Robot axis configuration and joint angle conversion method

Abstract

The application provides a robot axis configuration and joint angle conversion method, uses joint angles or positions in a Cartesian space, quaternions and axis configuration parameters to record a robot posture; determines joint limits of a mechanical arm, and uses the axis configuration parameters to describe a posture of the mechanical arm relative to a singular point; solves the axis configuration parameters according to a preset solving method; and converts input joint angles into the axis configuration parameters according to a preset conversion method.The robot axis configuration and joint angle conversion method has the beneficial effects that: through detailed analysis of the limit range of each joint of the robot, a quadrant number solving method (cf1, cf4, cf6) of an axis 1, an axis 4 and an axis 6, and a calculation method of a whole mechanical arm configuration number (cfx) are established. The robot joint position and posture are accurately solved by using a homogeneous transformation matrix and a standard D-H parameter model.

Description

Technical Field

[0001] This invention belongs to the field of robotic arms, and in particular relates to a method for robot axis configuration and joint angle conversion. Background Technology

[0002] In the field of robotics, posture control and joint angle transformation of robotic arms are key to achieving precise robot motion. There are two main traditional methods for recording robot posture: one is to record the posture using the robot's six joint angles in joint space; the other is to record the posture in Cartesian space using the position and posture of the robot's end effector (usually represented by quaternions) and axis configuration parameters.

[0003] However, within the working range of a 6-DOF serial robotic arm, three singularities exist. When certain joints of the robotic arm (such as axis 1, axis 4, and axis 6) need to rotate more than 180°, multiple possible robotic arm configurations emerge. This introduces complexity to the implementation of forward and inverse kinematics, path planning, and control algorithms.

[0004] In the existing technology, there is a lack of a unified and efficient algorithm to realize the conversion between joint angles and axis configuration parameters. As a result, in practical applications, robots may not be able to select the optimal motion path, which affects work efficiency and accuracy. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method for robot axis configuration and joint angle conversion, so as to at least solve one of the problems in the background art.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A method for robot axis configuration and joint angle conversion, characterized in that it includes:

[0008] Robot pose is recorded using joint angles or position, quaternions, and axis configuration parameters in Cartesian space.

[0009] Determine the joint limits of the robotic arm and use axis configuration parameters to describe the posture of the robotic arm relative to the singular point;

[0010] The axis configuration parameters are solved according to the preset solution method;

[0011] The input joint angles are converted into axis configuration parameters according to the preset conversion method.

[0012] Furthermore, the step of solving the axis configuration parameters according to the preset solution method includes:

[0013] Solving for axis configuration parameter cf1: The quadrant division of axis configuration parameter cf1 is limited to -2 to 1, and the input angle range is between -175° and 175°;

[0014] Solving for axis configuration parameter cf1: The quadrant division of axis configuration parameter cf4 is limited to between -2 and 1, and the input angle range is between -155° and 155°;

[0015] Solving for axis configuration parameter cf1: The quadrant division of axis configuration parameter cf6 is limited to -5 to 4, and the input angle range is between -395° and 395°.

[0016] Furthermore, the step of solving the axis configuration parameters according to the preset solution method includes:

[0017] The relative position is determined by calculating the axis configuration parameter cf2 based on the position of joint J2. The position relative to Axis1 is determined by the x-coordinate of joint 2, where:

[0018] If the x-coordinate is greater than 0, cf2 = 1;

[0019] If the x-coordinate is less than 0, cf2 = -1.

[0020] Furthermore, the method for solving the axis configuration parameter cf2 is as follows:

[0021] The homogeneous transformation matrix of the robot's J2 joint coordinate system {O1} relative to the base coordinate system {O0} is obtained as follows:

[0022]

[0023] That is: P J2 =[a1c1 a1s1 d1];

[0024] Then the x-coordinate of the center point of joint J2 in the base coordinate system is x. J2 =a1c1, then:

[0025] When x J2 When < 0, cf2 = -1;

[0026] When x J2 When cf2 > 0, cf2 = 1.

[0027] Furthermore, the step of solving the axis configuration parameters according to the preset solution method includes:

[0028] Based on the position of the wrist center relative to the lower arm, the direction of the rotation axis is determined using the right-hand rule with the rotation vector between J35 and J32, and the axis configuration parameter cf3 is solved, where:

[0029] When the direction of the rotation axis is consistent with the direction of the y-axis of the base coordinate system, cf3 = 1;

[0030] When the directions are opposite, cf3 = -1.

