On 5 May 2010 13:57, Leonardo Marsaglia <leonardomarsagli...@gmail.com> wrote:
> My first doubt is, can i use the spindle servo motor for positioning ? Yes. > Because the driver that comes with the spidle servo that i can buy in my > country, says that the only input is analog voltage. This is fairly normal. There are not all that many PWM-input drives. > So my idea is to use > the 7i33 to convert pwm to analog voltage and using the pid in emc to close > the loop i can handle the feedback, so in a few words, i would be using the > standard closed loop from emc but converting the pwm to analog voltage. You can use a 7i33, though it might not be necessary. To convert PWM to analogue voltage needs nothing more complex than a capacitor and resistor. These could even be connected directly to the spindle drive terminals. Accurate, linear, conversion is more complicated, but in a feedback servo system this is not so important as the feedback corrects the errors. > Then > the driver itself uses his own pid to rotate the motor at the desired speed. > I don't know if this is possible, or problematic because of the > latency..correct me if i'm wrong please. No, that works perfectly well for spindle speed control. > So if this is possible the switching between C axis and spindle mode, would > be very easy to make with hal, the only thing that i need to know is if i > can reset the position counter when i'm working the spindle as an axis, so > once i reached the 359º the counter starts all over again from 0º. I think the option of wrapped rotary axes has been added to EMC2, though it might not actually be necessary it might simplify things in your case. . Alternatively you could wire the spindle index-enable pin to the logic that sets the spindle to "spindle mode" and the encoder will zero itself every time it sees an index. -- atp ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
