Introduction
English, Revision 06, Date: 12.07.2011
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1
Introduction
1.1
Tracker
This document describes the Optical Line Tracker (interpreting unit) G 73840ZA which
is part of an Optical Guidance System for Automated Guided Vehicles (AGV) enabling
travelling along a contrast line on the ground. The Optical Line Tracker interprets the
location of this line within the view of the camera and outputs its position with regards
to the center of the produced picture. In addition, it is possible to detect branchings
from the original course. The Optical Line Tracker is made for the connection of two (2)
PAL standard video cameras with composite video signal, in order to automatically
guide a vehicle in two different directions of travel (forwards and backwards). It in-
cludes a video multiplex unit. It is possible to connect a video monitor in order to con-
trol the detected track/line. The detected track is indicated on the display. In addition,
an LED line indicates the location of the guidance line.
An optical track guidance is only suited for an application in which a minimum level of
cleanliness is guaranteed.
The firmware 73840A12.01 described in this documentation includes the decoding of
a 2/5 interleaved barcode. Decimal encoding can range from 0 to 99 — a code analysis
will not be carried out. The barcode provides a high-density information. Thus it is pos-
sible to limit the barcode width nearly to the track width.
The Optical Line Tracker is located inside a top hat rail casing. The suitable cameras
HG 73841ZA inside an M30 industrial casing with M12 connector are available from
Götting KG.
The data output is generated via:
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CAN-bus. A CAN open protocol (Device Profile DS 401) has been implemented.
-
Serial interface with an adjustable transferable parameter.
-
PLC interface with parallel inputs / outputs as well as an analog ’track offset' sig-
nal with a max. range of ±10 V is available. Offset and amplitude of this voltage
are adjustable.
The power supply of the cameras is generated via the built-in DC/DC converter. Out-
put voltage for the camera supply is 12 V.
The parameters of the Optical Line Tracker are either set via a serial interface using a
commonly available terminal program (e.g. Hyperterm) or via the various SDOs of the
CAN open protocol.
This description is valid for hardware version 73840ZA4 and software version 73840A3
2.01.
1.2
Track Detection
The video signal is imported with a resolution of 500 pixel per line. It is possible to se-
lect interpretation lines between the lines 30 and 255, as only these lines offer a useful
picture content. Up to 15 consecutive lines can be combined. The update rate for
each half-picture is 20 ms.
