Gearbox test bench automatic centering adjustment method and system

Abstract

The present application relates to the field of mechanical transmission test, and particularly relates to a gear box test bench automatic centering adjustment method and system, comprising the following steps: sending an instruction to the disk car mechanical arm end rotating actuator to make the test gear box shafting in an initial measurement angle state, and obtaining a current absolute angle value; outputting a spatial pose deviation data packet in the initial measurement angle after distortion correction and temperature drift compensation; generating a smooth spatial docking track; and completing iterative measurement-compensation closed loop according to a new measurement phase angle value and a shafting already in place state signal. The present application adopts non-contact laser centering measurement to obtain shafting pose deviation, combines a multi-phase measurement mode to eliminate interference of shafting shape and position error on measurement results, and realizes accurate compensation of multi-dimensional pose through a six-degree-of-freedom adjustment platform, thereby providing a stable measurement reference for gear box performance evaluation and fault feature extraction, and reducing damage to the gear box caused by misalignment operation.

Description

Technical Field

[0001] This invention relates to the field of mechanical transmission testing, specifically to an automatic centering adjustment method and system for a gearbox test bench. Background Technology

[0002] Gearboxes are core power transmission components in modern industrial systems, widely used in almost all heavy-duty and precision transmission fields, including wind power, shipbuilding, and construction machinery. A gearbox test bench is a precision measurement system for gearbox research and development and quality inspection; its core task is to obtain accurate and repeatable test data. Its shaft system connects the drive motor, sensors, load, etc., forming a measurement reference. Any deviation of the shaft centerline, i.e., misalignment, will directly distort this reference and contaminate all measurement results.

[0003] The additional force generated by shaft misalignment not only leads to errors in power calculations, but the resulting strong background vibrations can also mask fault characteristic signals of gears and bearings, making fault diagnosis impossible. Furthermore, during gearbox testing, poor alignment significantly increases the amplitude of the gearbox's double-frequency vibrations, which can severely damage the gearbox equipment.

[0004] In gearbox testing, the traditional method of gearbox alignment involves workers using instruments to measure the deviation between the two shafts to be aligned. Based on the deviation, they tap the gearbox with a copper rod to fine-tune the lateral deviation, pry up the four corners of the gearbox with a crowbar, and use shims to raise the corners to fine-tune the longitudinal and angular deviations. Then, they rotate the gear shaft to a certain angle and repeat the above process until the alignment error of the two shafts is within the required test range at multiple angles. This method is labor-intensive and time-consuming, and its accuracy is difficult to guarantee, making it unsuitable for the rapid testing needs of large-scale gearboxes. Summary of the Invention

[0005] This invention addresses the technical problems existing in the prior art by providing an automatic centering adjustment method and system for a gearbox test bench.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: An automatic centering adjustment method and system for a gearbox test bench, comprising the following steps: S1. Based on the area where the test gearbox turning interface is located, project coded structured light to perform visual recognition and preliminary positioning of the turning interface. Read the spatial pose matrix of the turning interface obtained by positioning in the coordinate system of the vision module. After determining the safe approach point, perform motion planning. After obtaining the status confirmation signal that the robot arm has reached the safe approach point, output the turning probe insertion confirmation signal and the contact force and torque data packet. Send the command to the end rotary actuator of the turning robot arm to make the test gearbox shaft system be in the initial measurement angle state and obtain the current absolute angle value. S2. Based on the laser centering measuring instrument, start single-point measurement, convert the emitted fan-shaped laser into an analog voltage signal and then into a digital signal, and calculate the orthogonal sway angle of the laser incident direction relative to the normal of the receiving unit measurement surface. After distortion correction and temperature drift compensation, output the spatial pose deviation data packet under the initial measurement angle. S3. Based on the first fixed offset, the second fixed offset, and the membrane disk installation spacing obtained from the system calibration, and combined with the created reference coordinate system, perform spatial coordinate transformation to obtain the three-dimensional coordinates of the origin of the ideal test gearbox shaft system target coordinate system in the reference coordinate system. The mapping of the test gearbox shaft system coordinate system in space should be used as the absolute ideal target alignment pose model. Based on the spatial pose deviation data packet under the initial measurement angle, obtain the current error state vector. Based on the pose represented by the absolute ideal target alignment pose model, use the pose as the trajectory endpoint. Use the current actual pose inversely deduced by combining the current error state vector and the current pose as the trajectory starting point to generate a smooth spatial docking trajectory and output the smooth spatial docking trajectory pose point sequence. S4. Perform inverse kinematics on the six-degree-of-freedom adjustment platform to solve the smooth spatial docking trajectory pose point sequence. After traversal calculation, obtain the expected motion velocity sequence and expected motion acceleration sequence of each electric cylinder at each moment. Output the expected length, velocity, and acceleration command sequence set for each electric cylinder. Then, send the sequence to the motion controller synchronously via a high-speed real-time motion bus with the same time step as the trajectory generation. Complete closed-loop trajectory tracking based on feedforward-feedback composite control. Use the feedback preliminary alignment motion completion status signal as the re-execution signal of S1. Complete the iterative measurement-compensation closed loop based on the new measured phase angle value and the axis system in place status signal. Output the final alignment accuracy status signal.

[0007] In a preferred embodiment, S1 projects coded structured light onto the area where the test gearbox turning interface is located based on a machine vision module fixed at the wrist of the turning arm and collects point cloud data and a two-dimensional grayscale image. The industrial computer calls a 3D template matching algorithm based on geometric features to process the point cloud data, including: extracting the outer cylindrical surface, end annular plane, and center hole edge of the point cloud data from a pre-stored computer-aided design model of the turning gear interface as rigid geometric primitives of the computer-aided design model; registering the computer-aided design model with the scene data using an iterative nearest-point algorithm based on the scene point cloud; and iteratively solving for the spatial position and orientation of the turning gear interface in the coordinate system of the machine vision module by minimizing the sum of squared Euclidean distances between the rigid geometric primitives and the corresponding points in the scene point cloud. The position and orientation are expressed as a 4x4 homogeneous transformation matrix, which describes the 3D coordinates of the geometric center point of the front face of the turning gear interface and the direction cosine of the front face normal vector, and outputting the spatial pose matrix of the turning gear interface in the coordinate system of the machine vision module. The industrial computer reads the spatial pose matrix of the turning interface in the vision module coordinate system, and calls the fixed coordinate transformation matrix of the machine vision module coordinate system relative to the turning manipulator base coordinate system obtained in advance through the hand-eye calibration program, as well as the center point calibration data of the turning probe tool. The spatial pose matrix is ​​transformed from the vision module coordinate system to the turning manipulator base coordinate system through matrix multiplication to obtain the target pose matrix of the turning interface in the manipulator base coordinate system. The industrial computer creates a safe approach point, including: using the axial length from the front end face of the turnaround probe to the shoulder as the effective length of the probe. It should be noted that the shoulder is a mechanical reference surface used to limit the insertion depth. This length is a known mechanical design constant stored in the parameter table of the industrial computer. The effective length of the probe is added to a preset additional buffer distance to obtain a safe distance. The additional buffer distance is determined by summing the maximum root mean square error of the machine vision positioning system and the maximum value of the end-positioning repeatability of the turnaround robot arm. Ultimately, this ensures that even when there is uncertainty in the vision guidance, the front end of the turnaround probe will never accidentally touch the turnaround interface during the rapid approach phase. The industrial computer extracts the three-dimensional coordinates of the center point of the front face of the interface and the interface normal vector based on the target pose matrix of the trolley interface in the coordinate system of the robot arm base, and translates the safe distance in the opposite direction of the normal vector. The reverse direction of the normal vector refers to the direction of exiting the interface. The spatial coordinate points are generated, and the coordinates of the spatial coordinate points are combined with the posture that makes the axis of the trolley probe parallel to the interface normal vector to construct a target pose matrix with a safe approach point. Based on the current end-effector center point pose of the rotary manipulator as the starting point and the target pose matrix of the safe approach point as the ending point, a straight path is planned using a trapezoidal velocity curve. Each interpolation point on the straight path is converted into the angle sequence of each joint of the rotary manipulator through inverse Jacobian numerical iteration. The angle sequence command of each joint is sent to the joint servo driver of the rotary manipulator, which drives the rotary probe carried at the end of the rotary manipulator actuator to move to the safe approach point and outputs a status confirmation signal that the manipulator has reached the safe approach point.

