Underwater laser shock light guide arm and workpiece robot collaborative control system and method

Abstract

The application discloses an underwater laser impact light guide arm and workpiece robot collaborative regulation system and method, and the method comprises the following steps: according to different shapes of workpieces to be machined, a work platform is built and adjusted, and a corresponding working environment is built in offline programming software; laser impact parameter setting is completed, a 3D visual dynamic scanning system is used, a double-robot trajectory is planned based on an A* algorithm and is sent to a terminal controller; the controller is connected with the double robot, a laser displacement sensor is started, and the system enters a standby state; the double robot is driven to point i according to the planned trajectory, a 3D visual feedback is performed on the relative pose of the light guide arm and the workpiece impact point and pose compensation is performed until the perpendicularity deviation is less than a threshold value; the laser displacement sensor feeds back the distance from the end to the workpiece and distance compensation is performed until the distance deviation is less than a threshold value, a laser pulse is triggered, and point i impact is completed; the above steps are repeated, and laser impact of the entire planned path is completed.

Description

Technical Field

[0001] This invention belongs to the field of underwater laser shock processing, specifically relating to a collaborative control system and method for an underwater laser shock beam guide arm and a workpiece robot. Background Technology

[0002] Laser shock lithography is a surface strengthening technology that uses the GPa-level shock wave generated by the coupling of nanosecond-level or faster pulsed laser with the plasma at the material interface to modify the surface of metals. It is widely used in the aerospace field and can be used for surface treatment of high-load, high-cyclic fatigue components such as wing leading edges, engine blades and landing gear.

[0003] In conventional laser shock peening, a thin water film serves as a confinement medium for the shock wave to constrain plasma expansion and increase the peak impact pressure. Underwater laser shock peening, by directly immersing the workpiece in liquid water, utilizes the high sound velocity and incompressibility of water to more effectively confine plasma expansion, thereby achieving a higher peak impact pressure, a deeper and more uniform residual compressive stress field, while effectively suppressing surface thermal damage and spatter contamination, significantly improving the fatigue life, crack resistance, and wear resistance of the material.

[0004] However, due to water pressure, refraction, and scattering effects in the underwater environment, the projected diameter of the laser spot on the incident surface is prone to fluctuation, and the focal length of the laser is also affected by the underwater environment. This makes it difficult to maintain a consistent laser power density for each impact, resulting in inconsistent strengthening depth and residual stress distribution, which severely restricts the accuracy and repeatability of underwater laser shock. In summary, there is an urgent need to break through the core key technologies and develop an underwater laser shock control system that can ensure a constant laser power density. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a collaborative control system and method for underwater laser shock beam guide arm and workpiece robot. By using dual robots to perform underwater laser shock in collaboration, the system effectively avoids the defocusing of the beam and energy density fluctuations caused by refraction or clamping deviations in traditional underwater laser shock.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A collaborative control system for an underwater laser shock beam guide arm and a workpiece robot, the system comprising: a laser emitting device (1), a six-degree-of-freedom beam guide robot (2), a six-degree-of-freedom workpiece clamping robot (3), a visual dynamic measurement system (4), a laser displacement sensor (5), an industrial control computer (6), and a water tank (7);

[0008] The laser emitting device (1) includes a laser generator (10), a six-degree-of-freedom light guide arm (11), and a light guide end effector (111);

[0009] The laser emitting device (1) is used to emit high-energy lasers;

[0010] The six-degree-of-freedom light-guiding robot (2) is used to hold the light-guiding end effector (111) and move it so as to conduct laser light along a preset path;

[0011] The visual dynamic measurement system (4) is used to calibrate the positional relationship between the six-degree-of-freedom light guide robot (2) and the six-degree-of-freedom workpiece clamping robot (3) in order to achieve dynamic control during the impact process;

[0012] The laser displacement sensor (5) is used to measure the vertical distance between the laser output port of the light guide end effector (111) and the impact point of the workpiece, thereby obtaining the focal length;

[0013] The water tank (7) is used to immerse the workpiece during the impact process;

[0014] The laser emitting device (1), the six-degree-of-freedom light-guiding robot (2), the six-degree-of-freedom workpiece clamping robot (3), and the water tank (7) constitute a collaborative laser shock processing system; the industrial control computer (6) is used to control the collaborative laser shock processing system and receive and process the information fed back by the visual dynamic measurement system (4) and the laser displacement sensor (5).

[0015] Preferably, the six-degree-of-freedom workpiece clamping robot (3) is located on one side of the laser emitting device (1), and a special clamp is installed at its end; the six-degree-of-freedom light guiding robot (2) is located on the other side of the laser emitting device (1), clamping the light guiding end effector (111), and a laser displacement sensor (5) is installed on the light guiding end effector (111); the visual dynamic measurement system (4) is located in front of the collaborative laser shock processing system, and ensures that the main measured coordinate system moves within its field of view; the water tank (7) is located below the six-degree-of-freedom workpiece clamping robot (3); the industrial control computer (6) connects the six-degree-of-freedom light guiding robot (2), the six-degree-of-freedom workpiece clamping robot (3), the visual dynamic measurement system (4), and the laser displacement sensor (5);

[0016] The laser displacement sensor (5) is equipped with a waterproof optical cover for underwater environments and compensates for window refraction and scattering losses.

