A robot motion control method and device based on spraying posture tolerance

Abstract

This application relates to the field of industrial robot motion control technology, and provides a robot motion control method based on spraying posture tolerance, including: acquiring the spraying trajectory and process parameters of the workpiece to be sprayed; constructing a spraying posture tolerance space model and an adjustable motion space based on the process parameters; acquiring the robot joint state and end effector pose in real time and evaluating and generating a motion capability evaluation value; responding to the motion capability evaluation value being lower than a preset threshold, dynamically adjusting the end effector posture of the spray gun within the tolerance space and generating control commands; and dynamically adjusting the allowable posture adjustment amount in the constrained direction based on the posture adjustment margin during the adjustment process. This application utilizes process tolerance to optimize the robot's motion state, improving the trajectory execution stability and motion adaptability under complex working conditions.

Description

Technical Field

[0001] This application relates to the field of industrial robot motion control, and in particular to a robot motion control method and device based on spraying posture tolerance. Background Technology

[0002] In automated industrial robot painting operations, to ensure coating thickness uniformity and coverage quality, robots typically need to strictly adhere to preset painting trajectories and target postures. However, when faced with complex curved surfaces, deep cavities, or confined spaces, robots often experience decreased motion coordination due to structural limitations, joint range constraints, or proximity to motion singularities. This can lead to unstable trajectory execution and sudden changes in joint speed. Existing technologies typically improve motion by replanning the trajectory or adjusting the workpiece layout, but these methods are costly and may disrupt the established process. In fact, the painting process itself allows for deviations in the spray gun's end-effector posture within a certain range without affecting coating quality. However, existing control strategies often treat the target posture as a rigid constraint, failing to effectively utilize this inherent process tolerance as a degree of freedom for kinematic optimization. This results in robots lacking flexible motion adjustment methods under complex conditions, making it difficult to balance painting quality and motion performance. Summary of the Invention

[0003] This application provides a robot motion control method and device based on spraying posture tolerance, which solves the technical problems of insufficient motion coordination ability of spraying robots under complex working conditions and ineffective utilization of spraying process tolerance resources in the prior art.

[0004] To achieve the above objectives, this application adopts the following technical solution: Firstly, a robot motion control method based on spraying posture tolerance is provided, including: Obtain the spraying trajectory of the workpiece to be sprayed and the corresponding spraying process parameters; Based on the spraying process parameters, determine the allowable tolerance range of the spray gun end posture and construct a spraying posture tolerance space model; Based on the spraying trajectory and the spraying posture tolerance space model, an adjustable motion space is constructed; The robot acquires joint states and end-effector poses in real time during operation, and evaluates its current motion capabilities based on these states and poses to generate a motion capability evaluation value. In response to the motion capability evaluation value being lower than a preset evaluation threshold, the attitude of the spray gun end is dynamically adjusted within the range defined by the spraying attitude tolerance space model, and robot control commands are generated based on the adjusted spray gun end attitude to control the robot to perform the spraying operation; wherein, during the dynamic adjustment process, the allowable attitude adjustment amount in the constrained adjustment direction is dynamically adjusted based on the attitude adjustment margin between the current spray gun end attitude and the boundary of the spraying attitude tolerance space model, so as to keep the spray gun end attitude within the tolerance range.

[0005] Based on the above technical solution, in the robot motion control method based on spraying posture tolerance provided in this application, the posture deviation allowed by the spraying process is transformed into redundant degrees of freedom that can participate in motion control, providing the robot with additional motion adjustment space without changing the original trajectory position constraints; at the same time, through the dynamic boundary constraint mechanism based on posture adjustment margin, it is ensured that the posture adjustment process always meets the process requirements and the control is smooth, thereby significantly improving the robot's motion adaptability and trajectory execution stability under complex working conditions while ensuring the spraying quality.

[0006] In conjunction with the first aspect above, in one possible implementation, the step of determining the allowable tolerance range of the spray gun end posture based on the spraying process parameters and constructing a spraying posture tolerance space model includes: Obtain the relative spatial relationship between the spray gun tip posture and the surface of the workpiece to be sprayed; A spraying process constraint model is established based on the spraying process parameters; Based on the spraying process constraint model, calculate the allowable range of change in the spray gun end posture to meet the coating quality requirements; The allowable variation range is mapped to the tolerance range of the spray gun end posture to establish the spray posture tolerance space model, which is used to characterize the space range that can be adjusted under the condition of meeting the spraying process requirements.

[0007] By establishing a quantitative mapping relationship between process parameters and attitude tolerance, the constructed tolerance space is ensured to have a clear process physical meaning, thus avoiding coating quality risks caused by blind adjustments.

[0008] In conjunction with the first aspect above, in one possible implementation, the spraying process parameters include spraying distance, spraying incident angle, spray gun moving speed, spraying flow rate, and allowable coating quality error; The establishment of the spraying process constraint model based on the spraying process parameters includes: Based on the spraying distance, the spraying incident angle, the spray gun moving speed, and the spraying flow rate, a spraying quality evaluation model is established to characterize the mapping relationship between the comprehensive quality index of the coating and the attitude change angle. The calculation of the allowable range of spray gun end posture variation to meet coating quality requirements based on the spraying process constraint model includes: The minimum coating quality threshold is determined based on the allowable coating quality error; Based on the spraying quality evaluation model, a set of attitude change angles that make the overall coating quality index greater than or equal to the minimum coating quality threshold are selected. The set of attitude change angles is taken as the allowable range of attitude change at the end of the spray gun.

[0009] By using a multi-parameter coupled quality assessment model, the safety adjustment boundary is accurately defined, improving the utilization rate and reliability of tolerance resources.

[0010] In conjunction with the first aspect above, in one possible implementation, the step of evaluating current motor ability based on the joint state and the end-effector pose to generate a motor ability evaluation value includes: A robot kinematic model is established based on the joint states, and a kinematic mapping matrix describing the mapping relationship between the robot joint motion and the end effector motion of the spray gun is obtained. Construct a motion capability evaluation matrix based on the aforementioned kinematic mapping matrix; The motion capability evaluation value is calculated based on the motion capability evaluation matrix. The motion capability evaluation value is used to characterize the motion coordination capability and end-effector reachability under the current joint configuration. The motion capability evaluation value decreases as the robot's motion state approaches the restricted motion state and increases as the robot's motion state moves away from the restricted motion state.