[0008] In a preferred embodiment, after receiving a status confirmation signal from an industrial computer indicating that the robotic arm has reached a safe approach point, S1 switches the control mode of the manipulator to admittance control. Based on a six-dimensional force and torque sensor installed between the wrist of the manipulator and the end effector, it collects contact force and contact torque data in real time. It should be noted that in the actual data collection process, this application sets virtual dynamic characteristics of the manipulator in the interface normal direction to make it exhibit the desired impedance behavior. That is, when the external force is zero, the end effector moves at a specified low speed inward towards the interface. When the end effector is obstructed, its movement speed will be adjusted according to the relationship between the force / torque and the set target impedance parameters. Based on the compliant feed motion performed by the trolley robotic arm from the safe approach point along the interface normal direction, and the continuous monitoring of the force component data of the six-dimensional force and torque sensor in the axial direction of the interface during the compliant feed motion, when the front guide cone of the trolley probe slides into the interface guide hole and the shoulder end face of the probe contacts the front face of the trolley interface, the axial force will undergo a steep step change from close to zero to exceeding the preset rigid contact force threshold. Based on the contact force and contact torque data, the torque components in the two orthogonal radial directions of the interface are calculated in real time. When the calculated axial force step amplitude exceeds the force threshold and the absolute values ​​of the calculated radial torque components do not exceed the preset safe torque threshold, it is determined that the trolley probe has reached the specified insertion depth and the shoulder of the trolley probe is completely in contact with the interface end face. The trolley robotic arm is then given a stop feed command, switched to position holding mode, all joints are locked, and the trolley probe insertion confirmation signal and the final contact force and torque data packet are output. After sending a command to the end effector of the manipulator to drive the manipulator probe to rotate at a constant speed, and continuously reading the absolute angular position feedback signal of the shaft system installed on the input shaft end of the test gearbox and / or converted by the joint encoder of the manipulator and the transmission ratio, if the shaft system angular position reaches a preset initial measurement angle, this angle is a preset constant, usually set to zero degrees or an integer angle. The end effector of the manipulator stops and activates the brake to keep the manipulator probe at the initial measurement angle, and outputs a signal that the test gearbox shaft system is at the initial measurement angle and the current absolute angle value.

[0009] In a preferred embodiment, S2 sends a start single-point measurement command to the laser alignment measuring instrument. The laser emitting unit of the laser alignment measuring instrument emits a fan-shaped laser beam from its internal laser diode to the laser receiving unit fixed on the housing of the diaphragm coupling bushing on the side of the test gearbox. The two-dimensional position sensitive detector built into the laser receiving unit senses the center position of the laser spot on the photosensitive surface, converts it into an analog voltage signal through a photoelectric conversion and amplification circuit, converts it into a digital signal through an analog-to-digital converter, and calculates two orthogonal yaw angles of the laser incident direction relative to the normal of the measuring surface of the receiving unit based on the tilt sensor and phase calculation circuit inside the laser receiving unit. The embedded processor of the laser alignment measuring instrument performs nonlinear distortion correction and temperature drift compensation on the two orthogonal yaw angles, including radial position signals and yaw angle signals, using the factory-calibrated intrinsic parameter matrix. It then obtains spatial pose deviation data, including the horizontal radial offset and vertical radial offset of the shaft system at the input end of the test gearbox in the measurement plane of the laser receiving unit, as well as the yaw angles in the horizontal and vertical planes relative to the reference axis. The current timestamp and angle label are added, and the spatial pose deviation data packet at the initial measurement angle is output.

[0010] In a preferred embodiment, S3 is based on reading length calibration parameters that have been pre-obtained and permanently stored in the memory through the measurement and system calibration process, including: a fixed distance along the longitudinal axis from the origin of the laser emitting unit measurement surface center coordinate system as the first fixed offset to the mounting end face of the diaphragm coupling bushing on the side of the acceleration gearbox; a fixed distance along the longitudinal axis from the origin of the laser receiving unit measurement surface center coordinate system as the second fixed offset to the mounting end face of the diaphragm coupling bushing on the side of the test gearbox; and an axial clearance between the two coupling end faces in the fully released state, determined according to the diaphragm coupling design, as the diaphragm mounting spacing. Based on the virtual reference coordinate system created in the memory, the definition of this coordinate system coincides with the coordinate system of the center of the measuring surface of the laser emitting unit of the high-precision laser alignment measuring instrument in terms of spatial position and attitude. Taking the reference coordinate system as the starting point, a synthetic spatial coordinate transformation operation is performed, including: translating the first fixed offset along the positive direction of the vertical axis of the reference coordinate system, then translating the diaphragm installation spacing, and finally translating the second fixed offset. The point obtained by translation is the three-dimensional coordinate of the origin of the ideal test gearbox shaft system target coordinate system under the reference coordinate system. For the attitude, the industrial computer sets the vertical axis direction of the target coordinate system to be consistent with the vertical axis direction of the reference coordinate system, that is, the dot product of the two spatial vectors is the product of their lengths, and the other two orthogonal axis directions of the two coordinate systems are also parallel to each other. The spatial coordinate transformation of the first synthesis is used as a mapping of the position and attitude of the test gearbox shaft system coordinate system in space to obtain an absolutely ideal target centering pose model, which is temporarily stored in the memory.

[0011] In a preferred embodiment, step S3 calls the spatial pose deviation data packet at the initial measurement angle. This deviation data, with reference to the reference coordinate system, describes the current position and attitude deviation of the laser receiving unit's measurement surface coordinate system. Since the longitudinal axis of the laser receiving unit's measurement surface coordinate system is defined to coincide with the center line of the test gearbox shaft system, and its relative relationship with the platform on the six-degree-of-freedom adjustment platform is known through calibration, the industrial computer 12 can use the spatial pose deviation data packet as the pose deviation of the test gearbox shaft system's current coordinate system relative to the reference coordinate system. Based on the pose deviation, it compares it with the absolutely ideal target centering pose model, calculates and obtains the spatial position error vector and attitude error vector that need to be eliminated from the current pose to the target pose, and obtains the current error state vector containing the spatial position error vector and attitude error vector. This vector contains three translation error components and three attitude error components, and the current actual pose can be deduced from the current error.

