KUKA supplies kinematic systems for applications, such as welding, adhesive bonding and laser machining.
The customer can also design his own mechanical systems, however. In this case, either KUKA motors with their own gear units or KUKA motor/gear units – MGUs – must be used.
KUKA MGUs are only to be used for driving rotational positioners, i.e. rotation-al kinematic systems. Linear units, Cartesian gantries, etc., can only be de-signed with KUKA motors with their own gear units.
Correct system planning according to the task and correct drive dimensioning in accordance with the load and desired acceleration and velocity are prereq-uisites for error-free operation.
It is always advisable to discuss the project with KUKA Roboter GmbH to ensure that the correct components are selected and or-dered for an external axis system.
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7 Start-up and configuration 7.1 Starting up external axis systems
Overview The steps required for starting up and configuring an external axis system vary, depending on the kinematic system used.
7.1.1 Starting up a KUKA linear unit
Procedure 1. Master KUKA linear unit.2. Only if KSS 5.6 is installed on the robot controller: calibrate the KUKA lin-ear unit if required.
7.1.2 Starting up a KUKA kinematic system
Procedure 1. Check that all hardware components are present and correct, install and connect them.
2. Master KUKA kinematic system.
3. If required: Optimize controller parameters under maximum load, then re-cord TRACE.
4. If required: Optimize acceleration parameters under maximum load, then record TRACE.
5. If required: calibrate KUKA kinematic system.
6. Archive all relevant data, including all trace recordings.
Installation, mastering, optimization and approval of external kine-matic systems for production operation must be performed only as specified in the operating or assembly instructions for the relevant component and only by personnel specially trained for this purpose.
Kinematic system Description
KUKA linear unit (>>> 7.1.1 "Starting up a KUKA linear unit"
Page 51) KUKA kinematic
sys-tem
(>>> 7.1.2 "Starting up a KUKA kinematic sys-tem" Page 51)
Kinematic system with MGU
(>>> 7.1.3 "Starting up a kinematic system with KUKA MGU" Page 52)
Kinematic system with KUKA motor
(>>> 7.1.4 "Starting up a kinematic system with KUKA motor" Page 52)
Further information about calibrating a linear unit is contained in the
“Operating and Programming Instructions for System Integrators”
(only KSS 5.6).
The machine data of the KUKA kinematic system are loaded into the robot controller by KUKA Roboter GmbH during commissioning. The machine data can also be found on the CD supplied.
Further information about calibration of an external kinematic system is contained in the Operating and Programming Instructions for Sys-tem Integrators.
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7.1.3 Starting up a kinematic system with KUKA MGU
Precondition The minimum bending radii and specified cable carrier properties for the cables used must be adhered to.
Procedure 1. Check that all hardware components are present and correct, install and connect them.
2. Check the compatibility of the serial numbers and version numbers of the hardware, software and machine data.
3. Define mastering position and axis ranges / software limit switches of the external axes.
4. Create machine data of the kinematic system, including transformation, if desired or necessary.
5. Load the machine data of the kinematic system into the robot controller.
6. Move the axes in axis-specific mode, set motion directions, check gear ra-tios.
7. Master external axes.
8. Check transformation: move axes in the WORLD coordinate system, check the directions of motion in the WORLD coordinate system.
9. Optimize controller parameters under maximum load, then record TRACE.
10. Optimize acceleration parameters under maximum load, then record TRACE.
11. If required: define reference point and tool base for calibration of the kine-matic system.
12. If required: calibrate kinematic system.
13. Archive all relevant data, including all TRACE recordings.
7.1.4 Starting up a kinematic system with KUKA motor
Precondition The minimum bending radii and specified cable carrier properties for the cables used must be adhered to.
Dimensioning of the gear unit and drive rating by system builder or KUKA Roboter GmbH.
Procedure 1. Check that all hardware components are present and correct, install and connect them.
2. Check the compatibility of the serial numbers and version numbers of the hardware, software and machine data.
3. Define mastering position and axis ranges / software limit switches of the external axes.
4. Create machine data of the kinematic system, including transformation, if Technical data and configuration data for KUKA motor/gear units can be found in the MGU documentation.
