Posts by diglo

Yes, they have AC units for the controller, but they don't sell AC units for the motors!

Hello everyone!

How do you evaluate the ammissible duty cycle of a robot in function of external ambient temperature?
The robot duty cycle sould be 100% if the robot is not dynamically and statically overloaded?
Do you derate the duty cycle (i.e. from 100% to 30%) when the ambient temperature is too high?

I didn't find anything in my manuals...

(attached a load comparison between 2 robots)

diglo

If you put the TCP in the center of your hemisphere and the base at the tip of your external tool, then you can just rotate the tool using angle-only movements:

LIN {A 15}
LIN {A 36, B 56}

Just keep in mind that robot rotations are based on the Eulerian system, so the rotations are applied orderly:
A: rotation around Z axis
B: rotation around the new Y axis (which may have changed orientation after the A rotation)
C: rotation around the new X axis (which may have changed orientation after the A and B rotation sequence)

Ahhh okay!

But I can't connect the KSI to the company network with other robots since it's directly connected to the system bus... Yup!

diglo

Ok, but i can do the same things over the KLI, which is connected directly to the KPC. The only difference seems to be the DHCP service...
(I never had the necessity to connect to the drives though)

Quote from Loipe

Hi there,
of course you can. You can connect your Laptop there to program/configure the Robot/Profinet over Workvisual and connect to Network drives on the Robot.
just because there is KUKA in the name means not that you cant use it.
Greeting
Loipe

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Ciao ragazzi!
Today a new robot has arrived in our workshop. There's a new ethernet port marked "KSI" on the KRC4 door near the USB connectors.

What's the purpose of that?
Manual says it's "Kuka Service Interface", so it means I can't do anything fancy with that?

diglo

I've found out what was that, it's called BOM, Byte Order Mark.
I was inserted by the OpenTextFileWriter to signal the UTF-8 encoding which is the default instead of ASCII: ""

https://en.wikipedia.org/wiki/Byte_order_mark

diglo

What the heck! You are right SkyeFire!
I've never seen something like this before, maybe It's related to text encoding, I don't understand how those chars got there...

EDIT:
I changed the code of my VB.NET application which is writing the text file.

Old code:

file = My.Computer.FileSystem.OpenTextFileWriter("\\" + tb_ipaddr.Text + "\UserFiles\logo_" + nu_writepos.Value.ToString + ".txt", False)

New code:

Dim file As New System.IO.StreamWriter("\\" + tb_ipaddr.Text + "\UserFiles\logo_" + nu_writepos.Value.ToString + ".txt", False)

And the rubbish is now gone!

diglo

Hi people!

I need to read a text file and put it into a CHAR array, but when I iteratively call the function

CWRITE($FCT_CALL, STAT, MODE, "krl_fgetc", FileHandle, read_char)

I always get first 3 rubbish characters BEFORE the actual file content, even if the STAT variable does not return any error condition.
The "rubbish" characters are always the same...

You can see that from the attached image, the file content begins with an underscore and then is just a list of #####...

How's that possible?
KRC4 KSS 8.3.26

What do you mean with "tries"?
You may monitor the actual torque of each axis with the system variable $TORQUE_AXIS_ACT[].

diglo

Thank you for your replies, I'll try the IOCL commands...

But what I'm looking for is a way to have the devices communicating but allow ACCIDENTAL disconnection!
With Profibus, if I uncheck the "always available" flag, the device still works fine, but if I disconnect its cable, the robot controller does not got into fault, prevening movements in EXT mode.

diglo

Hi people!

I'm working with a KRC4 8.3.27 which has 3 Profinet slave devices. 1x siemens IM151, 1x siemens PN/PN coupler, 1x custom device with a Hilscher PN board.
Everything works fine but when I uncheck the "always available" flag under Profinet device settings, the unchecked device stops communicating. (see attached image)

I usually deselect the "always available" flag when working with Profibus slaves and I don't want a device fault to stop the entire robot, but now with profinet it's not working as intended.
How do you allow disconnection for Profinet slave devices?