[0012] In a preferred embodiment, S3 uses the pose represented by the absolutely ideal target alignment pose model as the trajectory endpoint, and uses the current actual pose inversely deduced by combining the current error state vector with the current pose as the trajectory starting point to initiate the task space trajectory. This includes: using a multi-degree-of-freedom synchronous smoothing algorithm based on fifth-order polynomial interpolation to construct fifth-order polynomial functions with respect to time for the three positional degrees of freedom and the three pose degrees of freedom expressed using rotational quaternions. By forcibly setting the zeroth, first, and second-order derivatives of each polynomial at the trajectory starting point and trajectory ending point (where each order refers to the starting velocity and acceleration being zero, and the ending velocity and acceleration also being zero), all coefficients of the fifth-order polynomial are analytically solved. Based on a constant time step, the six polynomials are sampled over the total motion time to generate discrete, time-strictly aligned six-dimensional intermediate pose points, which constitute a complete spatial motion path that smoothly and without abrupt changes from the current pose to the target pose. The output is a sequence of pose points with smooth spatial docking trajectory.

[0013] In a preferred embodiment, step S4 performs inverse kinematics solution on each pose point in the smooth spatial docking trajectory pose point sequence using a calibrated six-degree-of-freedom adjustment platform inverse kinematics algorithm module. This module, as mentioned in this application, stores the precise three-dimensional coordinates of twelve hinge centers on the upper and lower platforms of the six-degree-of-freedom adjustment platform in their respective rigid body coordinate systems. Based on the successful solution and / or initial static equilibrium pose of each input pose point as the initial value for iteration, the nonlinear constraint equations are solved using the Newton-Raphson iterative method, and the solution is applied in each iteration. Starting from the currently guessed pose of the moving platform, the spatial distance between the center points of the upper and lower hinges of each electric cylinder is calculated using spatial vector operations to obtain the six theoretical rod lengths. Then, the length residual between the current rod length and the expected rod length is calculated, and a Jacobian matrix is ​​constructed to map the relationship between the length residual and the spatial distance. By obtaining the pseudo-inverse of the Jacobian matrix and multiplying it by the vector of the length residual, the correction amount of the moving platform pose is obtained until the root mean square value of the length residual is less than the preset convergence tolerance. Finally, the expected absolute extension length values ​​of the six electric cylinders corresponding to the pose point are obtained. After traversing and calculating all points in the smooth spatial docking trajectory pose sequence, six sets of strictly time-synchronized discrete length sequences are obtained. The six sets of discrete length sequences are then subjected to three-point central difference numerical differentiation in the time domain to obtain the expected motion velocity sequence and expected motion acceleration sequence of each electric cylinder at each moment. The summaries output a set of expected length, velocity, and acceleration command sequences for each of the six electric cylinders.

[0014] In a preferred embodiment, step S4 synchronously sends the desired length, speed, and acceleration command sequence sets of the six electric cylinders to the motion controller via a high-speed real-time motion bus at the same time step as trajectory generation. The motion controller maintains an independent closed-loop control channel for each electric cylinder, with the same control architecture for each channel, and performs feedforward-feedback composite control, including: reading the desired length, desired speed, and desired acceleration of the cylinder at the current moment; receiving the current actual extension / retraction length fed back by the absolute linear encoder installed inside the electric cylinder, and obtaining the actual speed through a hardware differential; calculating the desired length and... The difference in actual length is used as the position error; a velocity feedforward force component is generated based on the desired velocity, and a velocity feedforward force component is generated based on the desired acceleration; the position error is input to the PID controller, the proportional term generates a restoring force proportional to the error, the integral term accumulates historical errors to eliminate steady-state error, and the derivative term generates a damping effect based on the error change rate; the three are weighted and summed to obtain the feedback force component; the velocity feedforward force component, the acceleration feedforward force component, and the feedback force component are algebraically added to form the total control force command; the control force command is converted into a current command for the torque motor through a torque constant, and then amplified by the current loop to drive the electric cylinder. Therefore, this application provides the above-mentioned operation, which enables the actual movement of each electric cylinder to closely follow the desired trajectory, and forces the deviation represented by the current error state vector to be gradually eliminated. When the position tracking error of all electric cylinders converges to within the preset tracking error tolerance within a complete trajectory cycle, the motion controller feeds back the initial centering motion completion status signal to the industrial computer; The feedback signal indicating the completion of the initial alignment motion is used as the operation start signal for S1, and a new measured phase angle value and a signal indicating that the shaft system is in place are output.

[0015] This invention provides an automatic centering adjustment system for a gearbox test bench, the system comprising: Industrial computer; used to read the spatial pose matrix of the turning gear interface and laser measurement data, call the system calibration parameters to perform spatial coordinate transformation, construct an absolutely ideal target centering pose model, solve the current error state vector and generate a smooth spatial docking trajectory pose point sequence, complete the inverse kinematics solution of the six-degree-of-freedom adjustment platform and output a set of motion command sequences. A six-degree-of-freedom adjustment platform is used for rigid load-bearing test gearboxes. It performs six-degree-of-freedom position and posture adjustments according to motion commands, driving the test gearbox shaft system to complete the compensation and correction of centering deviations. A rotary manipulator arm; it is used to identify and locate the rotary interface by projecting coded structured light, and to complete the smooth insertion and docking of the rotary probe in admittance control mode, and to rotate the test gearbox shaft system to the specified measurement angle. Laser alignment measuring instrument; includes a laser emitting unit and a laser receiving unit respectively fixed to the diaphragm coupling bushing on the side of the acceleration gearbox and the diaphragm coupling bushing on the side of the test gearbox, used to collect spatial pose deviation data of the test gearbox shaft system relative to the reference axis at different measurement angles, and transmit it to an industrial computer; Motion controller; used to receive a set of motion command sequences issued by an industrial computer, synchronously drive each electric cylinder and the turning manipulator of the six-degree-of-freedom adjustment platform through a high-speed real-time motion bus, and complete closed-loop trajectory tracking and iterative centering adjustment based on feedforward-feedback composite control.

[0016] The beneficial effects of this invention are: it uses non-contact laser alignment measurement to obtain shaft system posture deviation, combines multi-phase measurement to eliminate the interference of shaft system's own form and position errors on the measurement results, and achieves accurate compensation of multi-dimensional posture through a six-degree-of-freedom adjustment platform, effectively reducing the additional load caused by shaft system misalignment, avoiding power calculation deviation and background vibration interference caused by misalignment conditions, ensuring the authenticity of core test data such as torque and vibration, providing a stable measurement benchmark for gearbox performance evaluation and fault feature extraction, and reducing damage to the gearbox caused by misalignment operation; The robotic arm automatically completes the identification of the gearbox interface, smooth docking, and shaft angle adjustment. Combined with laser measurement, trajectory calculation, and platform adjustment, the entire process is automated, replacing the tedious manual processes of repeated measurement, tapping calibration, and shim adjustment. This significantly shortens the alignment time of a single gearbox, reduces manpower input, and is suitable for fast-paced testing scenarios of batch gearbox R&D verification and factory testing. Attached Figure Description

[0017] Figure 1 This is a layout diagram of the automatic centering adjustment gearbox test bench of the present invention; Figure 2 This is a diagram showing the composition of the control unit of the automatic centering adjustment gearbox test bench of the present invention; Figure 3 This is a schematic diagram of the coordinate system of the measurement surface and the target position; Figure 4 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0018] The present invention will now be further described with reference to the accompanying drawings.

