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robotology / wb-toolbox

Simulink toolbox to rapidly prototype robot controllers
https://robotology.github.io/wb-toolbox/
GNU Lesser General Public License v2.1
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Variant of Jacobian and DotJNu in which the frame is an input and not a parameter #224

Closed traversaro closed 3 years ago

traversaro commented 3 years ago

Summary

It would be nice to have a variant of the Jacobian and DotJNu blocks in which the frame is given as input and not as parameter.

Motivation

@VenusPasandi asked about this, so probably she can provide a bit more details.

traversaro commented 3 years ago

My first idea is to add a JacobianWithFrameAsInput and DotJNuWithFrameAsInput block that duplicate the existing blocks but with frame passed as input, but perhaps there is some more intelligent strategy.

VenusPasandi commented 3 years ago

Actually, I found a way to use the current blocks Jacobian and DotJNu in a Simulink model where the frame name (which is the parameter of these blocks) changes during the simulation. So, I can get Jacobian and Jacobian derivative of different frames by using only one block. For this purpose, 1) I create a Simulink function having the Jacobian/DotJNu blocks. Lets call it mySimFunc. 2) In a matlab function block, I use set_param to set the Frame name of the Jacobian/DotJNu blocks, (Note that you must use coder.extrinsic('set_param') in the matlab function to be allowed to use set_param command), 3) In the matlab function block, after setting the Frame name, I call mySimFunc which output is the Jacobian and Jacobian derivative of the desired frame set in the step 2.

VenusPasandi commented 3 years ago

My first idea is to add a JacobianWithFrameAsInput and DotJNuWithFrameAsInput block that duplicate the existing blocks but with frame passed as input, but perhaps there is some more intelligent strategy.

I think Simulink blocks do not accept a string as input signal. So, the block can take the frame index as the input.

traversaro commented 3 years ago

My first idea is to add a JacobianWithFrameAsInput and DotJNuWithFrameAsInput block that duplicate the existing blocks but with frame passed as input, but perhaps there is some more intelligent strategy.

I think Simulink blocks do not accept a string as input signal. So, the block can take the frame index as the input.

Yes, that is correct for BlockFactory blocks, but just FYI in general Simulink blocks support string as signal type, see https://www.mathworks.com/help/simulink/ug/simulink-strings.html .

traversaro commented 3 years ago

Given @VenusPasandi solution, I think we can close the issue.