Tandem rigid rotor heavy-load unmanned aerial vehicle and control method thereof

Abstract

The invention belongs to the technical field of unmanned aerial vehicles, and discloses a tandem rigid rotor heavy-load unmanned aerial vehicle and a control method thereof. The tandem rigid rotor heavy-load unmanned aerial vehicle comprises a vehicle body, horizontal attitude control small propellers are installed at the two ends of the front portion and the two ends of the rear portion of the vehicle body respectively and used for roll control and pitching fine adjustment, a front main rotor is installed on the front side of the top of the vehicle body, and a rear main rotor is installed on the rear side of the top of the vehicle body. The front main rotor and the rear main rotor are used for generating lift force and adjusting pitching moment, and a plurality of vertical yaw control small paddles are installed at the bottom of the aircraft body and used for generating yaw control moment; driving systems are mounted on the small horizontal attitude control propellers, the front main rotor, the rear main rotor and the small vertical yaw control propellers, a controller system is further mounted at the top of the aircraft body and used for constructing a closed-loop feedback control framework, and the controller system is connected with the driving systems; according to the invention, the heavy load requirement can be met, and the cost benefit and the good flight control performance are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicles, and particularly to a tandem rigid rotor heavy-load unmanned aerial vehicle and a control method thereof. Background Art

[0002] With the rapid development of technology, unmanned aerial vehicles have become an important branch of modern aviation technology, showing great application potential in fields such as agricultural plant protection, industrial inspection, urban logistics, emergency rescue, and military reconnaissance. Currently, the mainstream types of drones on the market mainly include multi-rotors and fixed wings, and different forms of compound layouts have also emerged in recent years.

[0003] The advantages of multi-rotor drones are relatively simple structure, low cost, ability to take off and land vertically and hover, and flexible control. However, multi-rotor drones rely on multiple (usually four) small-sized rotors to provide lift and attitude control. This distributed small-propeller power system, although easy to control, has significant bottlenecks in load capacity and energy efficiency. The aerodynamic efficiency of a single small propeller is much lower than that of a large-diameter rotor under the same power, resulting in limited overall lift and difficulty in meeting the growing heavy-load transportation requirements. At the same time, both lift generation and attitude control are achieved by adjusting the rotational speeds of these small propellers, there are control coupling problems, and the performance is limited during high-speed or large-load maneuvers, and the energy consumption is relatively large.

[0004] To improve the load capacity and efficiency, researchers have also explored configurations with larger rotors, such as tandem dual-rotor drones. This layout draws on the design of large helicopters and provides lift through two large-sized main rotors at the front and rear. In theory, it has high load potential, aerodynamic efficiency, and good longitudinal stability. However, traditional tandem drones also face their own challenges - if a helicopter-style variable pitch main rotor is used, although efficient flight control can be achieved, its complex rotor head leads to extremely complex structure, high manufacturing cost, and difficult maintenance, which is contrary to the trend of drones pursuing low cost and easy maintenance; if a rigid or semi-rigid main rotor is used to simplify the structure and replace the variable pitch scheme, attitude control cannot be performed. In short, the current market demand for heavy-load drones is urgent, but the load and efficiency of typical multi-rotor structures such as quadcopters are insufficient; traditional helicopters have too high costs and complex structures. Summary of the Invention

[0005] The object of the present invention is to provide a tandem rigid rotor heavy-load unmanned aerial vehicle and its control method to overcome the problems existing in the prior art. The present invention can skillfully combine the high load / efficiency advantages of tandem large rotors with the low-cost / simple structure advantages of rigid rotors, and realizes the separation of attitude control and lift generation through auxiliary small rotors, so that the unmanned aerial vehicle proposed by the present invention can not only meet the heavy-load requirements, but also has cost-effectiveness and good flight control performance, effectively overcoming the disadvantages of existing quadrotors and traditional tandem unmanned aerial vehicles, and showing unique superiority.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In the first aspect, the present invention provides a tandem rigid rotor heavy-load unmanned aerial vehicle, including a fuselage. Horizontal attitude control small rotors are respectively installed at both the front and rear ends of the fuselage for roll control and pitch fine-tuning. A front main rotor is installed at the front side of the top of the fuselage, and a rear main rotor is installed at the rear side of the top of the fuselage. The front main rotor and the rear main rotor are used to generate lift and adjust the pitch moment. A plurality of vertical yaw control small rotors are installed at the bottom of the fuselage for generating yaw control torque; drive systems are installed on the horizontal attitude control small rotors, the front main rotor, the rear main rotor, and the vertical yaw control small rotors. A controller system is also installed at the top of the fuselage for constructing a closed-loop feedback control architecture, and the controller system is connected to the drive systems;

[0008] Further, the drive system includes a horizontal drive motor installed on the horizontal attitude control small rotor, main rotor drive motors respectively installed on the front main rotor and the rear main rotor, and a vertical drive motor installed on one side of the vertical yaw control small rotor. The horizontal drive motor, the main rotor drive motors, and the vertical drive motor are all connected to the controller system;