[0019] Please refer to the appendix. Figure 1-4 As shown, this embodiment provides: an automatic centering adjustment method for a gearbox test bench, including the following steps: S1. Based on the area where the test gearbox turning interface is located, project coded structured light to perform visual recognition and preliminary positioning of the turning interface. Read the spatial pose matrix of the turning interface obtained by positioning in the coordinate system of the vision module. After determining the safe approach point, perform motion planning. After obtaining the status confirmation signal that the robot arm has reached the safe approach point, output the turning probe insertion confirmation signal and the contact force and torque data packet. Send the command to the end rotary actuator of the turning robot arm to make the test gearbox shaft system be in the initial measurement angle state and obtain the current absolute angle value. S1 uses a machine vision module fixed at the wrist of the turning arm to project coded structured light onto the area where the turning interface of the test gearbox is located and collect point cloud data and two-dimensional grayscale images. The industrial computer 12 calls a 3D template matching algorithm based on geometric features to process the point cloud data, including: extracting the outer cylindrical surface, end annular plane, and center hole edge of the point cloud data from the pre-stored computer-aided design model of the turning gear interface as rigid geometric primitives of the computer-aided design model, and registering the computer-aided design model with the scene data using an iterative nearest point algorithm based on the scene point cloud. By minimizing the sum of squared Euclidean distances between the rigid geometric primitives and the corresponding points in the scene point cloud, the spatial position and orientation of the turning gear interface in the coordinate system of the machine vision module are obtained iteratively. The position and orientation are expressed as a 4x4 homogeneous transformation matrix, which describes the 3D coordinates of the geometric center point of the front face of the turning gear interface and the direction cosine of the front face normal vector. The spatial pose matrix of the turning gear interface in the coordinate system of the machine vision module is output. The industrial computer 12 reads the spatial pose matrix of the turning interface in the vision module coordinate system, and calls the fixed coordinate transformation matrix of the machine vision module coordinate system relative to the turning manipulator base coordinate system obtained in advance through the hand-eye calibration program, as well as the center point calibration data of the turning probe tool. The spatial pose matrix is ​​transformed from the vision module coordinate system to the turning manipulator base coordinate system through matrix multiplication to obtain the target pose matrix of the turning interface in the manipulator base coordinate system. The industrial computer 12 creates a safe approach point by: using the axial length from the front end face of the turnaround probe to the shoulder as the effective length of the probe. It should be noted that the shoulder is a mechanical reference surface used to limit the insertion depth. This length is a known mechanical design constant stored in the parameter table of the industrial computer 12. The effective length of the probe is added to a preset additional buffer distance to obtain a safe distance. The additional buffer distance is determined by summing the maximum root mean square error of the machine vision positioning system and the maximum value of the end-positioning repeatability of the turnaround robot arm. Ultimately, this ensures that the front end of the turnaround probe will never accidentally touch the turnaround interface during the rapid approach phase, even when there is uncertainty in the vision guidance. The industrial computer 12 extracts the three-dimensional coordinates of the center point of the front face of the interface and the interface normal vector from the target pose matrix in the coordinate system of the robot arm base based on the trolley interface. It then translates the interface forward by a safe distance along the normal vector. The reverse direction of the normal vector refers to the direction of exiting the interface. This generates spatial coordinate points. The coordinates of the spatial coordinate points are combined with the posture that makes the axis of the trolley probe parallel to the interface normal vector to construct a target position matrix with a safe approach point. Based on the current end-effector center point pose of the rotary manipulator as the starting point and the target pose matrix of the safe approach point as the ending point, a straight path is planned using a trapezoidal velocity curve. Each interpolation point on the straight path is converted into the angle sequence of each joint of the rotary manipulator through inverse Jacobian numerical iteration. The angle sequence command of each joint is sent to the joint servo driver of the rotary manipulator, which drives the rotary probe carried at the end of the rotary manipulator actuator to move to the safe approach point and outputs a status confirmation signal that the manipulator has reached the safe approach point.

[0020] After receiving a status confirmation signal from the industrial computer 12 indicating that the robotic arm has reached the safe approach point, S1 switches the control mode of the manipulator to admittance control. Based on the six-dimensional force and torque sensor installed between the wrist of the manipulator and the end effector, it collects contact force and contact torque data in real time. It should be noted that in the actual data collection process, this application sets the virtual dynamic characteristics of the manipulator in the interface normal direction to make it exhibit the desired impedance behavior. That is, when the external force is zero, the end effector of the robotic arm moves at a specified low speed inward towards the interface. When the end effector is obstructed, its movement speed will be adjusted according to the relationship between the force / torque and the set target impedance parameters. Based on the compliant feed motion performed by the trolley robotic arm along the interface normal direction starting from the safe approach point, and continuously monitoring the force component data of the six-dimensional force and torque sensor in the axial direction of the interface during the compliant feed motion, when the front guide cone of the trolley probe slides into the interface guide hole and the shoulder end face of the probe contacts the front face of the trolley interface, the axial force will undergo a steep step change from close to zero to exceeding the preset rigid contact force threshold. Based on the contact force and contact torque data, the torque components in the two orthogonal radial directions of the interface are calculated in real time. When the calculated axial force step amplitude exceeds the force threshold and the absolute values ​​of the calculated radial torque components do not exceed the preset safe torque threshold, it is determined that the trolley probe has reached the specified insertion depth and the shoulder of the trolley probe is completely in contact with the interface end face. The trolley robotic arm is then issued a stop feed command, switched to position holding mode, locked all joints, and outputs a trolley probe insertion confirmation signal and the final contact force and torque data packet. After sending a command to the end effector of the manipulator to drive the manipulator probe to rotate at a constant speed, and continuously reading the absolute angular position feedback signal of the shaft system installed on the input shaft end of the test gearbox and / or converted by the joint encoder of the manipulator and the transmission ratio, if the shaft system angular position reaches the preset initial measurement angle, this angle is a preset constant, usually set to zero degrees or an integer angle. The end effector of the manipulator stops and activates the brake to keep the manipulator probe at the initial measurement angle, and outputs a signal that the test gearbox shaft system is at the initial measurement angle and the current absolute angle value.

