systems. They are unmatched in terms of flexibility
and accuracy. Should it be necessary to change the
transportation path on short notice, this can be
performed for contour navigation very easily and
quickly at the click of a mouse in the higher-level
software, the so-called fleet management. Because
the sensor on the AGV is usually mounted close
to the floor, this navigation variant is suitable for
automatic high-lift trucks and tractors as well as for
the drive-under or platform vehicles described above.
For this type of navigation, neither further tools –
such as reflectors or optical or magnetic traces – nor
markings or codes are required.
Laser radar
Navigation by means of laser radar is similar in
flexibility to contour navigation. This navigation
variant does, however, always require an additional
optical connection of the sensor to the reflectors.
Each sensor must therefore be mounted high
enough on the AGV that it always has a clear view
of the reflectors. If the connection to the reflectors
is interrupted, e.g., when entering a shelf aisle, the
AGV must switch to another type of navigation. This
makes it more difficult to change to another room if
necessary, limiting the flexibility.
Optical and inductive guidance
Optical and inductive guidance are usually very
simple systems that follow a predefined trace. As a
result, they are very limited in terms of flexibility. On
the other hand, however, they represent a very cost-
optimized solution. Because the sensor on the AGV
is mounted only a short distance from the floor, such
a form of navigation is independent of the selected
vehicle type.
Navigation and safety monitoring of the
transportation path with the RSL 400
safety laser scanner
Grid navigation
With the so-called grid navigation, information is
embedded in a specified grid on or in the surface that
is traveled, e.g., 2D-codes or transponders. With the
help of the information ascertained while traveling
over the individual grid points – with a 2D-code
these are, e.g., the code information and reading
angle – the AGV can navigate between the individual
grid points and thereby reach any specified point
within the grid. This type of navigation is suitable
above all for clean surfaces and surfaces not subject
to heavy loading.
A general evaluation and recommendation for the
suitable navigation variant can only be determined
in combination with the function of the AGV within
the given application. At the present time, however,
there is a clear trend towards contour navigation with
integrated safety function.
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TUBE NEWS September 2019 9