[0011] By establishing a comprehensive evaluation index based on kinematic mapping relationships, the robot's current motion potential and limitations can be sensitively reflected, providing accurate triggering basis and optimization direction for posture optimization.

[0012] In conjunction with the first aspect above, in one possible implementation, the kinematic mapping matrix is ​​the robot Jacobian matrix; The construction of the motion ability evaluation matrix based on the kinematic mapping matrix includes: Multiplying the robot's Jacobian matrix by its transpose yields the motion capability evaluation matrix; The calculation of the athletic ability evaluation value based on the athletic ability evaluation matrix includes: Calculate the determinant of the athletic ability evaluation matrix, and take the square root of the determinant as the athletic ability evaluation value; The restricted motion state includes at least one of the following: motion singularity state, joint nearing the limit of range of motion state, joint motion speed nearing the upper limit of allowable speed state, and end-effector trajectory execution capability decline state.

[0013] By using operability as a quantitative indicator, we can comprehensively characterize the robot's motion transmission capability in all directions and effectively identify various types of motion-restricted states.

[0014] In conjunction with the first aspect above, in one possible implementation, dynamically adjusting the allowable attitude adjustment amount in the constrained adjustment direction based on the attitude adjustment margin between the current spray gun end attitude and the boundary of the spraying attitude tolerance space model includes: Calculate the attitude adjustment margin between the current spray gun end attitude and the nearest boundary of the spray attitude tolerance space model; A boundary constraint function is established based on the attitude adjustment margin, and the corresponding attitude adjustment gain is calculated based on the boundary constraint function. The allowable attitude adjustment amount in the constrained adjustment direction is determined based on the attitude adjustment gain; wherein, the constrained adjustment direction is the direction in which the current spray gun end attitude continues to change towards the nearest boundary; the attitude adjustment gain continuously increases as the attitude adjustment margin decreases, and continuously decreases as the attitude adjustment margin increases.

[0015] By introducing attitude adjustment margin and continuously varying constraint functions, soft boundary control is achieved, avoiding control oscillations or attitude abrupt changes caused by traditional hard threshold truncation, and ensuring the stability of the spraying process.

[0016] In conjunction with the first aspect above, in one possible implementation, the boundary constraint function is a continuous monotonic function; Determining the allowable attitude adjustment amount in the constrained adjustment direction based on the attitude adjustment gain includes: Obtain the theoretical attitude adjustment increment when no constraints are applied; Divide the theoretical attitude adjustment requirement increment by the attitude adjustment gain to obtain the allowable attitude adjustment amount in the constrained adjustment direction; When the attitude of the spray gun end approaches the nearest boundary, the attitude adjustment margin decreases, the attitude adjustment gain increases, and the allowable attitude adjustment decreases to limit the attitude from continuing to adjust towards the boundary. When the attitude of the spray gun tip moves away from the nearest boundary, the attitude adjustment margin increases, the attitude adjustment gain decreases, and the allowable attitude adjustment increases to retain adjustable space.

[0017] By clarifying the inverse adjustment mechanism between constraint strength and adjustment amount, the robot automatically converges the adjustment range when approaching the process limit and makes full use of the tolerance space when far from the limit, thus achieving a dynamic balance between safety and flexibility.

[0018] In conjunction with the first aspect above, in one possible implementation, the dynamic adjustment of the spray gun end posture within the range defined by the spraying posture tolerance space model includes: While maintaining the target spraying distance and target spraying angle between the spray gun and the surface of the workpiece to be sprayed in accordance with the process requirements, the spray gun is controlled to rotate and adjust around the spraying direction axis within a preset attitude tolerance range.

[0019] In conjunction with the first aspect described above, in one possible implementation, the method further includes: When the motion capability evaluation value is lower than the preset motion capability evaluation activation threshold, dynamic adjustment of the spray gun end posture is initiated. When the motion capability evaluation value reaches the preset motion capability evaluation recovery threshold, the spray gun end posture adjustment amount is gradually reduced according to the preset posture recovery strategy, so that the spray gun end posture gradually returns to the target spraying posture; wherein, the preset motion capability evaluation recovery threshold is greater than the preset motion capability evaluation activation threshold, and the preset evaluation threshold is the preset motion capability evaluation activation threshold.

[0020] This implementation utilizes rotation around an axis, a dimension that has a relatively small impact on coating quality but a significant improvement in kinematics, as a priority adjustment method. Furthermore, it employs a dual-threshold hysteresis control strategy to prevent frequent switching of the system in critical states, thereby further enhancing the robustness of control and the stability of the process.

[0021] In a second aspect, an electronic device is provided, comprising: a processor; and a memory for storing a computer program; wherein, when the computer program is executed by the processor, the processor causes the processor to execute the robot motion control method based on spraying posture tolerance as described above.

[0022] This application provides a robot motion control method and device based on spraying posture tolerance. It transforms the allowable posture tolerance of the spraying process into an adjustable space for kinematic optimization, breaking the limitation of treating the target posture as a rigid constraint in traditional control. It utilizes the redundant degrees of freedom inherent in the process itself to improve the robot's kinematic state, enhancing trajectory execution capability under complex working conditions without modifying the original trajectory or adjusting the site layout. Secondly, this application establishes a dynamic boundary constraint mechanism based on posture adjustment margin. By dynamically adjusting the allowable posture adjustment amount through a continuously monotonic constraint function, it achieves soft constraint control of the process boundary, effectively avoiding control oscillations, sudden joint velocity changes, or posture jumps caused by hard limits, ensuring the continuity and smoothness of the spraying process. Simultaneously, this application constructs a comprehensive motion capability evaluation system based on a kinematic mapping matrix. This system not only identifies motion singularities but also comprehensively reflects joint collaborative driving capability and end-effector reachability. Combined with a dual-threshold hysteresis control strategy and a rotation-priority adjustment mechanism around the axis, it achieves precise synergy between motion performance optimization and spraying quality assurance, improving the system's robustness and engineering applicability. Attached Figure Description

[0023] Figure 1 A flowchart illustrating a robot motion control method based on spraying posture tolerance provided in this application embodiment; Figure 2 A schematic diagram of the three-dimensional geometry and planar projection model of the spraying posture tolerance space provided in the embodiments of this application; Figure 3 The boundary constraint function curve and constraint effect diagram provided for the embodiments of this application. Detailed Implementation

[0024] In the description of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. The "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Furthermore, "at least one" means one or more, and "multiple" means two or more. The terms "first," "second," etc., do not limit the quantity or order of execution, and "first," "second," etc., do not necessarily imply differences.

