ACS螺距补偿手册

Dynamic Error CompensationApplication NoteAugust2014Document Revision:1.0Dynamic Error CompensationRelease Date:August2014Copyright©ACS Motion Control Ltd.2014.All rights reserved.Changes are periodically made to the information in this document.Changes are published as release notes and later incorporated into revisions of this document.No part of this document may be reproduced in any form without prior written permission from ACS Motion Control.TrademarksACS Motion Control,SPiiPlus,PEG,MARK,ServoBoost,MotionBoost,NetworkBoost and NanoPWN are trademarks of ACS Motion Control Ltd.Windows and Visual Basic are trademarks of Microsoft Corporation.EtherCAT is registered trademark and patented technology,licensed by Beckhoff Automation GmbH,Germany.Any other companies and product names mentioned herein may be the trademarks of their respective owners.support@sales@NoticeThe information in this document is deemed to be correct at the time of publishing.ACS Motion Control reserves the right to change specifications without notice.ACS Motion Control is not responsible for incidental,consequential,or special damages of any kind in connection with using this document.Revision HistoryDate Revision DescriptionAugust201401First releaseConventions Used in this GuideText FormatsFormat DescriptionBold Names of GUI objects or commands.BOLD+UPPERCASE ACSPL+variables and commands Monospace+grey background Code example.Italic Names of other documents.Blue Web pages,and e-mail addresses.[ ]In commands indicates optional item(s)|In commands indicates either/or items Flagged TextNote-includes additional information or programming tips.Caution-describes a condition that may result in damage to equipment.Warning-describes a condition that may result in serious bodily injury or death.Model-highlights a specification,procedure,condition,or statement that depends on theproduct model.Advanced-indicates a topic for advanced users.Table of Content1.Introduction52.ACSPL+functions for Implementing Dynamic Error Compensation52.1Connect52.2Depends63.Constructing a Correction Map64.Types of Dynamic Error Compensation74.1One Dimensional Dynamic Error Compensation74.1.1Related Functions84.2Two Dimensional Dynamic Error Compensation84.2.1Axis Position Collection at Fixed Intervals84.2.1.1Axis084.2.1.2Axis194.2.2Axis Position Collection Using Arbitrary Network of Points94.2.2.1Axis094.2.2.2Axis1104.2.3Related Functions105.Three Dimensional Dynamic Error Compensation116.Initializing APOS and RPOS After Homing Program127.Initializing APOS and RPOS After KILL or DISABLE138.Dynamic Error Compensation for Gantry System138.1Error Compensation for Flexible Stages148.2Error Compensation for Stiff Stages151. Introduction1.IntroductionMotion systems are influenced by mechanical imperfections resulting from manufacturing tolerances.You can measure and map the errors induced by these mechanical imperfections using external measurement devices such as a laser interferometer.These errors can then be corrected by changing the motion profile on the fly according to a correction map.The ability to change the motion profile according to a preset correction map is called Dynamic Error Compensation,and it can be applied to SPiiPlusNT controllers.A correction map may be constructed using the following methods:●by measuring the correct position of the motor at fixed intervals.