A multi-rope cooperative driving fatigue loading system and control method for full-size test of wind power blades

Abstract

The present application relates to the technical field of full-size structure test equipment of wind power blades, and provides a multi-rope cooperative driving fatigue loading system and a control method. The system comprises a square section frame fixed to a test foundation, eight rope driving units symmetrically arranged on four columns, a six-degree-of-freedom loading clamp connected with the eight driving ropes, and a central cooperative motion controller. The rope driving unit is composed of a servo motor, a winding wheel, a fixed pulley and a universal pulley. The system adopts an eight-rope spatial parallel pulling driving configuration, and achieves three-axis translation and three-axis torsion of the clamp and the blade test section through cooperative control, thereby simulating multi-dimensional time-varying composite load of the blade. In combination with kinematics calculation and tension optimization algorithm, the eight-rope cooperative precise control is realized through a six-step closed-loop control process. The present application improves the fidelity and reliability of wind power blade testing, and has the advantages of low energy consumption, light weight and no pollution.

Description

Technical Field

[0001] This invention relates to the field of wind turbine blade full-size structural testing equipment technology, and in particular to a multi-rope coordinated drive fatigue loading system and control method for wind turbine blade full-size structural testing. Background Technology

[0002] As a crucial component of wind turbine generators, the quality of wind turbine blades directly impacts the operational reliability of wind power equipment. Under normal operating conditions, wind turbine blades have a design lifespan of 20-25 years. Throughout their service life, wind turbine blades are subjected to aerodynamic loads, inertial loads, gravitational loads, and control loads, all of which change over time. Therefore, sound blade design, reliable quality, and superior performance are prerequisites for ensuring the normal and stable operation of wind turbine generators. To guarantee the quality of wind turbine blades, in addition to optimizing the design and relying on manufacturing processes, accurate and effective testing and evaluation of blade strength and lifespan are also necessary. Thus, full-scale structural testing technology for wind turbine blades has emerged. However, traditional platforms used for full-scale structural testing of wind turbine blades have several shortcomings. On the one hand, traditional full-scale testing often simplifies the load to two directions—flapping and swaying—and applies them sequentially, which differs from the multi-directional composite loads experienced by the blades in actual operation. On the other hand, poor positioning accuracy and the traction method using only 1-2 ropes provide insufficient constraint on the spatial displacement of the blades, making them susceptible to wind force, blade weight sway, and mechanical vibration during operation. Therefore, this invention proposes a multi-rope collaborative drive fatigue loading system and control method for full-size testing of wind turbine blades. The system uses eight parallel ropes to collaboratively traction the loading fixture, which can accurately simulate the multi-dimensional composite load path actually borne by the blade and achieve fully constrained active control of the blade's spatial pose, thereby significantly improving the fidelity and reliability of the test. Summary of the Invention

[0003] To address the shortcomings of existing full-scale wind turbine blade structural testing platforms in terms of load simulation realism, spatial constraint accuracy, and anti-interference capability, this invention proposes a multi-rope coordinated drive fatigue loading system and control method for full-scale wind turbine blade structural testing. This system utilizes eight drive ropes arranged in parallel to coordinate the traction of the end-loading fixture, enabling high-precision and high-rigidity simulation of the multidimensional, time-varying composite load paths experienced by the blade during actual operation. This solves the problems of traditional single-point or dual-axis sequential loading methods, such as inconsistency with real-world conditions, poor flexibility, incomplete load dimension coverage, and inaccurate control.

[0004] This invention is achieved through the following technical solution: a multi-rope coordinated drive fatigue loading system and control method for full-size testing of wind turbine blades. The system includes a rigid square profile frame fixed to the test foundation, forming the static support base of the system. Eight rope drive units are symmetrically arranged on the four vertical columns of the square profile frame, with two rope drive units integrated on each column. The drive ropes extending from the eight rope drive units are all connected to a six-degree-of-freedom loading clamp inside the frame. The clamp is controlled through coordinated traction. The clamp is used to clamp the test section of the wind turbine blade. Initially, the clamp is located at the center of the frame, and the eight ropes are tensioned. By coordinating the control of the eight rope drive units, the clamp and the clamped blade test section can achieve three-axis translation and three-axis torsion in space, thereby simulating the multi-dimensional, time-varying composite loads experienced by the blade during actual operation.

[0005] Furthermore, each of the eight rope drive units includes a servo motor, a winding pulley, a fixed pulley, and a universal pulley. For the two sets of rope drive units on each column, the components are arranged vertically in a specific order: Upper rope drive unit: from top to bottom, the upper universal pulley is located closest to the top of the frame; the upper fixed pulley is located below the upper universal pulley; the servo motor and winding pulley are located below the upper fixed pulley. Lower rope drive unit: from bottom to top, the lower universal pulley is located closest to the bottom of the frame; the lower fixed pulley is located above the lower universal pulley; the servo motor and winding pulley are located above the lower fixed pulley. The servo motor is fixed to the vertical column of the profile frame via a motor plate, and its output shaft is connected to the winding pulley, axially positioned by an end cap. The fixed pulley is used for initial guidance of the drive rope. The universal pulley is connected to the profile frame via a universal wheel L-plate, and its wheel groove can rotate freely around at least two axes.