[0017] The laser displacement sensor (5) and the light outlet of the light guide end effector (111) are spaced apart, and the measured distance should be reduced by the distance.

[0018] Preferably, the six-degree-of-freedom light-guiding robot (2) and the six-degree-of-freedom workpiece clamping robot (3) first plan their initial motion paths through offline programming. During the operation, the motion posture of the two robots is monitored in real time through digital twin technology. The visual dynamic measurement system (4) provides real-time on-site data of the relative position of the light-guiding end effector (111) and the workpiece impact point to guide the two robots to always keep the laser beam perpendicular to the workpiece impact point. The laser displacement sensor (5) provides real-time on-site distance between the light outlet of the light-guiding end effector (111) and the workpiece impact point to adjust the posture of the six-degree-of-freedom workpiece clamping robot (3) to ensure that the distance between the light-guiding end effector (111) and the workpiece impact point remains unchanged during each impact, thereby maintaining the predetermined laser spot diameter. The position accuracy of the two robots is ≤0.2mm, the posture accuracy is ≤0.1°, and the trajectory accuracy is ≤0.5mm.

[0019] This invention also provides a method for the coordinated control of an underwater laser shock beam guide arm and a workpiece robot, the method being implemented through the aforementioned system, the method comprising:

[0020] Step a: Based on the different shapes of the workpieces to be processed, build and adjust the work platform, and build the corresponding work environment in the offline programming software;

[0021] Step b: Complete the laser shock parameter setting, use the 3D vision dynamic scanning system, plan the dual robot trajectory based on the A* algorithm and send it to the terminal controller;

[0022] Step c: Connect the controller to the two robots, activate the laser displacement sensor, and the system enters standby mode;

[0023] Step d: Drive the dual robots to point i according to the planned trajectory. The 3D vision feedback light guide arm and the workpiece impact point are relatively in pose and the attitude is compensated until the verticality deviation is less than the verticality threshold.

[0024] Step e: The laser displacement sensor feeds back the distance from the end to the workpiece and performs distance compensation until the distance deviation is less than the distance threshold, then triggers the laser pulse to complete the point i impact;

[0025] Step f, repeat steps c, d, and e to complete the laser impact of the entire planned path.

[0026] Preferably, the implementation process of step b is as follows:

[0027] Turn on the laser emitting device (1), set the laser impact path, laser output power P and spot size ω, and check the absorption layer and water constraint layer; turn on the visual dynamic measurement system (4), and according to the laser impact path, use the A* algorithm to plan the motion path of the six-degree-of-freedom light guide robot (2) and the six-degree-of-freedom workpiece clamping robot (3) to complete the entire impact process and input it into the industrial control computer (6).

[0028] Preferably, the relationship between laser output power P and spot size ω is as follows: The laser power density I can be obtained from P and ω.

[0029] The specific process of starting the visual dynamic measurement system (4), planning the motion path of the six-degree-of-freedom light guide robot (2) and the six-degree-of-freedom workpiece clamping robot (3) to complete the entire impact process based on the laser impact path and inputting it into the industrial control computer (6) is as follows:

[0030] Step b1: A metrology-grade 3D scanner performs point cloud acquisition on the collaborative laser shock processing system to obtain the spatial information of the entire system, specifically including the actual digital model of the workpiece and the workpiece coordinate system; the joint joint space of the six-degree-of-freedom light-guiding robot (2) and the six-degree-of-freedom workpiece clamping robot (3) is defined as the state space, and the workpiece impact area is obtained from the point cloud digital model, with the initial joint configuration. As the root node, where, and This is the initial joint configuration vector in the joint joint space of the two robots: a light-guiding robot A and a workpiece clamping robot B; it reads the predefined laser impact path target pose sequence. Among them, P i R is the position vector of the i-th target pose. i Let be the pose of the i-th target pose, and N be the total number of target pose points that need to be laser-driven; set the joint space step size Δq, the heuristic function h(q), and the maximum number of iterations;

[0031] Step b2: For each impact pose (P) i ,R i ): Initialize list O to the root node state s0 = (q 0 ,i), close list C to be empty; select the state s from O that minimizes the evaluation function f(s)=g(s)+h(s). cur =(q cur ,i), and move it into C, where g(s) is the cumulative true cost from the initial node to the current state s, and h(s) is the sum of the true costs from the current state s to the current target pose (P i ,R i The estimated cost of s cur This is the currently searched state node, qcur It is the joint joint configuration of the two robots at the current moment; if s cur The corresponding robot position orientation satisfies (P) i ,R i If the target point is reached, then mark the i-th point as achieved and prepare to plan the (i+1)-th point; otherwise, based on the joint joint space, adjust the joint configuration vector q of the light-guiding robot A with a step size ±Δq. A The joint configuration vector q of the workpiece clamping robot B B Several neighbor states s are generated above. nbr =(q nbr ,i), calculate the cost increment g(s) nbr )=g(s cur )+ / / Δq / / , where s nbr It is s cur The neighbor state node, q nbr It is q cur Neighbor joint configuration, g(s) nbr ) is from the initial node to the current node s nbr The actual cost of the path taken, g(s) cur ) is from the initial node to the current node s cur The actual cost of the path taken, ‖Δq‖, is from q cur to q nbr If the step size cost is less than the original record, update its g value and add it to C, until O is empty or the target is found;

[0032] Step b3: After all the planning of point N is completed, the parent state pointer is traced back from the endpoint state to reconstruct the joint joint node sequence. The discrete sequence is smoothed by cubic spline interpolation to generate a continuous joint time parameter quantized trajectory. The industrial control computer (6) completes the path planning of robot A / B according to the interpolated trajectory.

