2012/12/20 Peter C. Wallace <[email protected]>: > > The 7I39 is a voltage output device. You should not limit the maximum PID > value or this will limit the maximum speed (but max PID should be limited to > about 95% for bootstrap gate drive reasons)
Could You, please, help me out with little more explanation? The way I see it: motor has some fixed resistance in ohms; since I = U/R, increasing voltage will increase also the current in motor phases. Is that correct? Or am I missing something here? When I increased max_output to 0.9 for Z axis motor, I got CR11 led turned on very quickly. I had not yet tuned PID parameters to get the motor stable, it was still vibrating as I tried to move it. So that is why I concluded that increasing max_output was the main reason for that. Another thing I do not understand is: how can PID get saturated immediately when I press a jog button? Sometimes I am getting this as well. Another thing is that joint moves in one direction, HalScope reports that pid output is below 0.5, but in opposite direction it reaches the limit of 0.67; I do not believe that there is such a difference - there are Hiwin rails, size 15, 2 bearing blocks on each rail, with motor removed I can easily push the whole thing with one finger. I simply do not understand, what is wrong. Acceleration is relatively low - 150 mm/s^2. According to my calcs, with 0.5 Nm rated torque, 16:1 planetary reducer and 27 teeth module 1 gear in a rack, I get more than 400 N linear force. Since the weight of gantry bridge is less than 40 kg, motor should be able to move it with acceleration of 1G, which is 9800 mm/s^2. Of course, I have not accounted for friction, efficiency of planetary reducer etc, but I am asking even less than 2% of its rated capabilities, I am not even thinking about the fractions of percent from a peak torque. > Overcurrent and fault conditions should be handled by having a reasonable > ferror setting (a motor in current limit will cause a stall thats is > detectable as a ferror) I agree, that is the best thing to do, when overcurrent fault has already happened. What I would like to do is to tune the motors so that they do not cause drive to exceed current limit. Even if it means reducing max velocity and acceleration that motors can achieve. -- 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