[0025] It should be noted that, in this application, the terms "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or illustration. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0026] Example 1 like Figure 1 As shown, this embodiment provides a robot motion control method based on spraying posture tolerance. This method transforms the allowable posture deviations of the spraying process into adjustable resources for kinematic optimization, and combines them with a dynamic boundary constraint mechanism to improve the robot's motion performance while ensuring spraying quality. The specific execution flow of this method includes the following steps.

[0027] Step S1: Obtain the spraying trajectory of the workpiece to be sprayed and the corresponding spraying process parameters.

[0028] The spraying trajectory is typically generated by offline programming software based on a 3D model of the workpiece, or obtained through on-site teaching via a teach pendant. It defines a predetermined sequence of path points at the tip of the spray gun in space. Spraying process parameters are a set of key variables that determine the coating quality, and may include, for example, the target spraying distance, the target spraying incident angle, the spray gun moving speed, the paint flow rate, and the atomization pressure.

[0029] This embodiment ensures that subsequent motion control optimization is always anchored to the specific process scenario by synchronously acquiring trajectory and process parameters, thus avoiding pure kinematic adjustments that are detached from actual working conditions.

[0030] Step S2: Determine the tolerance range of the allowable change in the spray gun end posture based on the spraying process parameters, and construct a spraying posture tolerance space model.

[0031] It should be noted that the spraying posture tolerance space model is not simply a geometric bounding box or a fixed angle limit; its physical essence is "a set of postures that meet the coating quality requirements".

[0032] Furthermore, the system will establish a quality evaluation model based on the spraying process parameters, and calculate the maximum allowable deviation of the spray gun tip from the ideal target posture without causing defects such as sagging, orange peel, or uneven film thickness.

[0033] For example, the tolerance range may be larger for some primer spraying processes that are less sensitive to the angle of incidence, while it may be relatively smaller for processes that require extremely high gloss of the topcoat.

[0034] Step S3: Based on the spraying trajectory and spraying posture tolerance space model, construct an adjustable motion space.

[0035] It should be noted that this step maps the attitude tolerance of the process domain into the available redundant degrees of freedom of the robot control domain. Since the spraying trajectory determines the positional constraints of the end effector, and the spraying attitude tolerance space model determines the attitude elasticity range of the end effector, the combination of the two forms a tubular or conical adjustable motion space attached to the trajectory.

[0036] Furthermore, within this space, the robot can flexibly choose specific end-effector posture configurations without changing its trajectory position.

[0037] This construction method transforms the process requirements, which were originally considered fixed constraints, into active adjustment variables that participate in kinematic optimization, providing additional solution space for solving motion-constrained problems under complex working conditions.

[0038] Step S4: Acquire the joint states and end-effector poses during the robot's operation in real time, and evaluate the current motion capability based on the joint states and end-effector poses to generate a motion capability evaluation value.

[0039] The joint status includes information such as the angle, angular velocity, and load torque of each joint, while the end effector pose reflects the current actual spatial state of the spray gun. The motion capability evaluation value is a comprehensive quantitative indicator used to characterize the robot's motion coordination ability, trajectory tracking stability, and remaining attitude adjustment potential in the current configuration.

[0040] For example, the evaluation value drops significantly when the robot approaches a motion singularity or joint limit position; conversely, the evaluation value is higher when the robot is in the dexterous working zone.

[0041] This embodiment establishes a continuous perception capability of the robot's motion health status by calculating the evaluation value in real time, providing accurate triggering criteria and optimization direction guidance for subsequent dynamic adjustments.

[0042] Step S5: In response to the motion capability evaluation value being lower than the preset evaluation threshold, the end posture of the spray gun is dynamically adjusted within the range defined by the spraying posture tolerance space model, and robot control commands are generated based on the adjusted end posture of the spray gun to control the robot to perform the spraying operation.

[0043] It should be noted that when the detected motion capability evaluation value is lower than the preset evaluation threshold, it indicates that there is a motion risk or performance bottleneck in the current configuration of the robot, and the system will then start the posture optimization strategy.

[0044] Furthermore, the optimization process is strictly limited to searching and adjusting within the spraying posture tolerance space model constructed in step S2; for example, the joint configuration is improved by fine-tuning the tilt angle or rotation angle of the spray gun, so that the motion capability evaluation value returns to a safe level. Although the adjusted posture deviates from the originally planned target posture, it is still within the quality acceptable range allowed by the process.

[0045] Based on the optimized new posture, the inverse kinematics are resolved to generate smooth joint control commands. This mechanism realizes the real-time conversion of "process tolerance" into "motion performance," effectively avoiding downtime, deceleration, or trajectory distortion caused by motion restrictions.

[0046] During the dynamic adjustment process, based on the attitude adjustment margin between the current spray gun end attitude and the boundary of the spraying attitude tolerance space model, the allowable attitude adjustment amount in the constrained adjustment direction is dynamically adjusted so that the spray gun end attitude remains within the tolerance range.

[0047] Specifically, attitude adjustment margin refers to the remaining safe distance between the current attitude and the nearest boundary of the tolerance space. A "soft boundary" constraint mechanism is adopted, in which the attitude adjustment gain continuously increases as the attitude adjustment margin decreases, thereby automatically reducing the allowable attitude adjustment in the constrained adjustment direction.

[0048] When the spray gun posture is far from the boundary, the system retains a large degree of adjustment freedom to fully optimize motion performance; while when the spray gun posture gradually approaches the process tolerance boundary, the constraint effect is smoothly enhanced, forcing the posture adjustment amount to gradually converge to zero, thus naturally preventing the posture from going out of bounds.