[0006] Furthermore, the servo motor has a built-in high-resolution encoder to achieve precise position control. At the same time, the motor has a real-time torque measurement and feedback function. By measuring the drive torque and combining it with the radius of the winding wheel, the current tension value of the rope can be estimated and output.

[0007] Furthermore, the drive rope is a synthetic fiber cable, one end of which is wound and fixed on the winding wheel, and the other end passes through the universal pulley and extends to the loading clamp and is reliably connected thereto.

[0008] Furthermore, the rope path of a single rope drive unit is as follows: it originates from the winding wheel of the servo motor, passes vertically around the fixed pulley, extends to the universal pulley, and finally leads from the universal pulley to the central clamp. The connection points of the eight ropes on the clamp are divided into upper and lower groups, with four connection points in each group, and are centrally symmetrically distributed along the circumference of the clamp. The upper and lower groups of connection points are staggered along the axial direction of the clamp to ensure that the rope tension can be synthesized into a three-dimensional force and a three-dimensional moment.

[0009] Furthermore, the system is equipped with a central coordinated motion controller. This controller collects the rope tension signal and encoder position signal fed back by the servo motors in real time, calculates the actual pose of the central clamp, and, based on the preset target load spectrum and pose trajectory, combines the system's inverse kinematics model and rope tension optimization algorithm. Through multivariable decoupling and real-time closed-loop control algorithms, it calculates and outputs comprehensive control commands for the position, speed, and tension of the eight servo motors in real time, achieving precise coordinated control of the length and tension of the eight ropes.

[0010] Furthermore, the square profile frame and loading fixture are both made of high-strength aluminum alloy.

[0011] Furthermore, the four columns of the square profile frame are defined as P1, P2, P3, and P4, respectively, and a world coordinate system is established. The bottom of column P1 is the origin of the world coordinate system. The z-axis is vertically upward with column P1 as the axis, and the P1P4 direction is the x-axis. The y-axis direction is determined using the right-hand rule.

[0012] Furthermore, P1, P2, P3, and P4 are four pillars; Ko is the world coordinate system, with the first pillar P1 defined as the z-axis and its bottom vertex as the origin. P1P4 is the positive x-axis direction, and P1P2 is the positive y-axis direction; Kp is defined as the motion coordinate system of the fixture, with the geometric center of the fixture defined as the origin; a, b, and h are the length, width, and height of the fixture, respectively; P is defined as... ji V is the connection point between the clamp and the rope; i The point where the rope exits from the omnidirectional pulley; l i Indicated by P ji Point V, indicating the point of exiting the rope i The rope displacement vector; a i Let b be the position vector from the origin of the world coordinate system to the point where the rope exits from the omnidirectional pulley. i This indicates the connection point P between the end of the clamp and the rope within the clamp's motion coordinate system Kp. ji The position vector; r represents the position vector of the origin of the fixture motion coordinate system Kp in the world coordinate system Ko; R represents the rotation transformation matrix of the end motion coordinate system Kp relative to the world coordinate system Ko. In equation (2) [ , , [] represents the terminal attitude, including roll angle, pitch angle, and yaw angle.

[0013] Furthermore, according to the vector closure principle, the motion loop of a single drive chain is:

[0014] (1)

[0015] Rotation transformation matrix:

[0016] (2)

[0017] In the formula: s is sine (sin); c is cosine (cos).

[0018] Furthermore, since the rope outlet of the multi-rope cooperative drive fatigue loading system is a universal pulley device, and the radius Rs of the universal pulley is relatively large, the rope outlet cannot be treated as a point. The pulley geometric model is as follows: Figure 3 As shown, taking the omnidirectional pulley at the top rope outlet of the first column as an example: Figure 3 Mid-V point and Figure 2 In equation (1), V1 represents the same point, M is the point of tangency between the pulley and the rope, and O is the center of the pulley. Therefore, in equation (1)... .

[0019] Furthermore, the inverse kinematics of the multi-rope cooperative drive fatigue loading system is performed: the pose of the clamp is known. Find the length of the eight ropes , , , , , , , .like Figure 3 The universal pulley model has the pulley center O, rope outlet V, rope tangent point M between the rope and the pulley, and rope connection point P between the rope and the clamp. ji According to formula (1), the geometric rope length l can be obtained from the known pose coordinates of the end effector. i That is, the connection point P between the rope and the clamp. ji To the rope outlet V i Straight-line distance. In a six-degree-of-freedom rope-traction parallel robot model, the actual rope length should be... .

[0020] Furthermore, V, P ji Given the coordinates, define the coordinates of the eight connection points between the rope and the clamp as follows: , ( =1,2⋯8). The coordinates of the pulley center O and V are in the same plane and Equal to the pulley radius Rs, and V, P jiO and O are in the same plane. The coordinates of O can be obtained by solving the equation as shown in equation (3).

[0021] (3)

[0022] V, O, P ji The coordinates of ∠OMP are known. ji Since the angle is right, P can be obtained using the Pythagorean theorem and the law of cosines. ji The length of M, ∠MOP ji ∠VOP ji As shown in equation (4).

