A forging and feeding method for a multi-axis palletizing robot

Abstract

The present invention relates to a forging and feeding method of a multi-axis palletizing robot, which is composed of three track segments, namely: a first segment MOVL linear motion, a second segment MOVJ joint motion and a third segment MOVL linear motion, and the forging and feeding process of the multi-axis palletizing robot is completed through the three track segments. Under the condition that the first segment MOVL linear motion and the third segment MOVL linear motion remain unchanged, the present invention combines the transition segments in the forging and feeding process into the second segment MOVJ joint motion process for unified consideration, and allows the robot to move at the maximum acceleration and maximum speed as much as possible, making full use of the speed performance of the robot, thereby achieving a shorter time effect and improving the efficiency of forging and feeding.

Description

Technical Field

[0001] The present invention relates to the field of numerical control technology, and in particular to a forging and feeding method for a multi-axis stacking robot, which is a forging and feeding method with the best efficiency under the premise of ensuring no interference. Background Art

[0002] In forging applications, due to the harsh working environment, if the loading process is completed by workshop workers, it is not only inefficient but also dangerous and prone to work injuries. The multi-axis palletizing robot is not affected by the environment and can well realize the automatic loading operation. The robot takes the blank from the loading table and then puts it on the forging table for forging. The entire loading process requires that the robot cannot touch the loading table and the processing table to cause interference, and that the robot's loading speed cannot be lower than the forging processing speed. Therefore, it is crucial to reasonably plan the robot's movement path and movement speed during the loading process.

[0003] Document 1, Chinese patent application No. 201810707695.5 discloses an industrial robot for loading and unloading forging machines, and Document 2, Chinese patent application No. 202111373131.0 discloses an industrial robot for loading and unloading forging machines. Both describe the method steps of forging loading, that is, using the robot to place the blank on the worktable of the forging machine, and using the hammer, anvil, punch or mold of the forging machine to apply pressure to the blank to cause plastic deformation, thereby obtaining the desired shape and size.

[0004] In the forging and feeding process, in order to avoid interference with the feeding table, the robot generally first performs linear motion (MOVE LINE, MOVL for short), starting from the feeding table, and moves to a safety point 1 which is a short distance away from the feeding table, and then performs joint motion (MOVE JOINT, MOVJ for short) at full speed to a safety point 2 which is a short distance away from the processing table, and finally, in order to avoid interference with the processing table, it performs linear motion (MOVL) again, starting from safety point 2, and moves to the workbench. In order to improve the execution speed of the entire process, it is required that each motion trajectory cannot stop, so a transition segment will be inserted between the first MOVL motion and the second MOVJ motion, and between the second MOVJ motion and the third MOVL motion. Therefore, the entire feeding process contains five trajectory segments: the first MOVL linear motion segment, the transition segment between MOVL and MOVJ, the MOVJ joint motion segment, the transition segment between MOVJ and MOVL, and the second MOVL linear motion segment.

[0005] The MOVL linear motion segment is designed to avoid interference with the loading table or processing table, the MOVJ joint motion is designed to ensure the loading speed, and the transition segment is designed to ensure smooth, coherent and uninterrupted movement throughout the process. This trajectory planning method can take into account the problems of collision interference and loading speed to a certain extent, but two transition segments are added, and the transition segment cannot ensure that the robot runs at full speed, and in order to ensure a smooth connection between the two segments, there may be a process of first increasing the speed and then decreasing the speed, which will limit the speed of the entire loading process. If the forging process speed is faster, the loading speed of the existing technology may not keep up. If a robot is required to feed two or even three forging processing tables at the same time, the loading method of the existing technology will be even more difficult to achieve. Summary of the invention

