2StartingUptheRMC
deltamotion.com33
oDuringtheconstantspeedportionofthemove,theActualPositionparallels
theTargetPosition.
Ifthesystembeginstooscillate,decreasethegain.Inthisstep,donotexpectthe
ActualPositiontotracktheTargetPositionverywellduringthemove.
Onceyougaincontroloverthesystem,increasethespeedsandaccelerationsofyour
commandstovaluesthatwillbeusedduringnormalmachineoperation.
Plots
Lookattheseplotsforexamplesofgoodandbadplotsatthisstep.Beawarethatnotall
systemswillbeliketheseexamples.
ToolittleProportionalGain
TheActualPositionlagstheTargetPositionandtakesalongtimetogettotheCommand
Position.
ToomuchProportionalGain
Theaxishasstartedtooscillate,whichisevidentfromtheActualSpeedandControl
Output.
RMC70/150andRMCToolsUserManual
34DeltaComputerSystems,Inc.
CorrectProportionalGain
TheActualPositionparallelstheTargetPositionduringtheconstantvelocityportionofthe
moveanddoesnotovershoot.
7.AdjusttheVelocityFeedForward
2StartingUptheRMC
deltamotion.com35
InmanysystemstheVelocityFeedForwardparameteristhemostimportantparameter
forpositiontrackingduringamove.ToadjusttheVelocityFeedForward:
StartwithasmallvalueofVelocityFeedForward.Rememberthatitisafloatingpoint
number,andyoumayhavetostartwithanumbersmallerthan1,dependingonyour
system.
Tip:
UsetheAdjustVFFbuttonintheTuningToolstoautomaticallydeterminethe
VelocityFeedForward.Makeamove,waitforittocomplete,thenclickAdjustVFF.
Repeatfortheotherdirection.
Makelongslowmovesinbothdirections.AdjusttheVelocityFeedForwarduntilthe
axistrackswithin10%inbothdirections.
IfyouareusingRatioedgains,makesuretoadjustbothVelocityFeedForwards.
ClicktheDownloadbuttontoapplythechangestotheRMC.
IftheSymmetrical/RatioedparameterissettoRatioed,youwillhavetwoVelocityFeed
Forwards,oneforeachdirectionofmotion.Makesuretotuneboth.
Plots
Lookattheseplotsforexamplesofgoodandbadplotsatthisstep.Beawarethatnotall
systemswillbeliketheseexamples.
ToolittleVelocityFeedForward
TheActualPositionlagstheTargetPositionduringtheentiremove.
ToomuchVelocityFeedForward
TheActualPositionstartsleadingtheTargetPosition.
RMC70/150andRMCToolsUserManual
36DeltaComputerSystems,Inc.
CorrectVelocityFeedForward
TheActualPositiontrackstheTargetPositionperfectlyduringthelatterhalfofthemove.
8.AdjusttheAccelerationFeedForward
2StartingUptheRMC
deltamotion.com37
TheAccelerationFeedForwardparameterisparticularlyusefulforsystemsmovinglarge
masseswithrelativelysmallcylinders.Suchsystemsoftenhaveadelaybeforethestart
ofmovement.TheAccelerationFeedForwardtermscanhelpcompensateforthisdelay.
StartwithasmallvalueofAccelerationFeedForward.Rememberthatitisafloating
pointnumber,andyouwillverylikelyhavetostartwithanumbermuchsmallerthan
1,suchas0.001,dependingonyoursystem.
Tip:
Fora2.5inborehydrauliccylinderwithamaxvelocityof30in/sec,the
AccelerationFeedForwardistypicallyontheorderof0.01to0.3.Startwithasmall
value.
Lookforfollowingerrorsduringaccelerationanddeceleration.Increasethe
AccelerationFeedForwardparameteruntiltheerrorsdisappear.
IfyouareusingRatioedgains,makesuretoadjustbothAccelerationFeedForwards.
ClicktheDownloadbuttontoapplythechangestotheRMC.
Plots
Lookattheseplotsforexamplesofgoodandbadplotsatthisstep.Beawarethatnotall
systemswillbeliketheseexamples.
ToolittleAccelerationFeedForward
TheActualPositionlagstheTargetPositionduringtheaccelerationatthebeginningofthe
move,andovershootsduringthedecelerationattheendofthemove.
ToomuchAccelerationFeedForward
TheActualPositionstartsleadingduringtheaccelerationandundershootsduringthe
deceleration.
RMC70/150andRMCToolsUserManual
38DeltaComputerSystems,Inc.
CorrectAccelerationFeedForward
TheActualPositiontrackstheTargetPositionwellduringtheaccelerationand
deceleration.
9.ReadjusttheProportionalGain
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