2012/12/20 Peter C. Wallace <[email protected]>: > > General flakey behaviour also points to incorrect commutation. > > I would first verify with motors unconnected to load, that you can get > symmetrical torque in both directions for the same amount of drive. > Then I would spin the motor for a number of minutes and retest the torque > to make sure you are not gaining/losing encoder counts (which will throw the > commutation off) >
There are only 2 patterns that turn unconnected motors with more or less the same velocity in both directions, when bldc.value is explicitly specified - 25 and 4. I spent more than an hour on finding the right hall pattern, I chose 25, I do not see a place for error there, but I will recheck with 4 tomorrow. How do You mean checking the torque of unconnected motor? Simply grabbing the motor shaft by hand and then deciding on the feeling? I will try that in the morning when I will be back there. 2012/12/20 Andrew <[email protected]>: > 2012/12/20 Viesturs Lācis <[email protected]> > >> Another thing I do not understand is: how can PID get saturated >> immediately when I press a jog button? > > > PID = P * ferror + etc. > With P=5 your PID is saturated when ferror = 0.15 or so. > > I guess that something is wrong with the motor or the settings. > The motor should work well with no load, PID should not saturate. > Maybe the motor just produces low torque. > Also check the bldc scales according > http://linuxcnc.org/docs/html/man/man9/bldc.9.html Motors have a load - they are installed in the machine. Sometimes PID gets saturated and runs away as soon as I touch jog button. Restarting LinuxCNC solves the issue and I can jog motor normally. The thing I have no explanation for is that if I try to jog it in positive direction, it runs away into negative direction. I would see some logic, if it moved in the same direction but now it does not make any sense to me. I am sure that bldc settings are correct - otherwise I would not be able to spin those motors either with setting bldc.value or by jogging. Bldc scale is -4000, because there are 1000 CPR encoders and encoder rawcounts pin increases/decreases by 4000, if I do a full turn of motor shaft by hand in one or another direction. I added the minus sign, because it did not work otherwise. I have set them as follows: loadrt bldc cfg=qh,qh,qh,qh setp bldc.n.scale -4000 setp. bldc.n.poles 8 setp bldc.n.pattern 25 Is there anything else I need to specify? -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
