WORLD OF INDUSTRIES 06/2018 (RU)

Sustainable
generation of
positioning systems
AUTOMATION
Large reading window and codes guarantee
SIL 3/PLe-compliant safety applications, or in other
words adherence to the most stringent safety
guidelines and optimum protection for human and
machine at all times. Achieving this level of safety
previously entailed a great deal of time and money,
but these problems will no longer affect future users
of a new positioning systems.
I
n 2011, Pepperl+Fuchs celebrated the first launch of its PCV (Position
Coded Vision) sensor, combining a 2-D camera as a reader
with a Data Matrix code tape for absolute positioning. The reader
extracts the information in the Data Matrix code, identifies the current
location, and then calculates the exact position in relation to
the center of the camera. The system is innovative in that it offers
the highest possible level of data security by always reading several
codes at the same time.
In 2014, the newly developed PGV (Position Guided Vision)
system – a navigation solution for automated guided vehicles (AGV)
– was released using the same technology. The method of using a
2-D code to tackle the task of positioning remains unique, and offers
major benefits over solutions using 1-D codes. For example, the
user can evaluate the Y axis as well as the X axis and use this data for
positioning purposes.
Both of these systems have undergone continuous optimization
and development over the past few years. The second generation of
the PCV successor model - the new PXV system - was presented late
last year. Yet despite the continuous efforts to enhance these positioning
devices, operators frequently reported a need for additional
safety solutions for absolute positioning and safe navigation.
Machines and plants which can be controlled by electrical or elec-
Author: Armin Hornberger, Head of Product Management for Industrial
Vision Components, Pepperl+Fuchs GmbH in Mannheim, Germany
tronic systems and sensors present a hazard to the humans working
with them. In order to protect these individuals, stringent statutory
requirements must be met. They are set out in the Machinery Directive,
and are intended to ensure that all the machines and plants
placed on the market are safe. With the safePGV and the safePXV
systems, Pepperl+Fuchs has developed a new generation of positioning
systems which achieves the required SIL 3/PLe compliance
for the first time – all with a single sensor.
What is so ground-breaking about this
safety solution?
To start with, SIL 3/PLe-compliant safe absolute positioning has
been virtually unachievable for plant operators to date owing to the
substantial amounts of time and money involved. Redundant
systems with different sensors or different technologies needed to
be constructed. It was furthermore necessary for the safe control
system to carry out plausibility checks of the data, and the overall
development process needed to be monitored by TÜV and ultimately
approved.
A single positioning system with just one sensor achieves all of
this in the new safePGV and safePXV systems from Pepperl+Fuchs.
The new safety technology is based on the particularly reliable combination
of a 2-D reader and the Data Matrix code, which has been
popular for many years. The new system however introduces a special
tape with two superimposed red and blue Data Matrix codes.
The 2-D reader is equipped with two different colored LED rings -
also red and blue. The two-color codes, in combination with twocolor
illumination, form the basis for this unique security solution.
Each individual code contains position and safety information
which is made visible by red or blue LED illumination and can
therefore be read by the camera.
Direct and safe data transfer to safety PLC
The real brain of these positioning systems can be found in the innovative
new firmware. It controls the different LED colors with an
algorithm rated as safe. Each code is then independently checked
for plausibility in the safety section of the sensor. The mathematically
random flash sequence must match the actual position. Since
the different LEDs are controlled via the safety section, the camera
36 WORLD OF INDUSTRIES 2018