Control Techniques UD70, User Manual

Page: 124 / 154

UD70
Issue code: 70nu2
8-26 Features
Non-rigid digital lock
Non-rigid digital lock is effectively a speed lock between the master
reference and slave axis. It is selected by setting
_ Q32%.27 = 1. When
digital lock is enabled ( _ Q32%.2 = 1), the slave axis will accelerate up to the
master speed, multiplied by the ratio, _ Q11%, using linear ramps. (NOTE: if
S-ramps are selected when digital lock is enabled, the slave will ramp up to
the master speed using S-ramps.) Any position error build up during
acceleration is ignored.
When speed lock is achieved, _ Q31%.12 is set, and position lock is used to
keep the slave axis speed locked to the master reference.
Speed
Time
_Q31%.12
Slave
speed
The effect of non-rigid digital lock on slave motor speed
Using S-Ramps with Digital Lock
If S-ramps are selected, the master speed must be kept as constant as
possible while the slave is accelerating to the master speed. Failure to
ensure this may cause problems when completing the S-ramp profile,
especially if the ramp rate is quite slow.
Using the marker pulse to enable Digital Lock
Digital lock can be enabled by using the auxiliary encoder marker pulse input,
by setting
_ Q32%.14 = 1. When the marker pulse occurs, _ Q32%.2 is set to 1,
and
_
Q32%.14 is reset to 0. If rigid lock is selected (
_
Q32%.27=), the slave
axis will catch up with the position lost relative to master from the point
when the marker pulse occurred.