[0006] The object of the present invention is to provide a forging and feeding method for a multi-axis palletizing robot to solve the problems encountered in the above-mentioned background technology.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A forging and feeding method for a multi-axis palletizing robot is composed of three track segments, namely: a first segment of MOVL linear motion, a second segment of MOVJ joint motion and a third segment of MOVL linear motion. The forging and feeding process of the multi-axis palletizing robot is completed through the three track segments; wherein the operation process of the first segment of MOVL linear motion and the third segment of MOVL linear motion is the same as that of the prior art, and the specific steps of the second segment of MOVJ joint motion are as follows:

[0009] S1, first determine the Cartesian coordinates of the previous interpolation period point P0 of the starting point, the starting point P1, the end point P2, and the next interpolation period point P3 of the end point;

[0010] S2. Then, according to the inverse kinematic solution method of the multi-axis palletizing robot, the joint coordinates corresponding to the points P0, P1, P2, P3, etc. are obtained;

[0011] S3, according to the joint coordinates, the total displacement, initial velocity and final velocity of each joint required to move are obtained;

[0012] S4. Determine the maximum speed and maximum acceleration of each joint based on the mechanical characteristics of the multi-axis palletizing robot;

[0013] S5, further deriving the shortest movement time of each joint of the multi-axis palletizing robot, and selecting the maximum value of each time as the unified movement time;

[0014] S6. Finally, the speed curve is planned for each joint of the multi-axis palletizing robot.

[0015] Compared with the prior art, the beneficial effect of the present invention is that, while the first section MOVL linear motion and the third section MOVL linear motion remain unchanged, the present invention combines the transition sections in the forging and feeding process into the second section MOVJ joint motion process for unified consideration, allowing the robot to move at the maximum acceleration and maximum speed as much as possible, making full use of the speed performance of the robot, thereby achieving a shorter time effect and improving the efficiency of forging and feeding. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The disclosure of the present invention is described with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them:

[0017] Figure 1 It is a flow chart of the motion process of the multi-axis palletizing robot in the present invention;

[0018] Figure 2 This is a flow chart of the operation method of the second stage MOVJ joint motion in the present invention;

[0019] Figure 3 A schematic diagram of the triangular acceleration and deceleration in the implementation of the present invention;

[0020] Figure 4 It is a schematic diagram of trapezoidal acceleration and deceleration when the present invention is implemented. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the present invention is now further described in detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the relevant components of the present invention.

[0022] According to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific implementation modes and the accompanying drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the entirety of the present invention or as a limitation or restriction to the technical solution of the present invention.

[0023] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0024] Embodiment 1, as Figure 1As shown, a forging and feeding method for a multi-axis palletizing robot is a forging and feeding method with the best efficiency under the premise of ensuring no interference. Different from the forging and feeding process in the prior art which includes five trajectory segments, the present invention only includes three trajectory segments, namely: the first segment MOVL linear motion, the second segment MOVJ joint motion and the third segment MOVL linear motion.

[0025] Among them, the trajectory segments of the first and third MOVL linear motions are consistent with the prior art, and their operation processes still use the methods and steps of the prior art, which will not be repeated here, while the trajectory segment of the second MOVJ joint motion is different, please refer to Figure 2 This embodiment takes a four-axis palletizing robot as an example to focus on this.

[0026] First, determine the Cartesian coordinates of the previous interpolation cycle point P0 of the starting point, the starting point P1, the end point P2, and the next interpolation cycle point P3 of the end point. Then, according to the inverse kinematic solution method of the four-axis palletizing robot, obtain the joint coordinates corresponding to the points P0, P1, P2, and P3. Then, according to the joint coordinates, obtain the total displacement, initial velocity, and final velocity of each joint that needs to move. According to the mechanical characteristics of the multi-axis palletizing robot, obtain the maximum velocity and maximum acceleration of each joint. Further, obtain the shortest movement time of each joint of the multi-axis palletizing robot, select the maximum value of each time as the unified movement time, and finally plan the speed curve for each joint of the multi-axis palletizing robot.