[0009] The controller system includes an aircraft control circuit board, and the aircraft control circuit board is connected to a battery; a main control chip is installed on the aircraft control circuit board, and the main control chip is respectively connected to an electronic speed controller module and an inertial measurement unit. The electronic speed controller module is respectively connected to the horizontal drive motor, the main rotor drive motors, and the vertical drive motor; the electronic speed controller module is connected to the battery;

[0010] Further, the front main rotor and the rear main rotor are symmetrically arranged, the diameters and airfoils of the front main rotor and the rear main rotor are the same, the rotation directions are opposite, and they are both rigid rotors;

[0011] Further, the relationship between the distance d1 between the front main rotor and the rear main rotor and the total length d2 of the fuselage is:

[0012] d1 = 0.5d2;

[0013] Further, the axis of the horizontal attitude control small propeller is arranged parallel to the plane of the airframe, and the thrust direction of the horizontal attitude control small propeller is arranged perpendicular to the transverse axis of the airframe;

[0014] Further, the plurality of vertical yaw control small propellers are symmetrically arranged, the thrust direction of the vertical yaw control small propeller is arranged perpendicular to the longitudinal axis of the airframe, and the distance relationship between the vertical distance h1 from the axis of the vertical yaw control small propeller to the rotation center and the height h2 of the airframe is:

[0015] h1 = (0.2 - 0.25)h2.

[0016] In a second aspect, the present invention provides a control method for a tandem rigid rotor heavy-load unmanned aerial vehicle, including the following steps:

[0017] Step 1, according to the dynamic analysis of the aerial vehicle, a dynamic model in six degrees of freedom is obtained;

[0018] Step 2, the pitch angle, roll angle and yaw angle information of the unmanned aerial vehicle, as well as the position and speed information of the unmanned aerial vehicle are measured in real time through the controller system to obtain the actual state information;

[0019] Step 3, the controller system calculates whether there is an error between the actual state information and the preset desired state information. If there is an error, the required total lift, pitch moment, roll moment, auxiliary pitch moment and yaw moment are calculated according to the dynamic model, and the controller system adjusts the thrusts of the front main rotor, rear main rotor, horizontal attitude control small propeller and vertical yaw control small propeller respectively according to the required total lift, pitch moment, roll moment and yaw moment, and step 2 is executed again;

[0020] If there is no error, step 2 is executed again;

[0021] Further, the dynamic model in the six degrees of freedom specifically includes the following formulas:

[0022]

[0023]

[0024] In the formula, m represents the total mass of the unmanned aerial vehicle; x represents the displacement of the unmanned aerial vehicle moving forward; y represents the displacement of the unmanned aerial vehicle left and right; z represents the displacement of the unmanned aerial vehicle up and down; represents the acceleration of the unmanned aerial vehicle in the forward direction; represents the acceleration of the unmanned aerial vehicle in the left and right directions; represents the acceleration of the unmanned aerial vehicle in the height direction; T f represents the lift of the front main rotor; T r represents the lift of the rear main rotor; Dx Denote the longitudinal aerodynamic drag; D y Denote the lateral aerodynamic drag; D z Denote the aerodynamic drag in the vertical direction; θ denotes the pitch angle; φ denotes the roll angle; ψ denotes the yaw angle; Denote the angular velocity of the pitch angle; Denote the angular velocity of the roll angle; Denote the angular velocity of the yaw angle; Denote the acceleration of the pitch angle; Denote the acceleration of the roll angle; Denote the acceleration of the yaw angle; g denotes the local acceleration due to gravity; I x Denote the moment of inertia of the unmanned aerial vehicle about the x-axis; I y Denote the moment of inertia of the unmanned aerial vehicle about the y-axis; I z Denote the moment of inertia of the unmanned aerial vehicle about the z-axis; d1 denotes the distance between the front main rotor and the rear main rotor; l denotes the horizontal distance from the horizontal attitude control small propeller to the center of mass; h1 denotes the vertical distance from the axis of the vertical yaw control small propeller to the rotation center; C p Denote the damping coefficient of the roll of the unmanned aerial vehicle; C q Denote the damping coefficient of the yaw of the unmanned aerial vehicle; C r Denote the damping coefficient of the pitch of the unmanned aerial vehicle; (i = 1, 2, 3, 4) denote the lift of the i-th horizontal attitude control small propeller, (i = 1, 2, 3, 4) denote the thrust of the i-th vertical yaw control small propeller on the left side; (i = 1, 2, 3, 4) denote the thrust of the i-th vertical yaw control small propeller on the right side;

[0025] Furthermore, the controller system includes an aircraft control circuit board, and the aircraft control circuit board is connected with a battery; the aircraft control circuit board includes a main control chip, the main control chip is respectively connected with an electronic speed controller module and an inertial measurement unit, the electronic speed controller module is respectively connected with a horizontal drive motor, a main rotor drive motor and a vertical drive motor; the electronic speed controller module is connected with the battery;