[0023] (4)

[0024] According to ∠MOP ji ∠VOP ji Given the pulley radius Rs, calculate... Length. As shown in equation (5).

[0025] (5)

[0026] The actual rope length can be obtained from formulas (3), (4), and (5). .

[0027] Furthermore, the kinematic correct solution of the multi-rope coordinated fatigue loading system is obtained: the lengths of the eight ropes in the multi-rope coordinated fatigue loading system are known. , , , , , , , Determine the fixture pose. According to the number of each column, the angle ∠VMO of the eight rope pulleys is set accordingly. , , , , , , , Define the coordinates of the eight rope exit points as follows: , ( =1,2⋯8). The coordinates of the eight rope exit points are known. The coordinates of the connection points between the clamp and the rope can be derived from the clamp's pose coordinates based on the clamp's structural parameters. Based on the mutual constraints of these parameters and the geometric model, a set of forward parameter constraint equations is established:

[0028] (6)

[0029] In formula (6), the eight central angles corresponding to the eight rope outlet pulleys are... , , , , , , , The eight coordinates of the connection point between the rope and the clamp end are all unknowns, while the lengths of the eight ropes and the pulley radius Rs are known parameters. Observation reveals that equation (6) contains more than the original fourteen unknown parameters, but it also lacks end-effector pose parameters. This is because, as mentioned earlier, the coordinates of the connection point between the end-effector and the rope can be derived from the end-effector pose coordinates based on the end-effector structural parameters. This significantly reduces the number of unknowns in the parameter constraint equations, leaving only eight central angles and fourteen end-effector pose unknowns. These fourteen unknowns are set as a 14×1 unknown matrix. A set of kinematic parametric equations for the multi-rope coordinated fatigue loading system is established. Since it is an overdetermined system of sixteen equations and fourteen unknowns, Newton's iteration method is employed. The Newton iteration equations are established, and iterative calculations are performed to obtain the least-squares solution.

[0030] Equation (6) is the parametric constraint equation for the forward kinematics solution. Newton iteration is used to solve it: by moving all position parameters to the left side of the equation, we obtain the iterative equation system of equation (7). For the iterative equation system Finding the partial derivative for each unknown variable yields a partial derivative matrix called the Jacobian matrix. The forward parameter constraint equations contain 14 unknowns, resulting in a 16×14 Jacobian matrix. Newton's iterative formula is then constructed. .

[0031] (7)

[0032] Newton's iterative equations are obtained. Based on the estimated position coordinates of the clamp according to the lengths of the eight ropes, a suitable initial value is set, and iterative calculations are performed to achieve the forward kinematics solution.

[0033] Compared with the prior art, the multi-rope cooperative drive fatigue loading system and control method for full-size testing of wind turbine blades provided by the present invention have the following beneficial effects:

[0034] 1. This multi-rope coordinated fatigue loading system employs a parallel mechanism of eight servo motors coordinating the drive ropes, enabling independent or coupled control of the three-dimensional spatial forces and torques acting on the blade clamp. Through precise coordinated control of the eight rope lengths by a central controller, it can achieve composite loading of translational motion (such as flapping or oscillation) and torsion around the axis on the blade test section in any direction within space, thereby simulating with high precision the complex coupled loads experienced by the blade during actual operation. This design fundamentally solves the problems of limited degrees of freedom, difficulty in applying pure torques or complex spatial force systems, and single loading dimension in traditional actuator loading methods, greatly improving the realism and coverage of the test.

[0035] 2. This multi-rope coordinated fatigue loading system primarily utilizes electric drive and lightweight rope transmission. Compared to traditional hydraulic loading systems, electric drive offers advantages such as low energy consumption, low noise, no oil pollution, and easy maintenance, better meeting the requirements of modern green and energy-saving laboratories. The parallel rope mechanism features a short transmission chain, high mechanical efficiency, and a modular symmetrical design with a clear force path, optimizing the structure while ensuring sufficient rigidity. This solution addresses the problems of high energy consumption, inflexible layout, and stringent requirements for installation foundations inherent in traditional heavy-duty loading equipment. Attached Figure Description

[0036] Figure 1 This is a flowchart of a multi-rope collaborative drive fatigue loading control method for full-size testing of wind turbine blades.

[0037] Figure 2 This is a geometric model and coordinate system definition diagram of a six-degree-of-freedom rope-traction parallel robot;

[0038] Figure 3 This is a schematic diagram of a universal pulley model;

[0039] Figure 4 This is a schematic diagram of a multi-rope coordinated drive fatigue loading system for full-size testing of wind turbine blades.

[0040] Figure 5 This is a schematic diagram of a rope-driven unit.