[0027] Example 2, based on Example 1, the specific planning scheme of the second stage MOVJ joint motion is as follows:

[0028] 1. Determine Cartesian coordinates

[0029] Set the starting point of the first MOVL linear motion trajectory segment to Q0 and the end point to Q1, and the starting point of the third MOVL linear motion trajectory segment to Q2 and the end point to Q3, that is:

[0030]

[0031] Assume that the motion speed of the first MOVL linear motion trajectory segment is V1, the motion speed of the third MOVL linear motion trajectory segment is V2, and the interpolation period is T. Then the Cartesian coordinates of the last interpolation period point P0 of the starting point of the second MOVJ joint motion trajectory segment are:

[0032]

[0033] The Cartesian coordinates of the starting point P1 of the second MOVJ joint motion trajectory segment are:

[0034]

[0035] The Cartesian coordinates of the end point P2 of the second MOVJ joint motion trajectory segment are:

[0036]

[0037] The Cartesian coordinates of the next interpolation period point P3 at the end point of the second MOVJ joint motion trajectory segment are:

[0038]

[0039] 2. Inverse solution to obtain joint coordinates

[0040] The previous step has obtained the Cartesian coordinates P0, P1, P2, and P3. The inverse solution is to find the joint coordinates J0, J1, J2, and J3 based on the Cartesian coordinates P0, P1, P2, and P3 of the robot.

[0041]

[0042] For the convenience of description, the Cartesian coordinates P0, P1, P2, and P3 are uniformly represented as P n (n=0,1,2,3), the joint coordinates J0, J1, J2, and J3 are uniformly represented as J n (n=0,1,2,3), that is:

[0043]

[0044] The detailed inverse solution method is as follows:

[0045]

[0046] Where j n1 、j n2 、j n3 、j n4The unit is degree, a1, d1, a2, a3, a4, b4 are the robot's connecting rod parameters, where a1 is the horizontal distance from joint 1 to joint 2 of the robot, d1 is the vertical distance from joint 1 to joint 2 of the robot, a2 is the distance from joint 2 to joint 3 of the robot, a3 is the distance from joint 3 to the virtual joint of the robot, a4 is the horizontal distance from the virtual joint to joint 4 of the robot, d4 is the vertical distance from the virtual joint to joint 4 of the robot, atan2 is the azimuth trigonometric function, cos is the cosine trigonometric function, sin is the sine trigonometric function, acos is the arccosine trigonometric function, c1 is the cosine value of the robot's joint 1 angle, s1 is the sine value of the robot's joint 1 angle, c3 is the cosine value of the robot's joint 3 angle, and s3 is the sine value of the robot's joint 3 angle. The solution obtained in the formula is multiple solutions, and it is necessary to select a point closest to the previous interpolation point from multiple solutions as the final inverse solution value.

[0047] 3. Determine the displacement of each joint

[0048] Set the displacements of joints 1 to 4 to L1, L2, L3, and L4. The displacements are the difference between the joint coordinates at the end and the start of the second segment, that is:

[0049]

[0050] 4. Determine the initial velocity of each joint

[0051] Set the initial velocities of joints 1 to 4 to Vs1, Vs2, Vs3, and Vs4. The initial velocities are the differentials of the joint positions at the starting point of the second segment, that is:

[0052]

[0053] 5. Determine the final velocity of each joint

[0054] Set the final velocities of joints 1 to 4 to Ve1, Ve2, Ve3, and Ve4. The final velocity is the differential of the joint position at the end point of the second segment, that is:

[0055]

[0056] 6. Determine the maximum velocity and maximum acceleration of each joint

[0057] Checking the robot's specification manual, we can find that the maximum speeds of joints 1 to 4 are Vm1, Vm2, Vm3, and Vm4, and the maximum accelerations of joints 1 to 4 are Am1, Am2, Am3, and Am4. The unit of the maximum speed is ° / s, and the unit of the maximum acceleration is ° / s. 2 .