[0049] This dynamic adjustment mechanism based on continuous functions completely eliminates control abrupt changes and joint shocks at the boundary, effectively preventing system oscillations caused by constraint switching and ensuring the stability and continuity of the spraying process throughout the entire process.

[0050] Through the coordinated execution of steps S1 to S5 above, this embodiment successfully transforms static process specifications into dynamic motion control resources.

[0051] On the one hand, the spraying posture tolerance space model was used to explore the process redundancy degree of freedom that was ignored by traditional methods, which improved the robot's ability to pass through and its work efficiency in complex working conditions such as corners and deep cavities. On the other hand, a soft boundary protection system that combines flexibility and safety is constructed through a dynamic boundary constraint mechanism based on attitude adjustment margin. This fundamentally ensures that the attitude optimization process will not sacrifice coating quality or introduce new control instability factors, thus achieving an organic unity between process quality assurance and robot motion performance optimization.

[0052] Example 2 Based on Example 1, this example further details the quantitative construction process of the spraying attitude tolerance space model.

[0053] As one implementation method, the tolerance range for allowable changes in the spray gun tip posture is determined based on the spraying process parameters, and a spraying posture tolerance space model is constructed, specifically including: Obtain the relative spatial relationship between the spray gun tip posture and the surface of the workpiece to be sprayed; Establish a spraying process constraint model based on spraying process parameters; Based on the spraying process constraint model, calculate the allowable range of change in the spray gun end posture to meet the coating quality requirements; The allowable range of variation is mapped to the tolerance range of the spray gun end posture to establish a spray posture tolerance space model, which is used to characterize the spatial range of adjustments that are allowed under the condition of meeting the spraying process requirements.

[0054] It should be noted that obtaining the relative spatial relationship is the geometric prerequisite for quantifying tolerance. The actual pose of the spray gun end effector at the current trajectory point is obtained through robot forward kinematics calculation, and the local surface normal vector and tangent plane information at this position are extracted by combining the workpiece 3D model, thereby establishing the pose transformation matrix between the spray gun coordinate system and the workpiece local surface coordinate system.

[0055] Based on this transformation matrix, the actual spraying distance and actual incident angle of the spray gun axis relative to the workpiece surface can be calculated in real time. These real-time geometric quantities constitute the input variables of the subsequent quality evaluation model.

[0056] The spraying process constraint model established on this basis is essentially a mathematical expression describing the nonlinear mapping relationship between "process parameters, attitude deviation, and coating quality".

[0057] This model can predict the changing trends of key quality indicators such as coating thickness, uniformity, and coverage under any given attitude deviation. Furthermore, by setting a quality qualification threshold, it can deduce the maximum allowable attitude deviation range to ensure that the quality does not exceed the standard.

[0058] Furthermore, the spraying process parameters include spraying distance, spraying incident angle, spray gun moving speed, spraying flow rate, and allowable coating quality error; A spraying process constraint model is established based on spraying process parameters, including: Based on spraying distance, spraying incident angle, spray gun moving speed and spraying flow rate, a spraying quality evaluation model is established to characterize the mapping relationship between the comprehensive quality index of the coating and the attitude change angle. Based on the spraying process constraint model, the allowable range of variation in the spray gun end posture to meet coating quality requirements is calculated, including: The minimum coating quality threshold is determined based on the allowable coating quality error; Based on the spraying quality evaluation model, a set of attitude change angles that make the overall coating quality index greater than or equal to the minimum coating quality threshold are selected. The set of attitude change angles is taken as the allowable range of attitude change at the end of the spray gun.

[0059] like Figure 2 As shown in the figure, this embodiment illustrates the three-dimensional geometry of the spraying attitude tolerance space and its projection onto a two-dimensional plane.

[0060] In some implementations, the coating quality evaluation model can be expressed as: ,in It is a comprehensive quality indicator for coatings, covering dimensions such as mean film thickness, film thickness variance, and effective coverage width; This is the actual spraying distance. This is the actual incident angle for spraying. For the spray gun movement speed, This refers to the spraying flow rate.

[0061] This function This reflects the coupling mechanism of various process parameters on coating quality, such as the effect of incident angle. When the deviation from the normal direction is too large, the projection of the paint mist on the workpiece surface is elliptical, resulting in a reduced amount of paint deposition per unit area and uneven film thickness at the edges; when the spraying distance... When the effective atomization cone range is exceeded, excessive solvent evaporation leads to dry spraying or decreased adhesion.

[0062] Based on this model, the minimum coating quality threshold is determined according to the allowable coating quality error of the current process. Furthermore, by using numerical search or analytical inverse methods, the inequalities can be solved. All combinations of attitude change angles form the attitude change angle set. This set This is the mathematical expression of the spraying attitude tolerance space at the current trajectory point.

[0063] It should be noted that the spraying attitude tolerance space is not a globally fixed constant, but a local property that dynamically changes with the geometric features of the workpiece surface.

[0064] like Figure 2 As shown in the three-dimensional schematic diagram, in the flat area of ​​the workpiece, due to the wide process window, the tolerance space may take the form of a large cone or prism; while in the deep cavity or sharp corner area, due to the limited space accessibility and paint mist rebound effect, the posture range that meets the quality requirements will shrink significantly, and the tolerance space will decrease accordingly.

[0065] This dynamic characteristic enables the robot control system to adaptively allocate and optimize resources based on the process tolerance of the current position: fully utilizing redundant degrees of freedom to improve kinematic performance in areas with high tolerance, and making careful adjustments in areas with low tolerance to ensure the bottom line of quality.

[0066] To make it more intuitive, let's take the common air spraying process as an example.

[0067] In this scenario, the target spraying distance is typically set between 180mm and 300mm, with a preferred range of 220mm to 280mm; the target spraying angle is when the spray gun axis is perpendicular to the workpiece surface, i.e., the incident angle is 0°.

[0068] Provided that the coating thickness uniformity and coverage requirements are met, the allowable deviation of the target spraying angle determined by process verification is usually ±5° to ±15°, preferably ±8° to ±12°. Therefore, as long as the actual incident angle of the spray gun is kept within the range of [-12°, +12°] and the actual spraying distance is kept within the range of [220mm, 280mm], the current attitude adjustment can be considered to be process safe.