[0041] In the diagram: 1. Frame; 2. Rope drive unit; 21. Servo motor; 22. Winding wheel; 23. Fixed pulley; 24. Universal pulley; 3. Rope; 4. Clamp; 5. Blade; 6. Motor plate; 7. Universal wheel L-plate. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Please see Figure 1-5 A multi-rope coordinated drive fatigue loading system and control method for full-size testing of wind turbine blades. The flowchart of the multi-rope coordinated drive fatigue loading control method for full-size testing of wind turbine blades proposed in this invention includes the following steps:

[0044] S01: System Initialization and Parameter Calibration. This step ensures the system starts operating from a known and consistent state. The process begins by powering on all motors and performing a zero-return operation to establish a unified mechanical and electrical zero point. Subsequently, all motors operate in low-torque mode, and the eight ropes are slightly tensioned to stabilize the central clamp near the geometric center of the frame. Next, the system reads the high-precision encoder values ​​of each motor and records the initial length of each rope as the reference for all subsequent length changes. Finally, the system confirms geometric parameters, such as the coordinates of the universal pulley exit point in the global coordinate system, completing the construction of the entire kinematic model.

[0045] S02: Load command input and inverse kinematics solution transform engineering requirements into machine-executable instructions. Users input test requirements via an interface or program file, which could be a time-varying load spectrum, such as flapping moment, oscillation moment, and axial force to be applied at the blade root. Upon receiving these targets, the cooperative motion controller invokes the built-in inverse kinematics and dynamics model. Based on the current system's geometric parameters and the blade segment's clamping stiffness, this model calculates the minute displacements and rotations required by the central clamp to generate the target load, and further determines the precise lengths required by the eight ropes.

[0046] S03: Rope Tension Optimization and Motor Command Generation. Since there is redundancy in the six-degree-of-freedom motion driven by eight ropes, this step aims to find an optimal set of rope tension solutions. The optimization algorithm takes the target length and base tension calculated in step two as input, and performs real-time calculations under strict constraints (all rope tensions must be greater than zero to prevent slack, and the resultant force and resultant torque of the eight ropes must be strictly equal to the target value). The algorithm outputs the optimal target tension values ​​for each of the eight ropes. Finally, the controller generates comprehensive servo commands for each motor, which include the target position, target velocity, and target tension.

[0047] S04: Multi-channel synchronous closed-loop control. After each motor channel receives its own integrated command, the servo driver runs an advanced force / position hybrid control algorithm. This algorithm uses the outer loop's "target position" and "target tension" as setpoints, and the inner loop's "current loop" as a fast execution unit. During operation, the motor itself provides all critical feedback.

[0048] Position feedback: The rotor angle is measured in real time by the encoder built into the motor, and the length of the rope to be released and retracted is accurately calculated.

[0049] Tension feedback: By sampling the motor's operating current in real time and using the model calibrated in the first step, the actual tension of the rope is calculated instantaneously.

[0050] The controller continuously compares the target value with these feedback values ​​and dynamically adjusts the output to ensure that each motor can accurately track the position and tension commands simultaneously.

[0051] S05: The monitoring and adjustment of the composite load based on the motor's calculated tension relies on the motor's own sensing capabilities. The system collects real-time tension values ​​calculated from the motor current through eight channels. These tension values ​​are input into the forward kinematic model, which then calculates the three-dimensional resultant force and three-dimensional resultant moment acting on the central clamp in real time. The controller compares this "calculated composite load" with the "target load" input in the second step in real time. If the error is within the allowable threshold, the system maintains the current control; if the error exceeds the limit, a dynamic adjustment mechanism is triggered.

[0052] S06: Coordinating motion and target load reproduction is the macroscopic presentation and ultimate goal of the entire control process. Through the cyclical execution of the aforementioned steps, eight motors work in concert, and eight ropes undergo complex and precise changes in length and tension. The macroscopic effect is that the central clamp drives the blade test section to move in three-dimensional space according to a predetermined pattern. The system continues to run until the load spectrum reproduction of the entire test cycle is completed, and finally all actions stop, ending the process.

[0053] A multi-rope coordinated drive fatigue loading system and control method for full-size wind turbine blade testing includes a rigid square profile frame 1, which is fixed to the test foundation, forming the static support foundation of the system. Eight independent rope drive units 2 are symmetrically arranged on the four vertical columns of the square profile frame, with two rope drive units 2 integrated on each column. Drive ropes 3 extending from the eight rope drive units 2 are all connected to a six-degree-of-freedom loading clamp 4 inside the frame 1. The clamp 4 is controlled through coordinated traction. The clamp 4 is used to clamp the test section of the wind turbine blade 5. Initially, the clamp 4 is located at the center of the frame 1, and the eight ropes 3 are tensioned. By coordinating the control of the eight sets of rope drive units 2, the clamp 4 and the clamped blade 5 test section can achieve three-axis translation and three-axis torsion in space, thereby simulating the multi-dimensional, time-varying composite loads experienced by the blade 5 during actual operation.

[0054] Furthermore, each of the eight rope drive units 2 includes a servo motor 21, a winding reel 22, a fixed pulley 23, and a universal pulley 24. For the two sets of rope drive units 2 on each column, their components are arranged vertically in a specific order: Upper rope drive unit: from top to bottom, the upper universal pulley 24 is located closest to the top of the frame 1; the upper fixed pulley 23 is located below the upper universal pulley 24; the servo motor 21 and the winding reel 22 are located below the upper fixed pulley 23. Lower rope drive unit: from bottom to top, the lower universal pulley 24 is located closest to the bottom of the frame 1; the lower fixed pulley 23 is located above the lower universal pulley 24; the servo motor 21 and the winding reel 22 are located above the lower fixed pulley 23. The servo motor 21 is fixed to the vertical column of the profile frame 1 via a motor plate 6, and its output shaft is connected to the winding reel 22, axially positioned via an end cap. The fixed pulley 23 is used for initial guidance of the drive rope 3. The omnidirectional pulley 24 is connected to the profile frame 1 via the omnidirectional pulley L plate 7. Its groove can rotate freely around at least two axes to provide final spatial vector guidance for the drive rope 3, ensuring that the rope 3 extends to the loading clamp 4 at a precise angle.

