Help! About real-time communication with Kuka robot

Hi Shuihua,

first of all I have to say that I have absolutely no experience with KUKA robots
so I can't answer a single of your technical questions.

But maybe I can suggest some ideas if you give a little more information:
- what precision/resolution do you want to achieve ?
- how fast do you want to move ? (mm/s)
- what is your method of measuring:
do you want to scan in straight lines over the object and take the distance/height from the laser
or do you want to keep the laser on constant distance to the object an take the height from
the robots position ?
- what objects do you want to scan ? (concave/convex) Do you need all 6-axis ?

addi

Shuihua,

OK, so what about not reading the position from the robot but calculate it yourself.

Idea: I think the robot will have the ability to move at constant speed with good accuracy (regarding the speed)
This is important for example in glueing applications.
So if you take the start- and stop-point of one straight scan movement (taking into account the acceleration/deceleration
ramps), you can calculate the scanner position at any point in time.
If the scanner is then triggered/read with an accurate time rate you will have a relatively accurate position without
the need of reading the robots position. All calculations can be done on the PC.

What do you think ?

regards
addi

Sounds like a SICK IVC Cam.

I had the same Problem a few weeks ago. But I only need a accuracy of 1-2mm.
I used a fix Velocity of the robot. The scanrange is 800mm. After the Robot reached the programmed velocity, the signal for the cam is triggerd on by an interrupt and off by "trigger on Path" 100mm before reaching the end position.
After the cam calculated the data i send via serialport to an opc-client and from the client to ProConOs Soft-PLC. The SoftPLC sends it to the Robot by SOFTPLCREAL[] Variables.

The solution suggested by IrrerPolterer presents a good work-around

In case such solution does not work for you, you might wanna use a fieldbus-card
in your robot, for example the Hilscher Profibus-Card. Fieldbus-Cards are options
to be ordered with the robot, but may also be retrofitted. However, you'll need to
explicitely state that you require a Hilscher Prodibus Card, as KUKA normally delivers
a Siemens-Card when ordering Profibus. The KRC internal communication with the
Siemens-Cards occurs in the IPO-cylce which is currently 12ms. However, from what
i know, the communication method KUKA uses for the Hilscher-Cards allows data
exchange in 4ms cycles.

Such card, in conjunction with the KUKA ProConOS Softplc you should allow you
to exchange data at a 4ms deterministic update rate. Your external PC would
also need to be equipped with a Fieldbus-Card of course.

According to the KUKA ProConOS manual, calling the function block which reads the
robots kartesian position from the real-time system should not be called in intervals
shorter than 12ms if the application allows so, as this call causes high CPU load, but
well, it says "should...". If your robot is a new generation robot with 2Ghz CPU then
calling the function block in 4ms intervals could well work. If the ProConOS task-
management and fieldbus is configured accordingly, 4ms should be achievable this
way. But don't take this as a guarantee. You might wanna talk with a KUKA-Expert
to get a *hopefully* binding answer.

Regards, Peter

Zitat von IrrerPolterer

Sounds like a SICK IVC Cam.

I had the same Problem a few weeks ago. But I only need a accuracy of 1-2mm.
I used a fix Velocity of the robot. The scanrange is 800mm. After the Robot reached the programmed velocity, the signal for the cam is triggerd on by an interrupt and off by "trigger on Path" 100mm before reaching the end position.
After the cam calculated the data i send via serialport to an opc-client and from the client to ProConOs Soft-PLC. The SoftPLC sends it to the Robot by SOFTPLCREAL[] Variables.

IrrerPolterer - two quick questions. I am struggling with an IVC-3D at the moment. When you say "after the robot reached the programmed velocity", do you 'guess' when the robot is at programmed speed, or is there a System Variable that I can use?

I have written a Visual Basic program that will run under XPe on the robot. The IVC will send information via TCP/IP to the VB program, which will then transfer the data into Global Variables using CrossCom. This sounds easier than your method of using ProConOs, but as I have never done it before, I am now concerned that my way will not work. Am I doing something wrong?

Zitat von MartinH

When you say "after the robot reached the programmed velocity", do you 'guess' when the robot is at programmed speed, or is there a System Variable that I can use?

I use $VEL_ACT for that...

DEF SCAN()
DECL REAL SPEED
SPEED=0.2
$CYCFLAG[1]=$VEL_ACT==SPEED
INTERRUPT DECL 8 WHEN $CYCFLAG[1] THEN DO START_CAM()
...
...
INTERRUPT ON 8
TRIGGER ON PATH=-200 DELAY=0 DO $OUT[1]==FALSE ;Cam off 200mm before reaching endpoint
LIN_REL {x 800}
...
...
END
DEF START_CAM()
INTERRUPT OFF 8
$OUT[1]=TRUE ;Cam on
FRAME_CAMSTART=$POS_INT ;Store Scan-Start Position
END

Zitat

I have written a Visual Basic program that will run under XPe on the robot. The IVC will send information via TCP/IP to the VB program, which will then transfer the data into Global Variables using CrossCom. This sounds easier than your method of using ProConOs, but as I have never done it before, I am now concerned that my way will not work. Am I doing something wrong?

The ProConOs does a lot of more in my application. Auto-Extern, Controlling some components and so on...ProConOs has it's own OPC-Server. And my VB-Client gets access using the dlls from ProConOs OPC-Server!
And the easiest way to send variables to the robot is the proconos library ExVarLib by KUKA! You can send REAL, BOOL or Integer Vars using this library. You can Use $SOFTPLCREAL[1...256?] /$SOFTPLCBOOL[...],$SOFTPLCINT[...] directly in the robotprogram.
Another way is the $SEN_PINT[] Variable

Zitat von IrrerPolterer

I use $VEL_ACT for that...

Then that's what I'll use too

I have my local Kuka salesman coming down on Thursday, so I'll talk to him about ProConOs

Zitat von Shuihua

Can someone give me some guidance of the programming of Ethernet-KRL and the serial communication on the robot?

Shuihua - attached is the English manual on Serial communications. Hope it helps