A method for decoupling the attitude of a UAV from the traction force for traction tasks
Patent Information
- Application Number
- CN202611079818.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-21
- Publication Date
- 2026-08-18
AI Technical Summary
[0003]然而，上述控制架构存在的突出缺陷在于姿态控制与牵引力控制之间强耦合
本申请通过构建双回路解耦控制体系，通过设置独立的牵引力控制回路和姿态控制回路，将姿态与牵引力分开计算并回馈控制，解决了现有多推进系统飞行器在牵引任务中“高精度张力控制”与“强鲁棒姿态稳定”无法兼得的技术难题；另一方面，本申请将牵引力扰动作为前馈量引入姿态控制回路，对外部载荷突变、阵风等扰动进行补偿，即使在大范围牵引力变化下仍能保持飞行姿态的稳定。
Smart Images
Figure CN122593352A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of towing unmanned aerial vehicle (UAV) control technology, and in particular to a method for decoupling the attitude and traction force of a UAV for towing missions. Background Technology
[0002] In applications where drones perform towing tasks (such as towing parachutes, banners, targets, or other towed payloads), multi-propulsion system aircraft, such as multi-rotor drones, are commonly used. In existing technologies, these aircraft generally employ a unified control architecture: the same propulsion system provides both lift to maintain flight altitude and horizontal thrust required to tow the object. A typical implementation involves centrally adjusting the output of each propulsion unit, for example, uniformly distributing throttle commands to each motor, while simultaneously influencing the aircraft's pitch, roll, and other attitude angles, as well as the traction force acting on the towing cable. In this architecture, flight attitude stability and traction control share the same actuators and control inputs, forming a control coupling relationship.
[0003] However, a significant drawback of the aforementioned control architecture lies in the strong coupling between attitude control and traction control. When the traction load changes due to external disturbances or encounters extreme conditions such as sudden load increases or rope breakage, the traction disturbance directly causes severe fluctuations or even instability in the aircraft's attitude. Simultaneously, changes in propulsion output made by the aircraft to adjust its attitude inevitably lead to unexpected changes in traction. This makes it difficult for the system to achieve precise and independent control of traction tension, reducing flight stability and mission safety in complex dynamic environments. The root cause of these problems is that the attitude control variables and traction control variables in the control architecture are not decoupled; they interfere with each other, making it difficult to simultaneously achieve precise traction output and stable flight attitude. Summary of the Invention
[0004] To overcome the limitations of the independent control accuracy of traction force and attitude described in the prior art, this invention provides a method for decoupling the attitude and traction force of a UAV for traction missions.
[0005] To achieve the above-mentioned technical effects, the technical solution of the present invention is as follows: A method for decoupling attitude and traction force control of a UAV for towing missions includes: Acquire attitude and traction status information of the towing drone; An attitude error is constructed based on the expected attitude target of the towing UAV and the attitude state information, and an attitude control loop is constructed based on the attitude error. The attitude control loop outputs an attitude control quantity to maintain the flight attitude stability of the towing UAV. A traction error is constructed based on the expected traction target and the traction state information, and a traction force control loop is constructed based on the traction error. The traction force control loop outputs a traction control quantity to control the traction force of the traction drone. Based on the traction state information and the traction control quantity, a traction compensation quantity is calculated, and the attitude control quantity is compensated based on the traction compensation quantity to obtain the compensated attitude control quantity. The compensated attitude control quantity is allocated to the vertical propulsion system of the towing UAV, and the traction control quantity is allocated to the forward traction propulsion system of the towing UAV. Attitude control is performed based on the vertical propulsion system, and traction control is performed based on the forward traction propulsion system.
[0006] As a preferred embodiment, the attitude state information includes at least the actual attitude angles, which include roll angle, pitch angle, and yaw angle; the traction state information includes at least the traction tension detected or estimated by sensors; the attitude control quantities include at least lift, roll moment, pitch moment, and yaw moment; and the traction control quantities include at least traction thrust.
