YEAH i got it
AREVIATION stand for ABREVIATION
OUch lucien, i got a bad head ache
YEAH i got it
AREVIATION stand for ABREVIATION
I meant the number chrunching Lucien. I Know it will help me a lot though.
Do you want me to make a litle excel work to make it more digest ?
It will work as long as the relay is the right one. Use a contactor instead of a normal relay with a N.C. contact closing the resistor circuit across the armature terminals. Use also a non inductive resistor for better results (in order to suppress contact arching). Remember to wait 100 milliseconds, at least, before sending movement commands when recovering from E-stop, so to leave some margin for the contactor to energize and open the shunt brake resistor circuit. Be careful, failure of this circuit will possibly overload the output stage (if the resistor stays in parallel with the armature during normal operation due to contactor failure). Over current circuit should kick-in in that case.
Last edited by kreutz; 05-25-2008 at 01:36 PM.
hello i write the program under excel for calculation of M parameter you must enter all the value in red you choose your unit inch or mm
if someone yant to make it a bit more clean this is absolutely public domain !!!
I can say I also did only about 75Khz stable without errors. My encoder is differential type with the 75114 as I remember, and I have put 75115 on the other side next to the UHU board.
Today I made some tests on my router and brought my scope to see the voltage level at my capacitors bank. I am using 4x8200mFD at 65V. I wanted to see how much of a rise I can get when decelerating. I was somehow surprised to see that when the motor decelerates the voltage did not actually go up but rather goes down just like when accelerating. ?? The next thing that passed through my mind was "Why do I need the regenerative power dump circuit?" in that case.
It is true that there was not so much mass connected to the motor except the pulleys, the belt, the screw and 2 linear bearings and the current limit was set a little lower to be safe if some mistake is made.
Todor
They higher the power supply capacitance the less the voltage will raise during deceleration (also the less it will drop during acceleration). The amount of charge delivered to the power supply capacitors due to regeneration is directly proportional to the motor load's mass and speed.
About the 75Khz limit, what value capacitors are you using connected to pin 4 and 12 of the 75115 chip?
Hello kreutz,
I am using 2.2nF as shown in the HP ver schematic. I remember some time before that there were not connected any capacitors at those pins and the situation was exactly the same, no difference.
I don't have ability now to change the encoder with some other type but I know this is a step that I should do some time. I was trying to start a discussion some time ago about what max frequencies have other people obtained but left without no one say something about this.
It is kind of strange having more than 3000 controllers sold and 166 pages of conversation about the UHU and as I can recall I have seen only 2 or 3 machines working with it - the one shown at Uli's site and the lathe with the spindle motor that was discussed recently. Maybe other people just don't want to share their setup with us here. I think it will be better if there was more talking and pictures of different machines and their PID tuning.
Todor
Todor and Lucien;
I don't think the differential interface circuit is limiting the maximum speed, at least not with a 500 ppr encoder, nor even with a larger than 1000 ppr encoder. The 2.2 nF capacitor will filter over 2Mhz noise, so it is not even near its limit. I think it might be worth digging a little more and call for the collaboration of more of the UHU users to share their setup and tell about their maximum speed limits.
I canot agree more since we have a very good electronic very stable it will be nice to have feed back from older userIt is kind of strange having more than 3000 controllers sold and 166 pages of conversation about the UHU and as I can recall I have seen only 2 or 3 machines working with it - the one shown at Uli's site and the lathe with the spindle motor that was discussed recently. Maybe other people just don't want to share their setup with us here. I think it will be better if there was more talking and pictures of different machines and their PID tuning.
about the 75khz limitation i was thinking that the problem come from us.
I am remembering your post 1 month ago
the question is are we the only stupid to get the problem ?
before to change your encoder try to get the answear to this question
Hi all,
Any alternative for Schottky Diodes SD103C (VR 20 V)
Does SD103A (VR 40 V) or BAT47 suitable for HP UHU ?
Khoo
i am working with 512 lines encoder 2048 points !!!I don't think the differential interface circuit is limiting the maximum speed, at least not with a 500 ppr encoder, nor even with a larger than 1000 ppr encoder. The 2.2 nF capacitor will filter over 2Mhz noise, so it is not even near its limit. I think it might be worth digging a little more and call for the collaboration of more of the UHU users to share their setup and tell about their maximum speed limits.
Kreutz,
I thought his problems were error count related and not achieving maximum speeds due to low voltage. Here I can go even over the motor's maximum speed but I am limited to about half the motor's capabilities because of this.
What if I change the capacitors for the frequency response to about 22nF which will limit to about 300Khz. Will this make the system more immune to noise?
I look for everything that could solve my problem, I tried also to put some ferrite toroids on all power lines but this helped nothing.
Todor
Todor:
Are you using twisted pairs for the differential signals?
I guess you refer to counts of encoder related problems (O parameter), instead of tracking errors (E parameter), O counts >0 implies different possible issues including: excessive noise, encoder signals out of quadrature,
EMI/RFI, or excessive motor speed (more than 150K 4x pulses per second).
Shielding the encoder cable should help if the problem is noise related.
If you are using the original UHU I would suspect excessive EMI/RFI noise produced by cross-conduction, even at low motor voltages, that is also the source of random chip resets experienced by many. That should not be the case for Lucien's problems. I think his problems could be related to using an improvised differential encoder.
Regards,
Kreutz.
Some UHU machines on youtube
enjoy
Yes, I am referring to the "O" parameter. There is some speed threshold above which I start to get errors. The more the speed the more the errors I get for a given time of travel.
My encoder cable is taken from an industrial machine - many pins in it - around 12 - A A_ B B_ C C_ + -. The pairs are twisted I think, I have not cut so much to see but they tend to come in color pairs. It is shielded one end only at the side of the drive. The encoder is bulgarian license of fanuc, very old one still used here.
Today happened a strange thing while playing with the PID parameters. I moved my keyboard a little away from the computer to be able to see the behavior of the axis and it started to go crazy hitting some buttons without me touch it. I was just clicking left and right to jog. I don't know if a keyboard cable is shielded but it was not even close to the motor power. Never had this while bench testing and is some kind of strange.