A robot joint planning method with external axes

Abstract

The application discloses a linkage planning method for a robot and an external shaft, and comprises the following steps: establishing the coordinate relationship of a linkage system of the robot and the external shaft, determining the motion attributes of the robot and the external shaft and a path to be planned, and reading a coordinate point to be processed; performing smoothing processing on a transition part by using a given switching error, and performing synchronous preprocessing; performing synchronous processing on the position of the external shaft; synchronously matching the coordinate point to be processed with the transition section of the external shaft; synchronously matching the coordinate point to be processed with the straight section of the external shaft; and calculating the interpolation point of the robot according to the coordinate relationship of the linkage system. The application realizes the continuous trajectory processing of the robot and the external shaft, avoids the step-by-step start-stop mode of the traditional linkage mode, and can effectively improve the processing efficiency and quality.

Description

Technical Field

[0001] This invention belongs to the field of industrial robot external axis control technology, specifically relating to a linkage planning method between a robot and its external axis. Background Technology

[0002] Industrial robots are widely used in the manufacturing field due to their ease of use, high flexibility, and high efficiency. However, when performing machining tasks on large workpieces, the limited working range of a robot with a fixed base makes it difficult to complete all machining tasks. Therefore, it is generally necessary to attach external axes to the robot to complete the machining tasks of large parts.

[0003] Traditionally, the method involves defining workstations and using multiple workstations to complete tasks. However, this approach is prone to poor quality at the connection points when machining large-scale continuous tasks. Major industrial robot manufacturers like KUKA support robot-external axis linkage for continuous trajectory operation, but this technology is closed, allowing only direct use and not further development. Patent CN115922704A discloses a method, device, and storage medium for coordinated control of a robot and external axes, providing a method for robot-external axis linkage operation, but it cannot achieve synchronization of continuous trajectories. Xu Yi, in "Research and Implementation of Cooperative Motion Control Technology for Industrial Robots," proposed a synchronous speed planning method based on extended linkage axes, suitable for segment-by-segment synchronous planning, but also unable to achieve synchronous planning of continuous trajectories. Therefore, a method is needed that enables coordinated planning of robot-external axis linkage to meet the needs of machining large-scale continuous trajectories. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a linkage planning method for a robot and an external axis. By establishing the coordinate transformation relationship of the linkage system, the path to be planned is determined, the path to be planned is preprocessed synchronously, and the transition segment and the straight segment are planned synchronously. This enables the continuous synchronous trajectory planning and operation of the robot and the external axis, avoiding the segmented start and stop method of the traditional linkage method, and can effectively improve processing efficiency and quality.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for planning the linkage between a robot and an external axis, comprising:

[0007] Step 1: Establish the coordinate relationship between the robot and the external axis linkage system, determine the motion attributes of the robot and the external axis and the path to be planned, and read the coordinate points to be processed;

[0008] Step 2: Based on the read coordinate points to be processed, use the given transition error to smooth the transition part and perform synchronous preprocessing;

[0009] Step 3: Based on Step 2, use the proportional mapping method to synchronize the position of the external axis;

[0010] Step 4: Calculate the speed of the transition section and use this speed to synchronize the time between the coordinate point to be processed and the transition section of the external axis;

[0011] Step 5: Use a speed synchronization planning strategy to perform time synchronization matching between the coordinate points to be processed and the straight line segments of the external axis;

[0012] Step 6: Calculate the interpolation point of the robot based on the established coordinate relationship between the robot and the external axis linkage system.

[0013] To optimize the above technical solution, the specific measures also include:

[0014] Step 1 above determines the motion attributes of the robot and the external axis as follows: the external axis is the master motion and the robot is the slave motion. The path to be planned includes the position of the external axis and the points to be processed in the workpiece coordinate system.

[0015] Step 2 above generates position and attitude transition curves according to the given transition error, and adjusts the length of the transition curves so that the sum of the two transition lengths on the same straight line is less than or equal to two-thirds of the sum of the total lengths; and the transition lengths on the first and last straight lines are less than one-half of the total length of the line segment.

[0016] Step 3 above uses the proportional method to map the external axis transition point corresponding to the workpiece coordinate system transition point.

