On Compensation for Saturation in Input Rate and Input Amplitude -
A Case Study for the Control of a Paper Machine Headbox.
John Erik Larsson
Report, Signals and Systems Group,
Uppsala University, Sweden, 1999.
A headbox is the initial part of paper machines. It
distributes liquid pulp into the machine,
where it is then dried and converted into paper.
is one of the most important subprocesses
on a paper machine, and considerable economic gains can be attained
by operating it well. Amplitude saturation in the
outlet-air valve, and rate saturation in the stock-pump system both
cause performance degradation if not compensated for. This motivates
our effort to develop better control strategies,
including saturation compensation.
This discussion introduces a general compensator structure
and design scheme, and then
focuses on design, tuning and synthesis of
a compensator applied to a LQR-based control system
to be used for the control of a paper machine headbox.
A model-based controller us proposed for minimizing
effects caused by saturation in input rate and input amplitude
in a headbox control system.
The headbox is here considered as having two inputs and
The proposed controller constitutes of a pre-existing
controller and a saturation compensator.
The design of the compensator can be carried out
using the same approach as used for the design
of the pre-existing controller.
ECC'97 paper on anti-windup
compensators for multivariable control systems.