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Topic: Wire guidance for robot lawnmower? (Read 8 times) previous topic - next topic

Paulware

Well done I have a friendly robotics lawn mower that I would like to hack with your approach.

My lawn mower starts to spin the wheels when it tries to go up a hill steeper than 15 degrees...It would be nice to detect slippage of wheels and change direction when this is detected. 

Does your yard have many hills?  Maybe the weight/wheel chair wheels don't have this issue

Jantje

Paulware
My 2 cents: replacing the wheels by more grippy ones may be easier.
Best regards
Jantje
Do not PM me a question unless you are prepared to pay for consultancy.
Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -

cr0sh


Well done I have a friendly robotics lawn mower that I would like to hack with your approach.

My lawn mower starts to spin the wheels when it tries to go up a hill steeper than 15 degrees...It would be nice to detect slippage of wheels and change direction when this is detected. 

Does your yard have many hills?  Maybe the weight/wheel chair wheels don't have this issue



I've got one of these, but I haven't taken the time yet to hack it (purchased it used off of Craigslist for $50.00!); surely there is some place on the motor driver board that is monitoring (or can be made to do so) the current to the motors; look between where the motor wires connect and the output h-bridge drivers - you might have to do some probing. Basically, you are looking for a point on the board where you can monitor a voltage representing the current consumption of the motors; it will be lower when the wheels slip. Good spots to probe for are any place marked "TPn" - where "n" is a number (stands for "test point" and is used for troubleshooting the boards, usually). Testing will be another thing (you'll want to build a pony brake with adjustable slip, and test the motor without the gearbox).
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

warren631

#13
Oct 25, 2012, 02:02 am Last Edit: Oct 25, 2012, 02:28 am by warren631 Reason: 1
Here is my "RoBoMo" in action:  See my previous description posted somewhere herein above.

http://youtu.be/bmf7OF1B-lo  and http://youtu.be/T9WiJkRTDTo

Still improving on it.  The speed and navigation need improvement.  It goes too slow up hills and too fast down hills (sometimes it overshoots the invisible dog fence wire boundary) so I need to add some kind of speed regulation - maybe I need 'IR Compensation' on the DC motors, or feedback to a PID control from tachs or encoders on the wheels?  I will try something simple first such as a tilt switch to switch between low and high speed to give more power when its going up a hill.  Any other suggestions?

What I have learnt for others:  Orientation of the four DC cutter motors was critical to minimize RF noise interference to the dog collar sensor.  I had a big problem trying to eliminate motor brush noise (using shielded cables, proper grounding, capacitors, etc.) then I noticed that if I just rotated the motors to a certain point, found from experimentation, I could almost eliminate the noise problem.  

The power wheel chair's joystick was very complicated using four hall-effect IC sensors on the joystick and a 'fly-by-wire' custom network cable down to the drive motor controllers.  So I used two servos (in the white inverted ice cream box on top) to actually move the joystick for speed (X servo (including forward and reverse)) and direction (Y servo).  This seems to be a simple solution.

Paulware

Nice video, I'd like to suggest a magnetic azimuth sensor to make straighter lines, but maybe it curving because it detects the doggie wire.  Very impressive.  What kind of cutter device are you using?
Thanks,
Paul

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