[0017] When using the proportional mapping method, if the coordinates of points A and B on the external axis are the same, then the coordinates of the transition positions on both sides of point B on the external axis are equal to point B; if the coordinates of points B and C on the external axis are the same, then the coordinates of the transition positions on both sides of points B and C on the external axis are equal to point B; if the coordinates of points B and C on the external axis are not the same, but the coordinates of points A and B are the same, then the coordinates of the transition positions on the corresponding side of the external axis near point B are adjusted to the position of point B; if the coordinates of points C and D are the same, then the coordinates of the transition positions on both sides of point C on the external axis are equal to point C; if A < B && B > C or A > B && B < C, then point B is the external axis reversal point, and the external axis transition positions on both sides of point B on the external axis are adjusted to the coordinates of point B; if B < C && C > D or B > C && C < D, then point C is the external axis reversal point, and the external axis transition positions on both sides of point C on the external axis are adjusted to the coordinates of point C.

[0018] In step 4 above, if the straight line before the transition curve is in an accelerating state, then the speed of the transition segment is the minimum of speeds 1) and 2) below; otherwise, it is speed 1):

[0019] 1) The minimum of the following four speeds: the achievable speed when accelerating from the starting point to the transition point, the maximum speed limit, the speed allowed during the transition section, and the maximum speed that can be accelerated to within half the length of the straight line after the transition curve;

[0020] 2) The maximum speed at which the starting speed can accelerate after it decelerates to 0 on a straight path.

[0021] The above step 4, which describes the time synchronization matching between the coordinate point to be processed and the transition section of the external axis, means that the transition section adopts a constant speed, calculates the time used for each section, and adjusts the other transition section with the longest movement time to achieve time synchronization matching of the transition section.

[0022] The speed synchronization planning strategy described in step 5 above is as follows: The speed curve adopts a trapezoidal speed curve. Based on the initial and final speeds of the line segment, it is determined whether it is a macroscopic acceleration or deceleration behavior. If it is an acceleration behavior, the maximum time required for acceleration + constant speed is calculated first. If the synchronization time is less than the maximum time, the overall curve is an acceleration + constant speed + deceleration behavior. Otherwise, the maximum time required for constant speed + acceleration is calculated. If the synchronization time is less than the maximum time required for constant speed + acceleration, the overall curve is an acceleration + constant speed + acceleration behavior. Otherwise, it is a deceleration + constant speed + acceleration behavior. By setting up a system of equations, the corresponding time and speed values ​​are obtained using Vieta's formulas. Similarly, the deceleration stage can also be obtained in this way, realizing time synchronization of single-segment straight machining paths and straight axis paths.

[0023] The method for calculating the robot's interpolation point in step 6 above is as follows: the machining position and the position of the external axis are interpolated and calculated separately for each interpolation cycle. Based on the coordinate transformation relationship of the linkage system, the end position of the robot in the base coordinate system is calculated in real time for each interpolation cycle.

[0024] The present invention has the following beneficial effects:

[0025] This invention establishes the transformation relationship of the linkage system to determine the path to be planned; it uses a given transition error to smoothly transition the machining trajectory and performs synchronous preprocessing; based on the preprocessed transition point, it performs synchronous preprocessing of the external axis position; it calculates the allowable speed of the transition segment and performs time synchronization matching of the transition segment and the straight segment; finally, it calculates the robot interpolation point position at each moment based on the transition relationship. This enables collaborative planning of continuous trajectories, thus avoiding repeated starts and stops at the starting point of each line segment; it also allows for limiting the speed and acceleration of external axes, thereby improving machining quality.

[0026] The linkage planning method provided by this invention is not limited to a single scenario; it is applicable to planning and interpolation methods for multi-robot synchronization and different types of robot linkage systems on external axes. Attached Figure Description

[0027] Figure 1 A flowchart for planning the linkage between the robot and external axes;

[0028] Figure 2 A planning model for the linkage between the robot and external axes;

[0029] Figure 3 A schematic diagram of speed synchronization planning;

[0030] Figure 4 Speed ​​planning curve for the processing trajectory;

[0031] Figure 5 A curve diagram showing the external axis speed planning for the machining trajectory;

[0032] Figure 6 This is a schematic diagram of machining trajectory interpolation.