[0031] Furthermore, the method for solving the axis configuration parameter cf3 is as follows:

[0032] The position of the wrist center point relative to the lower arm is determined by calculating the direction of the common perpendicular of vector axes J35 and J32 relative to the base coordinate system. Specifically:

[0033] When the right-hand rule is used to rotate from vector J35 to vector J32, and the direction of the common perpendicular of the rotation axis is consistent with the y-axis direction of the base coordinate system, it is denoted as cf3=1;

[0034] When the direction of the common perpendicular is opposite to the y-axis direction of the base coordinate system, it is denoted as cf3 = -1.

[0035] Furthermore, the method for solving the axis configuration parameter cf3 is as follows:

[0036] Based on the STD_DH method, the homogeneous transformation matrix between the coordinate systems of adjacent links is:

[0037]

[0038]

[0039] The homogeneous transformation matrix of the robot's J3 joint coordinate system {O2} relative to the base coordinate system {O0} is obtained as follows:

[0040]

[0041] That is: P J3 =[c1(a1+a2s2)s1(a1+a2s2)a2c2+d1];

[0042] The homogeneous transformation matrix of the robot's J5 joint coordinate system {O4} relative to the base coordinate system {O0} is:

[0043]

[0044] That is, P J5 =[c1(a1+a2s2+d4c 23 )s1(a1+a2s2+d4c 23 a2c2+d1-d4s 23 ],but:

[0045]

[0046] When n yWhen <0, cf3 = -1;

[0047] When n y When >0, cf3 = 1.

[0048] Furthermore, the step of solving the axis configuration parameters according to the preset solution method includes:

[0049] The solution axis configuration parameter cf5 is determined by the angle of the J5 joint, where:

[0050] If the angle of J5 is less than 0, cf5 = -1;

[0051] If the angle of J5 is greater than or equal to 0, then cf5 = 1.

[0052] Furthermore, cfx is solved based on the axis configuration parameters obtained from the solution, where the cfx parameter represents the overall configuration relative to the singular point.

[0053] Furthermore, the method for converting the input joint angles into axis configuration parameters according to a preset conversion method includes:

[0054] Input the joint angles of the robotic arm;

[0055] Determine the quadrant numbers cf1, cf4, and cf6 for each axis based on the joint angle range;

[0056] The position of joint 2 is calculated using the homogeneous transformation matrix, and cf2 is solved.

[0057] cf3 is determined by the positional relationship between joints 3 and 5;

[0058] Determine cf5 based on the angle of J5;

[0059] Finally, cfx is solved by combining cf2, cf3, and cf5;

[0060] Output the complete axis configuration parameters Confdata.

[0061] Compared with existing technologies, the robot axis configuration and joint angle conversion method described in this invention has the following advantages:

[0062] The robot axis configuration and joint angle conversion method described in this invention establishes a method for solving the quadrant numbers (cf1, cf4, cf6) of axes 1, 4, and 6 (through detailed analysis of the limiting range of each joint of the robot), as well as a method for calculating the overall configuration number (cfx) of the robotic arm. Using a homogeneous transformation matrix and a standard DH parameter model, the robot joint positions and orientations are accurately solved. Attached Figure Description

[0063] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0064] Figure 1 This is a schematic diagram illustrating the relative positions of the front and rear as described in an embodiment of the present invention (where (a) is a schematic diagram of the position of the J1 axis center relative to Axis1, and (b) is a schematic diagram of the position of the wrist center relative to the lower arm).

[0065] Figure 2 This is a schematic diagram of the robot's posture when cfx has different values, as described in an embodiment of the present invention. Detailed Implementation

[0066] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0067] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0068] This solution discloses the robot axis configuration and joint angle conversion method, and the specific implementation process is as follows:

[0069] First, any pose of the robot can be recorded in multiple ways, including: in joint space, recording a certain pose of the robot using the angles of the robot's six joints; or in Cartesian space, recording a certain pose of the robot using the position of the robot's end effector + quaternion (pose) + axis configuration parameters.

[0070] The following is an explanation of the robot axis configuration parameter `confdata` in RobotStudio:

[0071] For a serial 6-DOF robotic arm, there are three singularities within its working range. Axis configurations are used to describe the robotic arm's orientation relative to these three singularities. The 6-DOF robotic arm will detect whether axes 1, 4, and 6 will move more than 180°, using cf1, cf4, cf6, and cfx to represent axes 1, 4, and 6, and the possible different robotic arm configurations corresponding to cf1, cf4, and cf6.

