A robot external linear axis control strategy and inverse solution method

Abstract

The present invention belongs to the field of intelligent production, specifically a robot external linear axis control strategy and inverse solution method, including the following steps: S1. Discretize the target trajectory, and then convert it to the linear axis coordinate system; S2. Determine the external linear axis control strategy: adopt the projection distance strategy, and determine the projection distance; S3. Calculate the projection deviation value corresponding to the target point; S4. Establish a robot DH model, and inversely solve the robot joint according to the target position; S5. Determine whether the robot is singular. If the robot is in a singular position or there is no solution, modify the position of the external linear axis, and then jump to S4; S6. According to the posture of the robot's previous position point and the joint angle of the inverse solution in S4, select the optimal joint posture of the current position point. This application designs a control strategy for the robot's external linear axis, calculates the robot base position, and can quickly iterate to complete the control strategy and inverse solution of the robot's linear axis.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent production, and specifically relates to a robot external linear axis control strategy and an inverse solution method. Background Art

[0002] In the prior art, the DH method is used to establish the forward kinematics model of the robot; the angle range of each joint of the robot is determined; the robot inverse solution evaluation index is established; the robot inverse solution evaluation index is used as the optimization target, and the improved quantum particle swarm algorithm is used to solve the redundant degree of freedom robot inverse solution, but the iterative method cannot obtain an exact solution.

[0003] The existing patent number is CN202211480489.8, and the Chinese invention patent named "Method, device and storage medium for linkage and coordination control of robot and external axis" discloses the following content: This application discloses a method, device and storage medium for linkage and coordination control of robot and external axis, the method comprising: obtaining the mutual mapping relationship between the external axis coordinate system and the robot base coordinate system; in the external axis coordinate system, performing trajectory planning for the robot and the external axis to obtain the first motion trajectory of the robot and the second motion trajectory of the external axis; according to the mutual mapping relationship, converting the first motion trajectory to the robot base coordinate system to obtain the third motion trajectory; converting the first motion trajectory and the third motion trajectory into control information, and controlling the linkage and coordination movement of the robot and the external axis according to the control information. This application achieves the technical effect of improving the coordination efficiency of the robot's external axis by constructing a mutual mapping relationship to convert between the external axis coordinate system and the robot base coordinate system.

[0004] The above patent performs trajectory planning for the robot and the external axis to obtain the motion trajectory of the robot and the external axis; the external axis coordinate system and the robot base coordinate system are converted by building a mutual mapping relationship, and the robot and the external axis are controlled to move in coordination according to the control information. However, the above method has the problems of low computational efficiency and slow iterative optimization. Summary of the invention

[0005] In order to solve the above problems existing in the prior art and realize the inverse solution of the robot's external linear axis system, the present application proposes a robot's external linear axis control strategy and an inverse solution method to realize the inverse solution of the robot's external linear axis system.

[0006] In order to achieve the above-mentioned invention object, the technical solution provided by this application is as follows:

[0007] A robot external linear axis control strategy and inverse solution method, comprising the following steps:

[0008] S1. Discretize the target trajectory and then transform it into an external linear axis coordinate system;

[0009] S2. Determine the external linear axis control strategy: adopt the projection distance strategy and determine the projection distance;

[0010] S3. Calculate the projection deviation value corresponding to the target point;

[0011] S4. Establish a robot DH model and inversely solve the robot joints according to the target position;

[0012] S5. Determine whether the robot is in a singular position. If the robot is in a singular position or there is no solution, modify the position of the external linear axis and then jump to S4;

[0013] S6. According to the posture of the robot's previous position point and the joint angles obtained by the inverse solution in S4, select the optimal joint posture for the current position point.

[0014] Furthermore, S1 is specifically as follows: for a known target trajectory ,in Represents the discrete pose points on the trajectory curve, and its coordinate system is recorded as , the coordinate system with external linear axes is denoted by , transform the target trajectory to the external linear axis coordinate system, the transformation matrix is .