[0033] Figure 7 This is a schematic diagram of the external axis interpolation position corresponding to the machining trajectory. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] Although the steps in this invention are arranged by reference numerals, this is not intended to limit the order of the steps. Unless the order of the steps is explicitly stated or the execution of a step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" as used herein refers to and covers any and all possible combinations of one or more of the associated listed items.

[0036] A method for planning the linkage between a robot and an external axis involves establishing the coordinate transformation relationship of the linkage system, determining the path to be planned, performing synchronous preprocessing on the path, and planning the synchronous speed for transition segments and straight segments separately, thereby achieving continuous trajectory operation between the robot and the external axis. Figure 1 As shown, it specifically includes:

[0037] Step 1: Establish the coordinate relationship between the robot and the external axis linkage system, determine the motion attributes of the robot and the external axis and the path to be planned, and read the coordinate points to be processed;

[0038] Step 2: Based on the read coordinate points to be processed, use the given transition error to smooth the transition part and perform synchronous preprocessing;

[0039] Step 3: Based on the pre-processed coordinates of the transition points, use the proportional mapping method to synchronously process the external axis position;

[0040] Step 4: Calculate the speed of the transition section and use this speed to synchronize the time between the coordinate point to be processed and the transition section of the external axis;

[0041] Step 5: Use a speed synchronization planning strategy to perform time synchronization matching between the coordinate points to be processed and the straight line segments of the external axis;

[0042] Step 6: Calculate the interpolation point of the robot based on the established coordinate relationship between the robot and the external axis linkage system.

[0043] In this embodiment, in step 1, a laser tracker is used to establish the robot's base coordinate system, the external axis origin coordinate system, and the world coordinate system, and to establish the transformation relationship between the coordinate systems, i.e., the coordinate relationship of the linkage system. Based on the coordinate relationship of the linkage system and the robot's flexibility, the motion attributes of the robot and the external axis are determined as follows: the external axis is the master motion, and the robot is the slave motion. The path to be planned includes: the position of the external axis and the coordinate points to be processed in the workpiece coordinate system.

[0044] In step 2, synchronization preprocessing refers to the fact that the position and attitude transition curves generated according to the given transition error may not meet the synchronization requirements, i.e., curve overlap or the absence of straight segments between adjacent curves may occur. To avoid synchronization failure, the length of the transition curve needs to be adjusted. To avoid excessively reducing the transition speed, the sum of the lengths of two transition curves on the same straight line is set to be less than or equal to two-thirds of the sum of the total lengths. Figure 2 As shown, that is, L BB2 +L C1C <2 / 3×L BC Since there is only one transition length on the first and last straight lines, it should be less than one-half of the total length of the line segment.

[0045] In step 3, the synchronous processing of the external axis position refers to the following: after the machining point is transferred, since the external axis position planning has no transfer error constraints and can be regarded as a single degree of freedom planning, the external axis transition point corresponding to the workpiece coordinate system transition point is mapped by the equal scale method.

[0046] like Figure 2As shown, when using the proportional mapping method, if the coordinates of points A and B on the external axis are the same, then the coordinates of points B1 and B2 on the corresponding side of the external axis are equal to point B; if the coordinates of points B and C on the external axis are the same, then the coordinates of the transition positions B1, B2, C1, and C2 on the corresponding side of the external axis are all equal to point B; if the coordinates of points B and C on the external axis are not the same, but the coordinates of points A and B are the same, then the coordinates of the transition position B2 on the corresponding side of the external axis are adjusted to the position of point B; if the coordinates of points C and D are the same, then the coordinates of the transition positions C1 and C2 are equal to point C; if A < B && B > C or A > B && B < C, then point B is the external axis reversal point, and the external axis transition positions of points B1 and B2 are adjusted to the coordinates of point B; if B < C && C > D or B > C && C < D, then point C is the external axis reversal point, and the external axis transition positions of points C1 and C2 are adjusted to the coordinates of point C.

