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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt 1 6. Tuning of a position controller 6.1 Evaluation of the position control 6.2 Components of a industrial position controller 6.3 Set-up and tuning of a position control

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Evaluation of a position control t s t s 1 2 t s Overshooting, undershooting, Oscillation Pull–in error External disturbance Static positioning error t s Following error Motor erreicht Endposition, zeigt aber grössere Abweichung während der Uebergangsphase. 3 Overshooting (1), undershooting (2), Oscillation (3)

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Industrial position controller FF Acceleration (Feed Forward Acceleration) FF Acceleration (Feed Forward Acceleration) Current Offset (Force Offset) Current Offset (Force Offset) FF Deceleration (Feed Forward Deceleration FF Deceleration (Feed Forward Deceleration FF Friction (Feed Forward Friction) FF Friction (Feed Forward Friction) Filter P D I Current Maximal Current (Maximal Force) Curve 1 m s +m Load m s Masse Motor m Load Masse Last F v s a Overview of an industrial position controller. Separation in different blocks: a) limitation of requirements b) Applikation knowledge c) PID-controller d) Mechanical components b a a b b b d c c c d d actual-Position cfcf Required position

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Set-up and tuning 0.) Configuration and Default-values 1.) Generation of the profiles, limit v and a max (filter) avoid overloading 2.) Calculation of the Feedforward-Parameter application knowledge 3.) Tuning of the PID-Parameter (if needed) Example Horizontal stroke 140 mm mass of X-axes 4 kg friction ? Because the demonstration unit is not secured power will be reduced by 50 % !

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Configuration Selection of motor Controller-Parameter Selection of max a and v filter Profiles

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Set-up of the a v Filter (1) FF Acceleration (Feed Forward Acceleration) Current Offset (Force Offset) FF Deceleration (Feed Forward Deceleration FF Friction (Feed Forward Friction) Required position Filter P D I Current Maximal Current (Maximal Force) Curve 1 m s +m Load m s Masse Motor m Load Masse Last F v s a b a a b b b d c c c d d actual-Position cfcf Overview of an industrial position controller. Separation in different blocks: a) limitation of requirements b) Applikation knowledge c) PID-controller d) Mechanical components

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Set-up of the a v Filter (2) Control parameterP=1,5D= 5I=0 FeedforwardFF friction = 0FF accel =0FF dec =0 Filtera max = 300 m/s 2 v max =5 m/s Anforderung an den Motor sind zu gross! Der Antrieb kann der Sollkurve nicht folgen und zeigt ein unkontrolliertes Verhalten. No a v limitation.

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Set-up of the a v Filter (3) Control parameterP=1,5D= 5I=0 FeedforwardFF friction = 0FF accel =0FF dec =0 Filtera max = 24 m/s 2 v max =1,3 m/s Calculation of the av filter based on the data sheet - v max = 1.3 m/s - a max aus a:= F max / m = 120N / 5kg Figures from the datasheet about v max und F max are based on v=0 m/s !

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Set-up of the a v Filter (4) Control parameterP=1,5D= 5I=0 FeedforwardFF friction = 0FF accel =0FF dec =0 Filtera max = 14 m/s 2 v max =0.7 m/s Calculation of the filter parameter with LinMot Designer Still some following errors during acceleration and deceleration Feedforward Parameter

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt set-up of the Feedforward-Parameter (1) FF Acceleration (Feed Forward Acceleration) FF Acceleration (Feed Forward Acceleration) Current Offset (Force Offset) Current Offset (Force Offset) FF Deceleration (Feed Forward Deceleration FF Deceleration (Feed Forward Deceleration FF Friction (Feed Forward Friction) FF Friction (Feed Forward Friction) Filter P D I Current Maximal Current (Maximal Force) Curve 1 m s +m Load m s Masse Motor m Load Masse Last F v s a b a a b b b d c c c d d actual-Position cfcf Overview of an industrial position controller. Separation in different blocks: a) limitation of requirements b) Applikation knowledge c) PID-controller d) Mechanical components Required position

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt set-up of the Feedforward-Parameter (2) Control parameterP=1,5D= 5I=0 FeedforwardFF friction = 0FF accel =125FF dec =125 Vorfiltera max = 14 m/s 2 v max =0.7 m/s Feedforward parameters calculated based on the formula (or use the tool which is integrated in LinMot Talk): FF acc/dec := Masse/Motorkraftkonstante := 5000g / 40N/A = 125 Following error during acceleration ? Friczton?