[0007] As a preferred embodiment, the step of the attitude control loop outputting the attitude control quantity includes: The attitude control quantities are calculated based on the attitude angles of the expected attitude target and the actual attitude angles. The attitude control quantities include total lift and torque, and the torque includes at least one of roll torque, pitch torque, or yaw torque.
[0008] As a preferred embodiment, the attitude control loop includes an outer angle loop and an inner angular velocity loop. The outer angle loop calculates the attitude angle error based on the attitude angle of the expected attitude target and the actual attitude angle, and obtains the angular velocity of the expected attitude target through the attitude angle error. The inner angular velocity loop calculates the angular velocity error based on the angular velocity of the expected attitude target and the actual angular velocity, and obtains the attitude control quantity through the angular velocity error. The expression for the outer ring angle is as follows:
[0009] in, The angular velocity of the target at the expected attitude. , , These are the roll rate, pitch rate, and yaw rate of the target in the expected attitude, respectively. This is the attitude angle error vector. The attitude outer loop proportional gain matrix; The expression for the inner loop of angular velocity is as follows:
[0010] in, , and The PID control gain is the angular velocity. This is the angular velocity error vector; The desired torque for attitude control. These are the rolling moment, pitching moment, and yaw moment, respectively.
[0011] As a preferred embodiment, the step of the traction control circuit outputting the traction control quantity includes: The traction error is calculated based on the tension of the expected traction target and the traction state information; The traction control quantity is obtained based on the traction error, and its expression is as follows:
[0012]
[0013] in, , and The gain of the PID control for tension. This is the traction error vector. For traction control; To generate the tension expected to drive the target, This is traction status information; The total lift is calculated based on the traction angle of the towing UAV, and its expression is as follows:
[0014] in, For total lift, To determine the equivalent mass of the towing drone and the towing target, To reduce the drag on the drone, For traction angle, This refers to the acceleration along the traction direction.
[0015] As a preferred embodiment, the calculation of the traction compensation amount is performed when a triggering condition is met. The triggering condition includes: the rate of change of the traction state information exceeds a rate of change threshold, or the traction error exceeds a deviation threshold; the rate of change threshold is obtained by the difference in traction force at adjacent time points.
[0016] As a preferred embodiment, the step of calculating the traction compensation includes: The traction disturbance torque is constructed based on the position vector of the traction point relative to the center of mass of the traction UAV and the traction force vector. The traction compensation amount is obtained based on the traction disturbance torque; its expression is as follows:
[0017]
[0018] in, For position vectors, The traction force vector, traction tension, This is the unit vector representing the direction of the traction rope.
[0019] As a preferred embodiment, the step of compensating the attitude control quantity based on the traction compensation amount includes: adding the traction compensation amount to the torque of the attitude control quantity to obtain the compensated attitude control quantity, the expression of which is as follows:
[0020] in, For the compensated torque, For traction compensation, The torque is the force for attitude control.
[0021] As a preferred embodiment, the flight phases of the towing UAV include a takeoff phase, a tensioning phase, a steady-state towing phase, and an abnormal phase; during the abnormal phase, the towing UAV is protected and controlled, and the abnormal phase includes a sudden drop in traction tension, a sudden increase in traction tension, loss of traction tension feedback, or communication interruption, and the protection control includes reducing power, maintaining hovering, or automatic unhooking.
[0022] As a preferred embodiment, the vertical propulsion system includes multiple rotors for generating lift, and the forward traction propulsion system includes at least one forward propulsion device for generating traction thrust.
[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: This application solves the technical problem of the inability to achieve both "high-precision tension control" and "strong robust attitude stability" in traction missions of existing multi-propulsion system aircraft by constructing a dual-loop decoupled control system and setting up independent traction force control loops and attitude control loops, and calculating and feeding back the attitude and traction force separately. On the other hand, this application introduces traction force disturbances as feedforward quantities into the attitude control loop to compensate for disturbances such as sudden changes in external loads and gusts, so that the flight attitude can still be kept stable even under large-scale traction force changes. Attached Figure Description
[0024] Figure 1 This is a flowchart of the UAV attitude and traction force decoupling control method for traction missions in Example 1. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0027] Example 1 This embodiment proposes a method for decoupling the attitude and traction force control of a UAV for traction tasks, such as... Figure 1 The diagram shown is a flowchart of the UAV attitude and traction force decoupling control method for traction missions in this embodiment.