[0015] Furthermore, in S3, for a known target trajectory , the pose information of each point is ,in is the position coordinate of the i-th trajectory point, is the Euler angle attitude of the ith trajectory point. According to the external linear axis control strategy, the robot base position corresponding to each trajectory point is calculated. The target trajectory point is transformed into:

[0016]

[0017] In the formula, is the position coordinate of the i-th trajectory point in the external linear axis coordinate system, is the X-direction vector of the i-th trajectory point in the external linear axis coordinate system, is the Y direction vector of the i-th trajectory point in the external linear axis coordinate system, is the Z direction vector of the ith trajectory point in the external linear axis coordinate system.

[0018] Furthermore, the initial projection deviation and the final projection deviation are determined, and intermediate interpolation is performed: if the projection distance deviation corresponding to the starting point and the end point of the target trajectory is set to and , using the initial solution of the projection deviation of the start and end points and is the endpoint function value, with the path length of each trajectory point Perform linear interpolation for the interpolation node and calculate

[0019] ;

[0020] Where: is the shortest length of the trajectory, is the maximum length of the trajectory, is the projection deviation value corresponding to the i-th target trajectory point;

[0021] like ,but = .

[0022] Furthermore, according to the external linear axis control strategy, the position and posture of the target trajectory point in the robot coordinate system corresponding to each trajectory point are calculated. ; The projection distance is the distance between the projection point of the target trajectory point on the robot's external linear axis and the robot's base coordinates. , so the position and posture of the target trajectory point in the robot coordinate system is:

[0023]

[0024] Where: is the position and pose of the target trajectory point in the robot coordinate system; is the position coordinate of the i-th trajectory point in the robot coordinate system, is the X direction vector of the ith trajectory point in the robot coordinate system, is the Y direction vector of the i-th trajectory point in the robot coordinate system, is the Z direction vector of the ith trajectory point in the robot coordinate system.

[0025] Furthermore, in the robot DH parameters of S4, i represents the joint number, Indicates along X i Axis, from Z i Move to Z i+1 distance; Indicates around X i Axis, from Z i Rotate to Z i+1 Angle Indicates along Z i Axis, from X i-1 Move to X i distance.

[0026] Furthermore, S5 is specifically as follows: determine whether the robot is singular. If the robot is in a singular position or has no solution, set the step length of the external linear axis changed each time to , then the position of the external linear axis is updated as , then jump to S4; if the robot still has no solution, the robot's external linear axis is adjusted in the opposite direction. , jump to S4 again.

[0027] The beneficial effects of the present invention are:

[0028] 1. This application designs the control strategy of the robot's external linear axis, calculates the position of the robot's base, and can quickly iterate and complete the control strategy and inverse solution of the robot's linear axis.

[0029] 2. This application first converts the target trajectory to the robot coordinate system, then formulates the control strategy of the robot's external linear axis, adopts the strategy of setting the projection distance, and obtains the position value of the robot base corresponding to the target trajectory point. Then the robot is inversely solved. If a robot singularity point is encountered, the projection distance of the external linear axis is iteratively modified until the robot singularity is avoided. Finally, the inverse solution of the motion of the robot's external linear axis is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 for Figure 1 Flowchart of the robot's external linear axis control strategy and inverse solution method.

[0031] Figure 2 Schematic diagram of the projection distance of the robot's external linear axis.

[0032] Figure 3 This is the inverse solution diagram of the robot's external linear axis.

[0033] Figure 4 Inverse solution for the robot's six-axis joints. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is to explain the present invention rather than to limit the present invention. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] The specific implementation method of the present invention is described below with reference to the accompanying drawings and examples, but the present invention is not limited to this embodiment.