[0055] Furthermore, the servo motor 21 has a built-in high-resolution encoder to achieve precise position control. At the same time, the motor has a real-time torque measurement and feedback function. By measuring the drive torque and combining it with the radius of the winding wheel, the tension value of the current rope 3 can be estimated and output.

[0056] Furthermore, the drive rope 3 is a high-strength, low-elongation synthetic fiber cable, one end of which is wound and fixed on the winding wheel 22, and the other end passes through the universal pulley 24 and extends to the loading clamp 4 and is reliably connected thereto.

[0057] Furthermore, the rope path of the single rope drive unit 2 is as follows: it originates from the winding wheel 22 of the servo motor 21, passes vertically around the fixed pulley 23, extends to the universal pulley 24, and finally leads from the universal pulley 24 to the central clamp 4. The connection points of the eight ropes 3 on the clamp 4 are divided into upper and lower groups, with four connection points in each group, and are centrally symmetrically distributed along the circumference of the clamp 4. The upper and lower groups of connection points are staggered along the axial direction of the clamp 4 to ensure that the tension of the ropes 3 can be synthesized into a three-dimensional force and a three-dimensional torque.

[0058] Furthermore, the square profile frame 1 and the loading clamp 4 are both made of high-strength aluminum alloy to ensure the overall structure is lightweight and has high rigidity.

[0059] Furthermore, the four columns of the square profile frame 1 are defined as P1, P2, P3, and P4, respectively, and a world coordinate system is established. The bottom of column P1 is the origin of the world coordinate system. The z-axis is vertically upward with column P1 as the z-axis, and the direction of P1P4 is the x-axis. The y-axis direction is determined using the right-hand rule.

[0060] Furthermore, P1, P2, P3, and P4 are four pillars; Ko is the world coordinate system, with the first pillar P1 defined as the z-axis and its bottom vertex as the origin. P1P4 is the positive x-axis direction, and P1P2 is the positive y-axis direction; Kp is defined as the fixture motion coordinate system, with the geometric center of fixture 4 defined as the origin; a, b, and h are the length, width, and height of fixture 4, respectively; P... ji V is the connection point between the clamp 4 and the rope 3; i The point where the rope exits from the omnidirectional pulley; l i Indicated by P ji Point V, indicating the point of exiting the rope i The displacement vector of the rope 3; a i Let b be the position vector from the origin of the world coordinate system to the point where the rope exits from the omnidirectional pulley 24. i This indicates the connection point P between the end of clamp 4 and rope 3 within the clamp motion coordinate system Kp. ji The position vector; r represents the position vector of the origin of the fixture motion coordinate system Kp in the world coordinate system Ko; R represents the rotation transformation matrix of the end motion coordinate system Kp relative to the world coordinate system Ko. In equation (2) [ , , [] represents the terminal attitude, including roll angle, pitch angle, and yaw angle.

[0061] Furthermore, according to the vector closure principle, the motion loop of a single drive chain is:

[0062] (1)

[0063] Rotation transformation matrix:

[0064] (2)

[0065] In the formula: s is sine (sin); c is cosine (cos).

[0066] Furthermore, since the rope outlet of the multi-rope cooperative drive fatigue loading system is a universal pulley device, and the radius Rs of the universal pulley is relatively large, the rope outlet cannot be treated as a point. The pulley geometric model is as follows: Figure 3 As shown, taking the omnidirectional pulley 24 at the top rope outlet of the first column as an example: Figure 3 Mid-V point and Figure 2 In formula (1), V1 is the same point, M is the point of tangency between the universal pulley 24 and the rope 3, and O is the center of the pulley. .

[0067] Furthermore, the inverse kinematics of the multi-rope cooperative fatigue loading system is solved: the pose of clamp 4 is known. Find the length of the eight ropes , , , , , , , .like Figure 3 The universal pulley model has the pulley center O, rope outlet V, rope tangent point M between the rope and the pulley, and rope connection point P between the rope and the clamp. ji According to formula (1), the geometric rope length l can be obtained from the known pose coordinates of the end effector. i That is, the connection point P between rope 3 and clamp 4 ji To the rope outlet V i Straight-line distance. In a six-degree-of-freedom rope-traction parallel robot model, the actual rope length should be... .

[0068] Furthermore, V, P ji Given the coordinates of the rope 3 and the clamp 4, define the coordinates of the eight connection points as follows: , ( =1,2⋯8). The coordinates of the pulley center O and V are in the same plane and Equal to the pulley radius Rs, and V, P ji O and O are in the same plane. The coordinates of O can be obtained by solving the equation as shown in equation (3).