Diglo

Try with this. It is not guaranteed realtime, but it's worth a try:
It uses kukavarproxy to read robot variables and send values through a TCP connection.

https://www.robot-forum.com/ro…ibrary/msg86562/#msg86562

Auto-answered myself: the variable $FOL_ERROR[] does that.

Hello, fellow robot people!

Do you know if there is a system variable which allows to monitor the actual angular lag for each axis?
I'm using this function to set the torque limitation for a given axis, together with the allowed max angular lag, but how can we monitor the actual lag?

GLOBAL DEF limit_torque(ax:IN,range:IN, lag:IN)
   INT ax
   REAL range, lag
   DECL TorqLimitParam limits 
   IF range>0 THEN
      limits.monitor = #OFF
      limits.max_lag=  lag
      limits.max_vel=  400
      limits.lower =   -$TORQUE_AXIS_MAX[ax]*(range/100)
      limits.upper =   $TORQUE_AXIS_MAX[ax]*(range/100) 
      SET_TORQUE_LIMITS(ax, limits)
   ENDIF
END

diglo!

I solved the issue by running the heating cycle with torque limitation at 70%, this inherently limits the maximum current fed to the motors.
I didn't use the KUKA's warmup function.

The machine now works fine.

diglo

I tried the KUKA's Warmup option on a robot in our workshop, but it looks like it's just applying an automatic reduction equal to $WARMUP_MIN_FAC to the ovveride if the current exceeds the $WARMUP_CURR_LIMIT value, then raises the override by some %/s as defined in $WARMUP_SLEW_RATE.

What happens to me is that besides my warmup program is already excecuted at a really slow speed ($OV_PRO=3, VEL_PTP=70) I still get a message related to the current "KSS26010 Ackn current overload after 60.0s (A4) (HoldingCurrent)".

The KUKA's warmup function does not look like it's overriding the current monitoring so it does not look like it wil solve my problem...

diglo

Yes, I'm now experimenting with these...

I did not mention the robot or the controller because this problem may be the same across more models, btw my robot is a KR16-2 and the controller is a KRC4 8.3.15

The question was in other words: How do you usually cope with robot warmup?

diglo

Hi guys,

I've been working on a robot which has been installed on a plant in which the winter temperature gets as low as 5-6°C and this creates some issues, such as some overtorque alarms.
To overcome this, we implemented a "heating cycle" which is a dedicated set of movements performed initially at slow speed and then the speed gradually ramps up using the $OV_PRO.

But we still sometimes get the alarm "KSS26010 Ackn current overload after 60.0s (A4) (HoldingCurrent)" at the very beginning of the heating cycle, in which the $OV_PRO is 3.
Obviously, when temperature rises avove 15°C we do not get any alarms.

How do you usually deal with very cold enviroments?

FIY, this is my "heating cycle":
max_axis_temp() is a function which returns the maximum temperature among the 6 motors.
I know this is not related to gearbox temperature...

BAS (#INITMOV,0 )
BAS (#vel_ptp,70)
BAS (#acc_ptp,100)
cnt=0


PTP HOME_POSITION
$ov_pro=5


PTP {A5 0}
WHILE (cnt<90) AND (max_axis_temp()<37)
      $OV_PRO=MIN(3+cnt,100)
      PTP {A1 5, A2 -153, A3 130, A4 100, A6 -100}
      PTP {A1 -5, A2 -150, A3 125, A4 -100, A6 100}
      cnt=cnt+1
ENDWHILE


$OV_PRO=100
PTP HOME_POSITION

diglo

I found the problem, I made a mistake in the I/O configuration and started mapping the I/O of that device from 2501 instead of 2500!!
I didn't know that not mapping an i/o would have triggered that kind of error...

Fixed that, fixed everything!