Galil DMC-2X00 - Manual (Page 84)

The position tracking mode shouldn’t be confused with the contour mode. The contour mode allows
the user to generate custom profiles by updating the reference position at a specific time rate. In this
mode, the position can be updated randomly or at a fixed time rate, but the velocity profile will always
be trapezoidal with the parameters specified by AC, DC, and SP. Updating the position target at a
specific rate will not allow the user to create a custom profile.
The following example will demonstrate the possible different motions that may be commanded by the
controller in the position tracking mode. In this example, there is a host program that will generate the
absolute position targets. The absolute target is determined based on the current information the host
program has gathered on the object that it is tracking. The position tracking mode does allow for all of
the axes on the controller to be in this mode, but for the sake of discussion, it is assumed that the robot
is tracking only in the X dimension.
The controller must be placed in the position tracking mode to allow on the fly absolute position
changes. This is performed with the PT command. To place the X axis in this mode, the host would
issue PT1 to the controller if both X and Y axes were desired the command would be PT 1,1. The next
step is to begin issuing PA command to the controller. The BG command isn’t required in this mode,
the SP, AC, and DC commands determine the shape of the trapezoidal velocity profile that the
controller will use.
Example Motion 1:
The host program determines that the first target for the controller to move to is located at 5000
encoder counts. The acceleration and deceleration should be set to 150,000 cts/sec
2 and the velocity is
set to 50,000 cts/sec. The command sequence to perform this is listed below.
COMMAND DESCRIPTION
PT1 Place the X axis in Position tracking mode
AC150000 Set the X axis acceleration to 150000 cts/sec
2
DC150000 Set the X axis deceleration to 150000 cts/sec 2
SP50000 Set the X axis speed to 50000 cts/sec
PA5000 Command the X axis to absolute position 5000 encoder counts
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• Chapter 6 Programming Motion
DMC-2X00