[0028] A method for decoupling attitude and traction force control of a UAV for towing missions includes: S1. Obtain the attitude and traction status information of the towing drone; S2. Based on the expected attitude target of the towing UAV and the attitude state information, an attitude error is constructed, and an attitude control loop is constructed according to the attitude error. The attitude control loop outputs an attitude control quantity to maintain the flight attitude stability of the towing UAV. S3. Construct a traction error based on the expected traction target and the traction state information, and construct a traction force control loop based on the traction error. The traction force control loop outputs a traction control quantity to control the traction force of the traction drone. S4. Calculate the traction compensation amount based on the traction state information and the traction control amount, and compensate the attitude control amount based on the traction compensation amount to obtain the compensated attitude control amount. S5. The compensated attitude control quantity is allocated to the vertical propulsion system of the towing UAV, and the traction control quantity is allocated to the forward traction propulsion system of the towing UAV. S6. Perform attitude control based on the vertical propulsion system and perform traction control based on the forward traction propulsion system.
[0029] In this embodiment, decoupling at the control execution level is achieved by assigning attitude control and traction control tasks to physically separate vertical propulsion and forward traction propulsion systems. Furthermore, by calculating traction compensation to feedforward compensate the attitude control quantities, the disturbances to the aircraft attitude caused by traction force changes are actively counteracted, significantly improving the robustness and anti-interference capability of attitude control during traction operations and preventing flight attitude instability caused by sudden load changes or traction force adjustments. On the other hand, the decoupled control architecture allows the control parameters of the attitude and traction loops to be tuned independently, reducing the complexity of system parameter tuning and enabling each loop to achieve optimal dynamic response performance, thus improving the overall accuracy and safety of traction task execution.
[0030] In one optional embodiment, the attitude state information includes at least the actual attitude angles, which include roll angle, pitch angle, and yaw angle; the traction state information includes at least the traction tension detected or estimated by sensors; the attitude control quantities include at least lift, roll moment, pitch moment, and yaw moment; and the traction control quantities include at least traction thrust.
[0031] As an example, vertical propeller thrust distribution is based on the attitude control loop. Furthermore, the step of the attitude control loop outputting the attitude control quantity includes: The attitude control quantities are calculated based on the attitude angles of the expected attitude target and the actual attitude angles. The attitude control quantities include total lift and torque, and the torque includes at least one of roll torque, pitch torque, or yaw torque.
[0032] In this embodiment, input variables are provided for the subsequent construction of the control loop.
[0033] Furthermore, the attitude control loop includes an outer angle loop and an inner angular velocity loop. The outer angle loop calculates the attitude angle error based on the attitude angle of the expected attitude target and the actual attitude angle, and obtains the angular velocity of the expected attitude target through the attitude angle error. The inner angular velocity loop calculates the angular velocity error based on the angular velocity of the expected attitude target and the actual angular velocity, and obtains the attitude control quantity through the angular velocity error. The expression for the outer ring angle is as follows:
[0034] in, The angular velocity of the target at the expected attitude. , , These are the roll rate, pitch rate, and yaw rate of the target in the expected attitude, respectively. This is the attitude angle error vector. The attitude outer loop proportional gain matrix; The expression for the inner loop of angular velocity is as follows:
[0035] in, , and The PID control gain is the angular velocity. This is the angular velocity error vector; The desired torque for attitude control. These are the rolling moment, pitching moment, and yaw moment, respectively. The total lift is calculated based on the traction angle of the towing UAV, and its expression is as follows:
[0036] in, For total lift, To determine the equivalent mass of the towing drone and the towing target, To reduce the drag on the drone, For traction angle, This refers to the acceleration along the traction direction.
[0037] More specifically, the resistance model is as follows:
[0038] in: air density, To increase the windward area of the drone. V To guide the speed of the drone, This is the drag coefficient for towing the drone.