●by measuring the correct position of the motor at an arbitrary network of encoder readings.By using certain ACSPL+commands,you can then apply the correction map to manipulate the axis motion profile. 2.ACSPL+functions for Implementing Dynamic Error Compensation Dynamic Error Compensation is implemented through two ACSPL+functions:●Connect●Depends2.1ConnectConnect is used to implement Dynamic Error Compensation,Inverse Kinematics,Axes Transformation and more. Connect modifies axis profile generation by defining a relation(any function)between several variables:●Axis Position(APOS-virtual axis position)●Reference Position(RPOS–desired axis position)●Other variablesBy default,APOS and RPOS are equal.Once defined,Connect remains active until:●A new connect function is defined●The controller is shutdown●HWRESET/RESET commands are sent●MFLAGS(axis).#DEFCON flag is raisedConnect cannot be executed while the default connection bit of variable MFLAGS(axis).#DEFCONis raised.ExampleConnect RPOS(0)=(APOS(0)+APOS(1)+APOS(2))/3+1+AIN(1)Reference to axis zero is a function of APOS(0),APOS(1),APOS(2),AIN(1)and a constant value.Connect calculates the average between APOS(0),APOS(1)and APOS(2)+constant value of1and the value of the first analog input AIN(1).Figure 0:SPiiPlus Profile Generation MechanismConnect requires extra steps when the axis performs homing or when the motion was terminated by KILL or DISABLE commands.2.2DependsDepends specifies a logical dependence between a motor and axes.By default,the motor is assigned to its axis.Depends always follows Connect .ExampleDepends 0,(0,1,2)Explanation:RPOS of axis 0depends on APOS of axes 0,1and 2.3.Constructing a Correction MapThe correction map may be constructed in two ways:1.Actual values of axis positions are collected using axis commands (APOS)at fixedintervals.3. Constructing a Correction MapAxis CommandCorrect ValueEncoder Error-10100-53-805-558-31012-2Table 1:Correction Map Using Fixed Intervals 2.Actual values of axis positions are collected using an arbitrary network of encoder readings.Axis CommandCorrect ValueEncoder Error-10-122-3-3068-21214-21417-3Table 2:Correction Map Using Arbitrary Readings 4.Types of Dynamic Error CompensationDynamic error compensation may be a function of:●a single axis -one dimensional ●two axes –two dimensional ●three axes –three dimensional4.1One Dimensional Dynamic Error CompensationUse one dimensional dynamic error correction when the position error of the axis depends on the position of a single axis (usually the same axis).4.1.1Related FunctionsYou can also use the following functions for error compensation.The user should use the functions that best suit his application.Correction Map Correction Map Construction InterpolationType ExtrapolationMAP Base +fixed interval Linear Maximal/minimal values of encoder error are used for encoder readings outside the range defined in Correction Map.MAPB Base +fixed interval B-spline MAPN Network of points Linear MAPNB Network of points B-splineMAPS Base +fixed interval Catmull-Rom spline According to spline calculation.MAPNS Network of pointsCatmull-Rom splineExampleUse the following code to create a correction map using fixed intervals (see Table 1):GLOBAL REAL BASE,INCREMENT,CORRECTION_MAP (5)BASE =-10INCREMENT =5CORRECTION_MAP(0)=0;CORRECTION_MAP(1)=-8;CORRECTION_MAP(2)=-5;CORRECTION_MAP(3)=-3;CORRECTION_MAP(4)=-2MFLAGS(0).