[0033] Preferably, the implementation process of step c is as follows: the industrial control computer (6) connects the six-degree-of-freedom light guide robot (2) and the six-degree-of-freedom workpiece clamping robot (3), turns on the laser displacement sensor (5), and completes the preparation work.

[0034] Preferably, the implementation process of step d is as follows: the collaborative laser shock processing system starts the workflow, and after the previous point is impacted, the system moves to the next point to be impacted according to the motion path of step b; the visual dynamic measurement system (4) provides feedback on the real-time relative position between the light guide end effector (111) and the workpiece to be impacted; according to the feedback data, the industrial control computer (6) controls the six-degree-of-freedom light guide robot (2) or the six-degree-of-freedom workpiece clamping robot (3) to perform pose error compensation until the perpendicularity deviation between the light guide end effector (111) and the workpiece to be impacted is less than the set threshold.

[0035] Preferably, the method for adjusting the perpendicularity deviation between the light guide end effector (111) and the workpiece impact point by the visual dynamic measurement system (4) is as follows:

[0036] Step d1: A metrology-grade 3D scanner performs high-precision point cloud acquisition. Using the weighted iterative nearest point (ICP) algorithm, the reference feature coordinate system of the light guide end effector (111) is registered with the reference feature coordinate system of the workpiece impact point. The angular error Δθ between the optical axis of the light guide end effector (111) and the normal to the workpiece surface is calculated. The theoretical threshold for perpendicularity is θ. thr ;

[0037] Step d2: When |Δθ|>θ thr If the light guide end effector (111) joint is reachable within its workspace, then the joint increment of the light guide robot is calculated first. The attitude of the light guide end effector (111) is fine-tuned by inverse kinematic mapping; if the light guide end effector (111) exceeds its workspace, the joint increment of the workpiece clamping robot is calculated instead. This causes a corresponding micro-rotation on the workpiece surface;

[0038] Step d3: The industrial computer (6) will... and The commands are converted into synchronous end-effector control commands and sent to the two six-DOF robots to perform minor pose adjustments. After the adjustments are completed, the 3D scanner re-acquires point clouds and calculates new Δθ until |Δθ|≤θ is satisfied. thr Complete the verticality deviation compensation.

[0039] Preferably, the implementation process of step e is as follows:

[0040] After the verticality deviation is set, the laser displacement sensor (5) feeds back the real-time distance between the light outlet of the light guide end effector (111) and the workpiece impact point; according to the feedback data, the industrial control computer (6) controls the six-degree-of-freedom light guide robot (2) or the six-degree-of-freedom workpiece clamping robot (3) to perform posture error compensation until the distance between the light outlet of the light guide end effector (111) and the workpiece impact point is less than the set threshold, and then impacts the next point;

[0041] The specific method by which the laser displacement sensor (5) adjusts the distance between the light outlet of the light guide end actuator (111) and the impact point of the workpiece is as follows:

[0042] Step e1: The laser displacement sensor (5) obtains the distance d between the light outlet of the light guide end actuator (111) and the impact point of the workpiece by the triangulation method. Based on the light spot size set in step b, the theoretical distance d0 between the light outlet of the light guide end actuator (111) and the impact point of the workpiece is obtained. The distance error Δd = d - d0.

[0043] Step e2: Laser propagation in water will cause attenuation. Let the total attenuation coefficient per unit length of the laser during propagation in water be a, and the theoretical laser power density be I0. According to Beer-Lambert's law, the laser attenuates approximately exponentially, and the actual laser power density underwater is I = I0e. -aΔd It is necessary to ensure that I is at least I0 for η. min (η min ≥0.98 times, from which the maximum allowable defocus amount after power attenuation can be obtained: d thr This is the theoretical threshold for distance underwater;

[0044] Step e3: When |Δd|>d thr If the light guide end effector (111) joint is feasible, then the joint increment of the light guide robot should be calculated first. The pose of the light guide end effector (111) is compensated online by inverse kinematic mapping; if the light guide arm has reached its working limit, the calculation of the joint increment of the workpiece clamping robot is changed. This causes corresponding micro-translations on the workpiece surface;

