Guide Loop; Charging Station; Circuit Boards And Sensors - Husqvarna Automower 420 Workshop Manual

3.5 Guide loop

The guide wire, together with the part of the boundary
loop that comprises the return to the charging station, is
called the guide loop. The current in the guide loop
always goes from the guide wire to the left in the
connection between guide wire and boundary loop.
The strength of the guide signal varies like the A signal
depending on the distance to the guide loop. Inside the
guide loop the signal is positive and the strength
subsequently diminishes the farther away from the wire
you get. Outside the guide loop, the signal is negative
and the strength of the signal diminishes more rapidly.
Note: The product always tracks the left side of the
guide wire when facing the charging station, i.e. the
product follows the negative values on the guide signal.
CAUTION: Do not lay the guide wire at 90°
angles or less. Lay the wire in two 135° angles.
135º

3.6 Charging station

The placement of the charging station must be well
planned in order to give the best installation and
operation of the product. Refer to
station in the Operator's Manual.
Note: The battery is spared if charged in the lowest
possible ambient temperature. Consequently, it is
beneficial if the charging station is placed where it is
shaded, especially during the warmest parts of the day.
When the battery level has dropped to 600 mAh or the
battery voltage has dropped to 17.5 V, the product shuts
down the blade motor and starts searching for the
charging station.
1191 - 001 -
90º
135º
Installation - Charging

3.7 Circuit boards and sensors

The circuit boards and sensors in the product:
5
2
7
8
10
6
1. Main circuit board (rear loop sensors and tilt sensor)
2. HMI circuit board
3. Communication circuit board
4. Ultrasonic circuit board (450X/450XH/550/550H)
5. Ultrasonic sensors (450X/450XH/550/550H)
6. Front loop circuit board (front loop sensors)
7. Lift sensor circuit board (lift sensors)
8. Front collision circuit board (front collision sensor)
9. Rear collision circuit board (rear collision sensor)
10. Cutting height circuit board (cutting height sensor)
CAUTION: Some sensors contain a hall sensor
and a magnet. Because of the magnets south
and north pole, it is important that the magnet is
correctly installed.
3.7.1 Tilt sensor
The tilt sensor is a sensor on the main board that
detects the product's inclination in relation to the
horizontal plane. The X-angle indicates front to rear
inclination, and the Y-angle indicates left to right
inclination. The value from the tilt sensor is used, among
other things, to correct the speed of the drive wheels
when mowing in steep slopes.
3.7.2 Lift sensors
The lift sensors detect if the product is being lifted off the
ground. This is done with the help of the mechanical
design and magnets. If a lift signal is indicated, the blade
disc stops immediately. The product tries extrication
maneuvers by reversing and turning several times.
3.7.3 Loop sensors
The loop sensors measure the signals that the charging
station sends through the boundary loop (A signal), the
guide loop (Guide signal) and the baseplate (F signal).
The signals are used to control the product and keep the
product inside the work area. The product can only
detect the signals if it has been paired with the charging
Loop signal on page 56 .
station. Refer to
9
3
5
4
7
Product and installation - 7
1