[0026] The specific content of step two includes:

[0027] Through the inertial measurement unit, the angle information, angular velocity information and acceleration information of the pitch angle, roll angle and yaw angle of the unmanned aerial vehicle, as well as the position and speed information of the unmanned aerial vehicle are measured in real time to obtain the actual state information;

[0028] Furthermore, the specific content of step three includes:

[0029] Through the main control chip, it is calculated whether there is an error between the actual state information and the preset expected state information. If there is an error, then through (Tf +T r ) Calculate the total lift required for the front main rotor and the rear main rotor. By (T r -T f )·d1, calculate the pitching moment required for the front main rotor and the rear main rotor. By Calculate the roll moment required for the horizontal attitude control small propeller. By FP3 + FP4 - FP1 - FP2·l, calculate the auxiliary pitching moment required for the horizontal attitude control small propeller. By Calculate the thrust difference required for the vertical yaw control small propeller. By Calculate the yaw moment required for the vertical yaw control small propeller. The electronic speed controller module controls the drive system to adjust the thrusts of the front main rotor, the rear main rotor, the horizontal attitude control small propeller, and the vertical yaw control small propeller respectively, and then execute Step 2 again;

[0030] If there is no error, execute Step 2 again.

[0031] The above technical solution has the following advantages or beneficial effects:

[0032] First, the present invention provides a tandem rigid rotor heavy-load unmanned aerial vehicle. First of all, the structure of the present invention is simple and the cost is low: using rigid main rotors to replace the variable pitch rotors of traditional helicopters greatly simplifies the mechanical structure, reduces the manufacturing cost and maintenance difficulty, and at the same time retains the high load potential brought by large-size rotors; Secondly, the present invention has high load and high efficiency: the main lift is provided by two large-size tandem main rotors, which has higher aerodynamic efficiency and load capacity compared with the multi-rotor structure and is suitable for heavy-load scenarios; In addition, the control is decoupled and the response is fast: the lift / main pitching control (front main rotor and rear main rotor), roll / pitch fine-tuning control (horizontal attitude control small propeller), and yaw control (vertical yaw control small propeller) are assigned to different actuators (front main rotor, rear main rotor, horizontal attitude control small propeller, and vertical yaw control small propeller), achieving dynamic decoupling; In particular, the yaw control is responsible for by a dedicated vertical small propeller, which does not rely on the anti-torque difference of the main rotor, has a fast response speed and high control accuracy, and overcomes the problem of difficult yaw control in traditional tandem layouts; Moreover, the present invention has good stability: the tandem layout itself has good longitudinal stability, combined with the decoupled attitude control system, enabling the aircraft to maintain good stability and maneuverability under various working conditions, especially when the load changes; Finally, the present invention combines the advantages of large propellers and overcomes the disadvantages of multi-rotors: combining the high load and high efficiency of helicopter large propellers and the simple structure and low cost of multi-rotor rigid propellers, while overcoming the disadvantages of complex and expensive helicopter structures and low load and low efficiency of multi-rotors, providing a performance-balanced and practical heavy-load unmanned aerial vehicle solution.

[0033] Furthermore, the electronic speed regulator module is responsible for receiving instructions from the main control chip and accurately controlling the speed of all drive motors. The entire controller system constitutes the core of closed-loop feedback control, which can receive instructions and sensor data, calculate and output control signals to each drive motor. The controller system of the present invention has a compact structure, precise control, and rapid response, which greatly improves the flight performance and reliability of the unmanned aerial vehicle and meets the requirements of heavy-load flight missions.

[0034] Furthermore, the front main rotor and the rear main rotor are arranged symmetrically, so that the force on the aircraft is more balanced during flight, which can effectively reduce the lateral torque caused by unreasonable rotor layout, enhance the stability of the aircraft, and enable the aircraft to maintain stable flight in complex airflow environments, reduce the risk of loss of control due to attitude imbalance, and ensure the consistency of the lift characteristics generated by the rotor during rotation; at the same time, the design of opposite rotation directions cleverly offsets the anti-torque generated by the rotor rotation. Traditional co-rotating rotors will produce a large anti-torque, affecting the control of the aircraft, and this design does not require the addition of complex anti-torque compensation devices, thereby simplifying the aircraft structure; in addition, the use of rigid rotors, compared with flexible rotors, rigid rotors are less deformed when rotating at high speeds, can more accurately control lift and flight attitude, improve flight efficiency, and reduce energy loss.

[0035] Furthermore, by setting the relationship between the distance d1 between the front main rotor and the rear main rotor and the total length d2 of the fuselage, a better pitch control arm can be obtained. The front main rotor and the rear main rotor are the main lift components, which are used to generate lift and adjust the pitch moment.