[0058] It is worth noting that the maximum velocity and maximum acceleration here are signed, which can be positive or negative. The positive and negative signs of the maximum velocity and maximum acceleration of each joint are consistent with the positive and negative signs of the displacement. That is, if the displacement of a joint is positive, then the maximum velocity and maximum acceleration of the joint are also positive, and vice versa.

[0059] 7. Determine the movement time of each joint

[0060] For the convenience of description, the joint displacement, initial velocity, final velocity, maximum velocity, maximum acceleration, and movement time are uniformly expressed as L n , Vs n 、Ve n 、Vm n 、Am n ,t n (n=0,1,2,3).

[0061] The motion process of each joint may be a triangular acceleration and deceleration, that is, acceleration first and then deceleration, such as Figure 3 shown.

[0062] It may also be a trapezoidal acceleration and deceleration, that is, first accelerate, then maintain a constant speed, and finally decelerate, such as Figure 4 shown.

[0063] In order to determine whether the motion process of each joint is a triangle or a trapezoid, it is necessary to first determine the critical maximum velocity Vm of each joint. n临界 (n=0,1,2,3), first assume the motion process is a triangle, then:

[0064]

[0065] According to formula 12, the critical maximum speed can be obtained as:

[0066]

[0067] In formula 13, Vm n临界 (n=0,1,2,3) has the same sign as the displacement. If the displacement of a joint is positive, then the Vm of the joint is n临界 (n=0,1,2,3) takes +, otherwise takes -.

[0068] Combined with the results calculated in formula 13, for each joint, the critical maximum velocity Vm n临界 (n=0,1,2,3) and maximum speed Vm n (n=0,1,2,3) to judge, if Vm n临界 The absolute value of (n=0,1,2,3) is less than Vm n (n=0,1,2,3) is the absolute value, then the movement process of the joint is a triangle, and the movement time is:

[0069]

[0070] If Vm n临界 The absolute value of (n=0,1,2,3) is not less than Vm n (n=0,1,2,3) is the absolute value, then the motion process of the joint is trapezoidal, and the motion time is:

[0071]

[0072] 8. Determine a unified exercise time

[0073] The joints of the robot need to be linked, and the movement time in a single trajectory segment must be unified. According to the barrel theory, the movement time of the joint with the longest movement time among all joints is taken as the unified movement time t 统一 ,Right now:

[0074] t 统一 =Max(t1,t2,t3,t4) Equation 16

[0075] In the formula, Max represents the maximum value.

[0076] 9. Plan the speed of each joint separately

[0077] For a certain joint, if the movement time calculated in step 7 of this embodiment is equal to t 统一 If the movement time calculated in step 7 of this embodiment is less than t 统一 , it is necessary to further plan a trapezoidal acceleration and deceleration curve and set the actual maximum trapezoidal speed of the joint to Vm n实际 (n=0,1,2,3), we have:

[0078]

[0079] According to formula 17, the actual maximum trapezoidal speed can be obtained as:

[0080]

[0081] In formula (18), ± and displacement have opposite signs. If the displacement of a joint is positive, then - is taken, otherwise + is taken.

[0082] The trapezoidal acceleration time is:

[0083]

[0084] The trapezoidal deceleration time is:

[0085]

[0086] The trapezoidal uniform speed time is:

[0087] t n匀速 =t n统一 -t n加速 -t n减速 Formula 21

[0088] Embodiment 3, in order to further understand the present method, combined with the specific scheme in the above embodiment 2, the whole process is explained below in combination with a specific example data.