Further information about calibration of an external kinematic system is contained in the Operating and Programming Instructions for Sys-tem Integrators.
Technical data and configuration data for KUKA motors can be found in the motor data documentation.
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6. Move the axes in axis-specific mode, set motion directions, check gear ra-tios.
7. Master external axes.
8. Check transformation: move axes in the WORLD coordinate system, check the directions of motion in the WORLD coordinate system.
9. Optimize controller parameters under maximum load, then record TRACE.
10. Optimize acceleration parameters under maximum load, then record TRACE.
11. If required: define reference point and workpiece base for calibration of the kinematic system.
12. If required: calibrate kinematic system.
13. Archive all relevant data, including all TRACE recordings.
7.2 Machine data for external axes
The machine data that have to be configured or adapted when external axes are used are grouped together here.
Transformation data
(>>> 7.3.1 "Machine data for configuration of the transformation" Page 55)
Motor-specific machine data
These configuration data can be found in the motor data.
Load-specific machine data
Using the oscilloscope function, these configuration data can be optimized ac-cording to the maximum load to be moved.
(>>> 7.4 "Optimizing machine data with the oscilloscope" Page 60)
Further information about calibration of an external kinematic system is contained in the Operating and Programming Instructions for Sys-tem Integrators.
Further information about the machine data can be found in the ma-chine data documentation.
Variable Description
$VEL_AXIS_MA Rated motor speed
$SERVOFILE KSD/motor combination
$CURR_MAX Maximum KSD current over 2 s
$CURR_LIM Maximum current setpoint
$KT_MOT KT factor
$KT0_MOT KT0 factor
$CURR_MON Maximum standstill current over 60 s
$RAT_MOT_ENC Motor/resolver ratio
$RAISE_T_MOT Motor run-up time
$BRK_ENERGY_MAX Maximum switch work per braking operation
$BRK_COOL_OFF_C OEFF
Brake cooling factor
$BRK_TORQUE Dynamic braking torque
Variable Description
$G_VEL_PTP Speed controller proportional gain for PTP
$G_VEL_CP Speed controller proportional gain for CP
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Additional machine data
$I_VEL_PTP Integral-action factor speed controller for PTP
$I_VEL_CP Integral-action factor speed controller for CP
$LG_PTP Loop gain of position controller for PTP
$LG_CP Loop gain of position controller for CP
$RAISE_TIME Axis run-up time
$RED_ACC_EMX Reduction factor for path-maintaining braking after EMERGENCY STOP
$DECEL_MB Ramp for path-oriented braking in the case of maximum braking
Variable Description
Variable Description
$AXIS_TYPE Axis type
$MAMES Mastering position
$RAT_MOT_AX Motor/axis gear ratio
$DSECHANNEL Assignment of axes on the DSE
$PMCHANNEL Assignment of axes on the KPS module
$CURR_COM_EX Maximum current setpoint for jog mode
$VEL_CPT1_MA Reduction factor for CP motions in test mode T1
$AXIS_RESO Positioning resolution of the resolver measure-ment system
$RED_VEL_AXC Reduction factor for axial velocity (HOV)
$RED_ACC_AXC Reduction factor for axial acceleration (HOV)
$VEL_AX_JUS Velocity for EMT mastering
$L_EMT_MAX Maximum mastering distance for EMT mastering
$APO_DIS_PTP Maximum approximation distance
$SEQ_CAL Mastering sequence
$DIR_CAL Mastering direction
$BRK_MODE Brake control mode
$BRK_DEL_EX Brake delay time
$IN_POS_MA Positioning window
$SOFTN_END Negative software limit switch
$SOFTP_END Positive software limit switch
$TRAFO_AXIS Number of transformed axes
$AXIS_DIR Direction of rotation of the axes for the transfor-mation
$INC_EXTAX Axis-specific increment
$EX_AX_NUM Number of external axes
$ASR_ERROR Maximum speed deviation of external position encoder/motor encoder
$RAT_EXT_ENC Sensor wheel/sensor ratio
$AX_ENERGY_MAX Maximum energy of an axis
$AXIS_JERK Maximum axis jerk
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7.3 Transformation
7.3.1 Machine data for configuration of the transformation
Overview7.3.1.1 $EX_KIN
Description Identifier of external transformations
The variable of structure type EX_KIN can be used to assign a kinematic type to external transformations ET1 to ET6.
