SERVO TUNING PROCEDURE (BASIC)

3.GAIN TUNING BY TUNING NAVIGATORB-65264EN/013.1OUTLINE OF GAIN TUNING BY TUNING NAVIGATORIf you press the [Navigator] button in main bar , you see the followingdialog . Please select "Initial Gain-Tuning" at first and tune servo loopgain according to following procedure. In "Initial Gain-Tuning", the velocity gain is determined withlarge margin against the limit of vibration level. When you usethis tuning, the gain become a little larger than initial state, andthe resonance of the machine becomes more clear.Next, please select "Filter-Tuning" in order to suppress theresonance vibration."Gain-Tuning" is used for final determination without anyresonance. This function realizes the higher velocity loop gain byreducing the gain margin.The following table shows the items and contents to tune.Initial Gain-TuningThis is the automatic tuning of velocity gain. It determines thegain, moving the target axis and measuring frequencyresponse. When you've not tune the gain yet, please select thismenu first.Filter-TuningThis is the automatic tuning of HRV filters(Resonanceelimination filters). It determines the optimum filter setting bydetecting resonance frequency with the gain which isdetermined Initial Gain-Tuning.Gain-TuningAfter application of above filters, this wizard raise the gain moreby automatic tuning.High speed & Highprecision TuningThe wizard, which makes the tuning for High speed & Highprecision easy, will start. The plural parameters, which arerelated High speed & High precision function, can bedetermined easily by only one slider. The square with 1/4 arcprogram is used for the evaluation.- 11 -

3.GAIN TUNING BY TUNING NAVIGATOR3.2B-65264EN/01GAIN AND FILTER TUNING BY TUNING NAVIGATORBy using Tuning Navigator you can easily tune velocity loop gain. Asthe tuning of velocity loop gain is most important for all of servoperformance, please execute Tuning Navigator before following servotuning.[Initial Gain Tuning]At first, please select "Initial Gain-Tuning".Under 10dBUnder -20dBWideTuning Navigator shows bode-plot of velocity loop and you canunderstand the performance of velocity loop.Upper line in bode-plot shows gain characteristic and lower lineshows phase characteristic. Important points of this figure that youshould note are as follows. (About the details of bode-plot, pleaserefer to several books of basic control method) The width of 0dB level of gain line is important. By settinghigher velocity loop gain, it becomes wide.Gain level of resonance frequency has to be suppressed at leastunder -10dB.Gain level around cut-off frequency is less than 10dB.Gain level near 1000Hz has to be lower than -20dB.This bode-plot shows that 0 level of gain line becomes wider andperformance of velocity loop rises.- 12 -

B-65264EN/013.GAIN TUNING BY TUNING NAVIGATOR[Filter Tuning]Next, Please select "Filter Tuning". Following example shows thatgain line at two resonance frequencies (250Hz and 530Hz) aresuppressed by Filter Tuning.Under -10dB[Gain Tuning]Finally, Please select "Gain Tuning". Tuning Navigator decides thefinal result of gain tuning.- 13 -

4.TUNING OF ACCELERATION AND DECELERATION4TUNING OF ACCELERATION ANDDECELERATION- 14 -B-65264EN/01

4.TUNING OF ACCELERATION AND DECELERATIONB-65264EN/014.1TUNING OF TIME CONSTANT FOR RAPID TRAVERSEPlease rise time constant for rapid traverse by observing TCMD. Bellshape acceleration/deceleration is effective in order to avoid themechanical shock and to avoid TCMD limitation at high speed.Please set this time constant as small as possible. Normally TCMD hasto be smaller than 100% when maximum weight is put on yourmachine.Following figure shows the effect of this tuning. Tuning of rapidtraverse contributes to reduce cutting time me Constant for Rapid Traverse]Parameter No.16i/18i/21i/0i16201620DescriptionTime constant(ms) for linear-shaped Acc./Dec.Time constant(ms) for bell-shaped Acc./Dec.- 15 -

4.TUNING OF ACCELERATION AND DECELERATION4.2B-65264EN/01POSITION GAIN CHECKPlease set position gain 5000 and check TCMD and velocity at rapidtraverse. If there is no vibration please change position gain to 5000.- 16 -

