Welcome to myCobot 320 Arm repository
5.Coordinate System
Coordinate System
1 Joint coordinate system
The joint coordinate system is determined based on each moving joint. All joints are revolute joints. The range of motion is as follows
| joint | scope |
|---|---|
| J1 | -168 ~ +168 |
| J2 | -135 ~ +135 |
| J3 | -145 ~ +145 |
| J4 | -148 ~ +148 |
| J5 | -168 ~ +168 |
| J6 | -180 ~ +180 |
2 User coordinate system
The user coordinate system is a user-defined workbench coordinate system or workpiece coordinate system. Its origin and axis direction can be determined according to actual needs, which is convenient for measuring the position of each point in the working area and arranging tasks. The default user coordinate system is determined based on the center point of the robot base, and the positive direction of the Y axis is the direction of the heavy load line.
3 Tool coordinate system
The tool coordinate system is a coordinate system that defines the position of the tool center point (TCP) and the tool posture. Its origin and direction change with the position and angle of the final workpiece. The default tool coordinate system is determined based on the center point of the tool flange, and the positive direction of the Y axis is opposite to the direction of the aviation socket.
4 Joint connecting rod parameters and specifications
4.1 DH Range
For the rotation joint n, set 0 = 0.0, where the X axis is consistent with the X axis direction, and select the origin position of the coordinate system (N) to satisfy d. = 0.0. For the translation joint n, set the direction of the 8 axis to satisfy 0. = 0.0. When d. = 0.0, select the origin of the coordinate system (N) at the intersection of the XN-1 axis and the joint axis n.
Summary of linkage parameters in linkage coordinate system If the linkage coordinate system is fixed on the linkage device according to the above provisions, the linkage parameters can be defined as follows:
a_i-1: along x_i-1: the distance from z_i-1 to z_i
alpha_i-1: around x_i-1: from z_i-1 to z_i
d_i: represents the distance from x_i-1 to x_i along z_i
θ_i: around z_i: the angle from x_i-1 to x_i
Here is an article to refer to https://blog.csdn.net/hitgavin/article/details/104442034
4.2 SDH parameter list
| joint | theta | d | alpha | a | offset |
|---|---|---|---|---|---|
| 1 | theta_1 | 173.9 | PI/2 | 0 | 0 |
| 2 | theta_2 | 0 | 0 | -135 | -PI/2 |
| 3 | theta_3 | 0 | 0 | -120 | 0 |
| 4 | theta_4 | 88.78 | PI/2 | 0 | -PI/2 |
| 5 | theta_5 | 95 | -PI/2 | 0 | 0 |
| 6 | theta_6 | 65.5 | 0 | 0 | 0 |