[0069] This embodiment transforms abstract process specifications into precise mathematical boundaries, providing a safe and flexible feasible domain support for subsequent motion capability optimization.

[0070] Example 3 Based on Example 1, this example further details the generation mechanism and specific calculation method of the athletic ability evaluation value.

[0071] As one implementation method, current motor ability is assessed based on joint state and end-effector pose to generate a motor ability evaluation value, including: A robot kinematic model is established based on joint states to obtain a kinematic mapping matrix that describes the mapping relationship between robot joint motion and spray gun end motion. Construct a motion ability evaluation matrix based on the kinematic mapping matrix; Motion capability evaluation values ​​are calculated based on the motion capability evaluation matrix. These values ​​characterize the motion coordination capability and end-effector reachability under the current joint configuration. The motion capability evaluation values ​​decrease as the robot's motion state approaches a restricted motion state and increase as the robot's motion state moves away from a restricted motion state.

[0072] The motion capability evaluation value is not an artificially set empirical score, but a state quantity with clear physical meaning derived from the principles of robot kinematics. The motion of each joint of the robot is not directly equivalent to the motion of the nozzle tip; there is a complex nonlinear coupling relationship between the two. This nonlinear coupling relationship is expressed at the differential level as a kinematic mapping matrix, which describes how unit joint velocity is mapped to end-effector linear velocity and angular velocity. This mapping capability changes dynamically when the robot is in different configurations.

[0073] For example, in some configurations, even a small joint rotation can produce a large end-effector displacement, while in others, even with high-speed joint operation, the end-effector may remain almost stationary or only be able to move in a specific direction. The motion capability evaluation value is a comprehensive quantification of this mapping capability. A high evaluation value indicates that the robot's current configuration has good isotropy, with each joint able to coordinate and drive the end-effector motion in a balanced and efficient manner, and possessing sufficient potential for attitude adjustment. Conversely, a low evaluation value indicates decreased motion transmission efficiency, with some joints potentially approaching their motion limits or being in a mechanically disadvantageous zone. Forcing the execution of complex trajectories in this situation can easily lead to joint velocity exceeding limits or trajectory distortion. Therefore, using this evaluation value as a trigger criterion for attitude optimization can fundamentally prevent motion risks, rather than relying solely on passive protective measures such as position limits.

[0074] In some implementations, the kinematic mapping matrix is ​​the robot's Jacobian matrix; a motion capability evaluation matrix is ​​constructed based on the kinematic mapping matrix, including: Multiplying the robot's Jacobian matrix by its transpose yields the motion capability evaluation matrix; The athletic ability evaluation value is calculated based on the athletic ability evaluation matrix, including: Calculate the determinant of the athletic ability evaluation matrix and take the square root of the determinant as the athletic ability evaluation value; Restricted motion states include at least one of the following: motion singularity state, joint nearing range of motion limit state, joint motion speed near the upper limit of allowable speed state, and end-effector trajectory execution capability decline state.

[0075] For example, suppose the robot's current joint variable vector is ,in The number of degrees of freedom of the robot's joints. For the first The angle or displacement variables of each joint. The vector of the pose change rate of the spray gun tip in the task space. With joint velocity vector They satisfy a linear mapping relationship ,in This is the robot's Jacobian matrix, whose elements are composed of the partial derivatives of the end-effector pose with respect to each joint variable. To comprehensively evaluate the robot's motion capabilities in all directions, this embodiment constructs a motion capability evaluation matrix. From a geometric perspective, this matrix defines the shape and size of the terminal velocity ellipsoid, and its eigenvalues ​​represent the radii of the ellipsoid along each principal axis. Based on this, the performance evaluation value is determined. The calculation formula is as follows:

[0076] In the formula, This is a score for evaluating athletic ability. This represents matrix determinant operations. This formula is used to calculate the volume of the terminal velocity ellipsoid. When When the velocity ellipsoid approaches 0, it collapses into a plane or straight line in one or more dimensions, and the robot loses its ability to move in the corresponding direction, i.e., it enters a motion singularity state or a joint limit state; when When the value is large, the velocity ellipsoid is full and close to a sphere, and the robot has a balanced and efficient motion transmission capability in all directions. At this time, the margin for attitude adjustment is the largest.

[0077] It should be noted that the aforementioned restricted motion states have clear manifestations in engineering practice: In the singular motion state, the inverse kinematics solution may yield an infinite solution, causing the joint velocity command to suddenly increase to the physical upper limit; when the joint is close to the limit of its range of motion, the available motion space shrinks sharply, and the trajectory tracking error increases significantly; when the joint motion speed is close to the allowable upper limit, the motor output saturates, and the actual trajectory lags behind the planned trajectory; when the end-effector trajectory execution capability decreases, even if the singular point is not reached, small joint disturbances will be amplified into significant end-effector jitter.

[0078] Considering the differences in structural dimensions, joint configurations, and workspaces among different robot models, the original... The value may lead to a lack of universality in the preset evaluation threshold. Therefore, this embodiment preferably uses normalization processing to enhance the adaptability of the scheme.

[0079] Specifically, the maximum motion capability evaluation value of the robot within the current painting task workspace can be pre-calibrated or obtained through analytical calculation. Then calculate the normalized athletic ability evaluation value. Normalized evaluation value The value range is mapped to the interval [0, 1], eliminating the influence of units. In practical applications, the preset evaluation threshold can be uniformly set to a value between 0.15 and 0.40. For example, when The attitude optimization is activated automatically, and it is well applicable to most 6-axis serial painting robots, without the need to readjust parameters for each robot individually.

[0080] Example 4 Based on Example 1, this example further details the dynamic boundary constraint mechanism based on attitude adjustment margin.

[0081] As one implementation method, based on the attitude adjustment margin between the current spray gun end attitude and the boundary of the spray attitude tolerance space model, the allowable attitude adjustment amount in the constrained adjustment direction is dynamically adjusted, including: Calculate the attitude adjustment margin between the current spray gun end attitude and the nearest boundary of the spray attitude tolerance space model; Establish boundary constraint functions based on attitude adjustment margin, and calculate the corresponding attitude adjustment gain based on the boundary constraint functions; The allowable attitude adjustment amount in the constrained adjustment direction is determined based on the attitude adjustment gain; wherein, the constrained adjustment direction is the direction in which the current spray gun end attitude continues to change towards the nearest boundary; the attitude adjustment gain continuously increases as the attitude adjustment margin decreases, and continuously decreases as the attitude adjustment margin increases.

