Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: jop_bal on February 10, 2011, 12:26:05 AM
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err.... I am a layman. I am trying to design the following.
A hand held battery operated simple blade cutting lawn mower for farm use.
I have a 20K rpm DC motor @ no load operating with a 9V rechargeable battery.
A PWM circuit that is used for changing the speed.
Now, I need this motor to reverse the direction when it is struck(i.e. when rpm falls to zero) due to the load.
Note: I am not eager to measure the rpm. All I need is, if the motor does not run in one direction change the polarity, so that it strikes grass from the other direction.
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Use a current sensor on the motor leads, and reverse when nearing the motor's stall current.
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How do I do it?
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I'm not sure how to achieve it because I've never used one before; but have a look at this Wiki (http://en.wikipedia.org/wiki/Current_sensor) and this SoR page (http://www.societyofrobots.com/sensors_currentsensor.shtml) :)