[0021] S2. Based on the laser centering measuring instrument, start single-point measurement, convert the emitted fan-shaped laser into an analog voltage signal and then into a digital signal, and calculate the orthogonal sway angle of the laser incident direction relative to the normal of the receiving unit measurement surface. After distortion correction and temperature drift compensation, output the spatial pose deviation data packet under the initial measurement angle. S2 sends a start single-point measurement command to the laser alignment measuring instrument. The laser emitting unit of the laser alignment measuring instrument emits a fan-shaped laser from its internal laser diode to the laser receiving unit fixed on the housing of the diaphragm coupling bushing on the side of the test gearbox. The two-dimensional position sensitive detector built into the laser receiving unit senses the center position of the laser spot on the photosensitive surface, converts it into an analog voltage signal through a photoelectric conversion and amplification circuit, and converts it into a digital signal through an analog-to-digital converter. Based on the tilt sensor and phase calculation circuit inside the laser receiving unit, it calculates two orthogonal yaw angles of the laser incident direction relative to the normal of the measuring surface of the receiving unit. The embedded processor based on the laser alignment measuring instrument performs nonlinear distortion correction and temperature drift compensation on two orthogonal yaw angles, including radial position signals and yaw angle signals, using the factory-calibrated intrinsic parameter matrix. It obtains spatial pose deviation data, including the horizontal radial offset and vertical radial offset of the shaft system at the input end of the test gearbox in the measurement plane of the laser receiving unit, as well as the yaw angles in the horizontal and vertical planes relative to the reference axis. It adds the current timestamp and angle label and outputs the spatial pose deviation data packet at the initial measurement angle.

[0022] S3. Based on the first fixed offset, the second fixed offset, and the membrane disk installation spacing obtained from the system calibration, and combined with the created reference coordinate system, perform spatial coordinate transformation to obtain the three-dimensional coordinates of the origin of the ideal test gearbox shaft system target coordinate system in the reference coordinate system. The mapping of the test gearbox shaft system coordinate system in space should be used as the absolute ideal target alignment pose model. Based on the spatial pose deviation data packet under the initial measurement angle, obtain the current error state vector. Based on the pose represented by the absolute ideal target alignment pose model, use the pose as the trajectory endpoint. Use the current actual pose inversely deduced by combining the current error state vector and the current pose as the trajectory starting point to generate a smooth spatial docking trajectory and output the smooth spatial docking trajectory pose point sequence. S3 reads the length calibration parameters that have been pre-obtained and permanently stored in the memory through the measurement and system calibration process, including: a fixed distance along the longitudinal axis from the origin of the laser emitting unit's measurement surface center coordinate system as the first fixed offset to the mounting end face of the diaphragm coupling bushing on the side of the acceleration gearbox; a fixed distance along the longitudinal axis from the origin of the laser receiving unit's measurement surface center coordinate system as the second fixed offset to the mounting end face of the diaphragm coupling bushing on the side of the test gearbox; and an axial clearance between the two coupling end faces in the fully released state, determined according to the diaphragm coupling design, as the diaphragm mounting spacing. Based on the virtual reference coordinate system created in the memory, the coordinate system is defined to coincide with the coordinate system of the center of the laser emission unit of the high-precision laser alignment measuring instrument in terms of spatial position and attitude. Starting from the reference coordinate system, a synthetic spatial coordinate transformation operation is performed, including: translating a first fixed offset along the positive direction of the vertical axis of the reference coordinate system, then translating the diaphragm installation spacing, and finally translating a second fixed offset. The point obtained by the translation is the three-dimensional coordinate of the origin of the ideal test gearbox shaft system target coordinate system in the reference coordinate system. For the attitude, the industrial computer sets the vertical axis direction of the target coordinate system to be consistent with the vertical axis direction of the reference coordinate system, that is, the dot product of the two spatial vectors is the product of their lengths, and the other two orthogonal axes of the two coordinate systems are also parallel to each other. The spatial coordinate transformation of the first synthesis is used as a mapping of the position and attitude of the test gearbox shaft system coordinate system in space to obtain an absolutely ideal target centering pose model, which is temporarily stored in memory.

[0023] S3 calls the spatial pose deviation data packet at the initial measurement angle. This deviation data, with reference to the reference coordinate system, describes the current position and attitude deviation of the laser receiving unit's measurement surface coordinate system. Since the vertical axis of the laser receiving unit's measurement surface coordinate system is defined to coincide with the center line of the test gearbox shaft system, and its relative relationship with the platform on the six-degree-of-freedom adjustment platform is known through calibration, the industrial computer 12 can use the spatial pose deviation data packet as the pose deviation of the test gearbox shaft system's current coordinate system relative to the reference coordinate system. Based on the pose deviation, it compares it with the absolutely ideal target centering pose model, calculates and obtains the spatial position error vector and attitude error vector that need to be eliminated from the current pose to the target pose, and obtains the current error state vector containing the spatial position error vector and attitude error vector. It contains three translation error components and three attitude error components, and the current actual pose can be deduced from the current error.

[0024] S3 uses the pose represented by the pose model of the absolutely ideal target alignment as the trajectory endpoint, and the current actual pose inferred from the combination of the current error state vector and the current pose as the trajectory starting point to start the mission space trajectory. This includes: a multi-degree-of-freedom synchronous smoothing algorithm based on fifth-order polynomial interpolation, which constructs fifth-order polynomial functions with respect to time for the three positional degrees of freedom and the three pose degrees of freedom expressed by rotation quaternions, and forcibly sets the zeroth, first, and second order derivatives of each polynomial at the trajectory starting and ending times. Here, each order refers to the starting velocity and acceleration being zero, and the ending velocity and acceleration being zero, respectively. The coefficients of the fifth-order polynomial are analytically solved, and the six polynomials are sampled over the total motion time based on a constant time step to generate discrete, time-strictly aligned six-dimensional intermediate pose points. This constitutes a complete spatial motion path that smoothly and without abrupt changes from the current pose to the target pose, and outputs a sequence of pose points with smooth spatial docking trajectory.

[0025] S4. Perform inverse kinematics on the six-degree-of-freedom adjustment platform to solve the smooth spatial docking trajectory pose point sequence. After traversal calculation, obtain the expected motion velocity sequence and expected motion acceleration sequence of each electric cylinder at each moment. Output the expected length, velocity, and acceleration command sequence set for each electric cylinder. Then, send the sequence to the motion controller synchronously via the high-speed real-time motion bus with the same time step as the trajectory generation. Complete closed-loop trajectory tracking based on feedforward-feedback composite control. Use the feedback of the initial alignment motion completion status signal as the re-execution signal of S1. Complete the iterative measurement-compensation closed loop based on the new measured phase angle value and the axis system in place status signal. Output the final alignment accuracy status signal.