Syntax $EX_KIN={ET1 Kinematic type ET1 ...,ET6 Kinematic type ET6} Explanation of
the syntax
Example
External transformations ET1 and ET2 are BASE kinematic systems.
7.3.1.2 $ET1_AX
Description External axes of the 1st external transformation
The variable of structure type ET_AX defines the external axes that are used by external transformation ET1. This consists of max. 3 transformed axes.
Syntax $ET1_AX={TR_A1 External axis 1,TR_A2 External axis 2,TR_A3 External axis 3}
Explanation of the syntax
The transformed axes can be assigned the following values:
Variable Description
$EX_KIN (>>> 7.3.1.1 "$EX_KIN" Page 55)
$ETx_AX (>>> 7.3.1.2 "$ET1_AX" Page 55)
$ETx_NAME (>>> 7.3.1.3 "$ET1_NAME" Page 56)
$ETx_TA1KR (>>> 7.3.1.4 "$ET1_TA1KR" Page 56)
$ETx_TA2A1 (>>> 7.3.1.5 "$ET1_TA2A1" Page 56)
$ETx_TA3A2 (>>> 7.3.1.6 "$ET1_TA3A2" Page 57)
$ETx_TFLA3 (>>> 7.3.1.7 "$ET1_TFLA3" Page 57)
$ETx_TPINFL (>>> 7.3.1.8 "$ET1_TPINFL" Page 57)
Kinematic type Description
#EASYS to
#EFSYS
BASE kinematic system 1 to 6
#ERSYS ROBROOT kinematic system
#NONE No external transformation
$EX_KIN={ET1 #EASYS,ET2 #EBSYS,ET3 #NONE,ET4 #NONE,ET5 #NONE,ET6
#NONE}
The external axes of external transformations ET2 to ET6 are defined analogously with the variables $ET2_AX to $ET6_AX.
TR_A1…TR_A3 Description
#E1 … #E6 External axis E1 ... E6
#NONE No transformed axis
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Example
The external transformation consists of external axis E2.
7.3.1.3 $ET1_NAME
Description Name of the 1st external transformation
The variable defines the name of external transformation ET1. The name specified here is displayed in the Robot tab accessed via the menu sequence Help > Info.
Syntax $ET1_NAME[]="Name"
Explanation of the syntax
7.3.1.4 $ET1_TA1KR
Description Position of the first transformed axis of the external transformation ET1 The variable of structure type FRAME defines the position of the first trans-formed axis relative to the coordinate system in the root point of the external transformation ET1.
X, Y, Z: Offset of the origin along the axes in [mm]
A, B, C: Rotational offset of the axis angles in [°]
Example
The origin of the coordinate system is offset, relative to the root point of the external transformation, 280 mm along the Y axis and 510 mm along the Z axis into the joint of the first external axis. Axis angle B is rotated by 90° so that the positive Z direction coincides with the rotational axis of the first external ax-is.
7.3.1.5 $ET1_TA2A1
Description Position of the second transformed axis of the external transformation ET1 The variable of structure type FRAME defines the position of the second trans-formed axis relative to the position of the first transtrans-formed axis of the external transformation ET1.
X, Y, Z: Offset of the origin along the axes in [mm]
The assignment must begin with transformed axis TR_A1. No gaps are allowed in the aggregate.
$ET1_AX={TR_A1 #E2,TR_A2 #NONE,TR_A3 #NONE}
The names of external transformations ET2 to ET6 are defined anal-ogously with the variables $ET2_NAME to $ET6_NAME.
Element Description
Name Type: CHAR
The name can have a maximum length of 20 characters.
The variables $ET2_TA1KR to $ET6_TA1KR are available for the ex-ternal transformations ET2 to ET6.
$ET1_TA1KR={X 0.0,Y 280.0,Z 510.0,A 0.0,B 90.0,C 0.0}
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Example
The origin of the coordinate system is offset, relative to the first transformed axis of the external transformation, 324 mm along the Z axis into the joint of the second external axis. Axis angle B is rotated by 90° so that the positive Z direction coincides with the rotational axis of the second external axis.
