Robots and Siemens PLC

More and more robots are installed these days.

I'm interested in this subject.

Look at this for example: http://www.youtube.com/watch?v=I-N52Xh1noQ&feature=related

Are there Robot specialists out there ?

I'm interested in knowing the basics of such robotic system, like how several servos are controlled at the same time, how is this coded, these things...

thanks in forward

I've done some things with S7 & Yamaha robots over Profibus. It was a pallet type program. The robots were given all the info from WinAC RTX with WinCC Flexible interface. Are you wanting to know how that works or just how the robot works?

CharlesM said:

I've done some things with S7 & Yamaha robots over Profibus. It was a pallet type program. The robots were given all the info from WinAC RTX with WinCC Flexible interface. Are you wanting to know how that works or just how the robot works?

Click to expand...

I wanna know how you did the project, what are robotbasics, how does the robot work, how does the program works, did u draw flowcharts first, etc ... ?

I did make a few flow charts for the program but not an overall process type of thing. The process was simple.

1-machine makes a part
2-robot removed the part from machine
3-robot rotates part 180
4-debur part by running it back and forth through brushes
5-place the part on one of two scales
6-get the weight of the part
7-second robot gets part from scale
a-part is placed on pallet
b-part is rejected
c-part is placed in inspection drawer
8-repeat

First thing I did was to play with the robots a little. After I got the robots my distributor came by and gave me the basics. The about a week after I had Yamaha come in and teach a class. We had one day of programming and one day of maintenance of the robot. This was great because I had been playing with the robots I had an idea of how they worked. Also Yamaha shipped in another robot just for training. We completely disassembled the thing down to nuts bolts and gears. This was real good because you got to see how everything goes together without taking one of the new robots apart.

So my robots are programmed by four positions to a point X,Y,Z,R. I can have up to 5000 points. Then the robot program moves point to point. You can save each program on the robot up to the max memory on the robot or 100 programs (maybe more). The robot program is a sequence from top to bottom. One thing I wanted to do in my program was to keep the number of points the operator had to set to a minimum. So I used the points they teach and did calcualtions inside the robot to find the other points I needed to go from one place to another. For example the gripper closes on a part. I add 100mm to the Z axis of the pickup position to make a clear position above it. Then subtract 400mm from the X position to make another point. By doing this I can go P1 P2 P3 and get the part move up 100mm then move out 400mm. I was able to do this because my path was the same everytime just had different end points. Some applications this might not work.

The other major thing in the robots was the pallet layout. Most robot controllers have a pallet program built in. You teach 5 points 4 corners and a Z up. This makes a cube. You also have to tell the robot how many rows, cols, layers. So if you had a 10 rows 10 cols and 10 layers you would have 100 parts on each layer and 10 layers. In the robot program you have some type of loop running. Like a for next loop.

for i = 1 to 1000
Move P0, F10
P1, F10
next

This would move from point 0 to each of the 1000 points created in the pallet. I have the P1 this would be to pallet 1. You can define multiple pallets in the robot but they all work the same way.

I will come back with more on how the robot talks Profibus.

This

I have 2 RCX142 robot controllers setup on Profibus. After setting them up i HWconfig I have 2 memory areas. One is used to send commands. It has 2 dints for command & format info and 4 reals for the data. This can be used to send commands or point data to/from the controller. The other memory area is read/write of words. I think they gave me about 16 words to move back and forth. These are used to start programs and simple variables that need to go back and forth. The robots can also have their I/O mapped to this area. If the outputs are mapped then they can only be used by the PLC not the robot. My first task was reading and writing point data to the robots. If I could not get the point data I could not save them to a recipe in WinCC Flexible. This would have been bad because I wanted to save all the setup data back to the part number the machine uses. This makes for a simple setup. I had to get an upgrade to Step 7 pro to get SCL because STL is not good for me. I also got Graph with this. I was able to use graph to make the sequence that would upload and download the points to the robot. I also had some SCL to do the array work for the DB. Looking back I think it would have been best to do it all in SCL but at the time I went for what was easy.

I used the read/write words to help with the sequence between the PLC and the robots. I had bits that would set in the robot telling me when a part was placed on the scale and when the robot was clear of the scale. The robot also has an area output. You give the robot 2 points that make up a cube. Any time the robot is in this area it sets this bit. I made these areas around the scales so both robots would know when one was around the scale. This kept them from running into each other.

there is also a Hugh Jack book entitled integration and automation of manufacturing sytems that has some informativwe chapters on robotics however I have been unable to find a link to this manual I know it was posted on this site at one time I believe RSdoran may have posted the link before but not positive on that