#DEFCON =0CONNECT RPOS(0)=APOS(0)+MAP(APOS(0),CORRECTION_MAP,BASE,INCREMENT)DEPENDS 0,0STOPExampleUse the following code to create a correction map using arbitrary readings (see Table 2):GLOBAL REAL AXIS_COMMAND (5),CORRECTION_MAP(5)AXIS_COMMAND(0)=-10;AXIS_COMMAND (1)=-3;AXIS_COMMAND (2)=6;AXIS_COMMAND (3)=12;AXIS_COMMAND (4)=14CORRECTION_MAP(0)=2;CORRECTION_MAP(1)=0;CORRECTION_MAP(2)=-2;CORRECTION_MAP(3)=-2;CORRECTION_MAP(4)=-3MFLAGS(0).#DEFCON =0CONNECT RPOS(0)=APOS(0)+MAPN(APOS(0),AXIS_COMMAND,CORRECTION_MAP)DEPENDS 0,0STOP4.2Two Dimensional Dynamic Error CompensationUse two dimensional dynamic error correction when the position errors of the axis depend on the axis's position and the position of another axis.4.2.1Axis Position Collection at Fixed Intervals4.2.1.1Axis0The correct values of axis0positions are collected in a network defined by axis0commands with a fixed interval0between them.The point with smallest value is called base0.For each value of an axis0command,position errors of axis0are collected for several axis1commands.Axis1commands are chosen with a fixed interval1starting from base1.Axis1 CommandAxis0Command-10-505Axis0ActualEncoder0ErrorAxis0ActualEncoder0ErrorAxis0ActualEncoder0ErrorAxis0ActualEncoder0Error20-100-501-14130-122-83005040-133-3-2-116-1Table3:Two Dimensional Correction Map-Axis0(Fixed Intervals)4.2.1.2Axis1Correct values of axis1position are collected in a network defined by axis1commands with a fixed interval1 between them.The point with smallest value is called base1.For each value of an axis1command,position errors of axis1are collected for several axis0commands.Axis0commands are chosen with a fixed interval0starting from base0.Axis1/Auxilliary CommandAxis0Command-10-505Axis1ActualEncoder1ErrorAxis1ActualEncoder1ErrorAxis1ActualEncoder1ErrorAxis1ActualEncoder1Error2020021-122-222-2 3031-130031-132-2 4040041-1391400 Table4:Two Dimensional Correction Map-Axis1(Fixed Intervals)4.2.2Axis Position Collection Using Arbitrary Network of Points4.2.2.1Axis0Correct values of axis0position are collected at arbitrary network of points(encoder readings).Axis1 CommandAxis0Command-10-803Axis0ActualEncoder0ErrorAxis0ActualEncoder0ErrorAxis0ActualEncoder0ErrorAxis0ActualEncoder0Error20-100-5-31-130 25-122-91004-1 40-133-7-1-114-1 Table5:Two Dimensional Correction Map-Axis0(Arbitary Points)4.2.2.2Axis1Correct values of axis1position are collected at arbitrary network of points(axis0and axis1commands).Axis1 CommandAxis0Command-10-803Axis1ActualEncoder1ErrorAxis1ActualEncoder1ErrorAxis1ActualEncoder1ErrorAxis1ActualEncoder1Error2020020022-221-1 2526-125026-127-2 40400400391391 Table6:Two Dimensional Correction Map-Axis1(Arbitary Points)4.2.3Related FunctionsYou can also use the following functions for error compensation.The user should use the