[0039] Total lift Defined as the projection of the resultant force generated by the UAV multi-rotor system onto the glider's traction direction, its magnitude is obtained by the vector synthesis of the thrust of each propulsion unit:
[0040] Where N is the number of propulsion units, The thrust generated by the i-th propulsion unit It is a unit direction vector.
[0041] In this embodiment, the attitude control loop adopts a cascaded "angle outer loop - angular velocity inner loop" structure. The outer loop is responsible for slowly changing angle tracking and provides angular velocity commands to the inner loop; the inner loop is responsible for rapidly changing angular velocity adjustment, quickly suppressing disturbances and enhancing the ability to suppress high-frequency disturbances such as external gusts and sudden load changes, making attitude control more stable and precise.
[0042] Example 2 This embodiment makes further improvements based on the UAV attitude and traction force decoupling control method proposed in Embodiment 1 for traction tasks.
[0043] In an optional embodiment, the step of the traction control circuit outputting the traction control amount includes: The traction error is calculated based on the tension of the expected traction target and the traction state information; The traction control quantity is obtained based on the traction error, and its expression is as follows:
[0044]
[0045] in, , and The gain of the PID control for tension. This is the traction error vector. For traction control; To generate the tension expected to drive the target, This is traction status information.
[0046] As an example, ,in, h for t The height of time, v for t The speed of time Let be the tension angle at time t.
[0047] In this embodiment, by using a PID controller to convert the traction force error into a thrust command for the forward traction propulsion system in real time, the technical effect is that it enables the towing UAV to respond quickly to the step of the desired traction force and has a small steady-state error, thereby controlling the force applied to the towing target and avoiding damage to the target due to excessive pulling force or ineffective traction due to insufficient pulling force.
[0048] Example 3 This embodiment makes further improvements based on the UAV attitude and traction force decoupling control method proposed in Embodiment 1 or Embodiment 2 for traction tasks.
[0049] In an optional embodiment, the calculation of the traction compensation amount is performed when a triggering condition is met, the triggering condition including: the rate of change of the traction state information exceeds a rate of change threshold, or the traction error exceeds a deviation threshold; the rate of change threshold is obtained by the difference in traction force at adjacent time points.
[0050] More specifically, when the forward thrust changes, this application introduces a compensation term into the attitude controller so that the traction force of the propeller and the force of the paraglider pulling the UAV backward pass through the center of gravity of the aircraft, thereby offsetting the effect of the pitch moment.
[0051] The expression triggered by the rate of change is as follows:
[0052] in, For traction thrust, For traction tension, and This is the rate of change threshold. By compensating based on the rate of change threshold, we can cope with sudden pulls / winds and suppress attitude disturbances in advance.
[0053] The expression for deviation triggering is as follows:
[0054] in, The deviation threshold is corrected by a slow variable, which avoids attitude drift caused by continuous bias.
[0055] In an optional embodiment, the step of calculating the traction compensation includes: The traction disturbance torque is constructed based on the position vector of the traction point relative to the center of mass of the traction UAV and the traction force vector. The traction compensation amount is obtained based on the traction disturbance torque; its expression is as follows:
[0056]
[0057] in, For position vectors, The traction force vector, traction tension, This is the unit vector representing the direction of the traction rope.
[0058] In this embodiment, the physical disturbance process caused by the load target is transformed into a definite, mathematically expressible disturbance quantity, which provides a calculation basis for subsequent feedforward compensation and ensures the pertinence and effectiveness of the compensation.
[0059] In an optional embodiment, the step of compensating the attitude control quantity based on the traction compensation amount includes: adding the traction compensation amount to the torque of the attitude control quantity to obtain the compensated attitude control quantity, the expression of which is as follows:
[0060] in, For the compensated torque, For traction compensation, The torque is the force for attitude control.
[0061]
[0062] in, Total lift; For thrust.
[0063] In this embodiment, without changing the target angle and traction control quantity, compensation is introduced, dynamic decoupling of traction disturbance is achieved, and attitude maintenance accuracy under dynamic traction operation is improved.
