Rotor tension distribution method, system, and aircraft

Abstract

The application provides a rotor tension distribution method and system and an aircraft, and relates to the technical field of unmanned aerial vehicle control. The method comprises the following steps: obtaining an operation efficiency characteristic model of an upper rotor motor and a lower rotor motor, and a rotor load characteristic model of an upper rotor and a lower rotor; based on the rotor load characteristic model, a first corresponding relationship between the upper rotor torque and the upper rotor speed is established, a second corresponding relationship between the lower rotor torque, the upper rotor speed and the lower rotor speed is established, and a system total power loss function with the upper rotor speed and the lower rotor speed as variables is established; under the operation constraint condition of the current total arm tension demand, the optimal working point of the upper rotor speed and the lower rotor speed is determined by taking the minimized output value of the system total power loss function as the target, and the upper rotor motor and the lower rotor motor are controlled to operate. The method realizes efficient distribution of the upper and lower rotor tensions, can significantly reduce the system power loss, and improves the operation efficiency of the motor and the controller.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) control technology, and in particular to a rotor thrust distribution method, system, and aircraft. Background Technology

[0002] Multi-rotor drones are a common type of unmanned aerial vehicle (UAV) with advantages such as high stability and flexible operation. They are an important component and application platform for the low-altitude economy. Electric multi-rotor coaxial rotor UAVs have two motors with rotors on each arm. Compared to a single-axis, single-rotor structure, coaxial rotors can provide a larger payload at a lower speed, offering significant advantages.

[0003] Existing technologies typically reference a coaxial rotor torque self-balancing aerodynamic layout, where the upper and lower rotors on the same axis rotate in opposite directions at the same speed to achieve torque cancellation on the current rotor shaft. In this type of control strategy, due to the impact of the upper rotor's contraction wake, the thrust generated by the lower rotor is less than the thrust it would generate independently. Furthermore, the overall operating efficiency of the upper and lower motors is not optimal, leaving room for optimization in system power loss. Significant power loss leads to higher motor temperatures and higher junction temperatures of the controller's power devices, directly impacting system performance and lifespan. Summary of the Invention

[0004] This invention provides a rotor thrust distribution method, system, and aircraft to solve the defects in the rotor thrust distribution of existing multi-rotor coaxial dual-propeller UAVs, which result in the upper and lower motors not being at their optimal overall operating efficiency and the system power loss not being at its lowest.

[0005] This invention provides a rotor thrust distribution method, comprising: Obtain the operating efficiency characteristic models of the upper rotor motor and the lower rotor motor, as well as the rotor load characteristic models of the upper rotor and the lower rotor. Based on the rotor load characteristic model, a first correspondence between the upper rotor torque and the upper rotor speed is established, and a second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed is established. Based on the operating efficiency characteristic model, the first correspondence and the second correspondence, a system total power loss function is established with the upper rotor speed and the lower rotor speed as variables; Under the operational constraints of the current total arm pull requirement, the optimal operating points of the upper rotor speed and the lower rotor speed are determined with the goal of minimizing the output value of the total power loss function of the system. Based on the optimal operating point, control the operation of the upper rotor motor and the lower rotor motor.

[0006] According to a rotor thrust distribution method provided by the present invention, establishing a first correspondence between the upper rotor torque and the upper rotor speed includes: The upper rotor torque coefficient is set to a constant value; Based on the relationship between the upper rotor torque coefficient and the square of the upper rotor speed, a first correspondence is established.

[0007] According to a rotor thrust distribution method provided by the present invention, establishing a second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed includes: The lower rotor torque coefficient is determined to be a function of the upper rotor speed; A second correspondence is established based on the relationship between the lower rotor torque coefficient and the square of the lower rotor speed.

[0008] According to the rotor thrust distribution method provided by the present invention, the operating efficiency characteristic model is an efficiency MAP diagram of the motor and drive system on the torque-speed plane; The establishment of the system total power loss function with the upper rotor speed and the lower rotor speed as variables includes: Based on the efficiency MAP, determine the efficiency value of the upper rotor motor at a given speed and torque, and the efficiency value of the lower rotor motor at a given speed. According to the first correspondence, the upper rotor torque is determined by the upper rotor speed, and the upper rotor output power is obtained by combining the upper rotor speed; according to the second correspondence, the lower rotor torque is determined by the upper rotor speed and the lower rotor speed, and the lower rotor output power is obtained by combining the lower rotor speed. Based on the output power and corresponding efficiency value of the upper rotor, the power loss of the upper rotor is determined; based on the output power and corresponding efficiency value of the lower rotor, the power loss of the lower rotor is determined; the sum of the power loss of the upper rotor and the power loss of the lower rotor is used as the total power loss function of the system.