functions that best suit his application.Item Correction MapConstructionInterpolation Type ExtrapolationMAP2Base0+fixed interval0Base1+fixed interval1Linear Maximal/minimal values of Correct readingsare used for Encoder readings outside therange defined in Correction Map.MAP2B Base0+fixed interval0Base1+fixed interval1B-splineMAP2N Network of points LinearMAP2NB Network of points B-splineMAP2S Base0+fixed interval0Base1+fixed interval1Catmull-Rom spline According to spline calculation.MAP2NS Network of points Catmull-Rom splineExampleFollowing code should be implemented in order to create a correction map as described in Tables2.1.b and2.2.b:GLOBAL REAL BASE0,BASE1,INCREMENT0,INCREMENT1,CORRECTION_MAP0(3)(4),CORRECTION_MAP1(3)(4)BASE0=-10INCREMENT0=5BASE1=20INCREMENT1=10!Correction map for axis0CORRECTION_MAP0(0)(0)=0;CORRECTION_MAP0(0)(1)=0;CORRECTION_MAP0(0)(2)=-1;CORRECTION_MAP0(0)(3)=1CORRECTION_MAP0(1)(0)=2;CORRECTION_MAP0(1)(1)=3;CORRECTION_MAP0(1)(2)=0;CORRECTION_MAP0(1)(3)=0CORRECTION_MAP0(2)(0)=3;CORRECTION_MAP0(2)(1)=-1;CORRECTION_MAP0(2)(2)=1;CORRECTION_MAP0(2)(3)=-1!Correction map for axis1CORRECTION_MAP1(0)(0)=0;CORRECTION_MAP1(0)(1)=-1;CORRECTION_MAP1(0)(2)=-2;CORRECTION_MAP1(0)(3)=-2CORRECTION_MAP1(1)(0)=-1;CORRECTION_MAP1(1)(1)=0;CORRECTION_MAP1(1)(2)=-1;CORRECTION_MAP1(1)(3)=-2CORRECTION_MAP1(2)(0)=0;CORRECTION_MAP1(2)(1)=-1;CORRECTION_MAP1(2)(2)=1;CORRECTION_MAP1(2)(3)=0MFLAGS(0).#DEFCON=0CONNECT RPOS(0)=APOS(0)+MAP2(APOS(0),APOS(1),CORRECTION_MAP0,BASE0,INCREMENT0,BASE1,INCREMENT1)DEPENDS0,(0,1)MFLAGS(1).#DEFCON=0CONNECT RPOS(1)=APOS(1)+MAP2(APOS(0),APOS(1),CORRECTION_MAP1,BASE0,INCREMENT0,BASE1,INCREMENT1)DEPENDS1,(0,1)STOPExampleFollowing code should be implemented in order to create a correction map as described in Table 2.2.b:GLOBAL REAL AXIS0_COMMAND (4),AXIS1_COMMAND (3),CORRECTION_MAP0(3)(4),CORRECTION_MAP1(3)(4)!Correction map for axis0AXIS0_COMMAND (0)=-10;AXIS0_COMMAND(1)=-8;AXIS0_COMMAND(2)=0;AXIS0_COMMAND(3)=3AXIS1_COMMAND (0)=20;AXIS1_COMMAND(1)=25;AXIS1_COMMAND(2)=40CORRECTION_MAP0(0)(0)=0;CORRECTION_MAP0(0)(1)=-3;CORRECTION_MAP0(0)(2)=-1;CORRECTION_MAP0(0)(3)=0CORRECTION_MAP0(1)(0)=2;CORRECTION_MAP0(1)(1)=1;CORRECTION_MAP0(1)(2)=0;CORRECTION_MAP0(1)(3)=-1CORRECTION_MAP0(2)(0)=3;CORRECTION_MAP0(2)(1)=-1;CORRECTION_MAP0(2)(2)=1;CORRECTION_MAP0(2)(3)=-1!Correction map for axis1CORRECTION_MAP1(0)(0)=0;CORRECTION_MAP1(0)(1)=0;CORRECTION_MAP1(0)(2)=-2;CORRECTION_MAP1(0)(3)=-1CORRECTION_MAP1(1)(0)=-1;CORRECTION_MAP1(1)(1)=0;CORRECTION_MAP1(1)(2)=-1;CORRECTION_MAP1(1)(3)=-2CORRECTION_MAP1(2)(0)=0;CORRECTION_MAP1(2)(1)=0;CORRECTION_MAP1(2)(2)=1;CORRECTION_MAP1(2)(3)=1MFLAGS(0).#DEFCON =0CONNECT RPOS(0)=APOS(0)+MAP2N(APOS(0),APOS(1),CORRECTION_MAP0,AXIS0_COMMAND,AXIS1_COMMAND)DEPENDS 0,(0,1)MFLAGS(1).