[0082] Among them, the attitude adjustment margin is a key state quantity characterizing the remaining space between the current attitude of the spray gun tip and the process safety boundary. Let the current attitude angle of the spray gun tip be... The lower bound of the spraying attitude tolerance space model in the current adjustment dimension is: The upper limit is Then the attitude adjustment margin It can be defined as the absolute difference between the current pose and the nearest boundary, i.e. .

[0083] The constrained adjustment direction refers to the direction of the nearest boundary that the current attitude change trend points to. For example, if It is increasing and getting closer If the direction of adjustment is constrained, then the direction of adjustment is the positive direction.

[0084] Furthermore, the boundary constraint function is a continuous monotonic function; the allowable attitude adjustment in the constrained adjustment direction is determined based on the attitude adjustment gain, including: Obtain the theoretical attitude adjustment requirement increment when no constraints are applied; divide the theoretical attitude adjustment requirement increment by the attitude adjustment gain to obtain the allowable attitude adjustment in the constrained adjustment direction; when the spray gun end attitude is close to the nearest boundary, the attitude adjustment margin decreases, the attitude adjustment gain increases, and the allowable attitude adjustment decreases to limit the attitude from continuing to adjust towards the boundary; when the spray gun end attitude is far from the nearest boundary, the attitude adjustment margin increases, the attitude adjustment gain decreases, and the allowable attitude adjustment increases to retain adjustable space.

[0085] like Figure 3 As shown in the figure, this embodiment demonstrates the characteristic curve of the boundary constraint function and its constraint effect on attitude adjustment.

[0086] In some implementations, the boundary constraint function Designed for attitude adjustment margin A continuously monotonically decreasing function (or about) (a monotonically increasing function), whose core function is to establish a nonlinear damping field.

[0087] For example, the boundary constraint function can be expressed as: ,in The minimum gain coefficient, The maximum gain coefficient, This is the attenuation coefficient.

[0088] When attitude adjustment margin When it is large, Approaching At this point, the constraint effect is weak; when As it gradually decreases, It increases smoothly and continuously until it approaches a certain value at the boundary. This continuous monotonic characteristic is the mathematical basis for ensuring control stability, and it completely avoids the problem of discontinuous control signals caused by parameter jumps in traditional threshold judgment logic.

[0089] After obtaining the attitude adjustment gain, the system uses a division adjustment mechanism to calculate the final allowable attitude adjustment. Its calculation formula is In the formula, This represents the theoretical attitude adjustment requirement increment calculated solely based on the motion capability optimization objective without applying boundary constraints.

[0090] When the spray gun tip moves away from the boundary Larger Smaller (close to 1 or the baseline value). The system retains most of its optimization capabilities to improve motion performance; as the spray gun's end position gradually approaches the boundary, Decrease Continuous increase leads to Automatically and continuously decrease; when the attitude is extremely close to the boundary, It became very large, making Approaching zero, thus forcing the posture adjustment movement to naturally converge and stop within the boundary.

[0091] To provide a more intuitive understanding of how this mechanism works, a specific numerical calculation example is provided below.

[0092] Assume that in a certain spraying process, the tolerance range of the spray gun's rotation around its axis is... ,Right now Set the parameters of the boundary constraint function so that when the margin At that time, gain When margin At that time, gain If the motion capability optimization algorithm calculates the theoretical adjustment requirement at a certain moment... .

[0093] When the spray gun is near the center, margin At that time, the actual allowable adjustment amount The system fully executed the optimization commands; as the adjustments proceeded, the spray gun posture reached... Position, at this point the margin is reduced to The gain increased to The actual allowable adjustment amount becomes Therefore, it can be seen that although the optimization algorithm still hopes to adjust... However, the boundary constraint mechanism reduces its actual execution volume to one-fifth of the original. If the attitude continues to approach until the margin is only... The gain may rise to The allowable adjustment amount will further decrease to .

[0094] The dynamic boundary constraint mechanism employed in this embodiment has significant technical advantages. In traditional methods, the adjustment amount is [missing information] when the attitude does not exceed the limit. Once the limit is reached, the adjustment amount instantly becomes 0 or is clamped. This abrupt change introduces high-frequency components into the control loop, causing sudden changes in robot joint speed, motor torque surges, and even mechanical resonance. This can manifest in coating quality as uneven coating thickness or surface ripples. This application, however, achieves stepless speed regulation of constraint strength through a continuously monotonic boundary constraint function and a division adjustment mechanism, ensuring the smoothness and continuity of the attitude adjustment process across the entire stroke range. This not only eliminates the risk of control oscillations and protects the robot's structure, but more importantly, it guarantees the extreme stability of the coating process, ensuring highly consistent coating quality even under complex conditions with frequent attitude optimization triggers.

[0095] Example 5 Based on Examples 1 to 4, this example further details the specific execution dimensions and control start-stop strategies for the dynamic adjustment of the spray gun end posture.

[0096] As one implementation method, the attitude of the spray gun tip is dynamically adjusted within the range defined by the spray attitude tolerance space model, including: While maintaining the target spraying distance and target spraying angle between the spray gun and the surface of the workpiece to be sprayed in accordance with the process requirements, the spray gun is controlled to rotate and adjust around the spraying direction axis within the preset attitude tolerance range.

[0097] It should be noted that choosing rotation around the spraying direction axis as the priority adjustment dimension is based on a comprehensive consideration of the spraying process characteristics and the robot's kinematic characteristics. From a process perspective, the uniformity and coverage of the coating thickness mainly depend on the perpendicular distance between the spray gun and the workpiece surface (i.e., the spraying distance) and the angle between the spray gun axis and the surface normal (i.e., the spraying incident angle). As long as these two key parameters remain unchanged, the rotation of the spray gun around its own axis (i.e., the spraying direction axis) usually does not change the projection shape and deposition distribution of the paint mist on the workpiece surface, and therefore has a negligible impact on coating quality, belonging to the "zero-sensitive" degree of freedom in terms of process. However, from a robot kinematics perspective, this rotational degree of freedom corresponds to the angle change of the robot's wrist joint, and the wrist joint is often the key to determining the robot's end effector dexterity and singularity avoidance. By fine-tuning this rotation angle, the robot's joint configuration can be significantly changed without sacrificing spraying quality, moving it away from motion singularities or joint limit positions, thereby obtaining the maximum motion performance benefit with the minimum process cost.

