Saia PCD2.H310, Manual

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Function description PCD2.H31x
Page 5-2
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SAIA-Burgess Electronics Ltd.
(2H3-05-E.DOC)
26/762 E2
5.2 Generator for the velocity profile
The profile generator calculates theoretical speed according to the accel-
eration and velocity presets and as a function of time in position or speed
control mode. In position control operation, the difference between de-
sired and actual positions is fed to the PID controller during motion. Very
accurate positioning of the motion is thereby achieved.
Standard velocity profile
Velocity profile with desired velocity and destination position changed
during motion.
Velocity and destination position can be changed at any point along the mo-
tion and the controller will accelerate or brake accordingly at the defined rate
of acceleration. Acceleration and braking ramps are symmetrical.
In speed control mode, the controller accelerates to the user-defined desired
speed and runs on at a constant velocity until there is a stop command.
Operating principle of speed control:
The destination position is continuously augmented (according to the re-
quired velocity). The difference between destination and actual position
(captured with the encoder) is again conveyed to the PID controller. The
latter immediately compensates for speed fluctuations (caused by what-
ever disturbance) by making the controller output greater or smaller.
Preset velocity
Constant
acceleration
and delay
Destination position
v
t
v
t
+
v = velocity
t = time