[0089] ①Determine Cartesian coordinates

[0090] The units of the first three rows of Cartesian coordinates of each point of forging and feeding are mm, and the unit of the last row is °. The specific points collected by teaching are as follows:

[0091]

[0092] The motion speed of the first MOVL linear motion trajectory segment is V1 = 500 mm / s, the motion speed of the third MOVL linear motion trajectory segment is V2 = 500 mm / s, and the interpolation period is T = 0.001 s. According to equations 2 to 5, the Cartesian coordinates can be obtained:

[0093]

[0094] ② Inverse solution to obtain joint coordinates

[0095] The robot's connecting rod parameters are a1=270, d1=880, a2=1250, a3=1400, a4=250, b4=300. According to formula 8, the joint coordinates are:

[0096]

[0097] ③Determine the displacement of each joint

[0098] According to formula 9, we can get:

[0099]

[0100] ④Determine the initial velocity of each joint

[0101] According to formula 10, we can get:

[0102]

[0103] ⑤Determine the final velocity of each joint

[0104] According to formula 11, we can get:

[0105]

[0106] ⑥ Determine the maximum velocity and maximum acceleration of each joint

[0107] Check the robot's specification manual to get:

[0108]

[0109] ⑦ Determine the movement time of each joint

[0110] According to formula 13, we can get:

[0111]

[0112] The absolute value of the critical velocity of each joint is less than the absolute value of the maximum velocity of each joint, and the motion process is a triangle. According to formula 14, we can get:

[0113]

[0114] ⑧Determine a unified exercise time

[0115] According to formula 13, we can get:

[0116] t 统一 =0.526

[0117] ⑨ Plan the speed of each joint separately

[0118] The movement time of joints 1 and 4 in step 7 is equal to that in step 8. No speed planning is required. Only joints 2 and 3 need to be planned according to equations 18 to 21. The results are as follows:

[0119]

[0120] Using the method of the prior art, the time for the entire forging and loading process can be planned to be 1.079s. The time for the entire forging and loading process planned by the present invention is 0.826s (the first section MOVL time is 0.15s + the second section MOVJ time is 0.526s + the third section MOVL time is 0.15s). Compared with the prior art, the loading time of the present invention is shorter and the efficiency is higher.

[0121] In summary, the present invention combines the transition sections in the forging and feeding process into the second MOVJ joint motion process for unified consideration while keeping the first MOVL linear motion and the third MOVL linear motion unchanged, so as to make the robot move at the maximum acceleration and maximum speed as much as possible, and make full use of the speed performance of the robot, thereby achieving a shorter time effect and improving the efficiency of forging and feeding.

[0122] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-axis palletizing robot forging and feeding method, characterized in that: It consists of three trajectory segments, namely: the first segment MOVL linear motion, the second segment MOVJ joint motion and the third segment MOVL linear motion. The forging and feeding process of the multi-axis palletizing robot is completed through the three trajectory segments; wherein the multi-axis palletizing robot is a four-axis palletizing robot; the specific steps of the second segment MOVJ joint motion are as follows: S1, first determine the Cartesian coordinates of the previous interpolation period point P0 of the starting point, the starting point P1, the end point P2, and the next interpolation period point P3 of the end point; Set the starting point of the first MOVL linear motion trajectory segment to Q0 and the end point to Q1, and the starting point of the third MOVL linear motion trajectory segment to Q2 and the end point to Q3, that is: Assume that the motion speed of the first MOVL linear motion trajectory segment is V1, the motion speed of the third MOVL linear motion trajectory segment is V2, and the interpolation period is T. Then the Cartesian coordinates of the last interpolation period point P0 of the starting point of the second MOVJ joint motion trajectory segment are: The Cartesian coordinates of the starting point P1 of the second MOVJ joint motion trajectory segment are: The Cartesian coordinates of the end point P2 of the second MOVJ joint motion trajectory segment are: The Cartesian coordinates of the next interpolation period point P3 at the end point of the second MOVJ joint motion trajectory segment are: S2. Then, according to the inverse kinematic solution method of the multi-axis palletizing robot, the joint coordinates corresponding to the points P0, P1, P2, P3, etc. are obtained; According to the Cartesian coordinates P0, P1, P2, P3 of the robot, calculate the joint coordinates J0, J1, J2, J3. The Cartesian coordinates P0, P1, P2, and P3 are uniformly represented as P n (n=0,1,2,3), the joint coordinates J0, J1, J2, and J3 are uniformly represented as J n (n=0,1,2,3), that is: S3, according to the joint coordinates, the total displacement, initial velocity and final velocity of each joint required to move are obtained; S4. Determine the maximum speed and maximum acceleration of each joint based on the mechanical characteristics of the multi-axis palletizing robot; S5, further deriving the shortest movement time of each joint of the multi-axis palletizing robot, and selecting the maximum value of each time as the unified movement time; S6. Finally, the speed curve is planned for each joint of the multi-axis palletizing robot.