[0098] Furthermore, the method also includes: when the motion capability evaluation value is lower than the preset motion capability evaluation activation threshold, initiating dynamic adjustment of the spray gun end posture; When the motion capability evaluation value reaches the preset motion capability evaluation recovery threshold, the spray gun end posture adjustment amount is gradually reduced according to the preset posture recovery strategy, so that the spray gun end posture gradually returns to the target spraying posture; wherein, the preset motion capability evaluation recovery threshold is greater than the preset motion capability evaluation start threshold, and the preset evaluation threshold is the preset motion capability evaluation start threshold.

[0099] It should be noted that if the activation threshold and recovery threshold are set to the same value, the control system will frequently switch between "optimized mode" and "normal mode" when the robot's motion capability evaluation value fluctuates around that threshold. This high-frequency switching not only leads to discontinuity in attitude adjustment commands but may also trigger resonance in the mechanical structure, thus reducing coating stability. By setting hysteresis, i.e., setting a preset motion capability evaluation recovery threshold... Strictly greater than the preset threshold for evaluating athletic ability Once in the optimization state, it must wait until the motor function significantly improves and stabilizes above a high recovery threshold before exiting the optimization state.

[0100] For example, in practical engineering applications, a preset threshold for evaluating motor ability can be used. Set the normalized athletic ability evaluation value to 0.20, and restore the preset athletic ability evaluation threshold. The hysteresis is set to 0.30. This means that when the evaluation value drops below 0.20, rotation optimization around the axis is triggered, and the return to the original attitude is only considered when the evaluation value rises back above 0.30. This hysteresis range of 0.10 constitutes a stable state-holding band, effectively filtering out sensor noise and transient disturbances during motion, ensuring the robustness of the control logic.

[0101] The core of the preset attitude recovery strategy is to achieve a smooth transition from "optimized attitude" to "target attitude", rather than a step reset.

[0102] Furthermore, when the exercise capacity evaluation value reaches the recovery threshold, the posture adjustment amount is not immediately cleared to zero, but is gradually reduced according to the current exercise capacity surplus or the time process.

[0103] For example, a linear interpolation method can be used, setting a regression transition time window (such as 2 seconds or several trajectory points), within which the current rotation offset angle is linearly reduced to zero; or a first-order low-pass filtering algorithm can be used, with the target attitude as the filter setting value, so that the actual attitude approaches the target attitude in an exponentially convergent manner.

[0104] This progressive regression mechanism ensures the continuity of the spray gun tip angular velocity, avoiding uneven coating thickness or surface sagging defects caused by sudden changes in posture, making the entire optimization and recovery process transparent and imperceptible to the spraying process.

[0105] Example 6 This embodiment provides an electronic device that serves as the hardware carrier for executing the aforementioned robot motion control method based on spraying posture tolerance, ensuring the feasibility of the technical solution in actual industrial scenarios and the integrity of the legal basis. Specifically, the electronic device includes a processor and a memory. The memory stores a computer program, which, when executed by the processor, causes the processor to execute the robot motion control method based on spraying posture tolerance as described in any one of embodiments 1 to 5.

[0106] In practical implementation, the processor is the core of the electronic device's computation and control center. It can be one or a combination of general-purpose microprocessors (such as CPUs), digital signal processors (DSPs), field-programmable gate arrays (FPGAs), or application-specific integrated circuits (ASICs). When applied inside a painting robot controller, the processor typically also needs to integrate a real-time communication interface to read joint encoder data and issue servo drive commands at millisecond intervals. The memory is used to persistently or temporarily store the program code and intermediate data required to implement the method of this application. Its specific forms include, but are not limited to, computer-readable storage media such as read-only memory (ROM), random access memory (RAM), disks, optical discs, USB flash drives, or flash memory cards. For example, in a typical deployment, the core algorithm library, containing the tolerance space construction logic and boundary constraint functions, is stored in non-volatile memory, while real-time motion capability evaluation values, attitude adjustment margins, and other process variables are stored in high-speed RAM for frequent read and write operations by the processor.

[0107] It should be understood that the "computer program" mentioned in this embodiment is not an abstract intellectual rule, but rather a sequence of instructions that can be recognized and executed by a machine. These instruction sequences precisely correspond to the specific technical steps described in the foregoing embodiments, such as acquiring the spraying trajectory, constructing the attitude tolerance space model, evaluating motion capabilities, dynamically adjusting attitude, and applying boundary constraints. When the processor loads and runs the program, the electronic device transforms from a general-purpose computing device into a dedicated device with specific spraying motion control functions. This combination of hardware and software not only enables the technical solution of this application to move beyond pure theoretical derivation and be implemented as a practical industrial product, but also provides a clear legal basis for subsequent actions such as manufacturing, selling, or offering to sell controllers, robot bodies, or storage media equipped with this program. Furthermore, the electronic device can be used as an independent industrial control computer connected to the robot body via a bus, or it can be directly embedded inside the robot control cabinet as a main control unit. Regardless of the physical deployment form, as long as the program logic running inside it falls within the protection scope of the method flow of this application, it is considered an implementation method covered by this embodiment.

[0108] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0109] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of this application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from the spirit and scope of this application. Thus, if such modifications and modifications of this application fall within the scope of the claims of this application and their equivalents, this application is also intended to include such modifications and modifications.