[0064] In one optional embodiment, the flight phase of the towing drone includes a takeoff phase, a tensioning phase, a steady-state towing phase, and an abnormal phase; during the abnormal phase, the towing drone is protected by control measures, which include a sudden drop in traction tension, a sudden increase in traction tension, loss of traction tension feedback, or communication interruption. The protection control measures include reducing power, maintaining hovering, or automatic unhooking.
[0065] In this embodiment, by handling anomalies, the system's survivability and mission safety under extreme or unexpected conditions are improved, preventing the drone from going out of control and crashing due to sudden thrust changes.
[0066] In one alternative embodiment, the vertical propulsion system includes a plurality of rotors for generating lift, and the forward traction propulsion system includes at least one forward propulsion device for generating traction thrust.
[0067] In this embodiment, the complex power coupling and transition control problems of traditional tiltrotor schemes are avoided, resulting in higher system reliability; and the vertical and horizontal thrust can be independently and optimally designed for their respective mission objectives, achieving decoupling.
[0068] As an example, the vertical propulsion system uses four vertical propellers for attitude control, while the forward traction propulsion system uses two forward propellers for traction control. More specifically, for the vertical propulsion system, the thrust of its four vertical propellers is
[0069] The expression for the control objective is as follows:
[0070] in, For the allocation matrix:
[0071] in, As the lever arm, This is the rotor anti-torque coefficient.
[0072] The above formula can be used to solve for the thrust of different vertical propellers in a vertical propulsion system.
[0073] For the forward traction propulsion system, a symmetrical design is used as an example:
[0074] in, and This is the lift of the two forward propellers in the forward traction propulsion system.
[0075] Furthermore, considering yaw coupling compensation, its expression is as follows:
[0076] in: , This is the yaw compensation torque.
[0077] Example 4 This embodiment proposes a computer device, including a memory and a processor. The memory stores computer-readable instructions, wherein when the computer-readable instructions are executed by the processor, the processor performs the steps of the UAV attitude and traction force decoupling control method for traction tasks proposed in Embodiment 1.
[0078] Example 5 This embodiment proposes a storage medium storing computer-readable instructions, wherein when the computer-readable instructions are executed by a processor, the steps of the UAV attitude and traction force decoupling control method for traction missions proposed in Embodiment 1 are implemented.
[0079] By way of example, the storage medium includes, but is not limited to, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks or optical disks, and other media capable of storing program code.
[0080] By way of example, the instructions, programs, code sets, or instruction sets may be implemented using conventional programming languages.
[0081] By way of example, the processor includes, but is not limited to, smartphones, personal computers, servers, network devices, etc., for performing all or part of the steps of the UAV attitude and traction force decoupling control method for traction missions described in Example 1.
[0082] The terminology used in the accompanying drawings is for illustrative purposes only.
[0083] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A method for decoupling attitude and traction force control of an unmanned aerial vehicle (UAV) for traction tasks, characterized in that, include: Acquire attitude and traction status information of the towing drone; An attitude error is constructed based on the expected attitude target of the towing UAV and the attitude state information, and an attitude control loop is constructed based on the attitude error. The attitude control loop outputs an attitude control quantity to maintain the flight attitude stability of the towing UAV. A traction error is constructed based on the expected traction target and the traction state information, and a traction force control loop is constructed based on the traction error. The traction force control loop outputs a traction control quantity to control the traction force of the traction drone. Based on the traction state information and the traction control quantity, a traction compensation quantity is calculated, and the attitude control quantity is compensated based on the traction compensation quantity to obtain the compensated attitude control quantity. The compensated attitude control quantity is allocated to the vertical propulsion system of the towing UAV, and the traction control quantity is allocated to the forward traction propulsion system of the towing UAV. Attitude control is performed based on the vertical propulsion system, and traction control is performed based on the forward traction propulsion system.
2. The method for decoupling attitude and traction force control of a UAV for traction tasks according to claim 1, characterized in that, The attitude state information includes at least the actual attitude angles, which include roll angle, pitch angle and yaw angle; the traction state information includes at least the traction tension detected or estimated by the sensors; the attitude control quantities include at least lift, roll moment, pitch moment and yaw moment; and the traction control quantities include at least traction thrust.
