Del Tapparo
New Member
Has anyone implemented back emf speed control for small DC motors (less than 5 amps) using the PicAxe?
Back EMF motor control
- Thread starter Del Tapparo
- Start date
BeanieBots
Moderator
Certainly easy enough to do with an op-amp but I'm not sure how the theory would work in a digital environment.
I guess the same principle would apply. Measure the current drawn, average with some heavy RC if using PWM and then add proportionally to the drive demand. Extra care would be needed not to cause oscillation because there will be a time delay and the coarseness of integer maths could easily take you over unity gain.
At the end of the day, back emf is a fairly sloppy control method anyway. If you have a PICAXE to hand I would guess that there are many better ways to do it.
I guess the same principle would apply. Measure the current drawn, average with some heavy RC if using PWM and then add proportionally to the drive demand. Extra care would be needed not to cause oscillation because there will be a time delay and the coarseness of integer maths could easily take you over unity gain.
At the end of the day, back emf is a fairly sloppy control method anyway. If you have a PICAXE to hand I would guess that there are many better ways to do it.
It is being experimented with in the Openservo project http://www.openservo.com/
But, I am not sure how you would implement it in a Picaxe environment.
Cheers,
Wreno
But, I am not sure how you would implement it in a Picaxe environment.
Cheers,
Wreno
Steve Joblin
Member
I asked the same question just week or so ago.... check out what I found out on this thread on the Parallax forums... http://forums.parallax.com/forums/default.aspx?f=10&m=225021 and here on the Society of Robots forum... http://www.societyofrobots.com/robotforum/index.php?topic=2174.msg14475#msg14475