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  robot precision (accuracy) is affected by APO parameters ?

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June 29, 2017, 07:31:41 PM
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Robot-CNC


I am trying to understand if and how APO parameters could afect robot initial positioning when start a program that looks like:

------------------
BAS(#VEL_PTP, 10)
BAS(#ACC_PTP, 10)
PTP $POS_ACT
$APO.CDIS=0.1
$APO.CORI=1
$APO.CVEL=100
$APO.CPTP=50
BAS(#VEL_PTP, 75)
$IPO_MODE=#BASE
$BASE=BASE_DATA[17]
$TOOL=TOOL_DATA[1]
$VEL.CP=0.167
$VEL_EXTAX[1]=100
EX_BASE(17,2)
$VEL.CP=0.167
PTP {A1 83.87, A2 -52.86, A3 50.3, A4 -27.64, A5 91.81, A6 87.89, E1 90} C_PTP
LIN {X -347.47,Y 105, Z 808.92, A -174.89, B 17.3, C 1.52, E1 90} C_VEL
$VEL.CP=0.05
LIN {X -207.67,Y 105, Z 361.93, A -174.89, B 17.3, C 1.52, E1 90} C_VEL
$VEL.CP=0.167

In config.dat I have fallowing values:

; APO - parameters
;--------------------------------
INT DEF_APO_CPTP=50
INT DEF_APO_CVEL=100
REAL DEF_APO_CDIS=3.0
REAL DEF_APO_CORI=5.0

;==================================
 
The robot will aproximate motions according with config.dat values for APO or will consider those from src file?

APO.CORI , APO.CDIS APO.CVEL AND APO.CPTP are activated only when each line has in its end C_ORI,C_DIS,C_VEL or C_PTP ?


Thank you !
« Last Edit: June 29, 2017, 07:38:49 PM by signum »

Today at 04:58:24 AM
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June 29, 2017, 07:39:40 PM
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panic mode

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program is using whatever you put in that program.


check BAS.SRC, this is using default values from $CONFIG.DAT
so if you are using inline form motions (they make use of BAS.SRC) then those would be used...


$APO.CORI , $APO.CDIS, $APO.CVEL AND $APO.CPTP need to have values before you can use C_ORI, C_DIS, C_VEL or C_PTP with your motions.
if your motion does not use C_ORI, you don't have to initialize $APO.CORI etc.
« Last Edit: June 29, 2017, 07:52:46 PM by panic mode »
1) http://www.robot-forum.com/robotforum/kuka-robot-forum/read-first/
2) if you want reply about robot, post it in forum
3) read 1 and 2

June 29, 2017, 08:04:45 PM
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Robot-CNC


So in my inline example will be used default values from config.dat, if I figured out well

Is it possible to affect accuracy of positioning these parameters?

June 30, 2017, 02:34:38 AM
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SkyeFire

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The DEF_* parameters are only set by, IIRC, BAS(#INIT).  If you set the $APO values during your SRC program, those values will become active and be retained until the next SRC command that changes them -- either your command, or a call to BAS(#INIT).

June 30, 2017, 12:32:43 PM
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Robot-CNC


Without $advance=1..5 declared no aproximation will happen?
If I understood well from manual.

And noone said if aproximation parameter affect in any way robot accuracy of positioning.
« Last Edit: June 30, 2017, 02:21:47 PM by signum »

June 30, 2017, 06:53:14 PM
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panic mode

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$ADVANCE tells how many motions are to be buffered before main pointer arrives there.
as long as $ADVANCE is greater than zero, there is possibility to do approximated motion.
of course one still must specify approximation value and add suffix C_DIS or similar after motion instruction.


June 30, 2017, 08:25:37 PM
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SkyeFire

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$ADVANCE controls how many motion steps the system can "look ahead."  With a value of 0, it's impossible to look ahead and, as such, no approximation is possible.

Approximation will only effect the accuracy of positions that have approximated motion -- C_PTP, C_DIS, etc.  Motions that have no approximation on their motion will be entirely unaffected by the $APO values.

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July 01, 2017, 04:11:52 AM
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Robot-CNC


Thank you Skyfire.
And I supose that for a smooth moving is better to choose a higher value, this case 5.
Missing of this line  from a src head means that the value is considered zero and no aproximation happen?
Do you think that lack of aproximation could generate positioning error up to 3-4 mm ?



July 01, 2017, 04:35:46 PM
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panic mode

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why don't you just try it?



i am not sure where you are going with this... accuracy depends on many factors (correct mada, calibration, tuneup, load data etc.).

kuka courses are offered for a reason... i recommend taking training


and why would anyone want to NOT initialize parameters used by program?  :icon_eek:


« Last Edit: July 01, 2017, 04:38:10 PM by panic mode »

July 02, 2017, 10:43:42 PM
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SkyeFire

Global Moderator

The $APO distance defines a radius around the programmed point where the path planner can begin "cutting the corner."  In general, the larger the $APO value the faster and smoother the motion will be, but there are limits -- for one thing, no matter what the $APO value is set to, the path planner will not use an approximation radius larger than 50% of the distance between two consecutive points.
This is explained in great detail in the manuals.

As for accuracy... what EXACTLY are you trying to ask, here?  There are many different kinds of accuracy, including position accuracy, path accuracy, spatial, relative, etc.  Not to mention the critical distinction between accuracy and repeatability.


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