Defining Cartesian Groups
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Introduction
Cartesian groups are enhancements of groups. Like groups, they are a collection of axes that can be moved together. In addition, they have a predefined Cartesian model for defining the roll of each axis in the Cartesian space.
Creating a Cartesian Group
Cartesian groups are defined similar to ordinary groups, either in configuration file or as a terminal input. The only difference is that at the end the type of the group is defined by: model=1 of <point type>, where <point type> is a string that defines the actual Cartesian model, which can be one of the following:
Mnemonic Constant used in CASTPOINT |
Numerical Value used in CASTPOINT Function |
<point type> String |
Explanation |
NO_ROBOT | 0 | NONE | List-of-coordinates, uninitialized generic points |
TYPE_X | 1 | X | X coordinate only |
TYPE_XY | 2 | XY | X Y table |
TYPE_XYZ | 3 | XYZ | X Y Z |
TYPE_XYZU | 4 | XYZU | |
TYPE_XYZUV | 5 | XYZUV | |
TYPE_XYZUVW | 6 | XYZUVW | |
TYPE_XYR | 7 | XYR | X Y Roll |
TYPE_XYRZ | 8 | XYRZ | |
TYPE_XYRZU | 9 | XYRZU | |
TYPE_XYRZUV | 10 | XYRZUV | |
TYPE_XYZR | 11 | XYZR | X Y Z Roll |
TYPE_XYZRU | 12 | XYZRU | |
TYPE_XYZRUV | 13 | XYZRUV | |
TYPE_XYZURV | 14 | XYZURV | |
TYPE_XYZUR | 15 | XYZUR | |
TYPE_XYZRPU | 16 | XYZRPU | |
TYPE_XYZRP | 17 | XYZRP | X Y Z Roll Pitch |
TYPE_XYRURV | 18 | XYZRURV | |
TYPE_XYRUR | 19 | XYRUR | |
TYPE_XYRP | 20 | XYRP | X Y Roll Pitch |
TYPE_XYRPU | 21 | XYRPU | |
TYPE_XYRPUV | 22 | XYRPUV | |
TYPE_XYRPUQ | 23 | XYRPUQ | |
TYPE_XYZYPR | 24 | XYZYPR | X Y Z Yaw Pitch Roll |
TYPE_XYZPR | 36 | User defined point | |
TYPE_XYZA | 37 | XYZA | X Y Z A-angle |
TYPE_XYZAB | 38 | XYZAB | X Y Z A-angle B-angle |
TYPE_YPR | 50 | YPR | Yaw Pitch Roll |
TYPE_PR | 51 | PR | Pitch Roll |
TYPE_R | 52 | R | Roll |
For example, the following defines a Cartesian group called GXYZ:
common shared GXYZ as group Axnm = a1 Axnm = a2 Axnm = a3 model=1 of xyz
Usage
Cartesian groups implement robot models with 1-1 Inverse and Direct kinematics functions. For example, an XY Cartesian group is defined by following mapping:
J1 ←→ X
J2 ←→ Y
This means that coordinates of <group.setpoint and <group>.pcmd will have equal values.
Translation vs. Rotation
The greatest difference between ordinary groups and Cartesian groups is the separation of translational and rotational movements. This further means that axis type must mach the Cartesian model:
For example, in XYR group (X, Y and Roll) axistype must be set as:
Common Shared GXYR as Group AxisName=A1 AxisName=A2 AxisName=A3 model = 1 of XYR ... a1.axistype = 1 a2.axistype = 1 a3.axistype = 1 ConfigGroup GXYR
If axis type is not properly set, ConfigGroup command will return an error. When such a group is properly set it allows setting physical kinematics values of velocity, acceleration and jerk separated into translational and rotational parts in the same way it is done in robot models:
MoveS GXYR #{100,100,90} VelTran=100 VelRot=20
This will move the GXYR to the target point (X=100mm, Y=100mm, R = 90deg) with 100 mm/sec or 20 deg/sec, depending on which values dominates (takes more time).
Motion
The following motion interpolation types are defined in Cartesian groups:
- Move - joint interpolations, used Vcruise, Vfinal in non-physical user units.
- MoveS - "straight-line" interpolation with separated kinematics parameters (Vtra/Vrot, Atran/Arot, Jtran/Jrot) defined in physical units for rotation and translation.
- Circle - circular/helycal interpolation in XYZ space with proportional change of additional rotation axes with separated kinematics parameters (Vtra/Vrot, Atran/Arot, Jtran/Jrot) defined in physical units for rotation and translation.
NOTE | |
There is no difference in the path of Move and Moves interpolation, except for how the time derivatives are determined. |