[0069] (3)

[0070] V, O, P ji The coordinates of ∠OMP are known. ji Since the angle is right, P can be obtained using the Pythagorean theorem and the law of cosines. ji The length of M, ∠MOPji ∠VOP ji As shown in equation (4).

[0071] (4)

[0072] According to ∠MOP ji ∠VOP ji Calculate the pulley radius Rs. Length. As shown in equation (5).

[0073] (5)

[0074] The actual rope length can be obtained from formulas (3), (4), and (5). .

[0075] Furthermore, the kinematic correct solution of the multi-rope coordinated fatigue loading system is obtained: the lengths of the eight ropes in the multi-rope coordinated fatigue loading system are known. , , , , , , , Determine the fixture pose. According to the number of each column, the angle ∠VMO of the eight rope pulleys is set accordingly. , , , , , , , Define the coordinates of the eight rope exit points as follows: , ( =1,2⋯8). The coordinates of the eight rope exit points are known. The coordinates of the connection point between clamp 4 and rope 3 can be derived from the clamp pose coordinates based on the clamp structural parameters. Based on the mutual constraints of these parameters and the geometric model, a set of forward parameter constraint equations is established:

[0076] (6)

[0077] In formula (6), the eight central angles corresponding to the eight rope outlet pulleys are... , , , , , , , The eight coordinates of the connection points between rope 3 and clamp 4 are all unknowns, while the lengths of the eight ropes and the pulley radius Rs are known parameters. Observation reveals that equation (6) contains more than the original fourteen unknown parameters, but it also lacks end-effector pose parameters. This is because, as mentioned earlier, the coordinates of the connection points between the end-effector and the rope can be derived from the end-effector pose coordinates based on the end-effector structural parameters. This significantly reduces the number of unknowns in the parameter constraint equations, leaving only eight central angles and fourteen end-effector pose unknowns. These fourteen unknowns are set as a 14×1 unknown matrix. A set of kinematic parametric equations for the multi-rope coordinated fatigue loading system is established. Since it is an overdetermined system of sixteen equations and fourteen unknowns, Newton's iteration method is employed. The Newton iteration equations are established, and iterative calculations are performed to obtain the least-squares solution.

[0078] Equation (6) is the parametric constraint equation for the forward kinematics solution. Newton iteration is used to solve it: by moving all position parameters to the left side of the equation, we obtain the iterative equation system of equation (7). For the iterative equation system Finding the partial derivative for each unknown variable yields a partial derivative matrix called the Jacobian matrix. The forward parameter constraint equations contain 14 unknowns, resulting in a 16×14 Jacobian matrix. Newton's iterative formula is then constructed. .

[0079] (7)

[0080] Newton's iterative equations are obtained. Based on the estimated 4-position coordinates of the clamp according to the length of the eight ropes, a suitable initial value is set, and iterative calculations are performed to achieve the forward kinematic solution.

[0081] The specific usage and function of this embodiment are as follows:

[0082] 1. First, based on the test section of the wind turbine blade, select the position of the square rigid support frame 1 to ensure the stability of the entire loading system's foundation. Then, install eight rope drive units 2 at designated positions on the four vertical columns, ensuring the axes of the winding pulley 22, fixed pulley 23, and universal pulley 24 are aligned as designed. Wrap one end of each of the eight high-strength ropes 3 around and fix it to the corresponding winding pulley 22 driven by the servo motor 21. Next, guide each rope 3 sequentially through the fixed pulley 23 and universal pulley 24 of the same rope drive unit 2, and connect the free ends of all ropes 3 to the various connection points of the central load fixture in the designed spatial configuration. Finally, clamp and fix the five sections of the wind turbine blade to be tested onto the central fixture 4. At this point, the multi-rope collaborative drive fatigue loading system for full-size wind turbine blade testing is complete.

[0083] After the system is built and the electrical connections are completed, initialization and calibration are performed. The central controller is powered on and drives all servo motors 21 to execute the zeroing and tensioning procedures, establishing a unified kinematic zero point. Based on the target load spectrum, the controller simultaneously drives eight servo motors 21 to coordinate their operation and precisely release and retract eight ropes 3. By controlling the combination and changes in the length of ropes 3, the position and attitude of the central clamp 4 and the clamped blade segment in three-dimensional space are dynamically adjusted. Specifically, when it is necessary to simulate the fatigue load in the flapping direction of the blade 5, the system, based on the local coordinate system of the test section of the blade 5, controls the clamp 4 to perform reciprocating sinusoidal motion along the flapping direction through kinematic calculation. Based on real-time pose and load feedback, the controller generates the target flapping bending moment at the root section of the blade 5 through the coordinated release and retraction of the eight ropes 3. When it is necessary to simulate the coupled conditions of oscillation and torsion, the system synchronously controls the clamp to translate along the oscillation direction and torsion around the blade 5 axis. Through the coordinated distribution of the tension of the ropes 3, a coupled load spectrum of oscillation bending moment and torque is synthesized at the section of the blade 5. The controller calculates the required change in length of the eight ropes 3 in real time based on inverse kinematics and drives the corresponding servo motors 21 to precisely coordinate their extension and retraction, thereby pulling the clamp 4 and the blade segment to generate the target displacement. At this time, the resultant force of the tension in the ropes 3 constitutes the force acting on the blade 5 in the flapping direction. If it is necessary to simulate the coupled condition of oscillation and torsion, the clamp 4 can be instructed to move in the horizontal plane while rotating around the axis. The system controls the differential operation of the eight servo motors 21 to generate a resultant force in the plane while superimposing a pure torque. The combined tension of the eight ropes 3 finally generates the required spatial force and torque at the root of the blade 5 clamp. Throughout the process, the controller continuously collects the torque feedback of each servo motor 21 and the encoder position feedback. Through this multi-degree-of-freedom coordinated drive, the system can realize the complex spatial path movement or precise force-controlled loading of the test section of the blade 5, efficiently reproducing the flapping, oscillation and torsional load states it bears in real operation, thereby completing static, fatigue or dynamic mechanical performance tests.