[0047] In step 4, before performing time synchronization matching of the transfer segment, it is necessary to calculate the speed of the transfer segment.

[0048] The transition speed at the processing point and the constraint speed of the linear axis transition section are both taken as the minimum of four speeds. These four speeds are: the achievable speed during acceleration from the starting point to the transition point, the maximum limited speed, the permissible speed of the transition section, and the maximum speed that can be accelerated to half the length of the straight line after the transition curve. See the following formula:

[0049]

[0050] If the straight line before the transition curve is in an accelerating state, then it is necessary to calculate the maximum speed at which the starting speed can accelerate after decelerating to 0 on the straight path. The minimum value of the two is taken, and then the time synchronization of the corresponding transition segment between the point to be processed and the external shaft is performed.

[0051] The time synchronization matching between the processing point and the corresponding transition section of the external axis refers to: the transition section adopts a constant speed, calculates the time used for each, and adjusts the remaining short transition curves with the longest movement time as the synchronization time, thereby achieving the time synchronization matching of the transition section.

[0052] In step 5, the time synchronization matching between the point to be processed and the corresponding straight line segment of the external axis refers to: knowing the start and end speeds of the straight line segment, and the longest time taken for the planned straight line and the corresponding straight line segment of the external axis, using a speed synchronization planning strategy for time synchronization. Figure 3Taking the acceleration phase as an example, the speed synchronization planning strategy is as follows: A trapezoidal speed curve is used. The initial and final velocities of the line segment determine whether it's a macroscopic acceleration or deceleration behavior. If it's acceleration, the maximum time required for acceleration + constant speed (T3) is calculated first. If the synchronization time is less than the maximum time, the overall behavior is acceleration + constant speed + deceleration (A2 curve). If it's greater, the maximum time required for constant speed + acceleration (T5) is calculated. If the synchronization time is less than the maximum time, the overall behavior is acceleration + constant speed + acceleration (A4 curve); otherwise, it's deceleration + constant speed + acceleration (A6 curve). This method allows for the calculation of the corresponding time and speed values ​​using a system of equations and Vieta's formulas. Similarly, the deceleration phase can be calculated using this method. This enables time synchronization for single-segment straight machining paths and straight axis paths.

[0053] In step 6, the method for calculating the interpolation point of the robot is as follows: the machining position and the external axis position are calculated separately for each interpolation cycle. Based on the coordinate transformation relationship of the linkage system, the end position of the robot in the base coordinate system is calculated in real time for each interpolation cycle.

[0054] Example effect verification:

[0055] The maximum allowable speed of the machining trajectory is set to 50, the maximum acceleration to 1000, the maximum contour error to 0.1mm, the maximum bow height error to 0.05mm, and the interpolation cycle to 2ms. The point data of the path to be planned are shown in Table 1, and the postures are the same. The maximum allowable speed of the external axis is 10, the maximum acceleration is 100, and the corresponding external axis positions are [-10,10,-10,-10,-30,100,100,-10]. Figure 4-5 For the velocity curve, Figure 6-7 The interpolation results show the machining trajectory and the external axis. As can be seen from the effect diagram, the method of this invention can synchronize the planned machining points with the position of the external axis, and the machining time for corresponding line segments is the same.

[0056] Table 1. Data on locations to be planned

[0057] Serial Number x / mm y / mm z / mm 1 -310.715 7.005 290.002 2 210.85 235.51 385.04 3 210.85 235.51 390.04 4 297.99 289.73 390.04 5 297.94 302.19 390.04 6 204.72 347.07 390.04 7 204.72 347.07 390.04 8 -310.715 7.004 290.002