Claims

1. A robot motion control method based on spray pose tolerance, characterized by, include: Obtain the spraying trajectory of the workpiece to be sprayed and the corresponding spraying process parameters; Based on the spraying process parameters, determine the allowable tolerance range of the spray gun end posture and construct a spraying posture tolerance space model; Based on the spraying trajectory and the spraying posture tolerance space model, an adjustable motion space is constructed; The robot acquires joint states and end-effector poses in real time during operation, and evaluates its current motion capabilities based on these states and poses to generate a motion capability evaluation value. In response to the motion capability evaluation value being lower than a preset evaluation threshold, the attitude of the spray gun end is dynamically adjusted within the range defined by the spraying attitude tolerance space model, and robot control commands are generated based on the adjusted spray gun end attitude to control the robot to perform the spraying operation; wherein, during the dynamic adjustment process, the allowable attitude adjustment amount in the constrained adjustment direction is dynamically adjusted based on the attitude adjustment margin between the current spray gun end attitude and the boundary of the spraying attitude tolerance space model, so as to keep the spray gun end attitude within the tolerance range.

2. The method of claim 1, wherein, The step of determining the allowable tolerance range of the spray gun end posture based on the spraying process parameters and constructing a spraying posture tolerance space model includes: Obtain the relative spatial relationship between the spray gun tip posture and the surface of the workpiece to be sprayed; A spraying process constraint model is established based on the spraying process parameters; Based on the spraying process constraint model, calculate the allowable range of change in the spray gun end posture to meet the coating quality requirements; The allowable variation range is mapped to the tolerance range of the spray gun end posture to establish the spray posture tolerance space model, which is used to characterize the space range that can be adjusted under the condition of meeting the spraying process requirements.

3. The method of claim 2, wherein, The spraying process parameters include spraying distance, spraying incident angle, spray gun moving speed, spraying flow rate, and allowable coating quality error; The establishment of the spraying process constraint model based on the spraying process parameters includes: Based on the spraying distance, the spraying incident angle, the spray gun moving speed, and the spraying flow rate, a spraying quality evaluation model is established to characterize the mapping relationship between the comprehensive quality index of the coating and the attitude change angle. The calculation of the allowable range of spray gun end posture variation to meet coating quality requirements based on the spraying process constraint model includes: The minimum coating quality threshold is determined based on the allowable coating quality error; Based on the spraying quality evaluation model, a set of attitude change angles that make the overall coating quality index greater than or equal to the minimum coating quality threshold are selected. The set of attitude change angles is taken as the allowable range of attitude change at the end of the spray gun.

4. The method of claim 1, wherein, The process of assessing current motor ability based on the joint state and the end-effector pose, and generating a motor ability evaluation value, includes: A robot kinematic model is established based on the joint states, and a kinematic mapping matrix describing the mapping relationship between the robot joint motion and the end effector motion of the spray gun is obtained. Construct a motion capability evaluation matrix based on the aforementioned kinematic mapping matrix; The motor ability evaluation value is calculated based on the motor ability evaluation matrix. The motor ability evaluation value is used to characterize the motor coordination ability and end-effector reachability under the current joint configuration.

5. The method of claim 4, wherein, The kinematic mapping matrix is ​​the robot Jacobian matrix; The construction of the motion ability evaluation matrix based on the kinematic mapping matrix includes: Multiplying the robot's Jacobian matrix by its transpose yields the motion capability evaluation matrix; The calculation of the athletic ability evaluation value based on the athletic ability evaluation matrix includes: Calculate the determinant of the athletic ability evaluation matrix, and take the square root of the determinant as the athletic ability evaluation value; The restricted motion state includes at least one of the following: motion singularity state, joint nearing the limit of range of motion state, joint motion speed nearing the upper limit of allowable speed state, and end-effector trajectory execution capability decline state.

6. The method of claim 1, wherein, The dynamic adjustment of the allowable attitude adjustment in the constrained adjustment direction based on the attitude adjustment margin between the current spray gun end attitude and the boundary of the spraying attitude tolerance space model includes: Calculate the attitude adjustment margin between the current spray gun end attitude and the nearest boundary of the spray attitude tolerance space model; A boundary constraint function is established based on the attitude adjustment margin, and the corresponding attitude adjustment gain is calculated based on the boundary constraint function. The allowable attitude adjustment amount in the constrained adjustment direction is determined based on the attitude adjustment gain, wherein the constrained adjustment direction is the direction in which the current spray gun end attitude continues to change towards the nearest boundary; the attitude adjustment gain continuously increases as the attitude adjustment margin decreases, and continuously decreases as the attitude adjustment margin increases.

7. The method according to claim 6, characterized in that, The boundary constraint function is a continuous monotonic function; Determining the allowable attitude adjustment amount in the constrained adjustment direction based on the attitude adjustment gain includes: Obtain the theoretical attitude adjustment increment when no constraints are applied; Divide the theoretical attitude adjustment requirement increment by the attitude adjustment gain to obtain the allowable attitude adjustment amount in the constrained adjustment direction; When the attitude of the spray gun end approaches the nearest boundary, the attitude adjustment margin decreases, the attitude adjustment gain increases, and the allowable attitude adjustment decreases to limit the attitude from continuing to adjust towards the boundary. When the attitude of the spray gun tip moves away from the nearest boundary, the attitude adjustment margin increases, the attitude adjustment gain decreases, and the allowable attitude adjustment increases to retain adjustable space.

8. The method according to claim 1, characterized in that, Dynamically adjusting the spray gun tip attitude within the range defined by the spraying attitude tolerance space model includes: While maintaining the target spraying distance and target spraying angle between the spray gun and the surface of the workpiece to be sprayed in accordance with the process requirements, the spray gun is controlled to rotate and adjust around the spraying direction axis within a preset attitude tolerance range.

9. The method according to claim 8, characterized in that, The method further includes: When the motion capability evaluation value is lower than the preset motion capability evaluation activation threshold, dynamic adjustment of the spray gun end posture is initiated. When the motion capability evaluation value reaches the preset motion capability evaluation recovery threshold, the spray gun end posture adjustment amount is gradually reduced according to the preset posture recovery strategy, so that the spray gun end posture gradually returns to the target spraying posture. Wherein, the preset exercise ability evaluation recovery threshold is greater than the preset exercise ability evaluation activation threshold, and the preset evaluation threshold is the preset exercise ability evaluation activation threshold.

10. An electronic device, characterized in that, include: processor; Memory, used to store computer programs; When the computer program is executed by the processor, the processor performs the robot motion control method based on spraying posture tolerance as described in any one of claims 1 to 9.

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