2013/12/5 Kirk Wallace <kwall...@wallacecompany.com> > There often is a difference between the feedback resolution and the > motor resolution. For instance, if your motor can be moved to within a > degree of position, but your encoder feed back can report in tenths of a > degree. When you command a position, the motor will get to within a > degree, but your encoder says you are not there yet. Over time, your PID > will increase its power to make a correction and finally move the motor. > The motor moves another degree and over shoots the original position, > the encoder reports this and the PID tries to correct in the other > direction, causing an oscillation of +/- one degree or more. There > should be a deadband parameter you can set to tell the PID to ignore a > certain amount of error. Using HALscope to show the position or velocity > command and feedback show show this hunting and may give you an idea how > much there is. Posting your HALscope screen may help too. >
Well I guess that depends on the VFD itself. I'm still getting used to this VFD since it has a lot of options, even it can work as a PLC, also it has an optional internal PID for positioning works using an extra board for encoder reading. I'm gonna take a look to the deadband component and see if it can help. I also noticed today that I have a little offset between the 0 volts that the mesa sends to the variator and what the VFD thinks is 0 volts so when the command for velocity from LinucCNC is 0 I still have 1 hz or so. I can tune this within the VFD. Tomorrow I will take a look and then I'll tell if I can improve the behaviour of the motor. -- *Leonardo Marsaglia*. ------------------------------------------------------------------------------ Sponsored by Intel(R) XDK Develop, test and display web and hybrid apps with a single code base. Download it for free now! http://pubads.g.doubleclick.net/gampad/clk?id=111408631&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