[0036] Furthermore, by setting the distance relationship between the vertical distance h1 between the axis of the vertical yaw control propeller and the center of rotation and the height h2 of the fuselage, the yaw control efficiency of the propeller can be fully utilized. Neither the thrust effect will be insignificant due to a too small distance, nor will unnecessary structural complexity and energy loss be increased due to a too large distance. While ensuring the yaw control effect, the overall performance of the aircraft is optimized, its flight efficiency and maneuverability are improved, and it is particularly suitable for heavy-load flight missions.

[0037] Secondly, the present invention provides a control method for a tandem rigid rotor heavy-load unmanned aerial vehicle. Based on the dynamic analysis of the aircraft, a dynamic model with six degrees of freedom is obtained. The core idea of this control method is to use different power units to achieve decoupling control of different degrees of freedom; in terms of height and pitch control, by independently adjusting the front main rotor T f With the rear main rotor T r The speed controls the total lift T f +T r Achieve vertical lifting and lowering motion while utilizing the lift difference T between the front and rear main rotors r -T fGenerate pitching moment to achieve pitching attitude control; in terms of roll and pitch control, by independently adjusting the thrust of four horizontal attitude control small propellers the differential thrust of diagonal or same-side small propellers is used to generate roll moment and auxiliary pitching moment to achieve roll control and fine adjustment of the pitching control of the main rotor; in terms of yaw control, by independently adjusting the thrust of four groups of vertical yaw control small propellers (left right ), the differential thrust of the left and right small propellers is used to generate yaw moment and drive the UAV to deflect in the horizontal plane; this control method assigns the three main control tasks of lift / pitch, roll / pitch fine adjustment, and yaw to different actuators (front main rotor, rear main rotor, horizontal attitude control small propellers, and vertical yaw control small propellers), realizing the dynamic decoupling between control channels, achieving closed-loop feedback control of the pitch, roll, and yaw three-axis attitudes and positions, improving the response speed and stability of attitude control. Especially in yaw control, it gets rid of the traditional multi-rotor's dependence on anti-torque differential method, and the response is more direct and rapid. Description of the Drawings

[0038] Figure 1 is a schematic structural diagram of a tandem rigid rotor heavy-load UAV of the present invention;

[0039] Figure 2 is a schematic flow diagram of the control method of a tandem rigid rotor heavy-load UAV of the present invention;

[0040] In the figure, 1 - airframe; 2 - front main rotor; 21 - main rotor drive motor; 3 - rear main rotor; 4 - horizontal attitude control small propeller; 41 - horizontal drive motor; 5 - vertical yaw control small propeller; 51 - vertical drive motor; 6 - aircraft control circuit board; 61 - battery. Detailed Embodiments

[0041] The following further elaborates on the present invention in detail with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0042] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0044] Embodiment:

[0045] See Figure 1 , the present invention provides a tandem rigid rotor heavy-load unmanned aerial vehicle, including a fuselage 1, a horizontal attitude control small propeller 4, a front main rotor 2, a rear main rotor 3, a vertical yaw control small propeller 5, a controller system and a drive system; the controller system includes an aircraft control circuit board 6, a main control chip, an electronic speed controller module, an inertial measurement unit, a battery 61; the drive system includes a horizontal drive motor 41, a main rotor drive motor 21, a vertical drive motor 51 and a horizontal drive motor 41;

