MagnaTran 7.1 User’s Manual
Operation
MN-003-1600-00
Theory of Operation
Brooks Automation
Revision 2.2
6-11
Although the arms are driven simultaneously by the shoulder shafts, one always
extending while the other will stay at the retracted position, the linear motion profile
of the two arms will differ as the arms move from “Arm A” fully extended to “Arm
B” fully extended.
The software-set velocities and accelerations for radial motion apply only to the veloc-
ity and acceleration applied to the shoulder shaft rotation. The speeds for arm motion
are based upon the robot’s “knowledge” of wafer presence on the end effectors.
Wafer presence on each end effector is determined in several ways; wafer presence
will be assumed after a PICK, wafer presence will be assumed after power-up, and
wafer absence will be assumed after a PLACE.
The rotary motion of the shaft is profiled to accomplish smooth motion as the arms are
accelerated from or brought to rest.
The software-set profile always applies to both arms; the profile of one arm cannot be
set to a different value than that of the other arm since they are coupled at the shoul-
der shaft.
The fact that the linear motion profiles of the two arms differs at various points along
the path of motion is strictly a result of the kinematics of the BiSymmetrik arm struc-
ture.
Example:
When both arms are at the retracted position, the linear velocity is the
same. As one arm extends from the retracted to the extended position, however, the
other remains nearly stationary near the retracted position.
When Arm A extends, Arm B retracts, and, because the arms are semi-independent
and the stations are independent, sending Arm A to Station 1, for example, does not
send Arm B to either Station 1 or the station directly opposite Station 1.
NOTE:
The SET LOAD command can be used by an operator to specify the presence or
absence of a wafer on each end effector.
The actual speed of the arms in all three axes is determined by both the Pan ‘A’ and
Pan ‘B’ parameters. Full speed will only be achieved if both pans are empty. Arm
A is the default. When any software command is issued, if no arm is specified, the
robot assumes Arm A, and the action is performed using Arm A or information is
returned, set, or stored for Arm A.