[0036] Example 1

[0037] like Figure 1As shown, a robot external linear axis control strategy and inverse solution method include the following steps:

[0038] S1. Discretize the target trajectory and then transform it into an external linear axis coordinate system;

[0039] S2. Determine the external linear axis control strategy: adopt the projection distance strategy and determine the projection distance;

[0040] S3. Calculate the projection deviation value corresponding to the target point;

[0041] S4. Establish a robot DH model and inversely solve the robot joints according to the target position;

[0042] S5. Determine whether the robot is in a singular position. If the robot is in a singular position or there is no solution, modify the position of the external linear axis and then jump to S4;

[0043] S6. According to the posture of the robot's previous position point and the joint angles obtained by the inverse solution in S4, select the optimal joint posture for the current position point.

[0044] This application designs a control strategy for the robot's external linear axis, calculates the position of the robot's base, and can quickly iterate to complete the robot's linear axis control strategy and inverse solution. This application first converts the target trajectory to the robot coordinate system, and then formulates the control strategy for the robot's external linear axis. The projection distance setting strategy is used to obtain the position value of the robot base corresponding to the target trajectory point. The robot is then inversely solved. If a robot singularity point is encountered, the projection distance of the external linear axis is iteratively modified until the robot singularity is avoided. Finally, the inverse solution of the robot's external linear axis motion is achieved.

[0045] Example 2

[0046] like Figure 1 As shown, a robot external linear axis control strategy and inverse solution method include the following steps:

[0047] S1. Discretize the target trajectory and then transform it into an external linear axis coordinate system;

[0048] S2. Determine the external linear axis control strategy: adopt the projection distance strategy and determine the projection distance;

[0049] S3. Calculate the projection deviation value corresponding to the target point;

[0050] S4. Establish a robot DH model and inversely solve the robot joints according to the target position;

[0051] S5. Determine whether the robot is in a singular position. If the robot is in a singular position or there is no solution, modify the position of the external linear axis and then jump to S4;

[0052] S6. According to the posture of the robot's previous position point and the joint angles obtained by the inverse solution in S4, select the optimal joint posture for the current position point.

[0053] S1 is specifically: for a known target trajectory ,in Represents the discrete pose points on the trajectory curve, and its coordinate system is recorded as , the coordinate system with external linear axes is denoted by , transform the target trajectory to the external linear axis coordinate system, the transformation matrix is .

[0054] In S3, for a known target trajectory , the pose information of each point is ,in is the position coordinate of the i-th trajectory point, is the Euler angle attitude of the ith trajectory point. According to the external linear axis control strategy, the robot base position corresponding to each trajectory point is calculated. The target trajectory point is transformed into:

[0055]

[0056] In the formula, is the position coordinate of the i-th trajectory point in the external linear axis coordinate system, is the X-direction vector of the i-th trajectory point in the external linear axis coordinate system, is the Y direction vector of the i-th trajectory point in the external linear axis coordinate system, is the Z direction vector of the ith trajectory point in the external linear axis coordinate system.

[0057] Determine the initial projection deviation and the final projection deviation, and perform intermediate interpolation: If the projection distance deviation corresponding to the starting point and the end point of the target trajectory is set to and , using the initial solution of the projection deviation of the start and end points and is the endpoint function value, with the path length of each trajectory point Perform linear interpolation for the interpolation node and calculate

[0058] ;

[0059] Where: is the shortest length of the trajectory, is the maximum length of the trajectory, is the projection deviation value corresponding to the i-th target trajectory point;

[0060] like ,but = .

[0061] According to the external linear axis control strategy, calculate the position and posture of the target trajectory point in the robot coordinate system corresponding to each trajectory point ; The projection distance is the distance between the projection point of the target trajectory point on the robot's external linear axis and the robot's base coordinates. , so the position and posture of the target trajectory point in the robot coordinate system is:

[0062]

[0063] Where: is the position and pose of the target trajectory point in the robot coordinate system; is the position coordinate of the i-th trajectory point in the robot coordinate system, is the X direction vector of the ith trajectory point in the robot coordinate system, is the Y direction vector of the i-th trajectory point in the robot coordinate system, is the Z direction vector of the ith trajectory point in the robot coordinate system.