[0046] The horizontal attitude control small propellers 4 are respectively installed at both ends of the front and rear of the fuselage 1. The axis of the horizontal attitude control small propeller 4 is arranged parallel to the plane of the fuselage 1, and the thrust direction of the horizontal attitude control small propeller 4 is arranged perpendicular to the transverse axis of the fuselage 1. Specifically, they are symmetrically distributed on both sides of the longitudinal axis of the fuselage 1 and also symmetrically distributed on both sides of the transverse axis of the fuselage 1. A roll moment is generated by the thrust difference between the left and right horizontal attitude control small propellers 4, and an auxiliary pitch moment is generated by the thrust difference between the front and rear horizontal attitude control small propellers 4 for roll control and pitch fine-tuning. The installation position makes the moment arm for generating the roll moment approximately half of the fuselage width; the front main rotor 2 is installed at the front side of the top of the fuselage 1, and the rear main rotor 3 is installed at the rear side of the top of the fuselage 1. The front main rotor 2 and the rear main rotor 3 are symmetrically arranged. The diameters and airfoils of the front main rotor 2 and the rear main rotor 3 are the same, and the rotation directions are opposite. For example, when viewed from above, the front main rotor 2 rotates clockwise and the rear main rotor 3 rotates counterclockwise to cancel out most of the counter torque. The front main rotor 2 and the rear main rotor 3 are both rigid rotors, that is, the pitch is fixed, and the lift is changed by adjusting the rotational speed, which is convenient for simplifying the design and manufacturing. The relationship between the distance d1 between the front main rotor 2 and the rear main rotor 3 and the total length d2 of the fuselage 1 is: d1 = 0.5d2 to obtain a better pitch control moment arm. The front main rotor 2 and the rear main rotor 3 are the main lift components for generating lift and adjusting the pitch moment; several vertical yaw control small propellers 5 are installed at the bottom of the fuselage 1, located between the front main rotor 2 and the rear main rotor 3. The several vertical yaw control small propellers 5 are symmetrically arranged. The thrust direction of the vertical yaw control small propeller 5 is arranged perpendicular to the longitudinal axis of the fuselage 1. The distance relationship between the vertical distance h1 from the axis of the vertical yaw control small propeller 5 to the rotation center and the height h2 of the fuselage 1 is: h1 = (0.2 - 0.25) h2 is used to generate yaw control torque. Drive systems are installed on the horizontal attitude control small propellers 4, the front main rotor 2, the rear main rotor 3, and the vertical yaw control small propellers 5. The drive system includes a horizontal drive motor 41 installed on the horizontal attitude control small propeller 4, main rotor drive motors 21 respectively installed on the front main rotor 2 and the rear main rotor 3, and a vertical drive motor 51 installed on one side of the vertical yaw control small propeller 5. The horizontal drive motor 41, the main rotor drive motors 21, and the vertical drive motor 51 are all connected to the controller system. A controller system is also installed on the top of the fuselage 1. The controller system includes an aircraft control circuit board 6. The aircraft control circuit board 6 is connected to a battery 61, and the entire system is powered by the battery 61. A main control chip is installed on the aircraft control circuit board 6. The main control chip is respectively connected to an electronic speed controller module and an inertial measurement unit. The electronic speed controller module is respectively connected to the horizontal drive motor 41, the main rotor drive motors 21, and the vertical drive motor 51. The electronic speed controller module is responsible for receiving instructions from the main control chip and precisely controlling the rotation speeds of all drive motors (the vertical drive motor 51, the horizontal drive motor 41, and the main rotor drive motors 21). The electronic speed controller module is connected to the battery 61. The entire controller system constitutes the core of the closed-loop feedback control, receives instructions and sensor data, calculates, and outputs control signals to each drive motor;.

[0047] Preferably, the front main rotor 2 and the rear main rotor 3 are arranged symmetrically longitudinally;

[0048] Preferably, the number of the horizontal attitude control small propellers 4 is at least 4, and can also be 6, 8, 10, or other numbers that can achieve symmetrical arrangement. They are installed at the four corners of the fuselage 1. The thrust of each horizontal attitude control small propeller 4 is independently adjustable, mainly used to generate roll control torque, and combined with the two main rotors to control the pitch attitude;

[0049] Preferably, the number of the vertical yaw control small propellers 5 is at least 4, and can also be 6, 8, 10, or other numbers that can achieve symmetrical arrangement. They are symmetrically distributed on both sides of the middle section of the bottom of the fuselage 1, specifically on both sides of the longitudinal axis of the bottom of the fuselage 1. The thrust of each vertical yaw control small propeller 5 is independently adjustable, and generates yaw control torque by generating a left-right thrust difference;

[0050] Preferably, the rotation axis of the vertical yaw control small propeller 5 is substantially perpendicular to the horizontal plane of the fuselage 1, and the generated thrust direction is substantially parallel to the vertical axis of the fuselage 1;

[0051] Preferably, the inertial measurement unit includes sensors and a positioning and monitoring device (such as GPS), which is used to measure the three-axis attitude angles of the tandem rigid-rotor heavy-load unmanned aerial vehicle in real time through the inertial measurement unit, that is, the angle information, angular velocity information, and acceleration information of the pitch angle, roll angle, and yaw angle, as well as the position and velocity information of the tandem rigid-rotor heavy-load unmanned aerial vehicle through GPS or other monitoring and positioning devices to obtain the actual state information;

[0052] Preferably, the sensor can be a nine-axis inertial measurement unit sensor, which is used to obtain the angles and angular velocities of the attitude angles θ, φ, ψ in real time.

[0053] In an embodiment of the present invention, a control method for a tandem rigid-rotor heavy-load unmanned aerial vehicle is provided, including the following steps:

[0054] Step 1, obtaining the dynamic model: According to the dynamic analysis of the aircraft, the dynamic models in six degrees of freedom are obtained, and the specific formulas include:

[0055]

