Page 37 - Industrial Plant 2015

control and supervise aircraft by means of very few,
Amacroanalysis of industrial control over
the years shows a continuous trend
toward greater levels of autonomy. As
technology evolves, automation
increases its presence and its
importance, and automation takes
over on tasks once performed manually. This does not
apply only to production processes but it is part of a
more general pattern seen in many different industries
and environments.
A practical example of this trend comes from the world
of aviation: a Lockheed Constellation of 1945 required
a crew of five members (Pilot, Copilot, Navigator, Flight these actuator in a coordinated manner. In other words,
Engineer and Communications Operator) while today a
single pilot can fly an aircraft with very limited manual management moves from controlling a few key process
operations.
The huge progress of automation allowed a drastic
reduction of manual operations. A modern Flight
Management System, known as FMS, allow pilots to
high-level actions, compared to what necessary
decades ago, when the crew had to execute a endless
number of low-level actions, and among them, directly
interact with positioning of aerodynamic surfaces.
The level of flight automation is such that not only
electronics and electrical actuators move aerodynamics
surfaces, but automation will safeguard flight by not
allowing reaching critical conditions, such as a stall,
regardless inputs sent by the pilot.
This feature, known as flight envelope protection and
introduced in commercial aircraft in the 80s, is crucial in
order to safeguard operation of commercial aircraft in all
conditions [1].
In most of today flights, pilots directly manage the
airplane only in the take-off and landing phases, while
the airplane is flown by the autopilot for the remaining
part of the flight.
In general, newer technology and more automation
allow pilots to concentrate on fewer, higher-level
decisions, e.g. deciding flight route, and reduce the
need to perform continuous, low-level decision, like e.g.
moving the aerodynamic surfaces as needed.
Why advanced process control?
Moving back to industrial power plant and process
industries, we can identify a similar path toward more
automation and greater autonomy from manual actions.
Advanced Process Control (APC) technology
introduction is an important step in this path toward
greater autonomy.
The idea behind APC is to move away from implementing
multiple single-loop controllers that act independently
on a single actuator and introduce a multivariable
control system, able to optimize the operation of all
with the implementation of APC systems, process
variables separately to controlling an entire process unit
in a coordinate manner.
Computational power limits and interface complexity in
automation systems limited use of APC in its early days,
back in the 70s.
However, improvements in mathematical algorithms
and availability of computational capacity have eased
significantly implementation of APC, allowing use of
process models and configurable algorithms to reduce
the need for ad-hoc engineering.
APC technology has therefore become common in the
process industries since the early 80s. The first
applications were introduced in the refining and
petrochemical industry, but, over time, they gradually
spread to all process industries, from chemicals end to
power generation, from paper to food & beverage and
so on.
Industrial Plants - May 2015
35