simatic 300 and inverse kinematics

Hello everyone! I have question regarding simatic 300 plc and inverse kinematics. I have to program software for 4-axis SCARA manipulator. I'm newbie and have alredy calculated equations for inverse kinematics and now I have to implement it in my simatic 300 plc, manipulator constists 2 incremental encoders . Does anyone have any idea how to do it? Maybe any example or a tip where to start. THX in advance.

That questions is way to broad to answer in a forum

First, find a platform that is powerful enough to run the application. A PLC will not be fast enough unless you expect to have a very low performance system. I would find a DSP development board.

Second, get some nice development tools.

Third get the motors to work in closed loop control. This should be easy. Then add feed forwards.

Fourth, get the motors to follow a motion path in the actuator coordinates. The should consist of a PVA ( position, velocity and acceleration ) every millisecond.

Add your inverse kinematics translation routine and test it to make sure the user coordinates get translated into actuator coordinates correctly. Remember that you need to translate more than just position and angles. You must also translate the velocities and accelerations too. I would debug this without moving the actuators just incase there are bugs.

You will probably need to write a set of basic robotic commands and a means of entering them, compiling them, downloading them and debugging them. This will probably need to be entered on a PC and downloaded.

Finally run the whole program with everything enabled.

This a lot of stuff to do.

A simple way to go is to implement cubic splines. Then one can teach the points and have the spline interpolation move smoothly from point to point. The trick here is that you have a lot of points and you need to have a way of computing the time between the points that doesn't exceed position, velocity and acceleration limits.


There are all sorts of little details like limit checking.

Thx!

Why don't you try a more specific question

My company makes motion controllers. I can answer specific questions. You were asking me to write a book. There are some things you just don't want to do in a PLC. A S7 is pretty good at doing math in SCL but it is still too inefficient compared to a DSP or a motion controller with many 32 bit registers and programming in C or C++.

Peter; what do you think about the 'technology' cpu's from Siemens?

https://mall.automation.siemens.com...16-1334-1432-1437-1473-1474-1475-&jumpto=1475

I think this is a better fit than T-CPU

https://mall.automation.siemens.com...34-1432-1437-1473-1474-1475-2400-&jumpto=2400

Don't expect an unbiased opinion, you will not get one.

ivo.maenen said:

Peter; what do you think about the 'technology' cpu's from Siemens?

https://mall.automation.siemens.com...16-1334-1432-1437-1473-1474-1475-&jumpto=1475

Click to expand...

It looks OK for a PLC with added motion commands. However, I see no imagination or 'experience' with applications in the command set. For instance, our controller has the PVAT or Advanced Time Move command that allows one to use it in robotics applications where things must often change on-the-fly. I see NO such command in the S7s command set. The PVAT 'advanced time move' command comes in very handy in robotics the inverse kinematics can then update the actuator or motor positions every 10 millisecond and the PVAT command can make a smooth motion to the new point. However, it requires that the position, velocity and acceleration are calculated at each point along the motion path. A few days back on this thread
http://www.plctalk.net/qanda/showthread.php?t=48945
nettogrisen needed a command to move 25 degrees in 3 seconds. The advanced time move, PVAT, command could do that. No user calculations required. What made nettogrisen's application more challenging is that the initial velocity is not known and the motion profile must be calculated on-the-fly. So tell me, what S7 motion command would you use with nettogrisen's application?