[0056] In the formula, m represents the total mass of the tandem rigid-rotor heavy-load unmanned aerial vehicle; x represents the forward displacement of the tandem rigid-rotor heavy-load unmanned aerial vehicle; y represents the left-right displacement of the tandem rigid-rotor heavy-load unmanned aerial vehicle; z represents the up-down displacement of the tandem rigid-rotor heavy-load unmanned aerial vehicle; represents the acceleration in the forward direction of the tandem rigid-rotor heavy-load unmanned aerial vehicle; represents the acceleration in the left-right direction of the tandem rigid-rotor heavy-load unmanned aerial vehicle; represents the acceleration in the height direction of the tandem rigid-rotor heavy-load unmanned aerial vehicle; T f represents the lift of the front main rotor 2; T r represents the lift of the rear main rotor 3; D x represents the longitudinal aerodynamic drag; D y represents the lateral aerodynamic drag; D z represents the vertical aerodynamic drag; θ represents the pitch angle; φ represents the roll angle; ψ represents the yaw angle; represents the angular velocity of the pitch angle; represents the angular velocity of the roll angle; represents the angular velocity of the yaw angle; represents the acceleration of the pitch angle; represents the acceleration of the roll angle; represents the acceleration of the yaw angle; g represents the local acceleration of gravity; I x represents the moment of inertia of the tandem rigid-rotor heavy-load unmanned aerial vehicle about the x-axis; I y represents the moment of inertia of the tandem rigid-rotor heavy-load unmanned aerial vehicle about the y-axis; Iz represents the moment of inertia of the tandem rigid rotor heavy - load unmanned aerial vehicle about the z - axis; d1 represents the distance between the front main rotor 2 and the rear main rotor 3; l represents the horizontal distance from the horizontal attitude control small propeller 4 to the center of mass; h1 represents the vertical distance from the axis of the vertical yaw control small propeller 5 to the rotation center; C p represents the damping coefficient of the roll of the tandem rigid rotor heavy - load unmanned aerial vehicle; C q represents the damping coefficient of the yaw of the tandem rigid rotor heavy - load unmanned aerial vehicle; C r represents the damping coefficient of the pitch of the tandem rigid rotor heavy - load unmanned aerial vehicle; (i = 1, 2, 3, 4) represents the lift of the i - th horizontal attitude control small propeller 4, (i = 1, 2, 3, 4) represents the thrust of the i - th vertical yaw control small propeller 5 on the left side; (i = 1, 2, 3, 4) represents the thrust of the i - th vertical yaw control small propeller 5 on the right side;

[0057] Step 2, sensor data acquisition: The inertial measurement unit is used to measure the three - axis attitude angles of the tandem rigid rotor heavy - load unmanned aerial vehicle in real - time, that is, the angle information, angular velocity information and acceleration information of the pitch angle, roll angle and yaw angle, and the position and velocity information of the tandem rigid rotor heavy - load unmanned aerial vehicle through GPS or other monitoring and positioning devices, so as to obtain the actual state information;

[0058] Step 3, control instruction calculation: The main control chip calculates whether there is an error between the actual state information and the preset desired state information. If there is an error, through PID (Proportional - Integral - Derivative) or other advanced control algorithms (such as LQR, sliding - mode control, etc.), calculate the total lift, pitch moment, roll moment and yaw moment required for each control channel. Specifically, calculate the total lift required for the front main rotor 2 and the rear main rotor 3 through (T f +T r ), calculate the pitch moment required for the front main rotor 2 and the rear main rotor 3 through (T r -T f )·d1, calculate the roll moment required for the horizontal attitude control small propeller 4 through , calculate the auxiliary pitch moment required for the horizontal attitude control small propeller 4 through , calculate the thrust difference required for the vertical yaw control small propeller 5 through , calculate the thrust difference required for the vertical yaw control small propeller 5 through Calculate the yaw moment required for the vertical yaw control small propeller 5. The electronic speed controller module accurately controls the rotational speeds of the main rotor drive motor 21, the horizontal drive motor 41, and the vertical drive motor 51 according to the total lift, pitch moment, roll moment, and yaw moment obtained above, respectively, so as to adjust the thrusts of the front main rotor 2, the rear main rotor 3, the horizontal attitude control small propeller 4, and the vertical yaw control small propeller 5, respectively, and then execute Step 2 again; if there is no error, execute Step 2 again; the above process constitutes a closed-loop feedback control, continuously adjusting the motor output according to the sensor information, so that the tandem rigid rotor heavy-load unmanned aerial vehicle of the present invention can stably track the desired attitude and trajectory, resist external interference, and achieve decoupled control of the three-axis attitude and position.

[0059] The structure and working principle of the present invention will be further described below:

[0060] The purpose of the present invention is to provide a tandem rigid rotor heavy-load unmanned aerial vehicle. When using this device, under the condition of ensuring the same rotational speed of the main rotor drive motor 21, the rotational speeds of the front main rotor 2 and the rear main rotor 3 are adjusted to dynamically adjust the total lift and achieve altitude control; by independently adjusting the motor rotational speeds of the main rotor drive motor 21 of the front main rotor 2 and the rear main rotor 3, the pitch moment is dynamically adjusted to balance the center-of-gravity movement generated during the material transportation process of the unmanned aerial vehicle; by independently adjusting the horizontal drive motor 41 to control the thrust of the horizontal attitude control small propeller 4, the roll control moment and the auxiliary pitch moment are generated according to the roll and pitch requirements; by independently adjusting the vertical drive motor 51 to control the thrust of the vertical yaw control small propeller 5, the yaw control moment is generated; the rotational speeds of the front main rotor 2 and the rear main rotor 3, the pitch moment, the roll control moment, the auxiliary pitch moment, and the yaw control moment are transmitted to the controller system, and the controller system calculates and outputs motor control commands to achieve closed-loop feedback control of the three-axis attitude and position.

