Softmotion Dev. Module Tutorial

[paubine]

Any good tutorial for Softmotion Dev. Module?

I have used Softmotion for straight line move but my next application is contouring data taken by a CAD ... and I found it not easy to understand how the contouring Trajection Generator work... Can we constraint the speed/acceleration of the move?  ...

Thanks,

Patrick

[paubine]

I want my robot to follow a path that I took from a CAD model (from a 6 axis robot model) and give this path to the real robot... but I want to control the acceleration and the speed of how the robot make this path.

I read that the contouring move ignore the contraint move...? The only way is to play with the contouring move/write "internval"?

Thanks again,

Patrick

[Jochen]

Patrick,

in contourined mode you need to provide the trajectory information directly as position points in an array. The motion control algorithm splines through these position points in a fixed interval.

 Let's have a look at two imaginary sections of a contouring array for a single axis (absolute contouring):

Example 1:

...100, 200, 300, 400, 500, 600,...

 In this example, the axis moves with fixed velocity.

Example2:

...100, 200, 400, 800, 1600,...

This sequence accelerates the axis.

In contouring mode you need to generate the velocity profile by calculating the position points for the contouring array. Changing the update interval on the fly doesn't work, as this would have an significant  impact on the timing of the spline engine and the control algorithm.

Sometimes it's not trivial to convert CAD data to contouring data. If you don't want to do this by yourself, you could use smart contouring feature of the NI Motion Assistant. Even though the NI Motion Assistant is meant to be used with NI 73xx motion control boards, the CAD import and smart contouring can be used with SoftMotion, too.

I hope this helps,

Jochen Klier

National Instruments

[paubine]

Thank Jochen, you should do a tutorial day ... or a tutorial for this module... you are one of the rare that know Softmotion...

BTW, Do you have any informations on the new version supposed to go out in August? Better ? More documentation ?

I don't know how smart is NI Motion Assistant for the 3D CAD contouring but...

My plan is to use a program like Delmia or Robotworks to do deburring / polishing process via CAD. Once everything is well simulated, I want to take the contouring path and use it contouring mode in Softmotion.

I understand pretty well the spline engine, I used it in detail in a earlier project. I was giving point (with matrix / u32.u32...) directly to the spline engine without using Softmotion Module. If I understand well what you said... I'm a little bit deceived that the contouring method of Softmotion can't play with the acc/speed of the path by itself....I thought that have the 3D sketch or angle of each axis (just the path without caring about the acc or speed) and then telling Softmotion to deal with the total acceleration/speed of the path  (only a ramp profile would be perfect but with all axis together (like coordinated move)

We don't wanna start the move with an initial velocity... Maybe the software like delmia will do the acc/decc of the profile itself ...

Hope I was clear ...

Thanks

Patrick

[paubine]

NI Motion Assistant look like it's used only with linear axis robot?

And CAD move is only for 2D ?

Am I wrong?

[Jochen]

Patrick,

with this additional information I have to admit, that Smart Contouring in MA is not smart enough for your application, as it doesn't support your kinematic.

Robotics is getting more and more into NI's focus and there are currentyl several projects in R&D to support our initiatives in this field, but it's a little bit too early to talk about details in the public. With this statement I don't want to set the expectations too high. I don't think, that there will be a complete near-term solution from NI, so you should try to work with existing tools for the contour calculations.

Regards,

Jochen 

[paubine]

What are the existing tools you're talking about?

What is your opinion on programmating a VI for the kinematics of my robot mixed to softmotion compare to using fanuc/abb controllers?

[Jochen]

You were talking about delmia. I don't know this software very well, but the type of data required by the contouring mode of NI SoftMotion should be very similar to the type of move data required by motion simulations. I have worked a little bit with kinematics simulations in COSMOSMotion in SolidWorks and I was able to use the contouring data from my cRIO based motion system directly in the simulation (some scaling was required).

To answer your second question: As you know the NI SoftMotion Development Module is a tool to help you to develop your own motion control applications by alleviating the low level tasks of a motion control system. So it's not really fair to compare this tool with ready to run robot control solutions. In fact the most challenging part is probably calculating the inverse kinematics. the SoftMotion module doesn't help you with this part, but on the other hand for typical mechanical setups the math for this problem is well known and you "only" need to implement this set of matrix calculations into your code.

To prevent your next question: I'm not an expert in inverse kinematics and I don't know a good resource where you can find a sample implementation for your type of robot. 

Kind regards,

Jochen

[paubine]

Thanks for all your informations.

I'll study the best options.

Patrick