Galil Motion Control CDS-3310, User Manual

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CDS-3310 Chapter 6 Programming Motion
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Figure 2 Velocity (cts/sec) vs. Time (msec) Ramped Gearing
The slave axis for each figure is shown in the bottom portion of the figure; the master axis is shown in
the top portion. The shock to the slave axis will be significantly less in figure 2 than in figure1. The
ramped gearing does have one consequence. There isn’t a true synchronization of the two axes, until
the gearing ramp is complete. The slave will lag behind the true ratio during the ramp period. If exact
position synchronization is required from the point gearing is initiated, then the position must be
commanded in addition to the gearing. The controller keeps track of this position phase lag with the
_GP operand. The following example will demonstrate how the command is used.
Example – Electronic Gearing Over a Specified Interval
Objective: Run a geared motor at a speed of 1.132 times the speed of an external master.
Because the master is traveling at high speeds, it is desirable for the speeds to change slowly.
We will implement the gearing change over 6000 counts (3 revolutions) of the master axis.
GA DA Specify aux encoder as the master
GD 6000 Specify ramped gearing over 6000 counts of the master axis.
GR 1.132 Specify gear ratios
Question: What is the effect of the ramped gearing?
Answer: Had GD not been issued, gearing would take effect immediately and if the master
traveled 6000 counts, the slave would travel 6792 counts. Using the ramped gearing, the
slave will engage gearing gradually. Since the gearing is engaged over the interval of 6000
counts of the master, the slave will only travel ~3396 counts. The difference between these
two values is stored in the _GPn operand. If exact position synchronization is required, the IP
command is used to adjust for the difference.