[0061] The present invention proposes a brand-new tandem rigid rotor heavy-load unmanned aerial vehicle. Its core idea is to inherit the advantages of the tandem layout and large-size rotors: two rigid main rotors are used in the front and rear to generate the main lift, ensuring high load capacity and relatively high potential for energy efficiency. At the same time, the rigid blades simplify the main rotor structure and reduce costs; the control concept of multi-rotors is introduced for optimization: multiple groups of auxiliary electric small propellers are innovatively added to be specifically responsible for the attitude control and yaw control of the unmanned aerial vehicle.

[0062] The unmanned aerial vehicle of the present invention uses a tandem rigid main rotor system to achieve lift, and uses multiple auxiliary electric small propellers to achieve attitude and yaw control. The two main rotors are arranged along the longitudinal axis of the fuselage and rotate in opposite directions. The two main rotors are independently driven to adjust the total lift and pitch moment. Four horizontal attitude control small propellers 4 are installed at the four corners of the fuselage for roll control and pitch fine-tuning. Four vertical yaw control small propellers 5 are symmetrically distributed on both sides of the middle section of the fuselage 1 to generate yaw moment. The controller system integrates an inertial measurement sensor and an electronic speed controller to construct a closed-loop feedback control. This structure uses two rigid large propellers as the main rotors to generate the main lift, and uses the surrounding small propellers to generate attitude control. It not only gives full play to the load capacity and energy efficiency of the large propellers, but also gives play to the simple structure and low cost of the rigid propellers. It is equivalent to a composite model of a helicopter and a multi-rotor, combining the advantages of both and overcoming the disadvantages of both.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tandem rigid rotor heavy-load unmanned aerial vehicle, characterized in that It includes a fuselage (1). Horizontal attitude control small propellers (4) are respectively installed at the front and rear ends of the fuselage (1) for roll control and pitch fine-tuning. A front main rotor (2) is installed at the front side of the top of the fuselage (1), and a rear main rotor (3) is installed at the rear side of the top of the fuselage (1). The front main rotor (2) and the rear main rotor (3) are used to generate lift and adjust the pitch moment. A plurality of vertical yaw control small propellers (5) are installed at the bottom of the fuselage (1) for generating yaw control torque; drive systems are installed on the horizontal attitude control small propellers (4), the front main rotor (2), the rear main rotor (3) and the vertical yaw control small propellers (5). A controller system is also installed at the top of the fuselage (1) for constructing a closed-loop feedback control architecture, and the controller system is connected to the drive systems.

2. The tandem rigid rotor heavy-load unmanned aerial vehicle according to claim 1, wherein The drive system includes a horizontal drive motor (41) installed on the horizontal attitude control small propeller (4), main rotor drive motors (21) respectively installed on the front main rotor (2) and the rear main rotor (3), and a vertical drive motor (51) installed on one side of the vertical yaw control small propeller (5). The horizontal drive motor (41), the main rotor drive motors (21) and the vertical drive motor (51) are all connected to the controller system; The controller system includes an aircraft control circuit board (6), and the aircraft control circuit board (6) is connected with a battery (61); a main control chip is installed on the aircraft control circuit board (6). The main control chip is respectively connected with an electronic speed controller module and an inertial measurement unit. The electronic speed controller module is respectively connected with the horizontal drive motor (41), the main rotor drive motors (21) and the vertical drive motor (51); the electronic speed controller module is connected with the battery (61).

3. The tandem rigid rotor heavy-load unmanned aerial vehicle according to claim 1, characterized in that, The front main rotor (2) and the rear main rotor (3) are symmetrically arranged. The diameters and airfoils of the front main rotor (2) and the rear main rotor (3) are the same, and the rotation directions are opposite. They are both rigid rotors.

4. The tandem rigid rotor heavy-load unmanned aerial vehicle according to claim 1, wherein, The relationship between the distance d1 between the front main rotor (2) and the rear main rotor (3) and the total length d2 of the fuselage (1) is: d1 = 0.5d2.

5. The tandem rigid rotor heavy-load unmanned aerial vehicle according to claim 1, wherein The axis of the horizontal attitude control small propeller (4) is arranged parallel to the plane of the fuselage (1), and the thrust direction of the horizontal attitude control small propeller (4) is perpendicular to the transverse axis of the fuselage (1).

6. The tandem rigid rotor heavy-load unmanned aerial vehicle according to claim 1, wherein, The plurality of vertical yaw control small propellers (5) are symmetrically arranged. The thrust direction of the vertical yaw control small propellers (5) is perpendicular to the longitudinal axis of the fuselage (1). The distance relationship between the vertical distance h1 from the axis of the vertical yaw control small propeller (5) to the rotation center and the height h2 of the fuselage (1) is: h1 = (0.2 - 0.25)h2.