5.TUNING OF CIRCLEB-65264EN/015TUNING OF CIRCLE- 17 -

5.TUNING OF CIRCLE5.1B-65264EN/01TUNING OF FEED FORWARD COEFFICIENTTo set feed forward function is necessary to realize higherperformance. Feed forward function reduces position error and makesit 0 by setting 100% coefficient.Velocity feed-forwardVariable ratio of velocity command(acceleration) is transformed to torquecommand compensation. Thiscompensation reduces position errorand contour error mainly caused by thedelay of velocity loop.Feed-forwardPosition command from CNC istransformed to velocity commandcompensation. This compensationreduces position error and contourerror, which is mainly caused by thedelay of position loop.Velocityfeed-forwardαPositioncommand Kp -Velocityloop Position feedbackFollowing figure shows the effect of feed forward function. Feedforward function reduces 250um error to 0um.Feed forward coefficient 0%Feed forward coefficient 100%The error of radius isalmost 250µmThe error of radius isalmost 0µm- 18 -

5.TUNING OF CIRCLEB-65264EN/01If you want to adjust more, please adjust feed forward coefficient. Butyou have to note that we don't recommend to set feed forwardcoefficient over 100% because it indicates that the actual machinemoves ahead of its motion command.- 19 -

5.TUNING OF CIRCLE5.2B-65264EN/01TUNING OF BACKLASH ACCELERATIONIf there is position error at the point that the axis turns, please adjustbacklash acceleration amount.Please rise or reduce backlash acceleration amount step by step. Thestep value of this is about 10. If under cut occurs just after positiontuning, please stop adjusting. Big protrusion and under cut make theresult of cutting worse. Please try to tune this value so as to makeprotrusion under 5um.[Backlash Acceleration]Parameter No.16i/18i/21i/0iStandard setting valueDescription204850Backlash acceleration amount- 20 -

6.TUNING OF SQUAREB-65264EN/016TUNING OF SQUARE- 21 -

6.TUNING OF SQUARE6.1B-65264EN/01SETTING OF CORNER DECELERATIONCorner deceleration is necessary to reduce position error at corner.Please set about 500mm/min at first.[Corner Deceleration (Allowable Speed Difference)]AI CONTOURAI NANO CONTOURParameter No.16i/18i/21i/0iAI High Precision ContourAI Nano High Precision ContourParameter No.16i/18i/21i/0iStandard setting value17838410500Following figure shows the effect of corner deceleration. You can seethe position error becomes small.20µm20µm- 22 -

6.TUNING OF SQUAREB-65264EN/016.2TUNING OF TIME CONSTANT FOR CUTTING FEEDYou also have to note the value of time constant of corner decelerationand its shape when you tune the position error at the corner. Timeconstant before interpolation is applied to this deceleration. If youdon't use bell time constant the shape of tangent velocity at the cornerbecomes "V" as you can see in following figure. As the changing rateof its deceleration is decided by time constant before interpolation, toset large value to this time constant (to set small acceleration) leadsbetter result at the corner.ADYContourXCBStraightPart:F3000Velocity of X axisF3000ABCADBCDVelocity of Y axisCorner Part:F500Velocity of each axisTangent velocityIf you couldn't get good result by setting corner deceleration, pleaseadjust time constant. And to set bell-shape time constant is alsoeffective not only to corner performance but also arc cornerperformance. But you have to note that to set bigger time constantmakes cutting time longer.- 23 -

6.TUNING OF SQUAREB-65264EN/01[Time Constant Before Interpolation]AI CONTOURAI NANO CONTOURParameter No.16i/18i/21i/0iAI High Precision ContourAI Nano High Precision ContourParameter No.16i/18i/21i/0iDescription17701771-Maximum Cutting FeedrateTime-840019510Maximum Cutting FeedrateTime- 24 -

6.TUNING OF SQUAREB-65264EN/016.3TUNING OF VELOCITY FEED FORWARDVelocity feed forward can improve the shape at corner. Because itoutputs ideal TCMD for acceleration and deceleration and helps themovement of integration in velocity control. Please adjust thiscoefficient.If you don't use Nano-Interpolation, please set this coefficient under400.[Velocity Feed Forward]Parameter No.16i/18i/21i/0iStandardsetting value206950- 25 -DescriptionVelocity feed-forward coefficient

7.TUNING OF ARC SQUARE7B-65264EN/01TUNING OF ARC SQUARE- 26 -

7.TUNING OF ARC SQUAREB-65264EN/017.1SETTING OF ACCELERATION AT ARCAt the arc part the acceleration quickly changes and it makes positionerror. In order to avoid this problem, please set the limitation ofacceleration at the arc.Following figure shows how velocity changes by using this function.In this example feed rate at the arc is reduced till F1000 and becomesF4000 again after the arc. Deceleration rate before and after the arc isdecided by time constant before interpolation.DAYContourXCBStraight Part:F4000Velocity of X axisF4000F4000AABCBCDDVelocity of Y axisCorner Part:F1000Tangent VelocityVelocity of each axisFollowing figure shows the effect of applying this function. Positionerror at the arc is reduced.F4000F4000F400010µm error10µm error- 27 -F2000