[0072] For the robot, which is a 6-DOF robot, the limits of the 6 joint angles are shown in Table 1 below:

[0073] Table 1 Soft Limitations of Robot Joints

[0074] 1 axis ±175° 2-axis ﹢100°～-55° 3-axis ﹢50°～-200° 4-axis ±155° 5-axis ±93° 6-axis ±395°

[0075] Therefore, the values ​​of the axis configuration parameters cf1, cf4, cf6, and cfx are defined as follows:

[0076] (1) Solving cf1

[0077] Table 2cf1: Quadrant Numbers for Axis 1

[0078]

[0079] (2) Solving for cf4

[0080] Table 3cf4: Quadrant Numbers for Axis 4

[0081]

[0082] (3) Solving for cf6

[0083] Table 4cf6: Quadrant Numbers for Axis 6

[0084]

[0085] CFX Explanation: CFX numbers 0 to 7 represent one of eight possible robotic arm configurations. Table 5 below describes various configurations for placing the robotic arm relative to three singularities, such as... Figure 1 and Figure 2 As shown, with the robot's posture at the zero position as the reference, the left side of Axis1 is the rear, and the right side of Axis1 is the front; the left side of the Lower arm is the rear, and the right side of the Lower arm is the front.

[0086] Table 5cfx: Configuration numbers of robotic arms relative to the three singularities

[0087] 0 In the preceding statement, cf2 = 1 In the preceding text, cf3 = 1 Positive, cf5 = 1 1 In the preceding statement, cf2 = 1 In the preceding text, cf3 = 1 Negative, cf5 = -1 2 In the preceding statement, cf2 = 1 In the following, cf3 = -1 Positive, cf5 = 1 3 In the preceding statement, cf2 = 1 In the following, cf3 = -1 Negative, cf5 = -1 4 In the following, cf2 = -1 Previously, cf3 = -1 Positive, cf5 = 1 5 In the following, cf2 = -1 Previously, cf3 = -1 Negative, cf5 = -1 6 In the following, cf2 = -1 In the following, cf3 = 1 Positive, cf5 = 1 7 In the following, cf2 = -1 In the following, cf3 = 1 Negative, cf5 = -1

[0088] (4) Solving for cf2

[0089] First, the position of the center point of J2 relative to Axis1 can be represented by the position of point J2 on the x-axis in the base coordinate system {0}:

[0090] When the x-coordinate of the center point of J2 is greater than 0, it means that it is in front, and this is recorded as cf2 = 1;

[0091] When the x-coordinate of the center point of J2 is less than 0, it means that it is behind, and this is recorded as cf2 = -1.

[0092] The calculation method is as follows:

[0093] Based on the STD_DH method, the homogeneous transformation matrix of the robot's J2 joint coordinate system {O1} relative to the base coordinate system {O0} can be obtained as follows:

[0094]

[0095] That is: P J2 =[a1c1 a1s1 d1].

[0096] Then the x-coordinate of the center point of joint J2 in the base coordinate system is x. J2 =a1c1, then:

[0097] ●When x J2 When < 0, cf2 = -1;

[0098] ●When x J2 When cf2 > 0, cf2 = 1.

[0099] (5) Solving for cf3

[0100] Secondly, the position of the wrist center point relative to the lower arm can be determined by calculating the direction of the common perpendicular of vector axis J35 and vector axis J32 relative to the base coordinate system.

[0101] ●When using the right-hand rule, when rotating from vector J35 to vector J32, the direction of the common perpendicular of the rotation axis is perpendicular to the base.

[0102] When the y-axis of a coordinate system is in the same direction, it is denoted as cf3 = 1;

[0103] ●When the direction of the common perpendicular is opposite to the y-axis direction of the base coordinate system, it is denoted as cf3=-1.