7. A control method for a tandem rigid rotor heavy-load unmanned aerial vehicle, characterized in that, For a tandem rigid rotor heavy-load unmanned aircraft according to any one of claims 1 - 6, it includes the following steps: S1, according to the dynamic analysis of the aircraft, obtain the dynamic models in six degrees of freedom; S2, through the controller system, real-time measure the pitch angle, roll angle and yaw angle information of the unmanned aircraft, as well as the position and speed information of the unmanned aircraft, to obtain the actual state information; S3. Calculate whether there is an error between the actual state information and the preset desired state information through the controller system. If there is an error, calculate the required total lift force, pitch moment, roll moment, auxiliary pitch moment, and yaw moment according to the dynamic model. Then, through the controller system, control the drive system to adjust the thrust of the front main rotor (2), rear main rotor (3), horizontal attitude control small propeller (4), and vertical yaw control small propeller (5) respectively according to the required total lift force, pitch moment, roll moment, and yaw moment, and execute S2 again. If there is no error, execute S2 again.

8. The control method of a tandem rigid rotor heavy-load unmanned aerial vehicle according to claim 7, characterized in that, The dynamic models in the six degrees of freedom specifically include the following formulas: Wherein, m represents the total mass of the unmanned aerial vehicle; x represents the displacement of the unmanned aerial vehicle in the forward direction; y represents the displacement of the unmanned aerial vehicle in the left - right direction; z represents the displacement of the unmanned aerial vehicle in the up - down direction; represents the acceleration in the forward direction of the unmanned aerial vehicle; represents the acceleration in the left - right direction of the unmanned aerial vehicle; represents the acceleration in the height direction of the unmanned aerial vehicle; T f represents the lift of the front main rotor (2); T r represents the lift of the rear main rotor (3); D x represents the longitudinal aerodynamic drag; D y represents the lateral aerodynamic drag; D z represents the vertical aerodynamic drag; θ represents the pitch angle; φ represents the roll angle; ψ represents the yaw angle; represents the angular velocity of the pitch angle; represents the angular velocity of the roll angle; represents the angular velocity of the yaw angle; represents the acceleration of the pitch angle; represents the acceleration of the roll angle; represents the acceleration of the yaw angle; g represents the local acceleration of gravity; I x represents the moment of inertia of the unmanned aerial vehicle about the x - axis; I y represents the moment of inertia of the unmanned aerial vehicle about the y - axis; I z represents the moment of inertia of the unmanned aerial vehicle about the z - axis; d1 represents the distance between the front main rotor (2) and the rear main rotor (3); l represents the horizontal distance from the horizontal attitude control small propeller (4) to the center of mass; h1 represents the vertical distance from the axis of the vertical yaw control small propeller (5) to the rotation center; C p represents the damping coefficient of the roll of the unmanned aerial vehicle; C q represents the damping coefficient of the yaw of the unmanned aerial vehicle; C r represents the damping coefficient of the pitch of the unmanned aerial vehicle; represents the lift of the i - th horizontal attitude control small propeller (4), i = 1, 2, 3, 4; represents the thrust of the i - th vertical yaw control small propeller (5) on the left side, i = 1, 2, 3, 4; represents the thrust of the i - th vertical yaw control small propeller (5) on the right side, i = 1, 2, 3, 4.

9. The control method of a tandem rigid rotor heavy-load unmanned aerial vehicle according to claim 8, characterized in that The controller system includes an aircraft control circuit board (8), and the aircraft control circuit board (8) is connected to a battery (81); the aircraft control circuit board (8) includes a main control chip, which is respectively connected to an electronic speed controller module and an inertial measurement unit. The electronic speed controller module is respectively connected to a horizontal drive motor (41), a main rotor drive motor (21), and a vertical drive motor (51); the electronic speed controller module is connected to the battery (81). The specific content of S2 includes: Real-time measure the angle information, angular velocity information, and acceleration information of the pitch angle, roll angle, and yaw angle of the unmanned aircraft, as well as the position and speed information of the unmanned aircraft through the inertial measurement unit to obtain the actual state information.

10. The control method of a tandem rigid rotor heavy-load unmanned aerial vehicle according to claim 9, characterized in that, The specific content of S3 includes: The main control chip calculates whether there is an error between the actual state information and the preset desired state information. If there is an error, then through (T f +T r ) calculate the total lift required for the front main rotor (2) and the rear main rotor (3). Through (T r -T f )·d1 calculate the pitching moment required for the front main rotor (2) and the rear main rotor (3). Through calculate the roll moment required for the horizontal attitude control small paddle (4). Through calculate the auxiliary pitching moment required for the horizontal attitude control small paddle (4). Through calculate the thrust difference required for the vertical yaw control small paddle (5). Through calculate the yaw moment required for the vertical yaw control small paddle (5). The drive system is controlled by the electronic speed controller module to adjust the thrusts of the front main rotor (2), the rear main rotor (3), the horizontal attitude control small paddle (4) and the vertical yaw control small paddle (5) respectively, and S2 is executed again; If there is no error, execute S2 again.

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