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt set-up of the Feedforward-Parameter (3) FF Acceleration (Feed Forward Acceleration) FF Acceleration (Feed Forward Acceleration) Current Offset (Force Offset) Current Offset (Force Offset) FF Deceleration (Feed Forward Deceleration FF Deceleration (Feed Forward Deceleration FF Friction (Feed Forward Friction) FF Friction (Feed Forward Friction) Filter P D I Current Maximal Current (Maximal Force) Curve 1 m s +m Load m s Masse Motor m Load Masse Last F v s a b a a b b b d c c c d d Ist-Position cfcf F:= c f * I c f Motor force constant [N/A] Overview of an industrial position controller. Separation in different blocks: a) limitation of requirements b) Applikation knowledge c) PID-controller d) Mechanical components Required position

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt set-up of the Feedforward-Parameter (4) Control parameterP=0D= 0I=0 FeedforwardFF friction = 0FF accel =125FF dec =125 Filtera max = 14 m/s 2 v max =0.7 m/s Hint: Set P and D-factors to 0. Make a step movement and increase the feedforward FF friction parameter until curves fit Control parameterP=0D= 0I=0 FeedforwardFF friction = 0.42 AFF accel =125FF dec =125 Filtera max = 14 m/s 2 v max =0.7 m/s now the friction can be calculated backward: FF friction =: c f * FF friction = 40N/A * 0.42A = 16,8 N

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt set-up of the Feedforward-Parameter (5) Control parameterP=1.5D= 5I=0 FeedforwardFF friction = 0.42 AFF accel =125FF dec =125 Filtera max = 14 m/s 2 v max =0.7 m/s Moved mass can change during the movement cycle (gripper picks and places payload). In most application not a real problem In critical application it may be neccessary to adapt the parameters on the fly Optimized to : Mass:= 5 kg Increased mass: 5 kg + 1 kg = 6 Kg

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Tuning of the PID-Parameter (1) Control parameterP=1.5D= 5I=0 FeedforwardFF friction = 0.42 AFF accel =125FF dec =125 Vorfiltera max = 14 m/s 2 v max =0.7 m/s Higher P- and D-factors increase the performance regarding external disturbances. Control parameterP=6D= 20I=0 FeedforwardFF friction = 0.42 AFF accel =125FF dec =125 Vorfiltera max = 14 m/s 2 v max =0.7 m/s External disturbtion

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Tuning of the PID-Parameter (2) Control parameterP=6D= 20I=0 FeedforwardFF friction = 0.42 AFF accel =125FF dec =125 Filtera max = 14 m/s 2 v max =0.7 m/s Control parameterP=3D= 10I=0 FeedforwardFF friction = 0.42 AFF accel =125FF dec =125 Filtera max = 14 m/s 2 v max =0.7 m/s Control parameterP=6D= 20I=50 FeedforwardFF friction = 0.42 AFF accel =125FF dec =125 Filtera max = 14 m/s 2 v max =0.7 m/s Static positioning errors can be reduced with higher P-Factors.... Static positioning errors can be eliminated with the I- factor. (use I factor only if needed because I-factor may make the system instabel.

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Copyright NTI AG / LinMot Seminar2002_Reglertuning-V1.0.ppt Tuning / evaluation of current limits Controller parameters P=3D= 10I=50 FeedforwardFF friction = 0.42 AFF accel =125FF dec =125 Filtera max = 14 m/s 2 v max =0.7 m/s Evaluating motors currents we see the 3 A limit is not exceeded. The calculation based in the LinMot Designer shows that the power dissipation requirement is about 6 W and therefore well within the 37 W or 133W (with fan) dissipation capabilities.

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