[0009] According to a rotor thrust distribution method provided by the present invention, the output power of the upper rotor is determined by the product of the upper rotor torque and the upper rotor speed, and the upper rotor torque is obtained by converting the upper rotor thrust through a torque coefficient; The output power of the lower rotor is determined by the product of the lower rotor torque and the lower rotor speed. The lower rotor torque is obtained by converting the lower rotor thrust through a torque coefficient, and the lower rotor torque coefficient is a function of the upper rotor speed.

[0010] According to a rotor thrust distribution method provided by the present invention, the operating constraints further include at least one of the following: the upper rotor thrust does not exceed the maximum upper rotor thrust, the lower rotor thrust does not exceed the maximum lower rotor thrust, the upper rotor torque does not exceed the maximum upper rotor torque, and the lower rotor torque does not exceed the maximum lower rotor torque; Determining the optimal operating points for the upper rotor speed and the lower rotor speed includes: Under the stated operating constraints, an optimization problem is constructed with the objective of minimizing the output value of the total power loss function of the system. Solving the optimization problem yields the optimal operating points for the upper rotor speed and the lower rotor speed.

[0011] According to a rotor thrust distribution method provided by the present invention, solving the optimization problem includes: Solve using mathematical programming methods; or, The optimal operating point is obtained by looking up a pre-built speed-loss lookup table.

[0012] According to a rotor thrust distribution method provided by the present invention, before determining the optimal operating points of the upper rotor speed and the lower rotor speed, the method further includes: When the rate of change of throttle command exceeds a preset threshold, or when the current total pull demand of the arm exceeds the sum of the maximum pull of the upper rotor and the lower rotor, the upper rotor motor and the lower rotor motor are controlled to run at the maximum allowable speed and output the maximum pull. When the rate of change of throttle command is less than or equal to a preset threshold, and the current total thrust requirement of the boom is less than or equal to the sum of the maximum thrust of the upper and lower rotors, the optimal operating points of the upper rotor speed and the lower rotor speed are determined.

[0013] The present invention also provides a rotor thrust distribution system, comprising: The acquisition module is used to acquire the operating efficiency characteristic models of the upper rotor motor and the lower rotor motor, as well as the rotor load characteristic models of the upper rotor and the lower rotor. A module is established to establish a first correspondence between the upper rotor torque and the upper rotor speed based on the rotor load characteristic model, and to establish a second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed; based on the operating efficiency characteristic model, the first correspondence and the second correspondence, a system total power loss function is established with the upper rotor speed and the lower rotor speed as variables. The determination module is used to determine the optimal operating points of the upper rotor speed and the lower rotor speed under the operating constraints of the current total arm pull demand, with the goal of minimizing the output value of the total power loss function of the system; The control module is used to control the operation of the upper rotor motor and the lower rotor motor according to the optimal operating point.

[0014] The present invention also provides an aircraft that applies the rotor thrust distribution method as described in any of the preceding claims, or includes the rotor thrust distribution system as described in the preceding claims.

[0015] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the rotor thrust distribution method as described above.

[0016] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the rotor thrust distribution method as described above.

[0017] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the rotor thrust distribution method as described above.

[0018] This invention provides a rotor thrust distribution method, system, and aircraft. By transforming the thrust distribution problem into a rotational speed optimization problem and fully considering the coupling characteristics of the lower rotor thrust being affected by the upper rotor rotational speed, a total system power loss function with rotational speed as the variable is established. Under the operational constraints such as meeting the total thrust requirement, the optimal rotational speed operating point is solved with the goal of minimizing power loss, thereby achieving efficient distribution of upper and lower rotor thrust. This significantly reduces system power loss, improves the operating efficiency of motors and controllers, extends equipment lifespan, and enhances the reliability and economy of the UAV power system. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of the rotor thrust distribution method provided by the present invention; Figure 2 This is a schematic diagram of the process for determining the corresponding rotational speed operating point by force distribution provided by the present invention; Figure 3 This is a schematic diagram of the rotor thrust distribution system provided by the present invention; Figure 4 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0022] Figure 1 This is a schematic flowchart of the rotor thrust distribution method provided by the present invention.

[0023] like Figure 1 As shown, this embodiment provides a rotor thrust distribution method applied to a multi-rotor coaxial dual-propeller UAV. By transforming the coaxial dual-propeller thrust distribution problem into a rotational speed optimization problem, the method minimizes system power loss while meeting the total thrust requirements. The method mainly includes the following steps: 101. Obtain the operating efficiency characteristic models of the upper rotor motor and the lower rotor motor, as well as the rotor load characteristic models of the upper rotor and the lower rotor.

[0024] Specifically, the operating efficiency characteristic model is typically described using an efficiency map (MAP) of the motor and its drive system. This MAP reflects the efficiency distribution of the motor under different torques and speeds, and can be obtained through bench experiments or simulations. The rotor load characteristic model describes the physical relationship between the thrust, torque, and speed generated by the rotor during rotation, and can be derived through aerodynamic theory or calibrated through wind tunnel experiments. The operating efficiency characteristic model is used to accurately characterize the variation of motor and drive system efficiency with torque and speed. The rotor load characteristic model is used to clarify the correlation between rotor thrust, torque, and other parameters and speed.