#DEFCON =0CONNECT RPOS(1)=APOS(1)+MAP2N(APOS(0),APOS(1),CORRECTION_MAP1,AXIS0_COMMAND,AXIS1_COMMAND)DEPENDS 1,(0,1)STOP5.Three Dimensional Dynamic Error CompensationUse three dimensional dynamic error correction when the position errors of the axis depend on it’s own position and a position of two other axes.Correction is by interpolation between a set of two dimensional correction maps.Axis1CommandAxis0Command-10-505Axis 2Command =02000-11302300403-21-1Axis 2Command =1203-1023032-11404-1-10Axis 2Command =2202-1-11302-2-11401-10-1Axis 2Command =320101-130101-1401-2Table 7:Three Dimensional Correction Map -Axis0,Axis1,Axis25. Three Dimensional Dynamic Error CompensationGLOBAL REAL CORRECTION_MAP_1(3)(4),CORRECTION_MAP_2(3)(4),CORRECTION_MAP_3(3)(4),CORRECTION_MAP_4(3)(4)GLOBAL REAL BASE0,INCREMENT0,BASE1,INCREMENT1,BASE2,INCREMENT2CORRECTION_MAP_1(0)(0)=0;CORRECTION_MAP_1(0)(1)=0;CORRECTION_MAP_1(0)(2)=-1;CORRECTION_MAP_1(0)(3)=1CORRECTION_MAP_1(1)(0)=2;CORRECTION_MAP_1(1)(1)=3;CORRECTION_MAP_1(1)(2)=0;CORRECTION_MAP_1(1)(3)=0CORRECTION_MAP_1(2)(0)=3;CORRECTION_MAP_1(2)(1)=-2;CORRECTION_MAP_1(2)(2)=1;CORRECTION_MAP_1(2)(3)=-1CORRECTION_MAP_2(0)(0)=3;CORRECTION_MAP_2(0)(1)=-1;CORRECTION_MAP_2(0)(2)=0;CORRECTION_MAP_2(0)(3)=2CORRECTION_MAP_2(1)(0)=3;CORRECTION_MAP_2(1)(1)=2;CORRECTION_MAP_2(1)(2)=-1;CORRECTION_MAP_2(1)(3)=1CORRECTION_MAP_2(2)(0)=4;CORRECTION_MAP_2(2)(1)=-1;CORRECTION_MAP_2(2)(2)=-1;CORRECTION_MAP_2(2)(3)=0CORRECTION_MAP_3(0)(0)=2;CORRECTION_MAP_3(0)(1)=-1;CORRECTION_MAP_3(0)(2)=-1;CORRECTION_MAP_3(0)(3)=1CORRECTION_MAP_3(1)(0)=2;CORRECTION_MAP_3(1)(1)=-2;CORRECTION_MAP_3(1)(2)=-1;CORRECTION_MAP_3(1)(3)=1CORRECTION_MAP_3(2)(0)=1;CORRECTION_MAP_3(2)(1)=-1;CORRECTION_MAP_3(2)(2)=0;CORRECTION_MAP_3(2)(3)=-1CORRECTION_MAP_4(0)(0)=1;CORRECTION_MAP_4(0)(1)=0;CORRECTION_MAP_4(0)(2)=1;CORRECTION_MAP_4(0)(3)=-1CORRECTION_MAP_4(1)(0)=1;CORRECTION_MAP_4(1)(1)=0;CORRECTION_MAP_4(1)(2)=1;CORRECTION_MAP_4(1)(3)=-1CORRECTION_MAP_4(2)(0)=1;CORRECTION_MAP_4(2)(1)=0;CORRECTION_MAP_4(2)(2)=0;CORRECTION_MAP_4(2)(3)=-2BASE0=-10;INCREMENT0=5;BASE1=20;INCREMENT1=10;BASE2=0;INCREMENT2=1MFLAGS(2).17=0connect RPOS(2)=APOS(2)+(MAP2(APOS(0), APOS(1),CORRECTION_MAP_1,BASE0,INCREMENT0,BASE1,INCREMENT1)*(1.0-ABS(BASE2-APOS(2))/INCREMENT2)+MAP2(APOS(0), APOS(1),CORRECTION_MAP_2,BASE0,INCREMENT0,BASE1,INCREMENT1)*(ABS(BASE2-APOS(2))/INCREMENT2))*((APOS(2)–BASE2)/INCREMENT2< 1.0&(APOS(2)–BASE2)>0)+(MAP2(APOS(0), APOS(1),CORRECTION_MAP_2,BASE0,INCREMENT0,BASE1,INCREMENT1)*(1.0-ABS(BASE2+INCREMENT2 -APOS(2))/INCREMENT2)+MAP2(APOS(0), APOS(1),CORRECTION_MAP_3,BASE0,INCREMENT0,BASE1,INCREMENT1)*(ABS(BASE2+INCREMENT2 -APOS(2))/INCREMENT2))*((APOS(2)-BASE2-INCREMENT2)/INCREMENT2< 1.0&(APOS(2)-BASE2-INCREMENT2)>0)+(MAP2(APOS(0), APOS(1),CORRECTION_MAP_3,BASE0,INCREMENT0,BASE1,INCREMENT1)*(1.0-ABS(BASE2+INCREMENT2*2-APOS(2))/INCREMENT2)+MAP2(APOS(0), APOS(1),CORRECTION_MAP_4,BASE0,INCREMENT0,BASE1,INCREMENT1)*(ABS(BASE2+INCREMENT2*2-APOS(2))/INCREMENT2))*((APOS(2)-BASE2-INCREMENT2*2)/INCREMENT2< 1.0&(APOS(2)-BASE2-INCREMENT2*2)>0)DEPENDS0,(0,1,2)STOP6.Initializing APOS and RPOS After Homing ProgramAfter the controller powered up,the feedback position is zero.A homing program moves the axis to a known absolute position(as index position)and sets that position as zero(or any other value). If an error is present at the position where homing ends,value of APOS and FPOS should be updated.In this case,write separate SET commands for RPOS and for APOS.ExampleWhen homing is finished,reset the FPOS value according to the correction map:GLOBAL REAL BASE,INCREMENT,CORRECTION_MAP(5)BASE=1INCREMENT=1CORRECTION_MAP(0)=0.5; CORRECTION_MAP(1)=0.1;CORRECTION_MAP(2)=0;CORRECTION_MAP(3)=0.4;CORRECTION_MAP(4)=0.5STOPRUN_AFTER_HOMING:HALT(0)TILL^MST(0).