how to Get robot position in real-time?

Hello. This is my first time asking a question here, so I might be clumsy, and it might be a topic that has already been discussed elsewhere.

I want to collect the coordinates of a ROBOT's X, Y, Z, E1, E2 (rotary table).

To collect data in real-time, I have created a getpositions.sub file, and inside this file, I use the $ACT_POS function. This file continues to operate while the main file is running.

However, the $ACT_POS function requires that the TOOL and BASE are set; otherwise, it will not execute without errors. I have added a conditional statement to check the TOOL and BASE. But if the main file is reset, the TOOL and BASE are reset as well, leading to errors with the $ACT_POS function.

This is likely an error that occurs because the kuka robot pre-reads multiple lines of code, and it reads them quickly.

So, I added a conditional statement to check the status of the $POS_ACT function, but the result was the same.

As a solution, I placed wait sec 0.05 between the conditional statements to prevent the code from being pre-read. However, this delay affects my data collection. (I want to collect data at more than 100Hz.)

My final code is as follows (getpositions.sub).

IF VARSTATE("$ACT_POS") == #INITIALIZED TEHN
 WAIT SEC 0.05
 IF NOT($ACT_TOOL_C < 0) AND NOT($ACT_BASE_C < 0) THEN
  BASE = $ACT_BASE_C
  X_POS = ABS($ACT_POS.X)
  Y_POS = ABS($ACT_POS.Y)
  Z_POS = ABS($ACT_POS.Z)
  E1_POS = ABS($ACT_POS.E1)
  E2_POS = $ACT_POS.E2

  IF $POS_ACT.X < THEN
   X_SIGN = FALSE
  ELSE
   X_SIGN = TURE
  ENDIF

  IF $POS_ACT.Y < THEN
   Y_SIGN = FALSE
  ELSE
   Y_SIGN = TRUE
  ENDIF
...
 ENDIF
ENDIF

Is there a solution to this problem? Or is there a way to detect the signal that resets the main file? Or could it be that the settings of my robot are unusual?

Thank you for your response.

Quote from hermann

Code

IF VARSTATE("$ACT_POS") == #INITIALIZED

or

Code

IF (($ACT_TOOL > 0) AND ($ACT_BASE > 0))

is not the solution. This is running parallel to main interpreter and can be interrupted at any time.

So it is possible that it is interrupted just after that line. While interrupted the main program resets, and baaaam, submit interpreter will be stopped when interruption is finished and he tries to read $pos_act.

It will happen very very rarely, but believe me, it will happen at some time.

This is mutlitasking! You must have in mind that each task can be interrupted at any time!

hermann

Yes, you're right.. the above method is not a complete solution, and tasks related to the sub-program are often interrupted... However, I will refer to your answers to solve the problem. Thank you.

Quote from SkyeFire

Root issue here is that the Submit and Robot interpreters (Level 0 and Level 1, respectively) are completely asynchronous. And any event like a Program Cancel or Reset in the Robot interpreter will cause $POS_ACT (or $POS_ACT_MES) to become invalid -- #DECLARED but not #INITIALIZED, in VARSTATE terms.

This means that it's possible for $POS_ACT_MES to change from #INITIALIZED to #DECLARED in between two consecutive lines in the SPS. So VARSTATE is not a reliable test here.

As hermann said, look into using ON_ERR_PROCEED instead.

SkyeFire

Yes, that's exactly the problem I'm facing...
I will look into and try using ON_ERR_PROCEED.

Quote from panic mode

why greater than zero? that is excluding cases where tool or base number are zero...

btw (just a general note) one should also be mindful of using VarState() on structures....

structures are complex data types and this function will return true even if initialization is only partial.

example:

Code

DECL FRAME F
DECL BOOL b1,b2,b3


b1= VARSTATE("F")==#INITIALIZED   ; false, F is not initialized
F={X 0}
b2= VARSTATE("F")==#INITIALIZED     ; true although only F.X is initialized
b3= VARSTATE("F.B")==#INITIALIZED   ; false 

BASE_DATA[1]=BASE_DATA[14]:F        ; err since F is not fully initialized

one can letting code run in Submit and after while compare how robust solutions are.

and the safest way is to use ON_ERR_PROCEED.

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@pannic mode

When resetting the main program, TOOL and BASE return -1 if they are in (?state).
I initially wrote it incorrectly, but the correct condition is as follows.