[0025] 102. Based on the rotor load characteristic model, establish the first correspondence between the upper rotor torque and the upper rotor speed, and establish the second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed.

[0026] Specifically, based on the rotor load characteristic model, a first correspondence between the upper rotor torque and the upper rotor speed is established, as well as a second correspondence between the lower rotor torque and the upper and lower rotor speeds. The first correspondence reflects the independent aerodynamic characteristics of the upper rotor without interference, while the second correspondence fully considers the coupling characteristics of the lower rotor being impacted by the upper rotor wake, clarifying the quantitative relationship between torque and speed, providing a variable basis for constructing the power loss function, and fundamentally solving the defect of ignoring aerodynamic coupling in speed control.

[0027] 103. Based on the operating efficiency characteristic model, the first correspondence and the second correspondence, establish the system total power loss function with the upper rotor speed and the lower rotor speed as variables.

[0028] Specifically, based on the operating efficiency characteristic model and the first and second correspondences, a system total power loss function is established with the upper rotor speed and lower rotor speed as variables. This system total power loss function integrates the power loss of the dual-rotor system into a mathematical model with rotational speed as the sole variable, transforming the complex thrust distribution problem into a simple rotational speed optimization problem. This achieves a precise quantitative representation of the system's total loss, providing a clear objective for finding the optimal operating point.

[0029] 104. Under the current operational constraints of the total thrust requirement of the boom, determine the optimal operating points of the upper rotor speed and the lower rotor speed with the goal of minimizing the output value of the total power loss function of the system.

[0030] Specifically, under the operational constraints of the current total thrust requirement of the boom, the optimal operating points of the upper and lower rotor speeds are obtained by minimizing the output value of the total system power loss function. While meeting the thrust requirements of the UAV flight, the combination of speeds with minimal losses is found, significantly reducing the power loss of the motors and controllers. This avoids problems such as motor temperature rise and excessively high junction temperatures of controller power devices caused by high losses, effectively improving system performance and lifespan.

[0031] 105. Control the operation of the upper rotor motor and the lower rotor motor according to the optimal operating point.

[0032] Specifically, based on the optimal operating point, the upper and lower rotor motors are controlled to operate stably at optimal speeds. This allows the dual rotors to distribute thrust output power in the optimal ratio, significantly improving the overall system efficiency, extending the service life of the motors and controllers, enhancing the reliability and economy of the UAV's power system, and adapting to the needs of low-altitude, economical, long-duration operations.

[0033] Furthermore, based on the above embodiments, this embodiment establishes a first correspondence between the upper rotor torque and the upper rotor speed, including: determining the upper rotor torque coefficient as a constant value; and establishing the first correspondence based on the square relationship between the upper rotor torque coefficient and the upper rotor speed.

[0034] Specifically, in a coaxial twin-rotor system, the upper rotor is located upstream of the airflow, and the aerodynamic model is not affected by the lower rotor. The inflow distribution completely conforms to the standard single-rotor model. Therefore, the torque coefficient of the upper rotor is determined to be a constant value, completely eliminating the aerodynamic interference of the lower rotor and ensuring the stability and consistency of the first correspondence.

[0035] Based on the relationship between the upper rotor torque coefficient and the square of the upper rotor speed, a first correspondence is established. The upper rotor thrust is directly proportional to the square of the speed. The mathematical form of this correspondence is simple and the calculation response is fast. The corresponding thrust can be quickly calculated directly from the upper rotor speed, providing a direct and accurate basis for subsequent power calculations and improving the real-time performance of the control algorithm.

[0036] The mathematical expression of the first correspondence is (1): (1) in, Indicates the rotor torque; This represents the upper rotor torque coefficient, which is a constant value. Indicates atmospheric density; Indicates the rotational speed of the upper rotor; Indicates the rotor diameter.

[0037] By combining constant coefficients with square relationships, the calculation of upper rotor torque is free of redundant errors, improving the accuracy and convenience of upper rotor torque calculation and laying the foundation for optimizing the overall system efficiency.

[0038] Furthermore, based on the above embodiments, this embodiment establishes a second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed, including: determining the lower rotor torque coefficient as a function based on the upper rotor speed; and establishing the second correspondence based on the square relationship between the lower rotor torque coefficient and the lower rotor speed.

[0039] Specifically, the lower rotor is located below the upper rotor and will be continuously impacted by the contraction wake of the upper rotor. Its inflow distribution is directly affected by the inflow velocity induced by the upper rotor. Therefore, the torque coefficient of the lower rotor is no longer a constant value, but a function of the rotational speed of the upper rotor, which accurately reflects the aerodynamic coupling characteristics of the upper and lower rotors and avoids the deviation in thrust calculation caused by ignoring the influence of the wake.

