remote control module 60 is installed on the PCB loading platform 11, including a communication part and a remote control part, which is used to communicate with the ground station, receive the expected displacement parameters (motion direction or displacement of motion) issued by the ground communication station, and transmit them to the flight control module 70; A flight control module 70 is installed on the PCB loading platform 11, which is used to obtain the expected displacement parameters issued by the ground communication station received by the communication module and the motion attitude and displacement information of the current drone read by the sensor group. After calculating the obtained parameters, the voltages allocated to the brushless motors 40 corresponding to the four propellers 30 are obtained, and the allocated voltage information is transmitted to the corresponding brushless motors 40; The power battery 80 is installed on the PCB loading platform 11 and is used to supply power to the sensor group, the remote control module 60, and the flight control module 70.

[0024] Specifically, the flight control steps of the drone are as follows: S1: Fill the balloon with helium to form a helium balloon 20 so that its buoyancy is balanced with the gravity of the drone; S2: The flight control module 70 receives the motion attitude and displacement information from the sensor group, and receives the desired displacement information from the remote control module 60; S3: The flight control module 70 calculates the voltage that should be allocated to the brushless motors 40 of the four propellers 30 based on the information obtained from S2, and transmits the signals to the corresponding brushless motors 40 respectively; S4: The flight control module 70 controls the four brushless motors 40, where one set of diagonal propellers 30 rotates clockwise and the other set of diagonal propellers 30 rotates counterclockwise, that is, the propeller I 31, the propeller II 32, the propeller III 33, and the propeller IV 34 rotate in two positive and two reverse directions. The propeller I 31 and the propeller III 33 rotate clockwise, and the propeller II 32 and the propeller IV 34 rotate counterclockwise to cancel the counter torque and provide thrust in the horizontal and vertical directions, thereby realizing the stable flight of the device; S5: When vertical ascent is required, the flight control module 70 controls the rotation speeds of the four propellers 30 to rise simultaneously, so that a high-pressure area is formed between the helium balloon 20 and the PCB loading platform 11, which is superimposed with the buoyancy of the helium balloon 20 to push the drone upward; When vertical descent is required, the flight control module 70 controls the rotation speeds of two propellers 30 of one set of diagonals to rise simultaneously, and the other two propellers 30 maintain their original rotation speeds, so that a low-pressure area is formed between the helium balloon 20 and the PCB loading platform 11, weakening the buoyancy of the helium balloon 20 to make the drone descend; When horizontal movement is required, the flight control module 70 controls the rotation speed of the propellers 30 on one side to rise in a specific proportion, and the rotation speed of the propellers 30 on the other side to decrease in a specific proportion, so that the thrust magnitudes on both sides of the drone are inconsistent, generating a horizontal rotation moment to realize the horizontal movement of the drone; When circular motion is required, the flight control module 70 controls the rotation speeds of the two sets of diagonal propellers 30 to be asymmetric to generate a horizontal rotation moment to realize the circular motion of the drone.

[0025] The upward principle of the above drone is as follows: By creating a high pressure between the helium balloon 20 and the PCB carrying platform 11, the drone is pushed upward by the high-pressure air flow; specifically, it is set as follows: All four propellers 30 are arranged horizontally outward and rotate at the same speed. Therefore, no air pressure difference is formed between adjacent propellers 30, and air does not flow easily. Also, since the space formed between the helium balloon 20 and the PCB carrying platform 11 is relatively narrow, the outflow of air is blocked. Therefore, the air blown out accumulates between the helium balloon 20 and the PCB carrying platform 11, forming a local high-pressure area. According to Newton's third law, the air in the high-pressure area exerts an upward reaction force on the helium balloon 20.

[0026] The downward principle of the drone is as follows: By creating a low pressure between the helium balloon 20 and the PCB carrying platform 11, the lifting force of the helium balloon 20 is weakened, causing the drone to descend; specifically, it is set as follows: When only two sets of diagonal propellers 30 are operating, their respective wakes do not interfere with each other. The wakes are mainly concentrated around the blades of their respective propellers 30, and there is no fluid mixing effect between adjacent propellers 30. When two opposite-corner propellers 30 are operating, their airflows form a cycle in the central area of the platform. Due to the difference in the direction and speed of the two airflows, a high-pressure area is generated on one side of the PCB carrying platform 11. On the other side near the propellers 30, since the high-speed airflow generated by the rotating blades quickly evacuates the air, a low-pressure area is formed. However, this pressure distribution is not uniform. The high-pressure area is mainly concentrated locally, while the low-pressure area exists in a relatively large range. Therefore, the air suction effect formed by the low-pressure area weakens the lifting force of the helium balloon 20, thus causing the drone to descend.

