On Fri, 9 Dec 2016, Jon Elson wrote: > Date: Fri, 09 Dec 2016 14:28:48 -0600 > From: Jon Elson <jonelson...@gmail.com> > Reply-To: el...@pico-systems.com, > "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] Fanuc analog drive & LinuxCNC tuning > > > On 12/08/2016 03:56 PM, Frederic RIBLE wrote: >> As we can see a phase compensation circuit in the drive, we assume this >> is to compensate for delay on velocity feedback. >> So, we have tried to add some delay on the velocity feedback assuming >> original F/V converter from the Fanuc control board may be slower than >> what we have with Mesa. Not much success: that changes a little the >> oscillation period, but we cannot cancel oscillation. > No, it is probably FASTER. The Mesa probably is delayed by a ms reading > the encoder position, and then another ms sending the DAC output. The > circuit used by Fanuc was almost time-continuous except for the encoder > positional granularity. It was similar to the ST chip L290, which > decoded quadrature state changes into count-up and count-down pulses, > and fed them into a pair of analog integrators. These were then fed to a > differential summing amp. So, the response to a movement of the encoder > came out in some microseconds. >> >> Anyone knows how we can tune the drive (unfortunately we have not the >> documentation for this part number) ? >> >> > You might improve the results by decreasing the period of the servo thread. > > Jon
There are only some 10s of usec between reading the encoder and writing the PWM value, assuming the read and write functions are in the proper order in the hal file. Also Fred said that changing the servo thread from 1 to 10 KHZ made little difference, so I dont think its a loop bandwith issue Still waiting to see if they have the velocity scaling right on the velocity feedback output ( ~10V at max motor speed) Peter Wallace Mesa Electronics ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today.http://sdm.link/xeonphi _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