[0045] Step e4: The industrial computer (6) will... and The command is converted into a synchronous end-effector control command and sent to the two six-degree-of-freedom robots to perform micro-pose adjustments. After the adjustment is completed, the laser displacement sensor (5) remeasures until |Δd|≤d is satisfied. thr This completes distance deviation compensation.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] (1) This invention proposes a collaborative control system and method for an underwater laser shock beam guide arm and a workpiece robot. The system includes a laser emitting device, a six-degree-of-freedom beam guide robot, a six-degree-of-freedom workpiece clamping robot, a visual dynamic measurement system, a laser displacement sensor, an industrial control computer, and a water tank. The six-degree-of-freedom workpiece clamping robot is located on one side of the laser emitting device, and a special clamp is installed at its end. The six-degree-of-freedom beam guide robot is located on the other side of the laser emitting device and clamps the beam guide end effector. A laser displacement sensor is installed on the beam guide end effector. The visual dynamic measurement system is located in front of the collaborative laser shock processing system and ensures that the main measured coordinate system moves within its field of view. The water tank is located below the six-degree-of-freedom workpiece clamping robot. The industrial control computer connects the six-degree-of-freedom beam guide robot, the six-degree-of-freedom workpiece clamping robot, the visual dynamic measurement system, and the laser displacement sensor. The six-DOF light-guiding robot and the six-DOF workpiece clamping robot first plan their initial motion paths through offline programming. During operation, the motion posture of the two robots is monitored in real time through digital twin technology. The visual dynamic measurement system provides real-time on-site data on the relative positions of the light-guiding end effector and the workpiece impact point to guide the two robots to always keep the laser beam perpendicular to the workpiece impact point. The laser displacement sensor provides real-time on-site distance between the light-guiding end effector's light outlet and the workpiece impact point to adjust the posture of the six-DOF workpiece clamping robot to ensure that the distance between the light-guiding end effector and the workpiece impact point remains unchanged during each impact, thereby maintaining the predetermined laser spot diameter.

[0048] (2) Through metrological-grade 3D visual dynamic scanning and real-time correction by laser displacement sensor, the normal of the light guide arm and the workpiece impact point are always kept perpendicular and the focal length is kept constant, which effectively avoids the defocusing of the light spot and the fluctuation of energy density caused by refraction or clamping deviation in traditional underwater laser impact.

[0049] (3) The collaborative control of the six-degree-of-freedom workpiece clamping robot and the light guide robot can flexibly adjust the light path and workpiece posture, overcome the difficulties of space limitation and multi-axis curved surface processing, and realize continuous and uniform strengthening of components with high service performance requirements, poor openness and complex structure, such as landing gear and engine blades. Attached Figure Description

[0050] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of the underwater laser shock beam guide arm and workpiece robot collaborative control system according to an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of the laser emitting device in the underwater laser shock beam guide arm and workpiece robot collaborative control system according to an embodiment of the present invention;

[0053] Figure 3 This is a flowchart of the underwater laser shock beam guide arm and workpiece robot collaborative control method according to an embodiment of the present invention;

[0054] Figure 4 This is a schematic diagram of the laser shock process in the underwater laser shock light guide arm and workpiece robot collaborative control system according to an embodiment of the present invention;

[0055] Figure 5 This is a schematic diagram of the A* algorithm used for laser shock path planning in the underwater laser shock light guide arm and workpiece robot collaborative control system according to an embodiment of the present invention.

[0056] Figure 6 This is a flowchart illustrating the control process during the underwater laser shock beam guide arm and workpiece robot collaborative control method according to an embodiment of the present invention.

[0057] Wherein: 1—Laser emitting device; 2—Six-DOF light guiding robot; 3—Six-DOF workpiece clamping robot; 4—Vision dynamic measurement system; 5—Laser displacement sensor; 6—Industrial control computer; 7—Water tank; 10—Laser generator; 11—Six-DOF light guiding arm; 111—Light guiding end effector. Detailed Implementation

[0058] 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.

[0059] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] Example 1

[0061] The underwater laser shock guide arm and workpiece robot collaborative control system provided by this invention can ensure a constant laser power density. Figure 1 As shown, the system includes a laser emitting device 1, a six-degree-of-freedom light-guiding robot 2, a six-degree-of-freedom workpiece clamping robot 3, a vision dynamic measurement system 4, a laser displacement sensor 5, an industrial control computer 6, and a water tank 7.

[0062] like Figure 2As shown, the laser emitting device 1 includes a laser generator 10, a six-degree-of-freedom light guide arm 11, and an end effector 111.

[0063] Laser emitting device 1 is used to emit high-energy laser; six-degree-of-freedom light-guiding robot 2 is used to hold end effector 111 and move it to conduct laser along a preset path; visual dynamic measurement system 4 is used to calibrate the positional relationship between six-degree-of-freedom light-guiding robot 2 and six-degree-of-freedom workpiece clamping robot 3 to achieve dynamic control during the impact process; laser displacement sensor 5 is used to measure the vertical distance between the laser output port of end effector 111 and the workpiece to be impacted, thereby obtaining the focal length; water tank 7 is used to immerse the workpiece during the impact process; laser emitting device 1, six-degree-of-freedom light-guiding robot 2, six-degree-of-freedom workpiece clamping robot 3 and water tank 7 constitute a collaborative laser impact processing system; industrial control computer 6 is used to control the collaborative laser impact processing system and receive and process the information fed back by visual dynamic measurement system 4 and laser displacement sensor 5.

