Sensors - Husqvarna Automower 420 Technical Manual

1. FUNCTION

1.14 Sensors

There are several types of sensors in the mower. The
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front collision sensor (1), rear collision sensor (2), tilt
sensor (3) and lift sensors (4) have the task of protect-
ing both mower and user. The rear (5) and front (6) loop
sensors are used to control the mower within the working
area, to position the mower when docking, tracking the
guide wire, etc. The cutting height sensor (7) regulates
the cutting height of the blade disc.
1.14.1 Collision sensors
7
3
The collision sensors are the sensors that detect when
the mower has run into a fixed object. When the sen- 5
sors are activated, i.e. when the mower collides with an
object, the mower stops and backs away to then turn to
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continue in a different direction. The 4 collision columns
on the back of the mower capture the motion of the mow-
er body in relation to the mower chassis.
1.14.2 Tilt sensor
4
The tilt sensor is the sensor that detects the mower's
inclination in relation to the horizontal plane. X-angle
means front to rear inclination, and Y-angle means left
to right inclination. The value from the tilt sensor is used,
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among other things, to compensate the operation of the
wheel motors when mowing on slopes.
2
1.14.3 Lift sensors
4
The lift sensors are the sensors that detect if the mower is
being raised off the ground. This is done with the help of
the mechanical design and magnets in each of the 2 front
collision columns. If the "lift" signal is indicated, the mower
and the blade disc stop immediately. The mower will then
try to free itself of the obstacle that caused it to lift off the
ground by backing up and turning several times.
1.14.4 Loop sensors
The loop sensors detect the signals from the boundary
wire, the guide wires and the N and F fields from the
charging station. The mower can only detect the signals
if it has been coded with the charging station. See
3.10 New loop signal on page 43.
1.14.5 Cutting height sensor
The cutting height sensor detects the position of the cut-
ting disc and is used when adjusting the cutting height.
The cutting height sensor must be calibrated to obtain
the correct cutting height when the cutting height setting
is changed. The calibration of the sensor is carried out
during among others the start-up sequence.
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