7.3.1.6 $ET1_TA3A2
Description Position of the third transformed axis of the external transformation ET1 The variable of structure type FRAME defines the position of the third trans-formed axis relative to the position of the second transtrans-formed axis of the ex-ternal transformation ET1.
X, Y, Z: Offset of the origin along the axes in [mm]
A, B, C: Rotational offset of the axis angles in [°]
Example
The external transformation does not use a third external axis.
7.3.1.7 $ET1_TFLA3
Description Position of the FLANGE coordinate system of the external transformation ET1 The variable of structure type FRAME defines the position of the FLANGE co-ordinate system relative to the position of the third transformed axis of the ex-ternal transformation ET1.
X, Y, Z: Offset of the origin along the axes in [mm]
A, B, C: Rotational offset of the axis angles in [°]
In the case of ROBROOT kinematic systems, the robot stands on the flange of the kinematic system. In this case, the variable defines the offset and orien-tation of the robot in the FLANGE coordinate system of the kinematic system.
Example ROBROOT kinematic system
Axis angle B of the FLANGE coordinate system of the external transformation is rotated by -90°. In this orientation, the robot stands on the flange.
7.3.1.8 $ET1_TPINFL
Description Position of the reference pin of the 1st external transformation
The variables $ET2_TA2A1 to $ET6_TA2A1 are available for the ex-ternal transformations ET2 to ET6.
$ET1_TA2A1={X 0.0,Y 0.0,Z 324.0,A 0.0,B -90.0,C 0.0}
The variables $ET2_TA3A2 to $ET6_TA3A2 are available for the ex-ternal transformations ET2 to ET6.
$ET1_TA3A2={X 0.0,Y 0.0,Z 0.0,A 0.0,B 0.0,C 0.0}
The variables $ET2_TFLA3 to $ET6_TFLA3 are available for the ex-ternal transformations ET2 to ET6.
$ET1_TFLA3={X 0.0,Y 0.0,Z 0.0,A 0.0,B -90.0,C 0.0}
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This variable of structure type FRAME describes the position of the reference pin on the external transformation ET1 in relation to the FLANGE coordinate system of this external transformation.
X, Y, Z: Offset of the origin along the axes in [mm]
A, B, C: Rotational offset of the axis angles in [°]
Example
The origin of the coordinate system is offset, relative to the flange center point of the external transformation, 210 mm along the X axis into the reference pin.
7.3.2 Transformation of BASE kinematic system
Description The transformation starts at the root point of the kinematic system and ends at the reference pin of the kinematic system. The reference pin is the reference point for root point calibration of the kinematic system.
Procedure 1. Define the root point of the kinematic system.
2. Define the joints and rotational axes of the kinematic system.
The variables $ET2_TPINFL to $ET6_TPINFL are available for the external transformations ET2 to ET6.
$ET1_TPINFL={X 210.0,Y 0.0,Z 0.0,A 0.0,B 0.0,C 0.0}
Further information about root point calibration of an external kine-matic system is contained in the Operating and Programming Instruc-tions for System Integrators.
Fig. 7-1: Transformation chain of a BASE kinematic system
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4. Starting at the root point of the kinematic system, offset the coordinate sys-tem into the first joint (translation in X, Y and Z direction).
5. There, rotate the coordinate system so that the positive Z axis corre-sponds to the rotational axis of the first axis (rotation about the angles C, B, A).
6. If required, offset the coordinate system from the first joint to the second joint and from the second joint to the third joint by means of translation and rotation.
7. Starting at the last joint, offset the coordinate system to the flange center point by means of translation and rotation.
8. Starting at the flange center point, offset the coordinate system to the ref-erence pin on the kinematic system by means of translation and rotation.
Example (>>> 10.1 "Transformation for DKP 400" Page 95)
7.3.3 Transformation of ROBROOT kinematic system
Description In the case of ROBROOT kinematic systems, the robot stands on the flange of the kinematic system, e.g. KUKA linear unit. The flange is the baseplate on the linear unit.
