Device Description HG G-19370ZA | English, Revision 01 | Date: 17.05.2017 | www.goetting-agv.com
9
Chapter 2: Introduction
By evaluating the voltages induced in the two horizontal coils for each frequency a sum and
difference signal are calculated – U
sum
and U
diff
– and output via the CAN bus. The differ-
ence signal shows maxima at both sides of the wire (one positive and one negative) and
crosses zero directly above the wire. Thus it may be used to direct the vehicle.
Figure 2
Voltage curves sum and difference signal and Detect
Due to the two coils the sum voltage may show to maxima. This depends on the distance
to the guide wire. The sum voltage is solely used to detect a guide wire (Detect signal). For
this a detector circuit is implemented. The detector sets the Detect signal to 1 for valid fre-
quencies if the sum voltage exceeds a defined threshold. The Detect signal for all frequen-
cies is output via the CAN bus.
Note
Vehicle manufacturers may use the Detect signal as an aid to detect whether the verhicle
leaves the track.
‐300
‐200
‐100
0
100
200
300
400
‐150
‐100
‐50
0
50
100
150
U
sum
U
diff
Detect 0/1
(output via CAN)
Usum, signal strength decides
when to set Detect to 1
Udiff, vehicle control