7.TUNING OF ARC SQUAREB-65264EN/01If you are using AI Contour Control or AI Nano Contour Control, youcan select radius and feed rate. As this example radius 5mm and feedrate at the arc is F2000, you only have to set R 5000um and feed rate F2000.If you are using AI High Precision Contour Control or AI Nano HighPrecision Contour Control, you have to set by time constant oracceleration value.[Allowable Acceleration]AI CONTOURAI NANO CONTOURParameter No.16i/18i/21i/0iAI High Precision ContourAI Nano High Precision ContourParameter No.16i/18i/21i/0iDescription17301731-Feedrate (mm/min)Radius (um)-8470Allowable Acceleration- 28 -

7.TUNING OF ARC SQUAREB-65264EN/01Adjusting velocity feed forward coefficient is also effective to thispart. Position error is caused by a delay of velocity loop just afterentering the arc and just after the end of the arc. Velocity feed forwardcompensates this delay and position error is reduced.Position errorcaused by Yaxis’s delayYPosition errorcaused by Xaxis’s delayYXXWithout Velocity Feed ForwardWith Velocity Feed Forward[Velocity Feed forward]Parameter No.16i/18i/21i/0iStandard settingvalue206950- 29 -DescriptionVelocity feed-forward coefficient

8.HRV3 CONTROL8B-65264EN/01HRV3 CONTROLHRV3 Control is effective to get higher performance at high-speedand high-precision machining center. HRV3 Control manages currentcontrol twice faster than HRV2 Control. This contributes to makemotor current smooth and to make current response faster. If yourmachine's precision is over your target by HRV2 Control, HRV3Control will help you.HRV3 Control has a current control mode. When "High Speed HRVCurrent Control Mode" is on, cycle of current control becomes twicefaster than HRV2 Control. When it is off and rapid traverse, cycle ofcurrent control equals to HRV2 Control. By program code G5.4Q1and G5.4Q0 you can select "High Speed HRV Current ControlMode".- 30 -

8.HRV3 CONTROLB-65264EN/018.1BEFORE YOU SET HRV3 CONTROLBefore you set HRV3 Control you have to notice the number ofamplifiers. When HRV3 is set the maximum number of amplifier perone FSSB line is 4. So if the number of amplifier of your machine isover 4, you have to use two FSSB line.ServoCardHRV28 amplifiers and 1 module are available per one FSSB lineServoCardHRV3HRV34 amplifiers and 1 module are available per one FSSB line- 31 -

8.HRV3 CONTROL8.2B-65264EN/01PARAMETERS FOR HRV3 CONTROLTo set HRV3 Control from fundamental parameters which werecommends you have to set only three parameters. No.2013#0 is afunction bit of HRV3 Control. No.2334 and No.2335 aremagnification of current gain and velocity gain in HRV3 mode.[HRV3 Parameters]Parameter No.16i/18i/21i/0iStandard setting value2013 #023342335 *1)1150200DescriptionHRV3 (Current control cycle 62.5 µs)Current loop gain override in HRV3 modeVelocity loop gain override in HRV3 mode(*1) No.2202#1 is needed to valid this parameter.Following table shows fundamental parameters for HRV2 Control.HRV3 Control also needs these parameters. Please confirm theseparameters too.[Fundamental Parameters]Parameter No.16i/18i/21i/0iStandard setting valueDescription2004204020412003 #32017 #72006 #42202 #121070X000011Standard parameterStandard parameter1111150Current control cycle 125 µsCurrent integral gainCurrent proportional gainEnables PI functionEnables velocity loop high cycle management functionUses the latest feedback data for velocity feedback.Cutting/rapid traverse velocity loop gain variableVelocity loop gain override at cutting traverse- 32 -

8.HRV3 CONTROLB-65264EN/018.3HIGH SPEED HRV CURRENT CONTROL MODE IN HRV3CONTROLG5.4Q1 and G5.4Q0 are program codes to specify "High Speed HRVCurrent Control Mode". Program codes for cutting traverse betweenG5.4Q1 and G5.4Q0 is in "High Speed HRV Current Control Mode"and cycle of current loop becomes faster and magnification for controlgain is applied.High Speed HRV CurrentControl Mode ON- 33 -