[0064] The DH parameters of a robot are shown in Table 1. Where i represents the joint number, Indicates along X i Axis, from Z i Move to Z i+1 distance; Indicates around X i Axis, from Z i Rotate to Z i+1 Angle Indicates along Z i Axis, from X i-1 Move to X i The distance. The i in here represents 0, 1, 2, 3, 4, 5. and The meaning of the axis is the same, but the value of i is different. The corresponding value in the figure is .

[0065] S5 is specifically as follows: Determine whether the robot is singular. If the robot is in a singular position or has no solution, set the step length of the external linear axis changed each time to , then the position of the external linear axis is updated as , then jump to S4; if the robot still has no solution, the robot's external linear axis is adjusted in the opposite direction. , jump to S4 again.

[0066] Table 1:

[0067] .

[0068] Example 3

[0069] Based on Example 1 and Example 2, the robot's external linear axis control strategy and inverse solution method, the known target trajectory ,in Represents the discrete pose points on the trajectory curve, and the pose information of each point is ,in is the position coordinate of the i-th trajectory point, is the attitude value of the i-th trajectory point, and its coordinate system is recorded as The coordinate system with linear axes is denoted by . Convert the target trajectory to the external linear axis coordinate system. The target trajectory point is transformed into the external linear axis coordinate system:

[0070]

[0071]

[0072] yes Abbreviation of yes , and the others are similar. is the position coordinate of the i-th trajectory point in the external linear axis coordinate system, is the X-direction vector of the i-th trajectory point in the external linear axis coordinate system, is the Y direction vector of the i-th trajectory point in the external linear axis coordinate system, is the Z direction vector of the ith trajectory point in the external linear axis coordinate system.

[0073] Determine the external linear axis control strategy, that is, the projection distance control strategy, and determine the projection distance. If the projection distance deviation corresponding to the starting point and the end point of the target trajectory is set to and , using the initial solution of the projection deviation of the start and end points and is the endpoint function value, with the path length of each trajectory point Perform linear interpolation for the interpolation node and calculate

[0074] .

[0075] Where: is the shortest length of the trajectory, is the maximum length of the trajectory, is the projection deviation value corresponding to the i-th target trajectory point;

[0076] like ,but = .

[0077] For known target trajectories According to the external linear axis control strategy, the position and posture of the target trajectory point in the robot coordinate system corresponding to each trajectory point are calculated. The projection distance is the distance between the projection point of the target trajectory point on the robot's external linear axis and the robot's base coordinates, that is, , so the position and posture of the target trajectory point in the robot coordinate system is:

[0078]

[0079] Where: is the position and pose of the target trajectory point in the robot coordinate system; is the position coordinate of the i-th trajectory point in the robot coordinate system, is the X direction vector of the ith trajectory point in the robot coordinate system, is the Y direction vector of the i-th trajectory point in the robot coordinate system, is the Z direction vector of the ith trajectory point in the robot coordinate system.

[0080] Establish the robot DH model and inversely solve the robot joints according to the target positions.

[0081] Take the external linear axis of a robot as an example. Figure 2 As shown, the robot is on the external linear axis, and the processing target trajectory point is .

[0082] External linear axis projection distance control strategy, such as Figure 3 As shown, the projection distance is the distance between the projection point of the target trajectory point on the external linear axis of the robot and the robot base coordinates.

[0083] The DH parameters of a robot are shown in Table 2, where i represents the joint number. Indicates along X i Axis, from Z i Move to Z i+1 distance; Indicates around X i Axis, from Z i Rotate to Z i+1 Angle Indicates along Z i Axis, from X i-1 Move to X i Distance; Set the initial projection distance deviation , End projection distance deviation The inverse solution of a target trajectory is performed, and the projection distance control strategy is adopted to calculate the motion of the external linear axis. Figure 3 The corresponding inverse angles of each robot joint are shown as Figure 4 shown.

