making sure that a motion command can be performed

[RoboticsMan]

Hi

Is it possible to ask a KUKA robot whether it will be able to perform a specified motion? If it is unable because it cannot reach the destination (i.e. the arm is not long enough, or a joint limit is met), the answer should be 'no'.
I need this knowledge for a project involving vision guided robotics.

thanks in advance!

[schampneuf]

Hi,

Use undocumented KRL function INVERSE.
Calculate your point of destination.
Then use INVERSE. If you don't have an error code it means that you can reach your point...

[mookie]

can you give a quick example of syntax for this?

[schampneuf]

E6POS DESTINATION ; Point we want to reach
E6AXIS DESTINATION_AXIS
INT ERRORCODE

$TARGET_STATUS=#SOURCE
ERRORCODE=0
DESTINATION_AXIS=INVERSE(DESTINATION,XHOME,ERRORCODE)

IF (ERRORCODE<>0) THEN
    ; Go to Destionation
    PTP DESTINATION
ELSE
    ; Can't reach destination
    HALT
ENDIF

can you give a quick example of syntax for this?

[mookie]

im assuming that the inverse function returns a value of which axis is unable to attain the position?

[asimo]

Thanks a lot for sharing this one with us schampneuf. Do you know other "undocumented" function like that?

[SkyeFire]

 
We could probably create an entire sub-forum dedicated just to KUKA "Undocumented Features."  Like INV_POS(), the #TOOL switch for the LIN_REL command, and who knows how many others.

[schampneuf]

Yes,

There is also FORWARD that transforms an E6AXIS to an E6POS ...

Thanks a lot for sharing this one with us schampneuf. Do you know other "undocumented" function like that?

[bert]

We could probably create an entire sub-forum dedicated just to KUKA "Undocumented Features."  Like INV_POS(), the #TOOL switch for the LIN_REL command, and who knows how many others.

Please, feel free to give us more :) I'll pay you back some day.

[mookie]

hey bert, cant this function for finding if the position is acheivable be the answer for what you were looking for before?

[bert]

The problem I had before was that the position may well be achievable, but potentially undesirable. However, I have another cunning use for this function.

[SkyeFire]

Bert:  Found some data about the INVERSE and FORWARD commands, that reminded me of your earlier search for a way to un-init a variable.  According to my source, if the INVERSE or FORWARD command have a failure, the RETURNed value will be a blank {E6POS:} or {E6AXIS} value.  So if you *really* want to "blank" a pos or base variable, you could probably abuse one of these functions to do it.

However, it looks like these functions don't give any feedback on which axis, if any, would be violating its software limits in the event of an overreaching attempt.

[RoboticsMan]

I have tested the example, and I have a small correction:

IF (ERRORCODE<>0) THEN
...

Should instead be

IF (ERRORCODE==0) THEN
...

E6POS DESTINATION ; Point we want to reach
E6AXIS DESTINATION_AXIS
INT ERRORCODE

$TARGET_STATUS=#SOURCE
ERRORCODE=0
DESTINATION_AXIS=INVERSE(DESTINATION,XHOME,ERRORCODE)

IF (ERRORCODE<>0) THEN
    ; Go to Destionation
    PTP DESTINATION
ELSE
    ; Can't reach destination
    HALT
ENDIF

can you give a quick example of syntax for this?

[bert]

Bert:  Found some data about the INVERSE and FORWARD commands, that reminded me of your earlier search for a way to un-init a variable.  According to my source, if the INVERSE or FORWARD command have a failure, the RETURNed value will be a blank {E6POS:} or {E6AXIS} value.  So if you *really* want to "blank" a pos or base variable, you could probably abuse one of these functions to do it.

However, it looks like these functions don't give any feedback on which axis, if any, would be violating its software limits in the event of an overreaching attempt.

Thanks for that info. I'll have a bit of a play in the morning.