 IF NOT($ACT_TOOL_C < 0) AND NOT($ACT_BASE_C < 0) THEN

Quote from aknezevi.proton

Firstly, if you really want REAL-TIME robot position, use $POS_ACT_MES, as $POS_ACT is only the setpoint.

Secondly, there are two solutions to your problem. The first one is, as hermann mentioned, to use ON_ERROR_PROCEED.

The second one is to not use $POS_ACT unless both $ACT_TOOL and $ACT_BASE are set.

So instead of...

Code

IF VARSTATE("$ACT_POS") == #INITIALIZED

you can use...

Code

IF (($ACT_TOOL > 0) AND ($ACT_BASE > 0))

Lastly, WAIT SEC 0 also prevents code pre-reading. As does WAIT FOR TRUE. This is called advance run stop.

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@aknezevi.proton

Using $ACT_POS_MES instead of $ACT_POS is correct, thank you.

And,,, the same error occurs when using WAIT FOR 0.

I'll look into ON_ERROR_PROCEED.

@hermann

I've looked into ON_ERROR_PROCEED.

Thank you. It seems to be the command I was looking for, functioning much like the try: in Python language. From what I understand, it seems I can write the code as follows:

ON_ERROR_PROCEED
IF NOT($ACT_TOOL < 0) AND NOT($ACT_BASE_C) THEN
... my code
ENDIF

I will apply it to my robot right away and leave feedback.

...but what is the scope of the ON_ERROR_PROCEED feature? Is it just the immediately following conditional statement?

Quote from hermann

Yes.

But, because the answer is yes, your attempt is not complete, because if you use something like $pos_act or $pos_act_mes in ".... my code" you also have to use ON_ERROR_PROCEED just before that line.

And therefore you can leave out the "IF ..." complete, you must check the result after using $pos_act.

Once again: it is multitasking, have in mind that the submit can be interrupted at any line!

hermann

When using a function like $POS_ACT and an error occurs that you want to skip over, should ON_ERROR_PROCEED be declared before using a function like $POS_ACT?
Does this mean I have to declare ON_ERROR_PROCEED every time I try to receive the value of each coordinate?

ON_ERROR_PROCEED
X_POS = $ACT_POS.X
ON_ERROR_PROCEED
Y_POS = $ACT_POS.Y
...

Additionally, since the SUB file only serves the role of storing coordinate data in variables, it seems unnecessary to handle error handling. After all, it will return the coordinate values once the tool and base are specified.

hermann

Thank you. The code you suggested works precisely. Just as you mentioned, by using $POS_ACT once, I've reduced the parts where an error might occur and, by utilizing ON_ERROR_PROCEED, even if the main program resets and causes an error, the sub-program no longer stops. Thank you so much.

Additionally, to collect data up to the second decimal place (since SIGNAL DN_X_POS is in integer form), I multiplied the collected coordinates by 100. Later, in the process of handling the collected data, I use it adjusted to the second decimal place!

Anyway, thank you for helping it work well.

IF NOT($ACT_BASE_C < 0) AND NOT($ACT_TOOL_C < 0) THEN
   ON_ERROR_PROCEED
   DN_BASE_C = $ACT_BASE_C
   ON_ERROR_PROCEED
   POS_ARRAY = $POS_ACT_MES

   DN_X_POS = ABS(POS_ARRAY.X) * 100
   DN_Y_POS = ABS(POS_ARRAY.Y) * 100
   DN_Z_POS = ABS(POS_ARRAY.Z) * 100
   DN_E1_POS = ABS(POS_ARRAY.E1) * 100
   ;DN_E2_POS = ABS($POS_ACT.E2)

   IF POS_ARRAY.X < 0 THEN
    DN_X_SIGN = FALSE
   ELSE
    DN_X_SIGN = TRUE
   ENDIF
   IF POS_ARRAY.Y < 0 THEN
    DN_Y_SIGN = FALSE
   ELSE
    DN_Y_SIGN = TRUE
   ENDIF
   IF POS_ARRAY.Z <0 THEN
    DN_Z_SIGN = FALSE
   ELSE
    DN_Z_SIGN = TRUE
   ENDIF
   IF POS_ARRAY.E1 <0 THEN
    DN_E1_SIGN = FALSE
   ELSE
    DN_E1_SIGN = TRUE
   ENDIF
 ENDIF