#MOVESET FPOS(0)=BASEREAL NewAPOSNewAPOS=BASEMFLAGS(0).#DEFCON=1ENABLE(0)PTP/E(0),NewAPOS+MAP(NewAPOS,CORRECTION_MAP,BASE,INCREMENT)MFLAGS(0).#DEFCON=0CONNECT RPOS(0)=APOS(0)+MAP(APOS(0),CORRECTION_MAP,BASE,INCREMENT)DEPENDS0,0SET APOS(0)=NewAPOSSTOP7.Initializing APOS and RPOS After KILL or DISABLEThe APOS variable is no longer updated after KILL or DISABLE commands.Therefore,after these commands,a special procedure needs to be implemented to resume motion with Dynamic Error Compensation.This procedure involves:1.Initiating motion(without Dynamic Error Compensation)to the nearest correction position(a point in the cor-rection array).2.Resetting APOS and RPOS according to the Correction Map.3.Resuming motion with Dynamic Error Compensation.ExampleAdd the following code to execute Recovery after a KILL or DISABLE command(this example uses the correction map in Table1):RECOVER_AXIS:HALT(0)!Stop the axisTILL^MST(0).#MOVE!Wait till motion endsREAL NewAPOSNewAPOS=RPOS(0)!NewAPOS stores my current RPOS positionENABLE(0)MFLAGS(0).#DEFCON=1 !Set default connectionPTP/E(0),NewAPOS+MAP(NewAPOS,CORRECTION_MAP,BASE,INCREMENT)!Moves to nearest correction positionMFLAGS(0).#DEFCON=0 !Enable non-default Connect expressionCONNECT RPOS(0)=APOS(0)+MAP(APOS(0),CORRECTION_MAP,BASE,INCREMENT)!Define the Connect expressionDEPENDS0,0 !Define the Depends commandSET APOS(0)=NewAPOSSTOP8.Dynamic Error Compensation for Gantry SystemGantry systems consist of two motors whose feedback(FPOS(0)and FPOS(1))are transformed to new feedback by setting MFLAGS(0).25=1,MFLAGS(1).25=1.If,after setting these flags,FPOS(0)is set as Gantry0and FPOS(1)as Gantry1,then:1.Gantry0=(FPOS(0)+FPOS(1))/2–the mean value of the motor’s position.This axis is frequently referred to aslinear.2.Gantry1=FPOS(1)-FPOS(0)–the difference between the first and the second motors'positions.This axis isfrequently referred to as yaw.Generally,gantry pairs for most ACS products,are(0,2),(1,3)or(2,3).In the following example,Gantry0and Gantry1represent the FPOS0and FPOs1variables afterMFLAGS has been set.FPOS0and FPOS1are raw feedback readings before they are changed by MFLAGS.There are two compensation scenarios:●For mechanically stiff gantry stages–Gantry0axis is corrected for accuracy improvement and Gantry1axis iscorrected for reducing mechanical stress(motor currents).●For mechanically flexible gantry stages–accuracy improvement of both Gantry0and Gantry1axes.8.1Error Compensation for Flexible StagesPerform dynamic error compensation for both gantry feedback.To construct the correction tables for two gantry axes:1.Tune both gantry axes.2.Set the MFLAGS(0).25and MFLAGS(1).25bits.3.Move the gantry system(Gantry0)along points of interest where data for error correction should be collected.4.At each point of interest,collect the actual values of the motors'positions using an external device.5.Calculate the gantry feedback(Gantry0and Gantry1)at each point according to the equation in Section8..6.Calculate the gantry axes errors at each point.Gantry0should follow the command.Gantry1should