[0064] The six-degree-of-freedom light-guiding robot 2 and the six-degree-of-freedom workpiece clamping robot 3 first plan their initial motion paths through offline programming. During operation, the motion posture of the two robots is monitored in real time through digital twin technology. The visual dynamic measurement system 4 provides real-time on-site data of the relative position of the end effector 111 and the workpiece impact point to guide the two robots to always keep the laser beam perpendicular to the workpiece impact point. The laser displacement sensor 5 provides real-time on-site distance between the light outlet of the end effector 111 and the workpiece impact point to adjust the posture of the six-degree-of-freedom workpiece clamping robot 3 to ensure that the distance between the end effector 111 and the workpiece impact point remains unchanged during each impact, thereby maintaining the predetermined laser spot diameter. The position accuracy of the two robots is ≤0.2mm, the posture accuracy is ≤0.1°, and the trajectory accuracy is ≤0.5mm.

[0065] Example 2

[0066] This invention provides a method for the coordinated control of an underwater laser shock beam guide arm and a workpiece robot, such as... Figure 3 As shown, it includes the following steps:

[0067] Step a: Based on the different shapes of the workpieces to be processed, build and adjust the work platform, and build the corresponding work environment in the offline programming software;

[0068] Step b: Turn on the laser emitting device 1, set the laser impact path, laser spot size and energy, and check the absorption layer and water confinement layer; turn on the visual dynamic measurement system 4, and according to the laser impact path, use the A* algorithm to plan the motion path of the six-degree-of-freedom light guiding robot 2 and the six-degree-of-freedom workpiece clamping robot 3 to complete the entire impact process and input it into the industrial control computer 6.

[0069] Step c: Connect the industrial control computer 6 to the six-degree-of-freedom light-guiding robot 2 and the six-degree-of-freedom workpiece clamping robot 3, turn on the laser displacement sensor 5, and complete the preparation work;

[0070] Step d: The collaborative laser shock processing system starts its workflow. After the previous point is impacted, the system moves to the next point to be impacted according to the motion path in step b. The visual dynamic measurement system 4 provides feedback on the real-time relative position between the end effector 111 and the workpiece impact point. Based on the feedback data, the industrial control computer 6 controls the six-degree-of-freedom light-guiding robot 2 or the six-degree-of-freedom workpiece clamping robot 3 to perform pose error compensation until the perpendicularity deviation between the end effector 111 and the workpiece impact point is less than the set threshold.

[0071] After step e, the verticality deviation setting is completed, the laser displacement sensor 5 provides feedback on the real-time distance between the light output port of the end effector 111 and the workpiece impact point. Based on the feedback data, the industrial control computer 6 controls the six-degree-of-freedom light-guiding robot 2 or the six-degree-of-freedom workpiece clamping robot 3 to perform pose error compensation until the distance between the light output port of the end effector 111 and the workpiece impact point is less than the set threshold, and then impacts the next point.

[0072] Step f, repeat steps c, d, and e until the entire impact process is complete. Figure 4 This is a schematic diagram of the laser shock process.

[0073] The dual-robot path planning algorithm of this invention is implemented by combining the A* algorithm with offline programming software. The principle and flow of the A* algorithm are as follows: Figure 5 As shown, specifically:

[0074] (1) A metrology-grade 3D scanner performs high-precision point cloud acquisition on the collaborative laser shock processing system to obtain the spatial information of the entire system, specifically including the actual digital model of the workpiece and the workpiece coordinate system. The joint space of the six-degree-of-freedom light-guiding robot 2 and the six-degree-of-freedom workpiece clamping robot 3 is defined as the state space. The impact area of ​​the workpiece is obtained from the point cloud digital model, and the initial joint configuration is used. As the root node, where, and q is the initial joint configuration vector in the joint joint space of the two robots (light-guiding robot A and workpiece clamping robot B). 0 It is a vector formed by the combination of the joint angles (or joint positions) of the two robots; read the predefined target pose sequence of the laser impact path. Among them, P i R is the position vector of the i-th target pose. i is the pose of the i-th target pose, and N is the total number of target pose points that need to be laser-driven; set the joint space step size Δq, the heuristic function h(q), and the maximum number of iterations.

[0075] (2). For each impact pose (P) i ,R i ): Initialize list O to the root node state s0 = (q 0 ,i), close list C to be empty; repeat the following steps until O is empty or the target is found: select the state s from O that minimizes the evaluation function f(s)=g(s)+h(s). cur =(q cur ,i), and move it into C, where g(s) is the cumulative true cost from the initial node to the current state s, and h(s) is the sum of the true costs from the current state s to the current target pose (P i ,R i The estimated cost of s cur This is the currently searched state node, q cur It is the joint joint configuration of the two robots at the current moment; if s cur The corresponding robot position / orientation satisfies (P) i ,R i If point i is reached, then point i+1 is planned; otherwise, based on the joint joint space, the joint configuration vector q of the light-guiding robot (robot A) is adjusted by a step size ±Δq. A The joint configuration vector q of the workpiece clamping robot (robot B) B Several neighbor states s are generated above. nbr =(q nbr ,i), calculate the cost increment g(s) nbr )=g(s cur If )+ / / Δq / / is less than the original record, then update its g value and add it to C, where s nbr It is s cur The neighbor state node, q nbr It is q cur Neighbor joint configuration, g(s) nbr ) is from the initial node to the current node s nbr The actual cost of the path taken, g(s) cur ) is from the initial node to the current node s cur The actual cost of the path taken, ‖Δq‖, is from q cur to q nbr The cost of step size.