[0040] Based on the relationship between the lower rotor torque coefficient and the square of the lower rotor speed, a second correspondence is established. The lower rotor torque is simultaneously affected by both its own speed and the upper rotor speed, fully reflecting the actual aerodynamic load characteristics of the lower rotor. This ensures that the thrust calculation results are highly consistent with actual operating conditions, providing real data support for power loss optimization.

[0041] The mathematical expression of the second correspondence is (2): (2) in, Indicates the torque of the lower rotor; The lower rotor torque coefficient represents the variation of the upper rotor speed with respect to the upper rotor speed. Indicates atmospheric density; Indicates the rotational speed of the lower rotor; Indicates the rotor diameter.

[0042] By fully considering the aerodynamic coupling effect, the thrust distribution of the lower rotor is made more realistic, fully restoring the actual aerodynamic conditions of the lower rotor and further improving the overall operating efficiency of the system.

[0043] Furthermore, based on the above embodiments, the operating efficiency characteristic model in this embodiment is an efficiency MAP diagram of the motor and drive system on the torque-speed plane; a total system power loss function is established with the upper rotor speed and lower rotor speed as variables, including: determining the efficiency value of the upper rotor motor at a given speed and torque and the efficiency value of the lower rotor motor at a given speed according to the efficiency MAP diagram; determining the upper rotor torque from the upper rotor speed according to the first correspondence relationship, and obtaining the upper rotor output power by combining the upper rotor speed; determining the lower rotor torque from the upper rotor speed and lower rotor speed according to the second correspondence relationship, and obtaining the lower rotor output power by combining the lower rotor speed; determining the upper rotor power loss based on the upper rotor output power and the corresponding efficiency value; determining the lower rotor power loss based on the lower rotor output power and the corresponding efficiency value; and using the sum of the upper rotor power loss and the lower rotor power loss as the total system power loss function.

[0044] Specifically, the operating efficiency characteristic model is a MAP (Motor-Driven System) diagram of the motor and drive system on the torque-speed plane. This MAP diagram is obtained through experimental testing or simulation calibration, accurately characterizing the motor's operating efficiency under different torques and speeds. It is the core basis for calculating power losses, ensuring that the loss calculation results closely match the actual operating state of the motor. Based on the efficiency MAP diagram, the efficiency values ​​of the upper rotor motor and the lower rotor motor at a given speed are directly determined, quickly obtaining the efficiency parameters of the motor's current operating state, ensuring the accuracy and real-time performance of the loss calculation.

[0045] According to the first correspondence, the upper rotor torque is determined by the upper rotor speed, and the upper rotor output power is obtained by combining the upper rotor speed; according to the second correspondence, the lower rotor torque is determined by the upper rotor speed and the lower rotor speed, and the lower rotor output power is obtained by combining the lower rotor speed. The output power serves as the basic parameter for calculating power loss and provides core data for constructing the loss function. The rotor output power calculation formula is (3): (3) in, Indicates the rotor output power; Indicates the power factor; Indicates atmospheric density; Indicates the rotor speed; This indicates the rotor diameter. It should be noted that the rotor output power is physically equivalent to the product of the rotor torque and the rotor speed, where the rotor torque can be calculated from the rotor thrust using a torque coefficient.

[0046] Based on the output power and corresponding efficiency value of the upper rotor, the power loss of the upper rotor is calculated; based on the output power and corresponding efficiency value of the lower rotor, the power loss of the lower rotor is calculated; the sum of the power losses of the upper and lower rotors is used as the total power loss function of the system. This function directly quantifies the total loss of the dual-rotor system, providing a precise quantitative basis for solving the optimal operating point. As shown in formula (4): (4) in, Indicates power loss. Indicates the rotor output power; This indicates the operating efficiency of the motor and drive system.

[0047] In a coaxial twin-rotor system, the aerodynamic model of the upper rotor can be considered unaffected by the lower rotor, and its inflow distribution can be given according to a single-rotor model. Therefore, its torque coefficient can be considered a constant value. According to the rotor torque calculation formula, the upper rotor has a unique torque corresponding to different rotational speeds. Therefore, combined with the MAP diagram, its operating efficiency can be considered a univariate function with rotational speed as the variable. Efficiency can be expressed as (5): (5) in, This represents the functional mapping relationship between the operating efficiency of the upper rotor and the rotational speed of the upper rotor.

[0048] In a coaxial twin-rotor system, the lower rotor is affected by the wake of the upper rotor, and its torque coefficient is no longer considered constant, but rather related to the induced inflow velocity generated by the upper rotor. Therefore, the output thrust and torque of the lower rotor can be considered to depend on the rotational speed of the upper rotor and its own rotational speed. Thus, an efficiency function with the rotational speeds of both the upper and lower rotors can be established using its MAP diagram and the thrust corresponding to different upper rotor speeds. It can be represented as (6): (6) in, This represents the functional mapping relationship between the operating efficiency of the lower rotor and the rotational speeds of the upper and lower rotors.

