Hello All, I am trying to measure the velocity and acceleration of the individual axis in machinekit.
I have added the ddt components and included them in my hal. This is a copy of part of my hal file with the DDTs included. *# axis enable chain* *newsig emcmot.00.enable bit* *sets emcmot.00.enable FALSE* *net emcmot.00.enable axis.0.amp-enable-out => hpg.stepgen.00.enable pid.0.enable* *# position command and feedback* *net emcmot.00.pos-cmd axis.0.motor-pos-cmd => pid.0.command ddt.0.in* *net emcmot.00.vel-cmd axis.0.joint-vel-cmd => pid.0.command-deriv* *net emcmot.00.pos-fb hpg.stepgen.00.position-fb => axis.0.motor-pos-fb pid.0.feedback * *net emcmot.00.command pid.0.output => hpg.stepgen.00.velocity-cmd* *#net emcmot.00.pos-cmd => hpg.stepgen.00.position-cmd ddt.0.in* *setp pid.0.error-previous-target true* *setp pid.0.maxerror .001* *# Set the stepgen in velocity mode* *setp hpg.stepgen.00.control-type 1* *# timing parameters* *setp hpg.stepgen.00.dirsetup [AXIS_0]DIRSETUP* *setp hpg.stepgen.00.dirhold [AXIS_0]DIRHOLD* *setp hpg.stepgen.00.steplen [AXIS_0]STEPLEN* *setp hpg.stepgen.00.stepspace [AXIS_0]STEPSPACE* *setp hpg.stepgen.00.position-scale [AXIS_0]SCALE* *setp hpg.stepgen.00.maxvel [AXIS_0]STEPGEN_MAX_VEL* *setp hpg.stepgen.00.maxaccel [AXIS_0]STEPGEN_MAX_ACC* *# P8.9 X_Step* *setp hpg.stepgen.00.steppin 0x65* *# P8.10 X_Dir* *setp hpg.stepgen.00.dirpin 0x64* *# PID settings to prevent PRU pin hunting* *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* *setp pid.0.maxoutput [AXIS_0]MAX_OUTPUT* *# set the signals for the velocity and acceleration* *net Xvel ddt.0.out => ddt.1.in * *net Xacc <= ddt.1.out* This is, if I am correct, the same way Bas de Bruin showed in his setup. The derivative of the position is the speed ( with the problem that I don't know what unit is being used, since the time constant will be the servo-thread period ). And the derivative of the speed is the acceleration. I opened halscope and plotted the Xvel net. But instead of a "logical" speed graph I got the following: <https://lh3.googleusercontent.com/-IiOBZyfo24Y/WRxq4G0MgzI/AAAAAAAAAk0/Rf4VRJZzV4Y5ijrA7kWjJPQd3ukeQo8VgCLcB/s1600/HalScope%2BXAcceleration%2B2017-05-17-10-43.png> Does anybody know why this doesn't look like what I would expect ( something more of a straight line with nice slopes )?? With regards, Michel van der Breggen -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. To unsubscribe from this group and stop receiving emails from it, send an email to machinekit+unsubscr...@googlegroups.com. Visit this group at https://groups.google.com/group/machinekit. For more options, visit https://groups.google.com/d/optout.