[0076] (3) After all the planning for point N is completed, the parent state pointer is traced back from the endpoint state to reconstruct the joint node sequence. This discrete sequence is then smoothed using cubic spline interpolation to generate a continuous joint time parameterized trajectory. The industrial control computer 6 completes the path planning for robot A / B according to the interpolated trajectory.

[0077] like Figure 6As shown, before the single-point impact, the system adjusts the perpendicularity and distance deviation between the end effector 111 and the workpiece impact point, namely steps d and e.

[0078] The method for adjusting the perpendicularity deviation between the end effector 111 and the workpiece impact point in step d above is as follows:

[0079] (1) A metrology-grade 3D scanner is used to acquire high-precision point clouds. The weighted iterative nearest point (ICP) algorithm is used to register the reference feature coordinate system of the end effector 111 with the reference feature coordinate system of the workpiece impact point. The angular error Δθ between the optical axis of the end effector 111 and the normal of the workpiece surface is calculated, and a threshold θ is set. thr The angle is 0.1-0.5°.

[0080] (2). When |Δθ|>θ thr If the end effector 111 joint is reachable within its workspace, then the joint increment of the light-guiding robot will be calculated first. The inverse kinematics mapping is used to fine-tune the end effector's posture; if the end effector 111 exceeds its workspace, the calculation is changed to the joint increment of the workpiece clamping robot. This causes a corresponding micro-rotation on the workpiece surface;

[0081] (3). Industrial PC 6 will and The commands are converted into synchronous end-effector control commands and sent to the two six-DOF robots to perform minor pose adjustments. After the adjustments are completed, the 3D scanner re-acquires point clouds and calculates new Δθ until |Δθ|≤θ is satisfied. thr Complete the verticality deviation compensation.

[0082] The method for adjusting the distance between the laser displacement sensor 5 and the light output port of the end effector 111 and the impact point of the workpiece in step e above is as follows:

[0083] (1). The laser displacement sensor 5 obtains the distance d between the light outlet of the end effector 111 and the impact point of the workpiece by triangulation. Based on the light spot size set in step b, the theoretical distance d0 between the light outlet of the end effector 111 and the impact point of the workpiece is obtained. The distance error Δd = d - d0.

[0084] (2) Laser light attenuates as it propagates in water. Let the total attenuation coefficient per unit length during propagation be *a*, and the theoretical laser power density be *I0*. According to Beer-Lambert's law, the laser power attenuates approximately exponentially, and the actual laser power density underwater is *I* = *I0*e*. -aΔd It is necessary to ensure that I is at least I0 for η. min (η min≥0.98 times, from which the maximum allowable defocus amount after power attenuation can be obtained: d thr This is the theoretical threshold for distance underwater;

[0085] (3). When |Δd|>d thr If the light guide end effector 111 joint is feasible, then the joint increment of the light guide robot will be calculated first. The pose of the light guide end effector 111 is compensated online through inverse kinematic mapping; if the light guide arm has reached its working limit, the calculation is changed to the joint increment of the workpiece clamping robot. This causes corresponding micro-translations on the workpiece surface;

[0086] (4). Industrial PC 6 will and The commands are converted into synchronous end-effector control commands and sent to the two six-DOF robots to perform minor pose adjustments. After the adjustments are completed, the laser displacement sensor 5 remeasures until |Δd|≤d is satisfied. thr This completes the distance deviation compensation.