[0026] S4 performs inverse kinematics solution on each pose point in the smooth spatial docking trajectory pose point sequence using a calibrated six-degree-of-freedom adjustment platform kinematics inverse solution algorithm module. The module mentioned in this application internally stores the precise three-dimensional coordinates of the twelve hinge centers on the upper and lower platforms of the six-degree-of-freedom adjustment platform in their respective rigid body coordinate systems. Based on the successful solution and / or initial static equilibrium pose of each input pose point at the previous moment as the initial value of the iteration, the nonlinear constraint equation system is solved by the Newton-Raphson iterative method. In each iteration, starting from the currently guessed dynamic platform pose, the spatial distance between the upper and lower hinge center points of each electric cylinder is calculated using spatial vector operations to obtain the six theoretical rod lengths. Then, the length residual between the current rod length and the expected rod length is calculated, and the Jacobian matrix mapping the length residual to the spatial distance is constructed. By obtaining the pseudo-inverse of the Jacobian matrix and multiplying it by the vector of the length residual, the correction amount of the dynamic platform pose is obtained until the root mean square value of the length residual is less than the preset convergence tolerance. Finally, the expected absolute extension length values ​​of the six electric cylinders corresponding to the pose points are obtained. After traversing and calculating all points in the pose sequence of the smooth spatial docking trajectory, six sets of strictly time-synchronized discrete length sequences are obtained. The six sets of discrete length sequences are then subjected to three-point central difference numerical differentiation in the time domain to obtain the expected motion velocity sequence and expected motion acceleration sequence of each electric cylinder at each moment. The output consists of a set of expected length, velocity, and acceleration command sequences for each of the six electric cylinders.

[0027] S4 transmits the desired length, speed, and acceleration command sequences for each of the six electric cylinders synchronously to the motion controller via a high-speed real-time motion bus at the same time step as trajectory generation. The motion controller maintains an independent closed-loop control channel for each electric cylinder. Each channel has the same control architecture and performs feedforward-feedback composite control, including: reading the desired length, desired speed, and desired acceleration of the cylinder at the current moment; receiving the current actual extension / retraction length from the absolute linear encoder installed inside the electric cylinder and obtaining the actual speed through a hardware differential; and calculating the desired length and actual length. The difference in degrees is used as the position error; a velocity feedforward force component is generated based on the desired velocity, and a velocity feedforward force component is generated based on the desired acceleration; the position error is input to the PID controller, the proportional term generates a restoring force proportional to the error, the integral term accumulates historical errors to eliminate steady-state error, and the derivative term generates a damping effect based on the rate of change of error. The three are weighted and summed to obtain the feedback force component; the velocity feedforward force component, the acceleration feedforward force component, and the feedback force component are algebraically added to form the total control force command; the control force command is converted into a current command for the torque motor through a torque constant, and then amplified by the current loop to drive the electric cylinder. Therefore, this application provides the above-mentioned operation, which enables the actual movement of each electric cylinder to closely follow the desired trajectory, and forces the deviation represented by the current error state vector to be gradually eliminated. When the position tracking error of all electric cylinders converges to within the preset tracking error tolerance within a complete trajectory cycle, the motion controller feeds back the initial centering motion completion status signal to the industrial computer; The feedback signal indicating the completion of the initial alignment motion is used as the start signal for operation S1. This ensures that the turning probe of the turning manipulator can safely and accurately re-insert into the turning interface of the test gearbox after the adjustment platform has moved. Once inserted, the industrial computer reads the current contact force at the shoulder of the turning probe. After confirming safety, it sends a command to the rotary actuator at the end of the turning manipulator to drive it to rotate precisely by a preset incremental angle. This incremental angle is fixed at 90 degrees. At this point, the test gearbox shaft system has been turned to a new measurement phase, i.e., a position that has rotated 90 degrees relative to the initial measurement angle. The system outputs a new measurement phase angle value and a signal indicating that the shaft system is in place.

[0028] The present invention also provides an automatic centering adjustment system for a gearbox test bench, the system comprising: Industrial computer 12; used to read the spatial pose matrix of the turning gear interface and laser measurement data, call the system calibration parameters to perform spatial coordinate transformation, construct an absolutely ideal target centering pose model, solve the current error state vector and generate a smooth spatial docking trajectory pose point sequence, complete the inverse kinematics solution of the six-degree-of-freedom adjustment platform and output a motion command sequence set; A six-degree-of-freedom adjustment platform 7 is used for the rigid load-bearing test gearbox 6. It performs six-degree-of-freedom posture adjustment according to motion commands, driving the test gearbox shaft system to complete the compensation and correction of centering deviation. The 8-axis rotating robotic arm is used to connect a machine vision module and a six-dimensional force and torque sensor fixed at the wrist. The end is equipped with a rotary actuator and a rotating probe. It is used to project coded structured light to identify and locate the rotating interface, complete the smooth insertion and docking of the rotating probe in admittance control mode, and rotate the test gearbox shaft system to the specified measurement angle. The laser alignment measuring instrument 5 includes a laser emitting unit and a laser receiving unit respectively fixed to the diaphragm coupling bushing on the side of the acceleration gearbox and the diaphragm coupling bushing on the side of the test gearbox, used to collect spatial pose deviation data of the test gearbox shaft system relative to the reference axis under different measurement angles, and transmit it to the industrial computer 12. Motion controller 11 is used to receive a set of motion command sequences issued by industrial computer 12, and synchronously drive each electric cylinder of six-degree-of-freedom adjustment platform 7 and turning mechanical arm 8 through high-speed real-time motion bus, and complete closed-loop trajectory tracking and iterative centering adjustment based on feedforward-feedback composite control.

[0029] Please refer to the appendix. Figure 1-3 From left to right, the equipment consists of: drive motor 1, diaphragm coupling 2, acceleration gearbox 3, diaphragm coupling 4, high-precision laser alignment measuring instrument 5, test gearbox 6, six-degree-of-freedom adjustment platform 7, rotary mechanical arm 8, reduction gearbox 9, loading motor 10, motion controller 11, and industrial computer 12. Drive motor 1 provides the test speed for test gearbox 6, and loading motor 10 provides simulated loading resistance. The pre-test state is as follows: Figure 1 As shown, the equipment on the test bench is divided into fixed and adjustable parts. The fixed parts are rigidly connected to the test bench location after assembly and require no further adjustment. The test gearbox 6 is rigidly connected to the upper platform of the six-degree-of-freedom adjustment platform 7. When adjusting the test gearbox 6 for alignment, both ends of it are rigidly connected to one end of each of the two diaphragm disc couplings 4. The other ends of these couplings are rigidly connected to the acceleration gearbox 3 and the reduction gearbox 9, respectively, with the diaphragms in an uninstalled state. The laser emitting unit and laser receiving power supply of the high-precision laser alignment measuring instrument 5 are respectively fixedly connected to the two bushing housings of the diaphragm disc coupling 4 between the acceleration gearbox 3 and the test gearbox 6.

