The
Rasenmä
(The Name "Rasenmä"
is a german pun on "Rasen", wich means lawn and "mä"
which is the sound that sheep do.
Rasenmä is also the left
and major part of "Rasenmäher", which simply means lawnmower.
A english equivalent name could be Lawnmoo (as in MOO of a cow)
Both - sheep and cows eat grass, thats, whats the Rasenmä is supposed to.
I hope i did explain it clearly enough ;-)
Projekt: autonomous Lawnmower
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Description:
Hardware:
- Chassis made from 3mm hard-aluminum
and thick plywood.
- Wheels: Propulsion: 2x 1:8 R/C-cars
offroad wheels, Support: Ball-shaped wheels for easy change of direction.
- Motors 2x RB35 geared motor 12V
/ gear ratio 200:1. Vmax = 0,3 m/s
- Power of the mow blades comes
from: 2x Speed400 7,2V over PWM'd 12V
- "Slices" which hold
the 2 magnets for speed sensing
Elektronics:
- Conrad C-Control as master-controller
- 2x propulsion motor control over
2x PWM and 4x digi-out with L298 as Amplifier.
- Speed controlled operation of
the spindles by means of a hall-sensor, An ATTINY15, and a Power HexFET.
- 4 times distance measurement by
infrarot distance-meters with voltage output.
- Bumpers for Emergency-shutdown
/ recognition of hard barriers.
- Piezo Siren for warning right
before start of motion.
Software:
- Soft-Start by means of a push
button with warning prior to movement. (has to be pressed for 3 seconds)
- In standby mode every 30s an acustical
signal is given.
- Self diagnosis pre and during
the start. No start at a recognized barrier or blocked spindle.
- Governing of the driving speed
according to the mow-spindle load.
- The software chooses the direction
of driving according to where the most space is available. This has to be
refined for lawn mowing, as there it is required to mow along the corners.
- The software seeks also for holes
in the ground. If a hole is detected, the Rasenmä turns until there is
sufficient ground available to drive further. So no falling down (stairs)
is possible.
- If there is a constriction recognized,
the Rasenmä turns around about 180 degrees in a random turning direction.
The same function works also at dead ends.
- The ahead-speed is reduced in
the same ammount as the turning speed increases. This means, if it becomes
tight, the robot turns on the point.
- At a contact with one of the bumpers
the robot backs up a few cm and turns then about 20 degrees away from the
barrier. The contact of a bumper during mow operation will lead to a quick
shutdown of the blades.
- Planned: edge following mode;
systematic mowing, directed by spindle speed; finding of battery charger.
The
first mowing job is competed.
1. before
2. after from
top
3. after from
below
Elektronics:
Drawings:
Software:
The -more or less-
actual program for the C-Control:
rasenmae.bas
email?