[0049] For a coaxial twin-propeller system, the total system loss is calculated as (7) depending on whether the two motors work simultaneously or individually: (7) in, It is the output power of the upper rotor motor, which is determined by the product of the upper rotor torque and the upper rotor speed. The upper rotor torque is then calculated from the upper rotor thrust through the torque coefficient. It is the output power of the lower rotor motor, which is determined by the product of the lower rotor torque and the lower rotor speed. The lower rotor torque is obtained by converting the lower rotor thrust through the torque coefficient, and the lower rotor torque coefficient is a function of the upper rotor speed.

[0050] Furthermore, based on the above embodiments, in this embodiment, the output power of the upper rotor is determined by the product of the upper rotor torque and the upper rotor speed, and the upper rotor torque is obtained by converting the upper rotor thrust through a torque coefficient; the output power of the lower rotor is determined by the product of the lower rotor torque and the lower rotor speed, and the lower rotor torque is obtained by converting the lower rotor thrust through a torque coefficient, and the lower rotor torque coefficient is a function of the upper rotor speed.

[0051] Specifically, the upper rotor output power is determined by the product of the upper rotor torque and the upper rotor speed. The upper rotor torque is calculated from the upper rotor thrust through a torque coefficient. The upper rotor torque coefficient is a constant value, and the conversion relationship is stable and without deviation, allowing for accurate calculation of the upper rotor output power and ensuring the accuracy of the upper rotor loss calculation.

[0052] The output power of the lower rotor is determined by the product of the lower rotor torque and the lower rotor speed. The lower rotor torque is calculated from the lower rotor thrust through a torque coefficient, which is a function of the upper rotor speed. This setting perfectly matches the actual aerodynamic characteristics of the lower rotor affected by the wake, ensuring undistorted lower rotor power calculations and further improving the accuracy of system loss calculations.

[0053] Furthermore, based on the above embodiments, the operating constraints in this embodiment also include at least one of the following: the upper rotor thrust does not exceed the maximum upper rotor thrust, the lower rotor thrust does not exceed the maximum lower rotor thrust, the upper rotor torque does not exceed the maximum upper rotor torque, and the lower rotor torque does not exceed the maximum lower rotor torque; determining the optimal operating points of the upper rotor speed and the lower rotor speed includes: under the operating constraints, constructing an optimization problem with the objective of minimizing the output value of the total power loss function of the system; solving the optimization problem to obtain the optimal operating points of the upper rotor speed and the lower rotor speed.

[0054] Specifically, in addition to the current total thrust requirement of the boom, the operating constraints also include: the upper rotor thrust not exceeding the maximum upper rotor thrust, the lower rotor thrust not exceeding the maximum lower rotor thrust, the upper rotor torque not exceeding the maximum upper rotor torque, and the lower rotor torque not exceeding the maximum lower rotor torque. These multiple constraints comprehensively ensure that the rotors and motors do not operate under overload or over-torque conditions, protecting equipment safety from a hardware perspective and preventing overload damage.

[0055] Tension calculation formula: (8) (9) in, , These represent the upper rotor thrust and the lower rotor thrust, respectively. This represents the upper rotor thrust coefficient, which is a constant value; The lower rotor thrust coefficient represents the variation of the upper rotor speed with the upper rotor speed; Indicates atmospheric density; 、 These represent the rotational speeds of the upper and lower rotors, respectively. Indicates the rotor diameter.

[0056] Under all the above operational constraints, an optimization problem is constructed with the objective of minimizing the output value of the total system power loss function. This problem combines practical engineering constraints with efficiency optimization objectives, ensuring that the solution meets both efficiency requirements and is suitable for the actual flight conditions of the UAV. Solving this constrained optimization problem yields the optimal operating points for the upper and lower rotor speeds, minimizing power loss within safety constraints while balancing system efficiency and equipment reliability, and extending the lifespan of the power system. The following thrust distribution strategy is established to determine the operating point. This is used to achieve the operating goal of minimizing power loss and optimizing motor efficiency.

[0057] (1) Stretch limit: The output thrust of the upper and lower rotors must meet the total thrust requirement of the arm and must not exceed the upper limit of the thrust that the rotor can provide, as shown in formula (10): (10) in, , These correspond to the output thrust of the upper and lower rotors, respectively. , These correspond to the maximum output thrust of the upper and lower rotors, respectively. It is the total pulling force requirement of the boom.

[0058] (2) Torque limiting, used to protect the motor, as shown in formula (11): (11) in, , These correspond to the upper rotor torque and the lower rotor torque, respectively. , These correspond to the maximum output torque of the upper and lower rotors, respectively.

[0059] When the throttle command change rate exceeds a preset threshold, or the current total arm pull demand exceeds the sum of the maximum pull of the upper and lower rotors, the upper rotor motor and the lower rotor motor are controlled to operate at their maximum allowable speeds to output maximum pull. Otherwise, when the throttle command change rate is less than or equal to the preset threshold, and the current total arm pull demand is less than or equal to the sum of the maximum pull of the upper and lower rotors, the optimal operating points of the upper rotor speed and the lower rotor speed are determined.