8.HRV3 CONTROL8.4B-65264EN/01HOW TO CHECK THE STATE OF HRV3 CONTROLDiagnose No.700 is available to check the state of HRV3. After youset HRV3 Control(No.2013#0) and power off/on, please check Bit1 ofDGN700(HOK). When HRV3 Control is accepted to CNC, HOKbecomes 1.After you commands G5.4Q1 when HOK 1, Bit0 of DGN700(HON)becomes 1 in cutting traverse. This means cycle of current loopbecomes faster and magnification for control gain is applied.- 34 -

8.HRV3 CONTROLB-65264EN/018.5TORQUE COMMAND LIMITATION IN HIGH SPEED HRVCURRENT CONTROL MODEIn "High Speed HRV Current Control Mode" torque command isautomatically limited less than 70% of the maximum torque to protecttransistor in amplifier. So torque command is easy to be saturated bytorque limit. Please don't command high speed and high accelerationin "High Speed HRV Current Control Mode". Normally this mode inHRV3 Control is used for final cutting and 70% limit doesn't becomethe reason of trouble.Torque Curve in G5.4Q1TorqueHRV2 and HRV3 Rapid andHRV3 Cutting (G5.4Q0)70%HRV3 Cutting (G5.4Q1)Speed- 35 -

8.HRV3 CONTROL8.6B-65264EN/01ABOUT THE EFFECT IN HIGH SPEED HRV CURRENTCONTROL MODEFollowing result of circular shape and 10µm step are an actual resultof a machining center which uses HRV3 Control. You can see the patherror of circle is less than 2µm and smoothness is less than 1µm.There is no overshoot at the point of 10µm step.2µm/div10µm- 36 -

9.BACKLASH ACCELERATIONB-65264EN/019BACKLASH ACCELERATION- 37 -

9.BACKLASH ACCELERATION9.1B-65264EN/01ABOUT BACKLASH ACCELERATIONSThe shape of backlash acceleration is simple as following figure. Thisacceleration value is added to VCMD for velocity loop integration andit helps the movement of the integration at its reverse point. By thiseffect, position error at the reverse point is reduced.(Standard Backlash Acceleration)Backlash Acceleration AmountNo.2048No.2071VCMDBasically you only have to think two parameters. No.2071 means timewidth and its default value is 20. Normally you don't have to changethis value. No.2048 means amount of backlash acceleration. Please set100 at the start of tuning and change this value by watching circularshape.- 38 -

9.BACKLASH ACCELERATIONB-65264EN/019.2INITIAL PARAMETERS FOR BACKLASH ACCELERATIONBefore you start to tune backlash acceleration, please set the initialparameters as follows.[Fundamental Parameters for Backlash Acceleration]Parameter No.16i/18i/21i/0i18512003 #52006 #02009 #72009 #62223 #72015 #62146204820822071Standard setting valuemore than 110/11110501005 (1µm detection)50 (0.1µm detection)20DescriptionBacklash compensationEnables backlash acceleration0 : Semi-close system 1 : Full-close systemBacklash acceleration stopBacklash acceleration only at cutting feed (FF)Backlash acceleration only at cutting feed (G01)two-stage backlash accelerationStage-2 backlash acceleration end timerBacklash acceleration amountStop distance (detection unit)Backlash acceleration timeYou can set almost all of these parameters from parameter window.- 39 -

9.BACKLASH ACCELERATIONB-65264EN/019.3TUNING OF BACKLASH ACCELERATION9.3.1Initial StateFollowing figure shows initial state of circular shape with no servotuning. You can see about 2µm quadrant protrusion at the reversepoint of X axis and Y axis.Following figure shows the result after setting the initial parametersfor backlash acceleration in Section 9.2. By setting the initialparameters quadrant protrusion is suppressed well.- 40 -

9.BACKLASH ACCELERATIONB-65264EN/019.3.2When to Stop TuningAt first we have to know when to stop tuning of backlash accelerationamount.Following figure shows the result of No.2048 200. This figure shows"under cut" is occurred at reverse points. We have to avoid "undercut" because this cirtainly makes scratch on a surface of cutting work.So we have to stop tuning No.2048 just before "under cut" appears.By enlarging the error at the reverse point it becomes easier to judge if"under cut" occurs or not.By pushing "z" the e

FANUC AC SERVO MOTOR @*s series FANUC AC SERVO MOTOR @* series FANUC AC SERVO MOTOR #*s series SERVO TUNING PROCEDURE (BASIC) B-65264EN/01 No part of this manual may be reproduced in any form. All specifications and designs are subject to change without notice.