Hi Vasile, 2010/10/22 vasile surducan <[email protected]>
> Hi Seb, > > Looks to me that you have understand well that different DC motors will > give you different EMF values: > http://sirloon.net/loonaweb/sirblog/experimenting-back-emf-motion-feedback > <http://sirloon.net/loonaweb/sirblog/experimenting-back-emf-motion-feedback>So, > that's it, a poor method using an analog feedback, if you want universal > solutions seems to me you have to switch on digital feedback, which as far I > know can't be EMF. > Do you mean something like encoded wheels ? bemf is really nice to have because it's not invasive, you can control any DC motors without modifying the structure (which is great when hacking RC toys) > You can't do it without modifying dividers. > Is electronic that limited ?? C'mon, there should be a trick ! Cheers, Seb > Vasile > > On Fri, Oct 22, 2010 at 7:57 AM, Sebastien Lelong < > [email protected]> wrote: > >> Hi guys, hardware guys, >> >> >> Years ago, I built a DC motor control board, with back-emf sensor: >> http://sirbot.org/sirbot-modules/dc-motor-controller-board/ >> >> This board (and firmware) generates proper PWM signals to control 2 DC >> motors, and in the mean time, collect data about produced back-emf voltage, >> using ADC. There's no such power control of DC motors (which was actually >> done using RC tank transistors themselves), it's just about signaling. >> >> Using this board, there's a warning I'd like to get rid of today. It says >> "This board uses ADC (Analog-to-Digital-Conversion) to evaluate motor's >> speed. Voltages produced by motors are often far greater than those ADC can >> handle. There are voltage dividers on this board which keep those in correct >> range. These voltage dividers are designed so voltage produced by motors can >> be up to max 12V. If your DC motors produce more than 12V, you'll need to >> adjust voltage dividers' values or you will damage this board. You've been >> warned !!!" >> >> That is, if I'm using 24V DC motors, voltage coming to ADC will be too >> great and could damage the PIC (or worse, I could get wrong data). On the >> other side, using 5V DC motors, I'll obtain a narrow spectrum of values, as >> it's always divided by 2 (a little more). >> >> How can I perform a voltage normalization ? Whatever the incoming voltage >> produced by DC motors, I'd like it to be proportionally mapped to [0,5V]. >> I'd like this be dynamic (I don't want to unsolder/solder some resistors >> each time I plug a new DC motors). >> >> Please explain to me with very simple words :) >> >> >> TIA >> Cheers, >> Seb >> >> -- >> You received this message because you are subscribed to the Google Groups >> "jallib" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]<jallib%[email protected]> >> . >> For more options, visit this group at >> http://groups.google.com/group/jallib?hl=en. >> > > -- > You received this message because you are subscribed to the Google Groups > "jallib" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<jallib%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/jallib?hl=en. > -- Sébastien Lelong http://www.sirloon.net http://sirbot.org -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