Claims

1. An automatic centering adjustment method for a gearbox test bench, characterized in that, Includes the following steps: S1. Based on the area where the test gearbox turning interface is located, project coded structured light to perform visual recognition and preliminary positioning of the turning interface. Read the spatial pose matrix of the turning interface obtained by positioning in the coordinate system of the vision module. After determining the safe approach point, perform motion planning. After obtaining the status confirmation signal that the robot arm has reached the safe approach point, output the turning probe insertion confirmation signal and the contact force and torque data packet. Send the command to the end rotary actuator of the turning robot arm to make the test gearbox shaft system be in the initial measurement angle state and obtain the current absolute angle value. S2. Based on the laser centering measuring instrument, start single-point measurement, convert the emitted fan-shaped laser into an analog voltage signal and then into a digital signal, and calculate the orthogonal sway angle of the laser incident direction relative to the normal of the receiving unit measurement surface. After distortion correction and temperature drift compensation, output the spatial pose deviation data packet under the initial measurement angle. S3. Based on the first fixed offset, the second fixed offset, and the membrane disk installation spacing obtained from the system calibration, and combined with the created reference coordinate system, perform spatial coordinate transformation to obtain the three-dimensional coordinates of the origin of the ideal test gearbox shaft system target coordinate system in the reference coordinate system. The mapping of the test gearbox shaft system coordinate system in space should be used as the absolute ideal target alignment pose model. Based on the spatial pose deviation data packet under the initial measurement angle, obtain the current error state vector. Based on the pose represented by the absolute ideal target alignment pose model, use the pose as the trajectory endpoint. Use the current actual pose inversely deduced by combining the current error state vector and the current pose as the trajectory starting point to generate a smooth spatial docking trajectory and output the smooth spatial docking trajectory pose point sequence. S4. Perform inverse kinematics on the six-degree-of-freedom adjustment platform to solve the pose sequence of the smooth spatial docking trajectory. After traversal calculation, obtain the expected motion velocity sequence and expected motion acceleration sequence of each electric cylinder at each moment. Output a set of command sequences for the expected length, velocity, and acceleration of each electric cylinder. The command sequence set is synchronously sent to the motion controller via a high-speed real-time motion bus with the same time step as in the smooth spatial docking trajectory generation process. Complete closed-loop trajectory tracking based on feedforward-feedback composite control. Use the feedback of the initial alignment motion completion status signal as the re-execution signal of S1. Complete the iterative measurement-compensation closed loop according to the new measured phase angle value and the axis system in place status signal, and output the final alignment accuracy status signal.

2. The automatic centering adjustment method for a gearbox test bench according to claim 1, characterized in that, The S1 projected coded structured light onto the area where the test gearbox turning interface was located based on the machine vision module fixed at the wrist of the turning arm and collected point cloud data and a two-dimensional grayscale image. The point cloud data is processed by calling a 3D template matching algorithm based on geometric features, including: extracting the outer cylindrical surface, end annular plane and center hole edge of the point cloud data from the pre-stored computer-aided design model of the turning gear interface as rigid geometric primitives of the computer-aided design model, and registering the computer-aided design model with the scene data using an iterative nearest point algorithm based on the scene point cloud. By minimizing the sum of squared Euclidean distances between the rigid geometric primitives and corresponding points in the scene point cloud, the spatial position and orientation of the turning gear interface in the coordinate system of the machine vision module are iteratively solved, and the spatial pose matrix of the turning gear interface in the coordinate system of the machine vision module is output. The spatial pose matrix of the turning interface in the vision module coordinate system is read, and the fixed coordinate transformation matrix of the machine vision module coordinate system relative to the turning manipulator base coordinate system, which was obtained in advance through the hand-eye calibration program, and the center point calibration data of the turning probe tool are called. The spatial pose matrix is ​​transformed from the vision module coordinate system to the turning manipulator base coordinate system through matrix multiplication to obtain the target position matrix of the turning interface in the manipulator base coordinate system. Creating a safe approach point includes: taking the axial length from the front end face of the rotating probe to the shoulder as the effective length of the probe, and adding the effective length of the probe to a preset additional buffer distance to obtain a safe distance; Based on the target pose matrix of the trolley interface in the coordinate system of the robot arm base, the three-dimensional coordinates of the center point of the front face of the interface and the interface normal vector are extracted, and the safe distance is translated in the opposite direction along the normal vector to generate spatial coordinate points. The coordinates of the spatial coordinate points are combined with the posture that makes the axis of the trolley probe parallel to the interface normal vector to construct a target pose matrix with a safe approach point. Based on the current end-effector center point pose of the rotary manipulator as the starting point and the target pose matrix of the safe approach point as the ending point, a straight path is planned using a trapezoidal velocity curve. Each interpolation point on the straight path is converted into the angle sequence of each joint of the rotary manipulator through inverse Jacobian numerical iteration. The angle sequence command of each joint is sent to the joint servo driver of the rotary manipulator, which drives the rotary probe carried at the end of the rotary manipulator actuator to move to the safe approach point and outputs a status confirmation signal that the manipulator has reached the safe approach point.

3. The automatic centering adjustment method for a gearbox test bench according to claim 1, characterized in that, After receiving the status confirmation signal that the robotic arm has reached the safe approach point through the industrial computer 12, S1 switches the control mode of the turning mechanical arm to admittance control and collects contact force and contact torque data in real time based on the six-dimensional force and torque sensor installed between the wrist of the turning mechanical arm and the end of the actuator. Based on the compliant feed motion performed by the trolley robotic arm from the safe approach point along the interface normal direction, and the continuous monitoring of the force component data of the six-dimensional force and torque sensor in the axial direction of the interface during the compliant feed motion, when the front guide cone of the trolley probe slides into the interface guide hole and the shoulder end face of the probe contacts the front face of the trolley interface, the torque components in the two orthogonal radial directions of the interface are calculated in real time based on the contact force and contact torque data. When the calculated axial force step amplitude exceeds the force threshold and the absolute value of the calculated radial torque components does not exceed the preset safe torque threshold, it is determined that the trolley probe has reached the specified insertion depth and the shoulder of the trolley probe is completely in contact with the interface end face. The trolley robotic arm is then issued a stop feed command and outputs a trolley probe insertion confirmation signal and the final contact force and torque data packet. After sending a command to the end effector of the manipulator to drive the manipulator probe to rotate at a constant speed, and continuously reading the absolute angular position feedback signal of the shaft system installed on the input shaft end of the test gearbox and / or converted by the joint encoder of the manipulator and the transmission ratio, if the shaft system angular position reaches the preset initial measurement angle, the end effector of the manipulator stops and activates the brake to keep the manipulator probe at the initial measurement angle, and outputs a signal that the shaft system of the test gearbox is at the initial measurement angle and the current absolute angle value.

4. The automatic centering adjustment method for a gearbox test bench according to claim 3, characterized in that, S2 sends a start single-point measurement command to the laser alignment measuring instrument. The laser emitting unit of the laser alignment measuring instrument emits a fan-shaped laser beam from its internal laser diode to the laser receiving unit fixed on the housing of the diaphragm coupling bushing on the side of the test gearbox. The two-dimensional position sensitive detector built into the laser receiving unit senses the center position of the laser spot on the photosensitive surface, converts it into an analog voltage signal through a photoelectric conversion and amplification circuit, and converts it into a digital signal through an analog-to-digital converter. Based on the tilt sensor and phase calculation circuit inside the laser receiving unit, it calculates two orthogonal yaw angles of the laser incident direction relative to the normal of the measurement surface of the receiving unit. The embedded processor of the laser alignment measuring instrument performs nonlinear distortion correction and temperature drift compensation on the two orthogonal yaw angles, including radial position signals and yaw angle signals, using the factory-calibrated intrinsic parameter matrix. It then obtains spatial pose deviation data, including the horizontal radial offset and vertical radial offset of the shaft system at the input end of the test gearbox in the measurement plane of the laser receiving unit, as well as the yaw angles in the horizontal and vertical planes relative to the reference axis. The current timestamp and angle label are added, and the spatial pose deviation data packet at the initial measurement angle is output.