The following rules apply to the transformation of ROBROOT kinematic sys-tems:
In the case of kinematic systems with one axis, only $ETx_TA1KR is taken into consideration.
In the case of kinematic systems with 2 axes, $ETx_TA1KR and
$ETx_TA2A1 are taken into consideration.
In the case of kinematic systems with 3 axes, $ETx_TA1KR, $ETx_TA2A1 and $ETx_TA3A2 are taken into consideration.
$ETx_FLA3 defines the offset and orientation of the robot in the FLANGE coordinate system of the kinematic system and is always taken into con-sideration.
Procedure Here, the transformation is described using the example of a 1-axis ROB-ROOT kinematic system, i.e. a linear unit.
1. Define the root point of the kinematic system.
2. Starting at the root point of the kinematic system, offset the coordinate sys-tem into the flange center point of the kinematic syssys-tem (translation in X, Y and Z direction).
3. There, rotate the coordinate system so that the positive Z axis corre-sponds to the direction of travel (rotation about the angles C, B, A).
4. Rotate the coordinate system is such a way that the X axis, starting at the connector panel of the robot, points in the positive direction.
Example (>>> 10.2 "Transformation for KL 1500" Page 100)
Rotation must always be carried out in the sequence C, B, A.
Rotation must always be carried out in the sequence C, B, A.
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7.4 Optimizing machine data with the oscilloscope
Function The oscilloscope is a function of KUKA.HMI. This function can be used to re-cord, display and analyze different variables with the program running, e.g. ac-tual current, setpoint current, following error, etc.
Overview The oscilloscope is used to optimize machine data for external axes. Machine data must only be optimized after the kinematic system has warmed up. Dur-ing operation, gear units and other mechanical components begin to run more smoothly. Optimization with cold drives can result in the kinematic system be-ing over-optimized.
The following objectives are to be met:
Reduction of the cycle time
For this purpose, the following acceleration parameters are optimized:
Acceleration and braking ramp: $RAISE_TIME
Ramp for path-oriented braking in the case of maximum braking (STOP 0): $DECEL_MB
Ramp for path-maintaining braking after EMERGENCY STOP (STOP 1): $RED_ACC_EMX
(>>> 7.4.3 "Optimizing acceleration parameters" Page 66)
Increase of path and velocity accuracy
For this purpose, the following controller parameters are optimized:
Proportional component of speed controller: $G_VEL_PTP,
$G_VEL_CP
Integral component of speed controller: $I_VEL_PTP, $I_VEL_CP
Position controller: $LG_PTP, $LG_CP
(>>> 7.4.2 "Optimizing controller parameters" Page 60)
7.4.1 Optimization sequence
The following sequence must be adhered to when optimizing the parameters for external axes by means of the oscilloscope:
7.4.2 Optimizing controller parameters
It is advisable to optimize controller parameters with the maximum permissible load. Optimization with a smaller load may result in reduced cycle times. How-ever, no greater load can then be moved without first carrying out optimization again.
Detailed information about the oscilloscope is contained in the Oper-ating and Programming Instructions for System Integrators.
Step Optimization
7.4.2.1 Optimizing $G_VEL_PTP and $G_VEL_CP
Description The proportional component of the speed controller influences the dynamics of the velocity control.
The higher the proportional component, the greater the reaction of the controller output to a new setpoint value.
The higher the proportional component, the lower the following error.
The higher the proportional component, the greater the current pulse height.
If the control value is set too high, this causes the axis to overshoot and buzz.
If the control value is set too low, this results in termination of the motion with an error message.
The aim of the optimization is to reduce the following error as far as possible without causing the axis to overshoot or buzz. The optimized value for
$G_VEL_PTP and $G_VEL_CP depends on the motor type, the size of the ki-nematic system and the maximum load to be moved.
Procedure 1. Set the integral component of the speed controller $I_VEL_PTP to a high value, e.g. 9,999, in order to deactivate its function.
2. Set the proportional component of the speed controller $G_VEL_PTP.
3. Increase or decrease $G_VEL_PTP in increments until dynamic control
3. Increase or decrease $G_VEL_PTP in increments until dynamic control