Hello Andy, thanks a lot for your quick answer.. So let see if i'm thinking well..
I can use the same spindle servo motor as an positioning axis to make millings controlling it with analog voltage closing the loop in emc and then when required as a spindle motor , i was asking this because some servo drives as you know come with pulse/dir and analog input, but these servos have only analog input. (thanks for the tip of the pwm to analog voltage converter i will try that) I'm trying to understand this because my idea is to mill lobe shapes for making camshafts, and it would be very nice to make the roughing process with a mill. Another thing is.. what happens when i change from axis to spindle, the encoder will read the position everytime the spindle turns because i don't want to loose the home reference for the axis, but if the spindle turns several times per minute the position in the axis will be enormous, so i was needing to reset the position units to 0 everytime i reach the index pulse, this way the axis always has to make less than a turn to return to 0 when the spindle stops. Do you think this is possible? I'm trying to clear my doubts before i start to spend money on servos and encoders.. Thanks again and i hope i've clean about my doubt. Regards. 2010/5/5 Andy Pugh <a...@andypugh.fsnet.co.uk> > 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 > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