[0060] The flight control system monitors the flight status in real time. When the rate of change of throttle command exceeds a preset threshold, such as rapid acceleration, high load climb, or when the current total thrust demand of the arms exceeds the sum of the maximum thrust of the upper and lower rotors, it is immediately identified as an emergency condition. This quickly identifies special flight scenarios, ensuring that power response takes precedence over efficiency optimization. In emergency conditions, the flight control system directly controls both the upper and lower rotor motors to operate at their maximum permissible speeds, outputting maximum thrust to prioritize the UAV's emergency power needs, avoiding flight failures such as stall and crashes due to insufficient power, and ensuring flight safety. If the emergency condition is not met, the system then executes the steps to determine the optimal operating speed of the upper and lower rotors, achieving a perfect balance between emergency power assurance and conventional efficiency optimization. See formulas (12) and (13): (3) When the throttle input is a rapid acceleration command, or when the maximum thrust provided by the upper and lower rotors cannot meet the demand, both rotors will output maximum thrust: (12) (4) In other cases, the tension shall be distributed according to the strategy of minimizing power loss: (13) Furthermore, based on the above embodiments, solving the optimization problem in this embodiment includes: using mathematical programming methods to solve it; or, using a pre-constructed speed-loss lookup table to obtain the optimal operating point.

[0061] Specifically, mathematical programming methods are used to solve the problem analytically, employing linear and nonlinear programming algorithms. This approach offers high accuracy and precise results, making it suitable for UAV flight control scenarios with high precision requirements and ensuring the accuracy of the optimal operating point. The speed-loss lookup table method involves pre-constructing a speed-loss lookup table through simulation or experimentation. System loss values ​​for different speed combinations are pre-entered and stored, allowing for direct lookup of the table to obtain the optimal operating point during flight control. This method offers extremely fast response times, significantly reducing the computational burden on the flight controller and making it compatible with embedded flight control hardware with limited computing power. Both methods can quickly and accurately obtain the optimal speed operating point, meeting the real-time control needs of UAVs while improving the versatility of the methods.

[0062] By employing the method of this invention, the output thrust of the upper and lower rotors of the coaxial dual propeller can be rationally distributed with the goal of minimizing power loss. This allows the system to meet its total thrust requirements while ensuring good operating efficiency, thereby saving energy supply for the UAV power system, reducing the junction temperature of the power devices in the motor controller and the motor temperature, and improving the reliability of the UAV system.

[0063] Figure 2 This is a schematic diagram of the process for obtaining the corresponding rotational speed working point by force distribution provided by the present invention.

[0064] like Figure 2 As shown, in this embodiment, the process of performing thrust distribution and obtaining its corresponding speed operating point includes: marking the start of the upper / lower propeller speed traversal optimization process of the present invention. This process is used to find the optimal speed operating point that minimizes the total power loss of the system by traversing all candidate upper / lower propeller speed combinations under optimized operating conditions, providing a core basis for motor control.

[0065] The traversal index variable i for the propeller speed is initialized. The initial value is usually set to 1, which corresponds to the first candidate speed in the predefined discrete sequence of propeller speeds. This is used to traverse all candidate propeller speed values ​​in sequence.

[0066] Extract the i-th element from the pre-generated discrete sequence of propeller speeds as the candidate value of propeller speed in the current traversal cycle. This sequence is pre-calibrated and generated according to the rated speed range of the motor and the control accuracy requirements.

[0067] Determine if the current upper propeller speed index i does not exceed the maximum index of the upper propeller speed sequence. ,Right now ?, is the total length of the discrete sequence of upper propeller speed. If the judgment result is Y (yes): it means there are still untraversed upper propeller speed candidate values, and the lower propeller speed traversal stage is entered; if the judgment result is N (no): it means all upper propeller speed candidate values ​​have been traversed, and the process jumps to the optimal solution optimization stage and executes formula (12). .

[0068] The lower propeller speed traversal process is as follows: Under the current upper propeller speed candidate value, initialize the traversal index variable j of the lower propeller speed. The initial value is usually set to 1, corresponding to the first candidate speed in the predefined discrete sequence of lower propeller speeds, used to traverse all lower propeller speed candidate values ​​under the current upper propeller speed. Extract the j-th element from the pre-generated discrete sequence of lower propeller speeds as the lower propeller speed candidate value for the current traversal period. This sequence is also pre-calibrated and generated according to the motor's rated speed range and control accuracy requirements. Determine whether the current lower propeller speed index j does not exceed the maximum index of the lower propeller speed sequence. ,Right now ?, Let be the total length of the discrete sequence of lower propeller speeds. If the judgment result is Y (yes): it means there are still untraversed candidate values ​​for upper propeller speeds, and we enter the lower propeller speed traversal stage, i.e., j=j+1; if the judgment result is N (no), we enter the upper propeller speed traversal stage, i.e., i=i+1.