follow zerocommand for the whole range.Table8:Correction Map for Flexible StagesGantry0Command Axis0Actual Axis1Actual Gantry0Calculated Gantry1Calculated 000001001019910022002022002012300300302301-24004023984004Table9:Correction Map for Flexible StagesGantry0Gantry0Error Gantry1ErrorCommand0001000-2200-1-2300-124000-4ExampleImplementation of correction map for gantry stage in Table9:GLOBAL REAL COMMAND0(5),CORRECTION_MAP0(5),CORRECTION_MAP1(5)COMMAND0(0)=0;COMMAND0(1)=100;COMMAND0(2)=200;COMMAND0(3)=300;COMMAND0(4)=400;CORRECTION_MAP0(0)=0;CORRECTION_MAP0(1)=0;CORRECTION_MAP0(2)=-1;CORRECTION_MAP0(3)=-1;CORRECTION_MAP0(4)=0;CORRECTION_MAP1(0)=0;CORRECTION_MAP1(1)=-2;CORRECTION_MAP1(2)=-2;CORRECTION_MAP1(3)=2;CORRECTION_MAP1(4)=-4;MFLAGS(0).#DEFCON=0CONNECT RPOS(0)=APOS(0)+MAPN(APOS(0),COMMAND0,CORRECTION_MAP0)DEPENDS0,0SET APOS(0)=CORRECTION_MAP0(0)MFLAGS(1).#DEFCON=0CONNECT RPOS(1)=MAPN(APOS(0),COMMAND0,CORRECTION_MAP1)DEPENDS1,0SET APOS(1)=CORRECTION_MAP1(0)STOP8.2Error Compensation for Stiff StagesWhen running a stiff stage,mechanics may not allow achieving Gantry1axis zero error.An attempt to zero the error results in excessive motor currents.In this case,the command to the Gantry1axis should be“close”to its relieved position.To construct the correction tables for two gantry axes:1.Tune the linear(Gantry0)axis.2.Set the MFLAGS(0).25and MFLAGS(1).25bits.3.Reduce the Gantry1loop gain to avoid current saturation(set SLVKI(1)=0,SLPKP(1)=0.1).4.Move the gantry system(Gantry0)along points of interest where data for error correction should be collected.5.At each point of interest,collect the actual values of the motors'positions using an external device.6.Calculate the gantry feedback(Gantry0and Gantry1)at each point according to the equation in Section8..7.Calculate the gantry axes errors at each point.Gantry0should follow the command.Gantry1should follow zerocommand for the whole range.Table10:Correction Map for Stiff StagesGantry0Command Axis0Actual Axis1Actual Gantry0Calculated Gantry1Calculated 000001001019910022002022002012300300302301-24004023984004Table11:Correction Map for Stiff StagesGantry0Gantry0Error Gantry1ErrorCommand0001000-2200-1-2300-124000-4Commanding the gantry axis to be as close as possible to its relieved position will reduce the excessive current,but will not maintain zero error of this axis.You can increase the Gantry1loop gain in order to improve disturbance rejection.ExampleImplementation of correction map for gantry stage in Table10:GLOBAL REAL COMMAND0(5),CORRECTION_MAP0(5),CORRECTION_MAP1(5)COMMAND0(0)=0;COMMAND0(1)=100;COMMAND0(2)=200; COMMAND0(3)=300;COMMAND0(4)=400;CORRECTION_MAP0(0)=0;CORRECTION_MAP0(1)=0; CORRECTION_MAP0(2)=-1; CORRECTION_MAP0(3)=-1;CORRECTION_MAP0(4)=0;CORRECTION_MAP1(0)=0;CORRECTION_MAP1(1)=-2;CORRECTION_MAP1(2)=-2; CORRECTION_MAP1(3)=2;CORRECTION_MAP1(4)=-4;MFLAGS(0).#DEFCON=0connect RPOS(0)=APOS(0)+MAPN(APOS(0),COMMAND0,CORRECTION_MAP0)depends0,0set APOS(0)=CORRECTION_MAP0(0)MFLAGS(1).#DEFCON=0CONNECT RPOS(1)=MAPN(APOS(0),COMMAND0,CORRECTION_MAP1)DEPENDS1,0SET APOS(1)=CORRECTION_MAP1(0)STOP1Hataasia StRamat Gabriel Industrial ParkMigdal Ha’Emek2307037IsraelT:+97246546440F:+97246546443。