Simscape Multibody Collision doesn't work, and model disappears.

Hello there,

I am trying to utilize simscapes mulibody to help me with collision, my setup is:

Inside Drone Mechnical:

Inside: Ground

Issue

For some reason, the drone doesn't stop when hitting the ground, it just disapears, and I get no error, so I don't understand what is wrong. Can someone please help me with what is wrong?

[Yifeng Tang]

Is it possible to share the model for diagnostics? I wonder if we need to force some smaller time steps to allow the object to get "close" to the ground but now passing through.

[Markus Kenno]

Sorrry for the late response, but I've provided the files. Thank you :D

[Yifeng Tang]

Hi @Markus Kenno,

The attached model is still missing some step files for the file solid blocks, so I haven't been able to run your model. But I noticed the model is set to use fixed-step solver with auto-selection. Is the intention to be able to run this model using a fixed step solver? Maybe fore things like real-time simulation and/or controller testing?

When working with models that contains substantial amount of Simscape blocks, the standard workflow is to

(1) make sure the model runs OK and the results are accurate using a variable step solver. Auto selection will most likely give you DAESSC, the solver designed for Simscape. Treat this as the gold standard. You need to observe the "collision" in this step first.

(2) do a solver profiler session and find out if there is any potential small time steps that may need attention. This gives you the opportunity to check the numerical efficiency of the model.

(3) Find the solver configuration block (that F(x) = 0 thing), and turn on the local solver, choose a reasonable time step based on the information you saw from the solver profiler. This will make the Simscape part use a fixed-step (optionally fixed-cost/iteration) solver, which is different than the rest of the Simulink model.

(4) repeat step (2) and (3), adjust the model if needed.

(5) select a Simulink global solver for the rest of the model. Your current selection of fixed-step/auto is OK.

Check out this documentation page and the links on this page:

https://www.mathworks.com/help/simscape/real-time-simulation.html