[0069] Based on the currently traversed candidate values ​​of the upper and lower propeller speeds, and combined with the method for calculating the total system power loss, the total system power loss corresponding to this speed combination is calculated. and the combination The corresponding loss value is stored in the traversal result set for subsequent optimization.

[0070] After the optimization process is completed, the optimal speed combination is output, including the optimal upper propeller speed and the optimal lower propeller speed. The flight control system will then control the operation of the upper / lower propeller motors based on this optimal speed combination to minimize the total power loss of the system and improve the efficiency and reliability of the UAV's power system.

[0071] Figure 3 This is a schematic diagram of the rotor thrust distribution system provided by the present invention.

[0072] like Figure 3 As shown, this embodiment provides a rotor thrust distribution system, including: The acquisition module 301 is used to acquire the operating efficiency characteristic models of the upper rotor motor and the lower rotor motor, as well as the rotor load characteristic models of the upper rotor and the lower rotor. Module 302 is established to establish a first correspondence between the upper rotor torque and the upper rotor speed based on the rotor load characteristic model, and to establish a second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed; based on the operating efficiency characteristic model, the first correspondence and the second correspondence, a system total power loss function with the upper rotor speed and the lower rotor speed as variables is established. The determination module 303 is used to determine the optimal operating points of the upper rotor speed and the lower rotor speed under the operating constraints of the current total arm pull demand, with the goal of minimizing the output value of the total system power loss function; The control module 304 is used to control the operation of the upper rotor motor and the lower rotor motor according to the optimal operating point.

[0073] This invention also protects an aircraft that applies the rotor thrust distribution method as described in any of the above embodiments, or includes a rotor thrust distribution system as described in the above embodiments. The aircraft includes multi-rotor coaxial rotor unmanned aerial vehicles (UAVs), etc.

[0074] Figure 4 This is a schematic diagram of the structure of the electronic device provided by the present invention.

[0075] like Figure 4As shown, the electronic device may include: a processor 410, a communications interface 420, a memory 430, and a communications bus 440, wherein the processor 410, the communications interface 420, and the memory 430 communicate with each other through the communications bus 440. The processor 410 can call logic instructions in the memory 430 to execute a rotor thrust distribution method. This method includes: acquiring operating efficiency characteristic models of the upper and lower rotor motors, and rotor load characteristic models of the upper and lower rotors; establishing a first correspondence between the upper rotor torque and the upper rotor speed based on the rotor load characteristic models, and establishing a second correspondence between the lower rotor torque and the upper and lower rotor speeds; establishing a system total power loss function with the upper rotor speed and the lower rotor speed as variables based on the operating efficiency characteristic models, the first correspondence, and the second correspondence; determining the optimal operating points of the upper rotor speed and the lower rotor speed under the current operating constraints of the total arm thrust demand, with the goal of minimizing the output value of the system total power loss function; and controlling the operation of the upper and lower rotor motors according to the optimal operating points.

[0076] Furthermore, the logical instructions in the aforementioned memory 430 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0077] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the rotor thrust distribution method provided by the above methods. The method includes: obtaining the operating efficiency characteristic model of the upper rotor motor and the lower rotor motor, and the rotor load characteristic model of the upper rotor and the lower rotor; establishing a first correspondence between the upper rotor torque and the upper rotor speed based on the rotor load characteristic model, and establishing a second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed; establishing a system total power loss function with the upper rotor speed and the lower rotor speed as variables based on the operating efficiency characteristic model, the first correspondence, and the second correspondence; determining the optimal operating point of the upper rotor speed and the lower rotor speed under the operating constraints of the current total thrust requirement of the boom, with the goal of minimizing the output value of the system total power loss function; and controlling the operation of the upper rotor motor and the lower rotor motor according to the optimal operating point.

[0078] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements the rotor thrust distribution method provided by the above methods. The method includes: acquiring the operating efficiency characteristic models of the upper rotor motor and the lower rotor motor, and the rotor load characteristic models of the upper rotor and the lower rotor; based on the rotor load characteristic models, establishing a first correspondence between the upper rotor torque and the upper rotor speed, and establishing a second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed; based on the operating efficiency characteristic models, the first correspondence, and the second correspondence, establishing a system total power loss function with the upper rotor speed and the lower rotor speed as variables; under the operating constraints of the current total thrust demand of the boom, determining the optimal operating points of the upper rotor speed and the lower rotor speed with the goal of minimizing the output value of the system total power loss function; and controlling the operation of the upper rotor motor and the lower rotor motor according to the optimal operating points.

[0079] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0080] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rotor thrust distribution method, characterized in that, include: Obtain the operating efficiency characteristic models of the upper rotor motor and the lower rotor motor, as well as the rotor load characteristic models of the upper rotor and the lower rotor. Based on the rotor load characteristic model, a first correspondence between the upper rotor torque and the upper rotor speed is established, and a second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed is established. Based on the operating efficiency characteristic model, the first correspondence and the second correspondence, a system total power loss function is established with the upper rotor speed and the lower rotor speed as variables; Under the operational constraints of the current total arm pull requirement, the optimal operating points of the upper rotor speed and the lower rotor speed are determined with the goal of minimizing the output value of the total power loss function of the system. Based on the optimal operating point, control the operation of the upper rotor motor and the lower rotor motor.