5. The automatic centering adjustment method for a gearbox test bench according to claim 1, characterized in that, The S3 is based on reading the length calibration parameters that have been obtained and permanently stored in the memory through the measurement and system calibration process in advance. These parameters include: a fixed distance from the origin of the coordinate system of the center of the laser emitting unit measuring surface along the longitudinal axis to the mounting end face of the diaphragm coupling bushing on the side of the acceleration gearbox, which is the first fixed offset; a fixed distance from the origin of the coordinate system of the center of the laser receiving unit measuring surface along the longitudinal axis to the mounting end face of the diaphragm coupling bushing on the side of the test gearbox, which is the second fixed offset; and an axial clearance between the two coupling end faces in the fully released state, which is determined according to the design of the diaphragm coupling based on the diaphragm coupling. Based on the virtual reference coordinate system created in the memory, a synthetic spatial coordinate transformation operation is performed with the reference coordinate system as the starting point. This includes: translating the first fixed offset along the positive direction of the vertical axis of the reference coordinate system, then translating the membrane disk installation spacing, and finally translating the second fixed offset. The point obtained by the translation is the three-dimensional coordinate of the origin of the ideal test gearbox shaft system target coordinate system under the reference coordinate system. The spatial coordinate transformation of the first synthesis is used as a mapping of the position and attitude of the test gearbox shaft system coordinate system in space to obtain an absolutely ideal target centering pose model, which is temporarily stored in the memory.

6. The automatic centering adjustment method for a gearbox test bench according to claim 5, characterized in that, S3 calls the spatial pose deviation data packet under the initial measurement angle, uses the spatial pose deviation data packet as the pose deviation of the current coordinate system of the test gearbox shaft system relative to the reference coordinate system, and compares the pose deviation with the absolutely ideal target centering pose model to calculate and obtain the spatial position error vector and attitude error vector that need to be eliminated from the current pose to the target pose, and obtains the current error state vector containing the spatial position error vector and attitude error vector.

7. The automatic centering adjustment method for a gearbox test bench according to claim 6, characterized in that, S3 uses the pose represented by the absolutely ideal target alignment pose model as the trajectory endpoint and the current actual pose inversely deduced by combining the current error state vector with the current pose as the trajectory starting point to initiate the task space trajectory. This includes: a multi-degree-of-freedom synchronous smoothing algorithm based on fifth-order polynomial interpolation, which constructs fifth-order polynomial functions with respect to time for the three positional degrees of freedom and the three pose degrees of freedom expressed using rotational quaternions, and analytically solves for all coefficients of the fifth-order polynomial by forcibly setting the zeroth, first, and second derivative values ​​of each polynomial at the trajectory starting and ending times. Based on a constant time step, the six polynomials are sampled over the total motion time, and the generated six-dimensional intermediate pose points constitute a complete spatial motion path from the current pose to the target pose, outputting a smooth spatial docking trajectory pose point sequence.

8. The automatic centering adjustment method for a gearbox test bench according to claim 1, characterized in that, S4 performs inverse kinematics solution on each pose point in the smooth spatial docking trajectory pose point sequence using a calibrated six-degree-of-freedom adjustment platform inverse kinematics algorithm module. Based on the successful solution and / or initial static equilibrium pose of each input pose point as the initial value of the iteration, the nonlinear constraint equation system is solved by the Newton-Raphson iterative method. In each iteration, starting from the currently guessed dynamic platform pose, the spatial distance between the upper and lower hinge center points of each electric cylinder is calculated using spatial vector operations to obtain the six theoretical rod lengths. Then, the length residual between the current rod length and the expected rod length is calculated, and the Jacobian matrix mapping the length residual to the spatial distance is constructed. By obtaining the pseudo-inverse of the Jacobian matrix and multiplying it by the vector of the length residual, the correction amount of the dynamic platform pose is obtained, and finally, the expected absolute extension length values ​​of the six electric cylinders corresponding to the pose point are obtained. After traversing and calculating all points in the smooth spatial docking trajectory pose sequence, six sets of discrete length sequences are obtained. The six sets of discrete length sequences are then subjected to three-point center difference numerical differentiation in the time domain to obtain the expected motion velocity sequence and expected motion acceleration sequence of each electric cylinder at each moment. The summaries output a set of expected length, velocity, and acceleration command sequences for each of the six electric cylinders.

9. The automatic centering adjustment method for a gearbox test bench according to claim 8, characterized in that, S4 synchronously sends the desired length, speed, and acceleration command sequence sets of each of the six electric cylinders to the motion controller via a high-speed real-time motion bus at the same time step as trajectory generation, and performs feedforward-feedback composite control, including: reading the desired length, desired speed, and desired acceleration of the cylinder at the current moment; receiving the current actual extension length fed back by the absolute linear encoder installed inside the electric cylinder, and obtaining the actual speed through a hardware differential; calculating the difference between the desired length and the actual length as the position error; generating a speed feedforward force component based on the desired speed, and generating a speed feedforward force component based on the desired acceleration; inputting the position error to the PID controller to obtain the feedback force component; algebraically adding the acceleration feedforward force component, the acceleration feedforward force component, and the feedback force component to form a total control force command; converting the control force command into a current command for the torque motor through a torque constant, and driving the electric cylinder to move after being amplified by a current loop. The feedback signal indicating the completion of the initial alignment motion is used as the operation start signal for S1, and a new measured phase angle value and a signal indicating that the shaft system is in place are output.

10. An automatic centering adjustment system for a gearbox test bench, applied to the automatic centering adjustment method for a gearbox test bench as described in any one of claims 1-9, characterized in that, The system includes: Industrial computer; used to read the spatial pose matrix of the turning gear interface and laser measurement data, call the system calibration parameters to perform spatial coordinate transformation, construct an absolutely ideal target centering pose model, solve the current error state vector and generate a smooth spatial docking trajectory pose point sequence, complete the inverse kinematics solution of the six-degree-of-freedom adjustment platform and output a set of motion command sequences. A six-degree-of-freedom adjustment platform is used for rigid load-bearing test gearboxes. It performs six-degree-of-freedom posture adjustment according to motion commands, driving the test gearbox shaft system to complete the compensation and correction of centering deviation. A rotary manipulator arm; it is used to identify and locate the rotary interface by projecting coded structured light, and to complete the smooth insertion and docking of the rotary probe in admittance control mode, and to rotate the test gearbox shaft system to the specified measurement angle. Laser alignment measuring instrument; includes a laser emitting unit and a laser receiving unit respectively fixed to the diaphragm coupling bushing on the side of the acceleration gearbox and the diaphragm coupling bushing on the side of the test gearbox, used to collect spatial pose deviation data of the test gearbox shaft system relative to the reference axis at different measurement angles, and transmit it to an industrial computer; Motion controller; used to receive a set of motion command sequences issued by an industrial computer, synchronously drive each electric cylinder and the turning manipulator of the six-degree-of-freedom adjustment platform through a high-speed real-time motion bus, and complete closed-loop trajectory tracking and iterative centering adjustment based on feedforward-feedback composite control.

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