[0084] Although embodiments of the present invention have been shown and described, those skilled in the art should understand that various modifications, changes, substitutions or variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of protection of the present invention should be determined by the claims and their equivalents.

Claims

1. A multi-rope coordinated drive fatigue loading system for full-size testing of wind turbine blades, comprising a rigid square profile frame (1), the square profile frame (1) being fixed to the test foundation to form the static support foundation of the system; eight rope drive units (2) are symmetrically arranged on the four vertical columns of the square profile frame, each column having two sets of rope drive units (2) integrated along the vertical direction; the drive ropes (3) leading out from the eight rope drive units (2) are all connected to a six-degree-of-freedom loading fixture (4) inside the frame (1), and the fixture is controlled by coordinated traction. 4); The clamp (4) is used to clamp the test section of the wind turbine blade (5). In the initial state, the clamp (4) is located at the center of the frame (1), and the eight ropes (3) are in a tensioned state; the upper rope drive unit (2) at the top of the column is connected to the lower side of the clamp (4), and the lower rope drive unit (2) at the bottom of the column is connected to the upper side of the clamp (4), forming a spatial tension configuration; the system is used to coordinate the adjustment of the length and tension of each drive rope (3), so that the loading clamp (4) has the ability of three-axis translation and three-axis torsion to simulate the multi-dimensional time-varying composite load that the wind turbine blade (5) actually bears during operation.

2. The multi-rope cooperative drive fatigue loading system for full-size testing of wind turbine blades according to claim 1, characterized in that: Each of the eight rope drive units (2) includes a servo motor (21), a winding wheel (22), a fixed pulley (23), and a universal pulley (24). For the two sets of rope drive units (2) on each column, their components are arranged in a specific order along the vertical direction. The upper rope drive unit: from top to bottom, is the upper universal pulley (24), located closest to the top of the frame (1); the upper fixed pulley (23), located below the upper universal pulley (24); the servo motor (21) and the winding wheel (22), located below the upper fixed pulley (23). The lower rope drive unit: from bottom to top, is the lower universal pulley (24), located closest to the bottom of the frame (1); the lower fixed pulley (23), located above the lower universal pulley (24); the servo motor (21) and the winding wheel (22). Located above the lower fixed pulley (23); the servo motor (21) is fixed to the vertical column of the profile frame (1) through the motor plate (6), and its output shaft is connected to the winding wheel (22) and axially positioned through the end cover; the fixed pulley (23) is used to initially guide the drive rope (3), and the universal pulley (24) is connected to the profile frame (1) through the universal wheel L plate (7). Its wheel groove can rotate freely around at least two axes and is used to provide final spatial vector guidance for the drive rope (3); the rope path of a single rope drive unit (2) is as follows: it is led out from the winding wheel (22) of the servo motor (21), passes vertically around the fixed pulley (23), extends to the universal pulley (24), and finally leads from the universal pulley (24) to and connects to the clamp (4) in the center.

3. The multi-rope coordinated drive fatigue loading system for full-size testing of wind turbine blades according to claim 2, characterized in that: The servo motor (21) has a built-in high-resolution encoder to achieve precise position control. At the same time, the motor has real-time torque measurement and feedback functions. By measuring the driving torque and combining it with the radius of the winding wheel, the tension value of the current rope (3) can be estimated and output.

4. The multi-rope cooperative drive fatigue loading system for full-size testing of wind turbine blades according to claim 2, characterized in that: The drive rope (3) is a synthetic fiber cable, one end of which is wound and fixed on the winding wheel (22), and the other end passes through the universal pulley (24) and extends to the loading clamp (4) and is reliably connected thereto.

5. The multi-rope cooperative drive fatigue loading system for full-size testing of wind turbine blades according to claim 1, characterized in that: The system is equipped with a central coordinated motion controller, which collects the rope tension signal and encoder position signal fed back by the servo motor in real time and calculates the actual position and posture of the central clamp (4). Based on the preset target load spectrum and position trajectory, combined with the system kinematic inverse solution model and rope tension optimization algorithm, through multivariable decoupling and real-time closed-loop control algorithm, the system calculates and outputs the position, speed and tension integrated control command of the eight servo motors (21) in real time, so as to realize the precise coordinated control of the length and tension of the eight ropes (3).

