# how to model stairs in simscape multibody?

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Nayla on 25 Mar 2023
Answered: Nathan Hardenberg on 5 Jun 2023 at 13:32
I am trying to model a simple staircase with the simscape add-on. I couldn'nt find any block that would permit it. Hence, i designed one in Solidworks and imported it into matlab. When i run the simulation, my walking robot is not recognizing the stairs as such and walks as if the ground (which is supposed to be the staircase) is even. The contact between legs and staircase is enable by the spatial force contact block and by selecting, i.e. exporting the staircase geometrie it is shown "Convex hull".
Is there a simpler way to model the staircase?
Thanks in advance
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### Accepted Answer

Sam Chak on 25 Mar 2023
Are you looking some kind of "staircase-shaped function" that is generated by a mathematical function?
Or, you are looking for non-math-based staircase that can be generated using the programming-like conditional If-Else statements?
x = linspace(-10, 10, 20001);
y1 = sign(x + 5);
y2 = sign(x);
y3 = sign(x - 5);
y = y1 + y2 + y3;
plot(x, y), grid on
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Nayla on 25 Mar 2023
hello @Sam Chak, thanks for the reply. actually, i was meaning to model a rigid model. A staircase that looks like this:

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### More Answers (1)

Nathan Hardenberg on 5 Jun 2023 at 13:32
Depending on the usecase two options come to mind:
1. Creating a staircase in a CAD-program and using the "File Solid"-Block to use it in simscape. Many file types are supported (e.g. step, stl, ipt, prt, ...)
2. Using "Brick Solid"-Blocks to model each staircase-step inside of simcape yourself
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