[0087] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for coordinated control of an underwater laser shock beam guide arm and a workpiece robot, characterized in that, The method includes: Step a: Based on the different shapes of the workpieces to be processed, build and adjust the work platform, and build the corresponding work environment in the offline programming software; Step b: Complete the laser shock parameter setting, and use a 3D vision dynamic scanning system based on A The algorithm plans the trajectories of the two robots and sends them to the terminal controller. Step c: Connect the controller to the two robots, activate the laser displacement sensor, and the system enters standby mode; Step d: Drive the two robots to the planned trajectory. i The 3D vision feedback light guide arm is positioned relative to the workpiece impact point and the posture is compensated until the perpendicularity deviation is less than the perpendicularity threshold. Step e: The laser displacement sensor provides feedback on the distance from the end to the workpiece and performs distance compensation until the distance deviation is less than the distance threshold. Then, a laser pulse is triggered to complete the point. i Impact; Step f, repeat steps c, d, and e to complete the laser impact of the entire planned path; The implementation process of step b is as follows: Turn on the laser emitting device (1), and set the laser impact path and laser output power. and spot size Check the absorption layer and water confinement layer; turn on the visual dynamic measurement system (4), and according to the laser shock path, use A The algorithm plans the motion path of the six-degree-of-freedom light guide robot (2) and the six-degree-of-freedom workpiece clamping robot (3) to complete the entire impact process and enters it into the industrial control computer (6). Laser output power and spot size The relationship is: ,according to and Laser power density can be obtained ; The visual dynamic measurement system (4) is activated, and according to the laser impact path, A is used. The algorithm plans the motion paths of the six-degree-of-freedom light-guiding robot (2) and the six-degree-of-freedom workpiece clamping robot (3) to complete the entire impact process and records them into the industrial control computer (6). The specific process is as follows: Step b1: A metrology-grade 3D scanner collects point cloud data from the collaborative laser shock processing system to obtain the spatial information of the entire system, specifically including the actual digital model of the workpiece and the workpiece coordinate system; the joint space of the six-degree-of-freedom light-guiding robot (2) and the six-degree-of-freedom workpiece clamping robot (3) is defined as the state space, and the workpiece impact area is obtained from the point cloud digital model, with the initial joint configuration. As the root node, where, and This is the initial joint configuration vector of the joint joint space of the two robots, which include: a six-DOF light-guiding robot (2) and a six-DOF workpiece clamping robot (3); read the predefined laser shock path target pose sequence. ,in, It is the first The position vector of a target pose. It is the first The pose of a target position. This represents the total number of target pose points requiring laser shock processing; the joint space step size is set. Heuristic function And the maximum number of iterations; Step b2: For each impact pose : Initialize list O to the root node state Close list C to be empty; select valuation function from O. Minimum state And move it into C, where, From the initial node to the current state The cumulative real cost, It is the current state To the current target pose The estimated cost, This is the currently searched state node. It is the joint configuration of the two robots at the current moment; if The corresponding robot position orientation satisfies Then mark the first Point achieved, ready to plan the next step. Point; otherwise, based on the joint joint space with step length Joint configuration vectors of a six-degree-of-freedom light-guiding robot (2) Joint configuration vectors of a six-DOF workpiece clamping robot (3) Several neighbor states are generated above. Calculate the cost increment ,in, yes The neighbor state nodes, yes Neighbor joint configuration, From the initial node to the current node The actual cost of the path taken From the initial node to the current node The actual cost of the path taken From arrive If the step size cost is less than the original record, then update it. Value and add it to C until O is empty or the target is found; Step b3: When the first N After all the points are planned, the parent state pointer is traced back from the endpoint state to reconstruct the joint node sequence. The discrete sequence is smoothed by cubic spline interpolation to generate a continuous joint time parameter quantized trajectory. The industrial control computer (6) completes the path planning of the six-degree-of-freedom light guide robot (2) and the six-degree-of-freedom workpiece clamping robot (3) according to the interpolated trajectory. The implementation process of step d is as follows: the collaborative laser shock processing system starts the workflow. After the previous point is impacted, the system moves to the next point to be impacted according to the motion path of step b; the visual dynamic measurement system (4) feeds back the real-time relative position between the light guide end effector (111) and the workpiece to be impacted; according to the feedback data, the industrial control computer (6) controls the six-degree-of-freedom light guide robot (2) or the six-degree-of-freedom workpiece clamping robot (3) to perform pose error compensation until the perpendicularity deviation between the light guide end effector (111) and the workpiece to be impacted is less than the set threshold. The method for adjusting the perpendicularity deviation between the light guide end effector (111) and the workpiece impact point in the visual dynamic measurement system (4) is as follows: Step d1: A metrology-grade 3D scanner performs high-precision point cloud acquisition. Using the weighted iterative nearest point (ICP) algorithm, the reference feature coordinate system of the light guide end effector (111) is registered with the reference feature coordinate system of the workpiece impact point. The angular error between the optical axis of the light guide end effector (111) and the normal of the workpiece surface is calculated. The theoretical threshold for verticality is ; Step d2: When If the light guide end effector (111) joint is reachable within its workspace, then the joint increment of the light guide robot is calculated first. The attitude of the light guide end effector (111) is fine-tuned by inverse kinematic mapping; if the light guide end effector (111) exceeds its workspace, the joint increment of the workpiece clamping robot is calculated instead. This causes the workpiece surface to rotate accordingly. Step d3: The industrial computer (6) will... and The commands are converted into synchronous end-effector control commands and sent to the two six-DOF robots to perform minor pose adjustments. After the adjustments are completed, the 3D scanner re-acquires point clouds and calculates new poses. until satisfied Complete verticality deviation compensation; The implementation process of step e is as follows: After the verticality deviation is set, the laser displacement sensor (5) feeds back the real-time distance between the light outlet of the light guide end effector (111) and the workpiece impact point; according to the feedback data, the industrial control computer (6) controls the six-degree-of-freedom light guide robot (2) or the six-degree-of-freedom workpiece clamping robot (3) to perform posture error compensation until the distance between the light outlet of the light guide end effector (111) and the workpiece impact point is less than the set threshold, and then impacts the next point; The specific method by which the laser displacement sensor (5) adjusts the distance between the light outlet of the light guide end actuator (111) and the impact point of the workpiece is as follows: Step e1: The laser displacement sensor (5) obtains the distance between the light outlet of the light guide end effector (111) and the impact point of the workpiece using triangulation. Based on the light spot size set in step b, the theoretical distance between the light outlet of the light guide end effector (111) and the impact point of the workpiece is obtained. Distance error ; Step e2: Laser light attenuates as it propagates in water. Let the total attenuation coefficient per unit length of the laser light during its propagation in water be... The theoretical laser power density is According to Beer-Lambert's law, the laser power density decreases approximately exponentially underwater. It is necessary to ensure At least for of This multiple allows us to determine the maximum permissible defocus amount after power attenuation: , This is the theoretical threshold for distance underwater; Step e3: When If the light guide end effector (111) joint is feasible, then the joint increment of the light guide robot should be calculated first. The pose of the light guide end effector (111) is compensated online through inverse kinematic mapping; if the light guide arm has reached its working limit, the calculation of the joint increment of the workpiece clamping robot is changed to calculate the position of the light guide end effector (111). This causes corresponding micro-translations on the workpiece surface; Step e4: The industrial computer (6) will... and The commands are converted into synchronous end-effector control commands and sent to the two six-degree-of-freedom robots to perform minor pose adjustments. After the adjustments are completed, the laser displacement sensor (5) remeasures until the desired pose is achieved. This completes the distance deviation compensation.