6. The multi-rope coordinated drive fatigue loading system for full-size testing of wind turbine blades according to claim 1, characterized in that: The four columns of the square profile frame (1) are defined as P1, P2, P3, and P4, respectively, and a world coordinate system is established. The bottom of column P1 is the origin of the world coordinate system. The z-axis of column P1 is vertically upward, and the direction of P1P4 is the x-axis. The y-axis direction is determined by the right-hand rule. Kp is defined as the motion coordinate system of the fixture, and the geometric center of the fixture (4) is defined as the origin of the coordinate system. a, b, and h are the length, width, and height of the fixture (4), respectively. P is defined as... ji V is the connection point between the clamp (4) and the rope (3); i The point where the rope exits from the omnidirectional pulley; l i Indicated by P ji Point V, indicating the point of exiting the rope i The displacement vector of the rope (3); a i Let b be the position vector from the origin of the world coordinate system to the point where the rope exits from the universal pulley (24). i This indicates the connection point P between the end of the clamp (4) and the rope (3) within the clamp motion coordinate system Kp. ji The position vector; r represents the position vector of the origin of the fixture motion coordinate system Kp in the world coordinate system Ko; R represents the rotation transformation matrix of the end motion coordinate system Kp relative to the world coordinate system Ko. , , [] represents the terminal attitude, including roll angle, pitch angle, and yaw angle.

7. A multi-rope cooperative drive fatigue loading control method for full-size testing of wind turbine blades, characterized in that, Based on the multi-rope coordinated drive fatigue loading system for full-size testing of wind turbine blades as described in claim 1, the method includes the following steps: S01, System Initialization and Parameter Calibration: Power on all servo motors and perform a homing operation to establish a unified mechanical and electrical zero point; control all motors to run in low torque mode, pre-tension the eight drive ropes to stabilize the six-degree-of-freedom loading fixture at the geometric center of the square profile frame; read the encoder values ​​of each motor, record the initial length of each drive rope, confirm the system geometric parameters, and complete the kinematic model construction. S02, Load command input and inverse kinematics solution: Receive the target load spectrum command, call the built-in kinematics and dynamics inverse solution model, calculate the target pose of the six-degree-of-freedom loading fixture corresponding to the target load based on the system geometric parameters and blade clamping stiffness, and further calculate the target length that the eight drive ropes need to achieve. S03, Rope Tension Optimization and Motor Command Generation: Taking the target length and basic tension as input, under the constraints that the rope tension is greater than zero and the resultant force and resultant torque of the eight ropes are equal to the target load, the optimal target tension value of the eight ropes is calculated in real time through the tension optimization algorithm, and a comprehensive servo command containing the target position, target speed and target tension is generated for each servo motor. S04, Multi-channel synchronous closed-loop control: The driver of each servo motor receives comprehensive servo commands, executes the force / position hybrid control algorithm, takes the outer loop position and tension target as the set value, takes the inner loop current loop as the execution unit, collects encoder position signal and motor torque signal in real time, compares with the target value and dynamically adjusts the output to achieve accurate tracking of single-channel position and tension; S05, Synthetic Load Monitoring and Adjustment: Real-time acquisition of the real-time tension values ​​of eight servo motors, and calculation of the three-dimensional resultant force and three-dimensional resultant torque of the six-degree-of-freedom loading fixture through a forward kinematic model. The synthetic load is compared with the target load in real time. If the error exceeds the preset threshold, a dynamic adjustment mechanism is triggered. S06, Coordinated Motion and Target Load Reproduction: Repeat steps S02 to S05, control eight servo motors to work together, drive the six-degree-of-freedom loading fixture to move the wind turbine blade test section according to the preset law until the load spectrum reproduction of the entire test cycle is completed, and stop the system operation.

8. A multi-rope cooperative drive fatigue loading control method for full-size testing of wind turbine blades according to claim 7, characterized in that, The specific process of inverse kinematics solution in step S02 is as follows: Based on the geometric model of the universal pulley (24), determine the pulley center O, the rope outlet V, the tangent point M between the rope (3) and the universal pulley (24), and the connection point P between the rope (3) and the clamp (4). ji Given the pose coordinates of the end effector, the geometric rope length l can be obtained. i That is, the connection point P between the rope (3) and the clamp (4) ji To the rope outlet V i Straight-line distance; combining pulley radius and wrap angle parameters, the coordinates of the pulley center, the length of the tangent line segment, and the arc length corresponding to the pulley wrap angle are solved through geometric equations, and finally the actual rope length of the multi-rope collaborative drive fatigue loading system is calculated.

9. A multi-rope cooperative drive fatigue loading control method for full-size testing of wind turbine blades according to claim 7, characterized in that, The forward kinematics solution process of the forward kinematics model in step S05 is as follows: Given the lengths of the eight ropes in the multi-rope cooperative drive fatigue loading system, and combining the coordinates of the rope exit points of the eight universal pulleys and the pulley radius parameters, an overdetermined constraint equation set including the pulley central angles and the fixture pose parameters is established; the eight pulley central angles and the fixture pose parameters to be solved are constructed into an unknown matrix, and the overdetermined equation set is iteratively solved using the Newton iteration method to obtain the actual pose of the fixture.

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