[0104] The calculation method is as follows:

[0105] Based on the STD_DH method (ZX rule), the homogeneous transformation matrix between the coordinate systems of adjacent links is:

[0106]

[0107] Based on the STD_DH method, the homogeneous transformation matrix of the robot's J3 joint coordinate system {O2} relative to the base coordinate system {O0} can be obtained as follows:

[0108]

[0109] That is: P J3 =[c1(a1+a2s2)s1(a1+a2s2)a2c2+d1]

[0110] The homogeneous transformation matrix of the robot's J5 joint coordinate system {O4} relative to the base coordinate system {O0} is:

[0111]

[0112] That is: P J5=[c1(a1+a2s2+d4c 23 )s1(a1+a2s2+d4c 23 a2c2+d1-d4s 23 ]but

[0113]

[0114] When n y When <0, cf3 = -1;

[0115] ●When n y When >0, cf3 = 1.

[0116] (6) Solving for cf5

[0117] at last,

[0118] • When the angle of joint J5 is less than 0, it is recorded as cf5 = -1;

[0119] ●When the angle of joint J5 is greater than 0, it is recorded as cf5=1.

[0120] (7) Solving for cfx

[0121] Based on Table 5 and the obtained cf2, cf3, and cf5, cfx can be solved.

[0122] Algorithm verification results

[0123] Table 6 Algorithm Verification

[0124] [0,0,0,0,30,0] [0,0,0,0] [0,0,0,155,-30,0] [0,1,0,1] [0,90,-180,0,30,0] [0,0,0,2] [0,90,-180,0,-30,0] [0,0,0,3] [-175,-90,-40,-155,30,0] [-2,-2,0,4] [-175,-90,-40,0,-60,0] [-2,0,0,5] [-175,-30,-150,0,30,0] [-2,0,0,6] [-175,-30,-150,0,-30,0] [-2,0,0,7]

[0125] Those skilled in the art will recognize that the units and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0126] In the several embodiments provided in this application, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the division of units described above is merely a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. The aforementioned units may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

[0128] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for robot axis configuration and joint angle conversion, characterized in that, include: Robot pose is recorded using joint angles or position, quaternions, and axis configuration parameters in Cartesian space. Determine the joint limits of the robotic arm and use axis configuration parameters to describe the posture of the robotic arm relative to the singular point; The axis configuration parameters are solved according to the preset solution method; The input joint angles are converted into axis configuration parameters according to the preset conversion method. The process of solving the axis configuration parameters according to the preset solution method includes: Solving for axis configuration parameter cf1: The quadrant division of axis configuration parameter cf1 is limited to -2 to 1, and the input angle range is between -175° and 175°; Solving for axis configuration parameter cf4: The quadrant division of axis configuration parameter cf4 is limited to between -2 and 1, and the input angle range is between -155° and 155°; Solving for axis configuration parameter cf6: The quadrant division of axis configuration parameter cf6 is limited to -5 to 4, and the input angle range is between -395° and 395°; The method for solving the shaft configuration parameter cf2 is as follows: Obtain the robot's J2 joint coordinate system Relative to the base coordinate system The homogeneous transformation matrix is: (1) in, , ; Right now: ; Then the x-coordinate of the center point of joint J2 in the base coordinate system is: ,but: when At that time, cf2 = -1; when At that time, cf2=1; The method for solving the shaft configuration parameter cf3 is as follows: Based on the STD_DH method, the homogeneous transformation matrix between the coordinate systems of adjacent links is: Obtain the robot's J3 joint coordinate system Relative to the base coordinate system The homogeneous transformation matrix is: (2) Right now: ; Robot J5 Joint Coordinate System Relative to the base coordinate system The homogeneous transformation matrix is: (3) Right now ,but: (4) when At that time, cf3 = -1; when At that time, cf3=1.

2. The robot axis configuration and joint angle conversion method according to claim 1, characterized in that: The method for converting input joint angles into axis configuration parameters according to a preset conversion method includes: Input the joint angles of the robotic arm; The quadrant numbers cf1, cf4, and cf6 for each axis are determined based on the joint angle range. The position of joint J2 is calculated using the homogeneous transformation matrix, and cf2 is solved. cf3 is determined by the positional relationship between the J3 and J5 joints; cf5 is determined based on the angle of the J5 joint; Finally, cfx is solved by combining cf2, cf3, and cf5; Output the complete axis configuration parameters Confdata.

3. The robot axis configuration and joint angle conversion method according to claim 1, characterized in that, The process of solving the axis configuration parameters according to the preset solution method includes: The shaft configuration parameter cf5 is determined by the angle of the J5 joint, where: If the angle of J5 is less than 0, cf5 = -1; If the angle of J5 is greater than or equal to 0, then cf5 = 1.

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