On 01/01/2014 12:52 PM, Jon Elson wrote: > On 01/01/2014 10:27 AM, Ed wrote: >> I am working on a mill with a Pico Systems setup and am having troubles >> with the tuning. >> >> Wells-Index 3 axis mill, similar to a Bridgeport, formerly using Gecko 320's >> >> Pico Systems UPC PWM controller >> >> 3 Ea. PWM DC servo amps set at 10 Amps >> >> Original nominal 90 Volt supply >> >> With the P set to 100 I set to 0 and D set to 0 the axis will hold >> against turning the screw in one direction very well but the other >> direction faults out very easily. >> >> Changing the current limit resistors did not make an appreciable difference. >> >> Setting P to a higher value does help some but using any D sets it into >> oscillation. Many other settings have been tried but it has been mostly >> a blind change and try thing. > You need to tell us a lot more about the system. Are the > encoders > directly on the motors, or somewhere else in the system?
Encoders are on the end of the screw, 2-1 belt drive from motor, 1000 line/4000 count > What is the encoder resolution? Are the motors direct-drive, or > coupled by belts? >> It will jog at about 10 IPM then faults when stopping. >> >> The difference in torque in the different directions is what has me baffled. >> > If you are not using the velocity estimation mode, it is HIGHLY > recommended. it uses a feature of the newer boards (since > early 2013) > to use time between encoder counts to more accurately measure > velocity). In the sample configs, there is univpwm (without > velocity) > and univpwmv (with velocity estimation). It is easier to > tune the > servo response with the velocity estimation. I have tried both with and w/o Vel Est with little or no difference. The board is a Ver 3.1 At 16 IPM it jogs fine then faults when stopping. Keyboard input for all functions. All axis have the tendency to have a lot of resistance to influence the screw in one direction and much less in the other, Y axis is the worst, Z axis is the best > > The current limit feature depends on 5 milli-Ohm resistors in > the servo amp. So, it is very sensitive to the resistance > of the > traces on the board. Resistors on the board were set to try to > balance the variation, but it is not perfect. But, you > should not be > getting into the current limit under normal conditions, only > during hard acceleration. I did not notice a difference with the higher current limit. > You might want to step back and > test your motors for performance. They ran fine (72 IPM)when hooked to 320 gecko's at half the voltage. > Your machine should > move smoothly on one Amp of motor current. When initially setting up the machine a 12V battery was used to move the axis to the middle of their travels, did not check the amps but it moved smoothly at about 25 IPM. > If it doesn't, > the cause should be found. What is the current rating of > your motors? Don't know the ratings but they are ElectroCraft E723 motors that came on the machine OEM > Is that continuous or peak? Do the motors produce something > close to rated torque at rated current? If not, the magnets are > cooked, which is not all that rare. What value are the current > set resistors you are using on the servo amps? 290 000 Ohms for 10 Amps > > Jon > > ------------------------------------------------------------------------------ > Rapidly troubleshoot problems before they affect your business. Most IT > organizations don't have a clear picture of how application performance > affects their revenue. With AppDynamics, you get 100% visibility into your > Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! > http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