[0027] The horizontal flight principle of the drone is as follows: For horizontal flight control, only the thrust of the corresponding side brushless motor 40 needs to be increased. For example, for forward movement: Increase the rotation speed of the two front propellers 30 and decrease the rotation speed of the two rear propellers 30. The greater the rotation speed, the greater the airflow near the propeller 30 and the lower the air pressure. Therefore, the air thrust at the rear increases. According to Newton's third law, the drone moves forward; the same principle applies to the backward and left-right movement of the drone.

[0028] Furthermore, the control method for the flight control module 70 to distribute the voltages of the four brushless motors 40 is as follows: S1: Use the IMU sensor 51 to obtain the current acceleration, angular velocity of the drone, the optical flow sensor 52 to obtain the current translational speed of the drone, and the ToF sensor 53 to obtain the height information of the current drone, so as to obtain the current attitude of the drone. The attitude information specifically includes the yaw angle, displacements in the X-axis, Y-axis, and Z-axis directions, accelerations in the X-axis, Y-axis, and Z-axis. After obtaining the desired displacements in the X-axis, Y-axis, and Z-axis of the drone and the desired yaw angle of the drone from the remote control module 60, the obtained information is transmitted to the flight control module 70, and the sensor group continues to sense the attitude of the drone; S2: The flight control module 70 calculates the voltage to be allocated to each brushless motor 40 using a control algorithm. Specifically: First, with the help of the Euler-Lagrange motion equation: (1) , Then, with the help of the PID control algorithm, and based on the desired Z, X, Y-axis displacements and the real-time UAV motion attitude and Z, X, Y-axis displacements, we get: Equation (2): , Equation (3): , Calculated from the above equations to obtain and , and further calculate the thrust magnitudes of the brushless motors 40 corresponding to the four propellers 30 according to Equation (4): Equation (4) , where is the thrust moment of each propeller 30, obtained by motor thrust * angle * action distance. The thrust moments of the four propellers 30 are respectively 1 , 2 , 3 , 4 ; is the sum of two thrust moments, = 1 + 3 , = 2 + 4 ; , , are aerodynamic coefficients, , , are PID control coefficients. The aerodynamic coefficients are obtained through the simulation environment; is the mass of the UAV device; are the accelerations in each direction; V is the velocity in each direction; is the desired velocity, is the desired displacement, , Similarly; is the yaw angle, is the desired yaw angle, is the expected yaw rate; is the angular acceleration; r is the radius of the helium balloon 20; the speed and displacement are both measured by the sensor group, and the expected displacement is obtained by the user through the remote control module 60.

[0029] S3: Through experimental measurement, the input voltage is controlled by using the PWM signal, the PWM duty cycle, voltage and the corresponding thrust value of the propeller 30 are recorded, the PWM signal duty cycle, the input voltage and the measured thrust are plotted into a curve, and an empirical formula is obtained. It is concluded that the thrust and the input voltage are approximately in a quadratic relationship. Finally, according to the quadratic relationship and the thrust required for each propeller 30, the input voltage of each brushless motor 40 is controlled by the PWM signal.

[0030] In this embodiment, the flight control module 70 includes an STM32F405RGT6 single-chip microcomputer and a PWM signal generator (TB6612FNG); the remote control module 60 uses DX-BT-24 and is connected to the single-chip microcomputer through a UART interface.

[0031] In this embodiment, all sensors or modules are connected to the single-chip microcomputer. The IMU sensor 51 is of model BMI088 and is connected to the single-chip microcomputer through the I2C interface. The optical flow sensor 52 is of model PMW3901 and is connected to the single-chip microcomputer through the SPI interface. The ToF sensor 53 is of model VL53L1X and is connected to the single-chip microcomputer through the I2C interface. The single-chip microcomputer obtains the measurement from the sensor group. The present invention also provides a long-endurance UAV, which uses the above-mentioned UAV flight system, wherein the PCB loading platform 11 is rectangular as a whole, wherein the IMU sensor 51 is installed on the upper end of the PCB loading platform 11, and the optical flow sensor 52 and the ToF sensor 53 are installed on the lower end of the PCB loading platform 11.

