Geometries with orientation support
Chapter 4
Rockwell Automation Publication MOTION-UM002F-EN-P - February 2018
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The reference frame is a Cartesian frame which is the base frame for the robot and
all the target points are specified with respect to this base frame. The robot
transformations are set up from base frame to end of arm frame to transform any
Cartesian target positions in to joint space and vice versa. In order for the
transformations to work correctly, it is required to establish the origins for all the
axes in the joint space with respect to the robot base Cartesian frame.
Establish the Base frame
The reference XYZ frame (Base frame) for the Delta geometry is located near the
center of the base plate. Joint 1, Joint 2, and Joint 3 are actuated joints and placed
at 120 apart, shown as α1, α2, and α3.
Top view
Side view
Configuring a Delta J1J2J3J4J5 coordinate system in the Logix Designer
application with the joints homed as 0 in the XY plane, then L1 of one of the
link pairs is aligned along the X positive axis as shown in top view. The side view
shows the X axis passing through the center of Joint 1’s motor to the center of
Link L1 and L2 joint.
Moving in the counter clockwise direction from Joint 1 to Joint 2 and Joint 3, the
Y axis is orthogonal to the X axis. Based on the right hand rule, Z positive axis is
the axis pointing up in side view (out of the paper in the top view).
•
+J1 rotation is measured clockwise around the -Y axis at the Base frame (+Y
axis is pointing inside in side view).
•
As each top link (L1) moves downward, its corresponding joint axis (J1, J2,
or J3) is rotating in the positive direction.
Establish the End of Arm frame
Joint 4 and Joint 5 are the swing arm axes used for rotation and tilt movement of
the Swing Arm. End of Arm (EOA) XYZ reference frame is set at the end of the
Swing Arm. The EOA frame direction is rotated by Rx =180 with Base frame.
Establish the reference frame
for a Delta J1J2J3J4J5 robot