Danaher Motion 06/2005 Groups
M-SS-005-03 Rev E 121
6. GROUPS
Groups allow you to control multiple axes as a single mechanism. With
groups, the position command and feedback signals are no longer single
values, but instead, are vectors with two or three elements. Velocity and
acceleration no longer apply to a motor, but instead, apply to the combination
of two or three motors moving in concert.
6. 1 SET UP
Groups are combinations of axes. These axes must be orthogonal if their
scalar properties (velocity) are to be correct. For example, a group can be
used to drive an x-y table. Groups are supported for two- and three-axis
machines. In fact, any number of axes can be added to a group.
To set up a group, first set up each of the axes that will be in the group.
Then, use Common Shared to form the group:
Common Shared MyGroup as Group AxisName = xAxis AxisName = yAxis
There is no limitation to the number of axes in a group. All axes in the system
(including simulated axes) may be part of one group.
It is necessary to set VELOCITYFACTOR, ACCELERATIONFACTOR,
and JERKFACTOR for the group. As a first approximation, set
<group>.VFAC = 1/1000, set AFAC=VFAC/1000, and set
JFAC=AFAC/1000.
6. 2 DELETEGROUP
DELETEGROUP deletes the specified group. The participating axes
thereafter function only as independant axes. They must not be moving. No
tasks may be loaded.
DeleteGroup MyGroup
6. 3 ACCELERATION PROFILES
As with single axes, the MC provides controlled acceleration profiles for
groups. This reduces vibration and wear on the machine, and allows the
highest acceleration rates. You can independently control the acceleration
and deceleration rates.
6.3.1. Acceleration and Deceleration
<group>.ACCELERATION and <group>.DECELERATION control the
acceleration rates of the group mechanism. For example, the following lines
change the acceleration rates for MyGroup:
MyGroup.Acceleration = 1000
MyGroup.Deceleration = 1000
<group>.ACCELERATION and <group>.DECELERATION apply to the
combined motion of the individual axes. For example, if MyGroup is a three-
axis group formed with Axis1, Axis2, and Axis3, then:
MyGroup.Acc = (Axis
1
.Accel
2
+ Axis2.Accel
2
+ Axis3.Accel
2
) ½
