Neil Baylis wrote: > I'm currently tining a small fast linear axis. It uses a DC servo, timing > belt, and linear encoder. I'm using Axis. This is the Y axis of my machine. > > It's basically working, but I have a few questions: > > 1) Is it possible to make Axis re-load the ini file, or do I need to exit > and re-start Axis to do this? > > If you are using the machine/calibration GUI that changes the PID/FFx/deadband etc. parameters, then it is constantly updating those settings every time you "OK" them. If you want to revert to the original settings completely, then I think you need to restart EMC. > 2) I'm repeatedly doing the following MDI commands: g0y0 g0y8 while I take > a plot with Halscope to monitor the results. Is it possible to assign these > commands to function keys on the keyboard, or buttons on the GUI, so they > are more convenient? > > You can recall old MDI commands with the up arrow and down arrow keys. Or, you could make a tiny G-code program : G0 Y0 G0 Y8 M02 and then re-run it each time with a single R key. > 3) The Calibration tool shows three tabs, one for each axis. For some > reason, the 3 tabs do not show the same tuning variables for each axis. What > is it that controls which tuning variables are shown in the Calibration tool > tabs? > > There will be a difference either in those variables in your ini file, or the way they are linked up in your hal file. The ini file variables are pulled from there and sent as parameters to the PID component. This code for the univpwm controller is in univpwm_servo.hal and looks like the following :
setp pid.0.Pgain [AXIS_0]P setp pid.0.Igain [AXIS_0]I setp pid.0.Dgain [AXIS_0]D setp pid.0.bias [AXIS_0]BIAS setp pid.0.FF0 [AXIS_0]FF0 setp pid.0.FF1 [AXIS_0]FF1 setp pid.0.FF2 [AXIS_0]FF2 setp pid.0.deadband [AXIS_0]DEADBAND The [AXIS_n]<name> syntax pulls the parameter <name> from the [AXIS_n] section of the ini file. > 4) None of the tabs in the Calibration tool shows FF2 as a tunable > parameter. To tune FF2, I shut down Axis, tweak the INI file manually, and > then restart Axis. Am I missing something? > Either there is no FF2 parameter listed in your ini file, or the stanza in univpwm_servo.hal is missing the line that brings over that parameter. If that line (which would be setp pid.1.FF2 [AXIS_1]FF2 in this case) was missing, then putting the value in the ini file would not have any effect, as it is not getting loaded into the PID component, anyway. > 5) FF2 seems to have no effect. I added it in the INI file immediately after > FF1. I've heard that it's very sensitive, and tried values from 0 up to 0.5, > but on Halscope the error plot looks identical. As a reference point, my FF1 > value is 0.25. My servo amp is a voltage amp (PWM input LMD18200 H Bridge), > driving a small DC servo. > Reason described in above paragraph. Jon ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