[0032] In order to ensure sufficient power supply and extend the use time of the drone as much as possible, two power batteries 80 are installed, and the two power batteries 80 are symmetrically placed on the PCB loading platform 11.

[0033] In order to realize functions such as shooting route, monitoring and investigation, auxiliary navigation and obstacle avoidance, etc. A visual camera 90 is also installed on the front side of the frame 10, and the visual camera 90 is connected to the flight control module 70.

[0034] In order to ensure that the drone can be parked stably on the ground and take off stably, the frame 10 is also provided with a tripod 12 distributed in a rectangular shape.

[0035] To ensure the stable installation of the helium balloon 20, four mounting rods 13 are further provided at the upper ends of the four corner ends of the PCB carrier platform 11. The four mounting rods 13 form a mounting position convenient for installing the helium balloon 20. In this embodiment, the material of the helium balloon 20 is rubber. The helium balloon 20 is fixedly connected to the frame 10, and can be adhered to the frame 10, or can be fixedly connected by tying the helium balloon 20 to the mounting rod with a connecting rope or other means.

[0036] To enable the helium balloon 20 and the PCB carrier platform 11 to form a narrow space, facilitating the formation of a high-pressure area and a low-pressure area. The helium balloon 20 is installed above the PCB carrier platform 11 and is 2.5 cm away from the PCB carrier platform 11.

[0037] The above description is only a specific example of the present invention and does not constitute any limitation to the present invention. Obviously, for professionals in the field, after understanding the content and principle of the present invention, various modifications and changes in form and details may be made without departing from the principle and structure of the present invention. However, these corrections and changes based on the idea of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A UAV flight system capable of hovering by means of an external object, characterized in that: It comprises a frame (10), wherein a PCB loading platform (11) is provided in the middle of the frame (10); A helium balloon (20) filled with helium is installed on the frame (10) and uses its buoyancy to drive the drone to rise and achieve hovering, with a space formed between the helium balloon and the PCB loading platform (11); Four propellers (30) are arranged on the frame (10) and are symmetrically divided into two groups along the center line of the frame (10), each group is in an "X" shape and is arranged horizontally outward, for realizing the flight of the unmanned aerial vehicle; Four brushless motors (40), respectively arranged corresponding to the four propellers (30), and used to drive the propellers (30) to rotate; A sensor group, mounted on the PCB loading platform (11), comprising an IMU sensor (51) for obtaining the acceleration and angular velocity of the current drone; an optical flow sensor (52) for obtaining the translation velocity of the current drone; and a ToF sensor (53) for obtaining the altitude information of the current drone; A remote control module (60) is mounted on the PCB loading platform (11) and is used to communicate with the ground station and receive the desired displacement parameter (movement direction or movement displacement) issued by the ground communication station; The flight control module (70) is mounted on the PCB loading platform (11) and is used to obtain the expected displacement parameters sent by the ground communication station received by the communication module and the motion posture and displacement information of the current unmanned aerial vehicle read by the sensor group, calculate the obtained parameters, obtain the voltages allocated to the brushless motors (40) corresponding to the four propellers (30), and transmit the allocated voltage information to the corresponding brushless motors (40); A power battery (80) is mounted on the PCB loading platform (11) and is used to provide power to the sensor group, the remote control module (60), and the flight control module (70).