3. The method for decoupling attitude and traction force control of a UAV for traction tasks according to claim 2, characterized in that, The steps for the attitude control loop to output the attitude control quantity include: The attitude control quantities are calculated based on the attitude angles of the expected attitude target and the actual attitude angles. The attitude control quantities include total lift and torque, and the torque includes at least one of roll torque, pitch torque, or yaw torque.
4. The method for decoupling attitude and traction force control of a UAV for traction tasks according to claim 3, characterized in that, The attitude control loop includes an outer angle loop and an inner angular velocity loop. The outer angle loop calculates the attitude angle error based on the attitude angle of the expected attitude target and the actual attitude angle, and obtains the angular velocity of the expected attitude target through the attitude angle error. The inner angular velocity loop calculates the angular velocity error based on the angular velocity of the expected attitude target and the actual angular velocity, and obtains the attitude control quantity through the angular velocity error. The expression for the outer ring angle is as follows: in, The angular velocity of the target at the expected attitude. , , These are the roll rate, pitch rate, and yaw rate of the target in the expected attitude, respectively. This is the attitude angle error vector. The attitude outer loop proportional gain matrix; The expression for the inner loop of angular velocity is as follows: in, , and The PID control gain is the angular velocity. This is the angular velocity error vector; The desired torque for attitude control. These are the rolling moment, pitching moment, and yaw moment, respectively. The total lift is calculated based on the traction angle of the towing UAV, and its expression is as follows: in, For total lift, To determine the equivalent mass of the towing drone and the towing target, To reduce the drag on the drone, For traction angle, This refers to the acceleration along the traction direction.
5. The method for decoupling attitude and traction force control of a UAV for traction tasks according to claim 2, characterized in that, The steps of the traction control circuit outputting the traction control quantity include: The traction error is calculated based on the tension of the expected traction target and the traction state information; The traction control quantity is obtained based on the traction error, and its expression is as follows: in, , and The gain of the PID control for tension. This is the traction error vector. For traction control; To generate the tension expected to drive the target, This is traction status information.
6. The method for decoupling attitude and traction force control of a UAV for traction tasks according to claim 5, characterized in that, The calculation of traction compensation is performed when a triggering condition is met. The triggering condition includes: the rate of change of the traction state information exceeds a rate of change threshold, or the traction error exceeds a deviation threshold. The rate of change threshold is obtained by the difference in traction force at adjacent time points.
7. The method for decoupling attitude and traction force control of a UAV for traction tasks according to claim 6, characterized in that, The steps for calculating the traction compensation amount include: The traction disturbance torque is constructed based on the position vector of the traction point relative to the center of mass of the traction UAV and the traction force vector. The traction compensation amount is obtained based on the traction disturbance torque; its expression is as follows: in, For position vectors, The traction force vector, traction tension, This is the unit vector representing the direction of the traction rope.
8. The method for decoupling attitude and traction force control of a UAV for traction missions according to claim 6, characterized in that, The step of compensating the attitude control quantity based on the traction compensation amount includes: adding the traction compensation amount to the torque of the attitude control quantity to obtain the compensated attitude control quantity, the expression of which is as follows: in, For the compensated torque, For traction compensation, The torque is the force for attitude control.
9. The method for decoupling attitude and traction force control of a UAV for traction tasks according to any one of claims 1 to 8, characterized in that, The flight phases of the towing UAV include takeoff, tensioning, steady-state traction, and abnormal phases. During the abnormal phases, the towing UAV is protected and controlled. The abnormal phases include sudden drops in traction tension, sudden increases in traction tension, loss of traction tension feedback, or communication interruption. The protection and control measures include reducing power, maintaining hovering, or automatic unhooking.
10. The method for decoupling attitude and traction force control of a UAV for traction tasks according to any one of claims 1 to 8, characterized in that, The vertical propulsion system includes multiple rotors for generating lift, and the forward traction propulsion system includes at least one forward propulsion device for generating traction thrust.