User guide

GEL100340
speedobs
F MeaSpd F MeaSpd
w AccFFwd w AccFFwd
speedobsspeedobs
Speed P Speed P
w Taul w Taul
FTW2FTW2 Act ›- Act ›-
11
Description
SPEED OBServer estimates Speed [x] and acceleration (Acc[x/sec]) from measured speed (MeasSpd [xl)
using a algorithm with two time constants: Taul[sec] and Tau2[sec], ‘Ik[sec] is the sample time of the control.
Here [x] is the unit of the measured speed.
It can be used to estimate motor angular speed and motor angular acceleration from motor speed coming from
a tachometer or encoder. Motor speed is filtered to output estimated motor speed, and derivate to output
estimated motor acceleration. Estimated motor acceleration can be used to determine current feed-forward to
drive the motor faster.
AccFFwd [x/set] is used by observer to obtain a better speed and acceleration estimation. If no feed-forward
of acceleration is hewn, this input can be leave zero.
Let us make a simple example:
Consider a machine that manufactures a material. This machine has two motors using to move material, one is
the master and other is the slave. Slave drive can read master encoder and a digital signal from master that
indicates when master is acceleration (this signal can come from master ramp function). Slave can use
speedobs block to estimate line speed and acceleration. So MeasSpd [rpm] is master speed from its encoder,
AccFFwd is calculated as follows:
if (master is acceleration)
AccFFwd=SlaveAcc;
else
AccJ?Fwd=O;
So speedobs block can use this information (AccFFwd) to obtain a better speed and acceleration estimations.
The resulting Speed obtained from speedobs can use to calculate slave speed reference, and Act can use as
slave current feed-forward (after appropriate scaling depending on master acc/dec ramp times, master and
slave gear-box ratios and slave motor inertia) to improve slave response at master ramp acceleration.
As explained above, AccFFwd can leave zero but speed and acceleration would be estimated with a delay.
144