[0058] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0059] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for planning the linkage between a robot and an external axis, characterized in that, include: Step 1: Establish the coordinate relationship between the robot and the external axis linkage system, determine the motion attributes of the robot and the external axis and the path to be planned, and read the coordinate points to be processed; Step 2: Based on the read coordinate points to be processed, use the given transition error to smooth the transition part and perform synchronous preprocessing; Step 3: Based on Step 2, use the proportional mapping method to synchronize the position of the external axis; Step 3 uses the proportional method to map the external axis transition point corresponding to the workpiece coordinate system transition point. When using the proportional mapping method, if the coordinates of points A and B on the external axis are the same, then the coordinates of the transition positions on both sides of point B on the external axis are equal to point B; if the coordinates of points B and C on the external axis are the same, then the coordinates of the transition positions on both sides of points B and C on the external axis are equal to point B; if the coordinates of points B and C on the external axis are not the same, but the coordinates of points A and B are the same, then the coordinates of the transition positions on the corresponding side of the external axis closest to point B are adjusted to the position of point B; if the coordinates of points C and D are the same, then the coordinates of the transition positions on both sides of point C on the external axis are equal to point C; if... or If point B is the external axis reversal point, then the external axis transition points on both sides of point B should be adjusted to the coordinates of point B; if or If point C is the external axis reversal point, then the external axis transition points on both sides of point C are adjusted to the coordinates of point C. Step 4: Calculate the speed of the transition section and use this speed to synchronize the time between the coordinate point to be processed and the transition section of the external axis; Step 5: Use a speed synchronization planning strategy to perform time synchronization matching between the coordinate points to be processed and the straight line segments of the external axis; Step 6: Calculate the interpolation point of the robot based on the established coordinate relationship between the robot and the external axis linkage system.

2. The linkage planning method between a robot and an external axis according to claim 1, characterized in that, Step 1 determines the motion attributes of the robot and the external axis as follows: the external axis is the master motion and the robot is the slave motion. The path to be planned includes the position of the external axis and the points to be processed in the workpiece coordinate system.

3. The method for planning the linkage between a robot and an external axis according to claim 1, characterized in that, Step 2 generates position and attitude transition curves according to the given transition error, and adjusts the length of the transition curves so that the sum of the two transition lengths on the same straight line is less than or equal to two-thirds of the sum of the total lengths; and the transition lengths on the first and last straight lines are less than one-half of the total length of the line segment.

4. The method for planning the linkage between a robot and an external axis according to claim 1, characterized in that, In step 4, if the straight line before the transition curve is in an accelerating state, then the speed of the transition segment is the minimum of speeds 1) and 2) below; otherwise, it is speed 1): 1) The minimum of the following four speeds: the achievable speed when accelerating from the starting point to the transition point, the maximum speed limit, the speed allowed during the transition section, and the maximum speed that can be accelerated to within half the length of the straight line after the transition curve; 2) The maximum speed at which the starting speed can accelerate after it decelerates to 0 on a straight path.

5. The linkage planning method between a robot and an external axis according to claim 1, characterized in that, Step 4, which describes the time synchronization matching between the coordinate point to be processed and the transition section of the external axis, means that the transition section adopts a constant speed, calculates the time used for each section, and adjusts the other transition section with the longest movement time to achieve time synchronization matching of the transition section.

6. The method for planning the linkage between a robot and an external axis according to claim 1, characterized in that, The speed synchronization planning strategy described in step 5 is as follows: The speed curve adopts a trapezoidal speed curve. Based on the initial and final speeds of the line segment, it is determined whether it is a macroscopic acceleration or deceleration behavior. If it is an acceleration behavior, the maximum time required for acceleration + constant speed is calculated first. If the synchronization time is less than the maximum time, the overall curve is an acceleration + constant speed + deceleration behavior. Otherwise, the maximum time required for constant speed + acceleration is calculated. If the synchronization time is less than the maximum time required for constant speed + acceleration, the overall curve is an acceleration + constant speed + acceleration behavior. Otherwise, it is a deceleration + constant speed + acceleration behavior. By setting up a system of equations, the corresponding time and speed values ​​are obtained using Vieta's formulas. Similarly, the deceleration stage is obtained in the same way, realizing time synchronization of the single-segment straight machining path and the straight axis path.

7. The linkage planning method between a robot and an external axis according to claim 1, characterized in that, The method for calculating the robot's interpolation point in step 6 is as follows: the machining position and the position of the external axis are interpolated and calculated separately for each interpolation cycle. Based on the coordinate transformation relationship of the linkage system, the end position of the robot in the base coordinate system is calculated in real time for each interpolation cycle.

Images