2. The UAV flight system capable of hovering by means of external objects according to claim 1, characterized in that: The flight control steps of the UAV are: S1: injecting helium into the balloon to form a helium balloon (20), so that its buoyancy is balanced with the gravity of the drone; S2: the flight control module (70) receives the motion attitude and displacement information from the sensor group, and receives the expected displacement information from the remote control module (60); S3: The flight control module (70) calculates the voltages to be distributed to the brushless motors (40) of the four propellers (30) based on the information obtained from S2, and transmits the signals to the corresponding brushless motors (40); S4: The flight control module (70) controls the four brushless motors (40), wherein one set of diagonal propellers (30) rotates clockwise, and another set of diagonal propellers (30) rotates counterclockwise; S5: When vertical ascent is required, the flight control module (70) controls the rotation speeds of the four propellers (30) to increase simultaneously, so that a high-pressure area is formed between the helium balloon (20) and the PCB loading platform (11), which is superimposed with the buoyancy of the helium balloon (20) to propel the drone upward; When vertical descent is required, the flight control module (70) controls the rotation speeds of two diagonal propellers (30) in one group to increase simultaneously, while the other two propellers (30) maintain their original rotation speeds, so that a low-pressure area is formed between the helium balloon (20) and the PCB loading platform (11), thereby weakening the buoyancy of the helium balloon (20) and causing the drone to descend; When horizontal movement is required, the flight control module (70) is used to control the rotation speed of the propeller (30) on one side to increase at a specific ratio, and the rotation speed of the propeller (30) on the other side to decrease at a specific ratio, so that the thrusts on both sides of the drone are inconsistent, generating a horizontal rotation torque, and achieving horizontal movement of the drone; When circular motion is required, the flight control module (70) controls the rotation speeds of the two sets of diagonal propellers (30) to be asymmetric, thereby generating a horizontal rotation torque and achieving circular motion of the drone.

3. The UAV flight system capable of hovering by means of external objects according to claim 2, characterized in that: The control method of the flight control module (70) distributing the voltages of the four brushless motors (40) is: S1: using an IMU sensor (51), an optical flow sensor (52), and a ToF sensor (53) to obtain the attitude of the current drone, including the yaw angle, displacements in the directions of the X-axis, Y-axis, and Z-axis, and accelerations in the X-axis, Y-axis, and Z-axis, and obtaining the desired displacements in the X-axis, Y-axis, and Z-axis of the drone and the desired yaw angle of the drone from a remote control module (60), the obtained information is transmitted to a flight control module (70), and the sensor group continues to sense the attitude of the drone; S2: The flight control module (70) uses a control algorithm to calculate the voltage to be distributed to each brushless motor (40), specifically: First, we use the Euler-Lagrange equations of motion: （1） ， Then, with the help of PID control algorithm, the expected Z, X, and Y axis displacements and the real-time UAV motion posture and Z, X, and Y axis displacements are obtained: Equation (2): , Equation (3): , Calculated from equation (3): and , and further calculate the thrust of the brushless motor (40) corresponding to the four propellers (30) according to equation (4): Equation (4) , in is the thrust torque of each propeller (30), and the thrust torques of the four propellers (30) are respectively 1.

2.

3.

4. is the sum of the two thrust moments, = 1+ 3. = 2+ 4. , , is the aerodynamic coefficient, , , is the PID control coefficient, The quality of the drone device, is the acceleration in all directions, V is the velocity in all directions, is the expected speed, is the expected displacement, , Same reason. is the yaw angle, is the desired yaw angle, is the desired yaw rate, is the angular acceleration, r is the radius of the helium balloon (20); S3: Control the input voltage through the PWM signal, record the PWM duty cycle, voltage and the corresponding propeller (30) thrust value, plot the PWM signal duty cycle, input voltage and measured thrust into a curve, obtain an empirical formula, and conclude that the thrust and input voltage are approximately in a quadratic relationship. Finally, according to the quadratic relationship and the thrust required by each propeller (30), control the input voltage of each brushless motor (40) through the PWM signal.

4. A long-endurance drone, characterized in that: Apply the UAV flight system described in any one of 1-3.

5. The long-endurance UAV according to claim 4, characterized in that: Two power batteries (80) are installed, and the two power batteries (80) are symmetrically installed on the PCB loading platform (11).

6. The long-endurance UAV according to claim 4, characterized in that: A visual camera (90) is also installed on the front side of the frame (10), and the visual camera (90) is connected to the flight control module (70).

7. The long-endurance UAV according to claim 4, characterized in that: The frame (10) is also provided with a tripod (12) that enables convenient and stable parking.

8. The long-endurance UAV according to claim 4, characterized in that: Four mounting rods (13) are also provided at the upper end of the frame (10), and the four mounting rods (13) are formed with mounting positions for conveniently mounting the helium balloons (20).

9. The long-endurance drone according to claim 4, characterized in that: The helium balloon (20) is installed above the PCB loading platform (11) and is 2.5 cm away from the PCB loading platform (11).

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