2. The rotor thrust distribution method according to claim 1, characterized in that, Establishing the first correspondence between the upper rotor torque and the upper rotor speed includes: The upper rotor torque coefficient is set to a constant value; Based on the relationship between the upper rotor torque coefficient and the square of the upper rotor speed, a first correspondence is established.

3. The rotor thrust distribution method according to claim 1, characterized in that, The establishment of the second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed includes: The lower rotor torque coefficient is determined to be a function of the upper rotor speed; A second correspondence is established based on the relationship between the lower rotor torque coefficient and the square of the lower rotor speed.

4. The rotor thrust distribution method according to claim 1, characterized in that, The operating efficiency characteristic model is a MAP diagram of the efficiency of the motor and drive system on the torque-speed plane. The establishment of the system total power loss function with the upper rotor speed and the lower rotor speed as variables includes: Based on the efficiency MAP, determine the efficiency value of the upper rotor motor at a given speed and torque, and the efficiency value of the lower rotor motor at a given speed. According to the first correspondence, the upper rotor torque is determined by the upper rotor speed, and the upper rotor output power is obtained by combining the upper rotor speed; according to the second correspondence, the lower rotor torque is determined by the upper rotor speed and the lower rotor speed, and the lower rotor output power is obtained by combining the lower rotor speed. Based on the output power and corresponding efficiency value of the upper rotor, the power loss of the upper rotor is determined; based on the output power and corresponding efficiency value of the lower rotor, the power loss of the lower rotor is determined; the sum of the power loss of the upper rotor and the power loss of the lower rotor is used as the total power loss function of the system.

5. The rotor thrust distribution method according to claim 4, characterized in that, The output power of the upper rotor is determined by the product of the upper rotor torque and the upper rotor speed, and the upper rotor torque is obtained by converting the upper rotor thrust through a torque coefficient; The output power of the lower rotor is determined by the product of the lower rotor torque and the lower rotor speed. The lower rotor torque is obtained by converting the lower rotor thrust through a torque coefficient, and the lower rotor torque coefficient is a function of the upper rotor speed.

6. The rotor thrust distribution method according to claim 1, characterized in that, The operational constraints also include at least one of the following: the upper rotor thrust does not exceed the maximum upper rotor thrust, the lower rotor thrust does not exceed the maximum lower rotor thrust, the upper rotor torque does not exceed the maximum upper rotor torque, and the lower rotor torque does not exceed the maximum lower rotor torque; Determining the optimal operating points for the upper rotor speed and the lower rotor speed includes: Under the stated operating constraints, an optimization problem is constructed with the objective of minimizing the output value of the total power loss function of the system. Solving the optimization problem yields the optimal operating points for the upper rotor speed and the lower rotor speed.

7. The rotor thrust distribution method according to claim 6, characterized in that, Solving the optimization problem includes: Solve using mathematical programming methods; or, The optimal operating point is obtained by looking up a pre-built speed-loss lookup table.

8. The rotor thrust distribution method according to claim 1, characterized in that, Before determining the optimal operating points for the upper rotor speed and the lower rotor speed, the method further includes: When the rate of change of throttle command exceeds a preset threshold, or when the current total pull demand of the arm exceeds the sum of the maximum pull of the upper rotor and the lower rotor, the upper rotor motor and the lower rotor motor are controlled to run at the maximum allowable speed and output the maximum pull. When the rate of change of throttle command is less than or equal to a preset threshold, and the current total thrust requirement of the boom is less than or equal to the sum of the maximum thrust of the upper and lower rotors, the optimal operating points of the upper rotor speed and the lower rotor speed are determined.

9. A rotor thrust distribution system, characterized in that, include: The acquisition module is used to acquire the operating efficiency characteristic models of the upper rotor motor and the lower rotor motor, as well as the rotor load characteristic models of the upper rotor and the lower rotor. A module is established to establish a first correspondence between the upper rotor torque and the upper rotor speed based on the rotor load characteristic model, and to establish a second correspondence between the lower rotor torque and the upper rotor speed and the lower rotor speed. Based on the operating efficiency characteristic model, the first correspondence and the second correspondence, a system total power loss function is established with the upper rotor speed and the lower rotor speed as variables; The determination module is used to determine the optimal operating points of the upper rotor speed and the lower rotor speed under the operating constraints of the current total arm pull demand, with the goal of minimizing the output value of the total power loss function of the system; The control module is used to control the operation of the upper rotor motor and the lower rotor motor according to the optimal operating point.

10. An aircraft, characterized in that, The rotor thrust distribution method as described in any one of claims 1-8 is applied, or the rotor thrust distribution system as described in claim 9 is included.

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