2. The method according to claim 1, characterized in that, The implementation process of step c is as follows: the industrial control computer (6) connects the six-degree-of-freedom light guide robot (2) and the six-degree-of-freedom workpiece clamping robot (3), turns on the laser displacement sensor (5), and completes the preparation work.

3. The method according to claim 1, characterized in that, The method is achieved through an underwater laser shock light guide arm and workpiece robot collaborative control system, the system including: a laser emitting device (1), a six-degree-of-freedom light guide robot (2), a six-degree-of-freedom workpiece clamping robot (3), a visual dynamic measurement system (4), a laser displacement sensor (5), an industrial control computer (6), and a water tank (7). The laser emitting device (1) includes a laser generator (10), a six-degree-of-freedom light guide arm (11), and a light guide end effector (111). The laser emitting device (1) is used to emit high-energy lasers; The six-degree-of-freedom light-guiding robot (2) is used to hold the light-guiding end effector (111) and move it so as to conduct laser light along a preset path; The visual dynamic measurement system (4) is used to calibrate the positional relationship between the six-degree-of-freedom light guide robot (2) and the six-degree-of-freedom workpiece clamping robot (3) in order to achieve dynamic control during the impact process; The laser displacement sensor (5) is used to measure the vertical distance between the laser output port of the light guide end effector (111) and the impact point of the workpiece, thereby obtaining the focal length; The water tank (7) is used to immerse the workpiece during the impact process; The laser emitting device (1), the six-degree-of-freedom light guiding robot (2), the six-degree-of-freedom workpiece clamping robot (3), and the water tank (7) constitute a collaborative laser shock processing system; the industrial control computer (6) is used to control the collaborative laser shock processing system and receive and process the information fed back by the visual dynamic measurement system (4) and the laser displacement sensor (5).

4. The method according to claim 3, characterized in that, The six-degree-of-freedom workpiece clamping robot (3) is located on one side of the laser emitting device (1), and a special clamp is installed at its end; the six-degree-of-freedom light guiding robot (2) is located on the other side of the laser emitting device (1), clamping the light guiding end effector (111), and a laser displacement sensor (5) is installed on the light guiding end effector (111); the visual dynamic measurement system (4) is located in front of the collaborative laser shock processing system, and ensures that the measured coordinate system moves within its field of view; the water tank (7) is located below the six-degree-of-freedom workpiece clamping robot (3); the industrial control computer (6) connects the six-degree-of-freedom light guiding robot (2), the six-degree-of-freedom workpiece clamping robot (3), the visual dynamic measurement system (4), and the laser displacement sensor (5). The laser displacement sensor (5) is equipped with a waterproof optical cover for underwater environments and compensates for window refraction and scattering losses. The laser displacement sensor (5) and the light-guiding end effector (111) have a certain distance between their light outlets, and the measured distance should be reduced by the distance.

5. The method according to claim 3, characterized in that, The six-degree-of-freedom light-guiding robot (2) and the six-degree-of-freedom workpiece clamping robot (3) first plan their initial motion paths through offline programming. During the operation, the motion posture of the two robots is monitored in real time through digital twin technology. The visual dynamic measurement system (4) provides real-time on-site data of the relative position of the light-guiding end effector (111) and the workpiece impact point to guide the two robots to always keep the laser beam perpendicular to the workpiece impact point. The laser displacement sensor (5) provides real-time on-site distance between the light outlet of the light-guiding end effector (111) and the workpiece impact point to adjust the posture of the six-degree-of-freedom workpiece clamping robot (3) to ensure that the distance between the light-guiding end effector (111) and the workpiece impact point remains unchanged during each impact, thereby maintaining the predetermined laser spot diameter. The position accuracy of the two robots is ≤0.2mm, the posture accuracy is ≤0.1°, and the trajectory accuracy is ≤0.5mm.

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