2. A multi-axis palletizing robot forging and feeding method according to claim 1, characterized in that: In step S3, the displacements of joints 1 to 4 are set to L1, L2, L3, and L4, and the displacements are the differences between the joint coordinates of the end point and the starting point of the second segment, that is:

3. A multi-axis palletizing robot forging and feeding method according to claim 1, characterized in that: In step S3, the initial velocities of joints 1 to 4 are set to Vs1, Vs2, Vs3, and Vs4, and the initial velocities are the differentials of the joint positions at the starting point of the second segment, that is:

4. A multi-axis palletizing robot forging and feeding method according to claim 1, characterized in that: In step S3, the final velocities of joints 1 to 4 are set to Ve1, Ve2, Ve3, and Ve4, and the final velocity is the differential of the joint position at the end point of the second segment, that is:

5. The forging and feeding method of a multi-axis palletizing robot according to claim 1, characterized in that: In step S4, the joint displacement, initial velocity, final velocity, maximum velocity, maximum acceleration, and movement time are uniformly expressed as L n , Vs n 、Ve n 、Vm n 、Am n ,t n (n=0,1,2,3); In order to determine whether the motion process of each joint is a triangular acceleration / deceleration state or a trapezoidal acceleration / deceleration state, it is necessary to first determine the critical maximum speed Vm of each joint. n临界 (n=0,1,2,3), first set the motion process to be a triangular acceleration and deceleration state, then: According to formula 12, the critical maximum speed can be obtained as: In formula 13, Vm n临界 (n=0,1,2,3) has the same sign as the displacement. If the displacement of a joint is positive, then the Vm of the joint is n临界 (n=0,1,2,3) take +, otherwise take -; Combined with the results calculated in formula 13, for each joint, the critical maximum velocity Vm n临界 (n=0,1,2,3) and maximum speed Vm n (n=0,1,2,3) to judge, if Vm n临界 The absolute value of (n=0,1,2,3) is less than Vm n (n=0,1,2,3) is the absolute value, then the movement process of the joint is a triangle, and the movement time is: If Vm n临界 The absolute value of (n=0,1,2,3) is not less than Vm n (n=0,1,2,3) is the absolute value, then the motion process of the joint is trapezoidal, and the motion time is:

6. A forging and feeding method for a multi-axis palletizing robot according to claim 1, characterized in that: In step S5, the movement time of the joint with the longest movement time among all joints is taken as the unified movement time t 统一 ,Right now: t 统一 =Max(t1,t2,t3,t4) Equation 16 In the formula, Max represents the maximum value.

7. A forging and feeding method for a multi-axis palletizing robot according to claim 1, characterized in that: In step S5, for a joint of the multi-axis palletizing robot, if the motion time calculated in step S4 is equal to t 统一 If the movement time calculated in step S4 is less than t 统一 , it is necessary to further plan a trapezoidal acceleration and deceleration curve and set the actual maximum trapezoidal speed of the joint to Vm n实际 (n=0,1,2,3), we have: According to formula 17, the actual maximum trapezoidal speed can be obtained as: In formula (18), ± and displacement have opposite signs. If the displacement of a joint is positive, then take -, otherwise take +. The trapezoidal acceleration time is: The trapezoidal deceleration time is: The trapezoidal uniform speed time is: t n匀速 =t n统一 -t n加速 -t n减速 Formula 21.

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