Is it possible to change the color of an object in Simscape Multibody during a simulation?

I would like to be able to visually communicate system parameters by the color of a body. For example, a linkage turns yellow when it gets within 10 degrees of its limits, or a wheel turns red when it stops turning, etc.

Is this possible? Or does anyone have any tricks to convey this information synchronously with the model animation?

[Ameer Hamza]

I suppose this should be possible, but it is not natively supported in Simulink, and there is no straightforward way. Making it work will require a bit of digging. Here is a starting point for you: https://blogs.mathworks.com/simulink/2011/03/08/how-do-i-change-a-block-parameter-based-on-the-output-of-another-block/.

This next blog further extend this idea: https://blogs.mathworks.com/simulink/2013/01/25/accessing-block-data-during-a-simulation/

[Ameer Hamza]

Also, I must mention you may be able to change the color property of the solid block using the event_listener method, but wether the animation renderer also update the color is not clear.

[Cyndia Cao]

Is there any way to export the results instead to another visualization / rendering software that has that capability? And are there any softwares that allow that? It would be really helpful for debugging and observing the system, but I'd rather not devote the majority of my time to making that feature work.

[Ameer Hamza]

I tried the event listener approach; it appears that it does not work for the blocks inside the simscape library.

I am not sure about any other software, but If you have the 3D model of each link of your robot, then you can create an animation using the graphics function provided by MATLAB, e.g., patch(). It will require a bit of knowledge about 3D transformations, but eventually, you will be able to control the appearance of each link independently.

[Cyndia Cao]

Ok thanks for helping me look into this!

Answer 1

[Steve Miller]

Through MATLAB release R2021a, you cannot cannot change the color of a solid based on an input signal. What you can do, though, is put another solid just behind it that has the new color, and then when you want the color to change move that solid in front of the other solid.

In the video in this LinkedIn post, we used a set of solids to have the battery color change gradually as it heats up:

https://www.linkedin.com/feed/update/urn:li:activity:6684719626217127936/

--Steve

[Dean Hockley]

Hi Steve - how is it that you "move" a solid in front of another during simulation?

[Steve Miller]

Hi Dean,

To give the appearance that a solid's color has changed, you can

1. For something like a lamp or an indicator....create two solids of different colors (for example red and blue), and mount one of them on a prismatic joint (for example, the blue one). At the start of the simulation, make sure the blue one is positioned "behind" the red one along the viewpoint axis. When you want the color of the lamp to change, move the blue one so that it is in front of the red one. This will obviously only work along one axis.
2. For something like the batteries in the simulation above, we created a set of Variable Brick Solid blocks each assigned a different color. As we wanted the color to change, we changed the dimensions of the Variable Brick Solid with the desired color to "big" and make all other Variable Brick Solid blocks small (but not zero)

--Steve

[Dean Hockley]

Thank you Steve, all clear now.