[0084] Table 2:

[0085] .

Claims

1. A robot external linear axis control strategy and inverse solution method, characterized in that: The steps include: S1. Discretize the target trajectory and then transform it into an external linear axis coordinate system; S2. Determine the external linear axis control strategy: adopt the projection distance strategy and determine the projection distance; S3. Calculate the projection deviation value corresponding to the target point; S4. Establish a robot DH model and inversely solve the robot joints according to the target position; S5. Determine whether the robot is in a singular position. If the robot is in a singular position or there is no solution, modify the position of the external linear axis and then jump to S4; S6. Select the optimal joint posture at the current position according to the posture of the robot at the previous position and the joint angle obtained by the inverse solution in S4; The S1 is specifically: for a known target trajectory ,in Represents the discrete pose points on the trajectory curve, and its coordinate system is recorded as , the coordinate system with external linear axes is denoted by , transform the target trajectory to the external linear axis coordinate system, the transformation matrix is ; In S3, for a known target trajectory , the pose information of each point is ,in is the position coordinate of the i-th trajectory point, is the Euler angle attitude of the i-th trajectory point. According to the external linear axis control strategy, the robot base position corresponding to each trajectory point is calculated; The target trajectory point is transformed into the external linear axis coordinate system: In the formula, is the position coordinate of the i-th trajectory point in the external linear axis coordinate system, is the X-direction vector of the ith trajectory point in the external linear axis coordinate system, is the Y direction vector of the i-th trajectory point in the external linear axis coordinate system, is the Z direction vector of the i-th trajectory point in the external linear axis coordinate system; Determine the initial projection deviation and the final projection deviation, and perform intermediate interpolation: If the projection distance deviation corresponding to the starting point and the end point of the target trajectory is set to and , using the initial solution of the projection deviation of the start and end points and is the endpoint function value, with the path length of each trajectory point Perform linear interpolation for the interpolation node and calculate ； Where: is the shortest length of the trajectory, is the maximum length of the trajectory, is the projection deviation value corresponding to the i-th target trajectory point; like ,but = ; According to the external linear axis control strategy, the position and posture of the target trajectory point in the robot coordinate system corresponding to each trajectory point are calculated. ; The projection distance is the distance between the projection point of the target trajectory point on the robot's external linear axis and the robot's base coordinates. , so the position and posture of the target trajectory point in the robot coordinate system is: Where: is the position and pose of the target trajectory point in the robot coordinate system; is the position coordinate of the ith trajectory point in the robot coordinate system, is the X direction vector of the ith trajectory point in the robot coordinate system, is the Y direction vector of the ith trajectory point in the robot coordinate system, is the Z direction vector of the ith trajectory point in the robot coordinate system.

2. A robot external linear axis control strategy and inverse solution method according to claim 1, characterized in that: In the S4 robot DH parameters, i represents the joint number. Indicates along X i Axis, from Z i Move to Z i+1 distance; Indicates around X i Axis, from Z i Rotate to Z i+1 Angle Indicates along Z i Axis, from X i-1 Move to X i distance.

3. A robot external linear axis control strategy and inverse solution method according to claim 2, characterized in that: When i is 1, the corresponding and is 0; when i is 2, the corresponding is 0; when i is 3, the corresponding and is 0; when i is 5, the corresponding and is 0; when i is 6, the corresponding and is 0.

4. The robot external linear axis control strategy and inverse solution method according to claim 1, characterized in that: S5 is specifically as follows: Determine whether the robot is singular. If the robot is in a singular position or has no solution, set the step length of the external linear axis changed each time to , then the position of the external linear axis is updated as , then jump to S4; if the robot still has no solution, the robot's external linear axis is adjusted in the opposite direction. , jump to S4 again.

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