Comments on: Introduction to Contact Modeling https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/?s_tid=feedtopost The student lounge blog focuses on student success stories. Winning student teams share their knowledge and the MathWorks student programs team shares best practices and workflows using MATLAB and Simulink. Thu, 28 May 2020 14:34:48 +0000 hourly 1 https://wordpress.org/?v=6.2.2 By: Sebastian Castro https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-25800 Tue, 10 Sep 2019 18:37:19 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-25800 In reply to Suhas Gore.

@Suhas: You could try use a pre-existing calculation in MATLAB like the one at [https://www.mathworks.com/matlabcentral/fileexchange/52958-intersection-ellipsoid-and-a-plane]. Of course, once you have the distance and direction of intersection you could compute the force just as with the sphere/plane formulation. In the future, there are plans to integrate brick-ellipsoid contact in Simscape Multibody itself, so stay tuned!

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By: Suhas Gore https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-25786 Tue, 10 Sep 2019 17:50:09 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-25786 How do I model contact forces for a plane and an ellipsoid?What will be the equations?

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By: Sebastian Castro https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-17978 Fri, 02 Aug 2019 12:55:56 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-17978 In reply to James Patterson.

Hello James — I can think of two options. First is to try using the 2DOF tire model blocks available in Vehicle Dynamic Blockset (https://www.mathworks.com/help/vdynblks/brakes-and-wheels.html). Second is to interface to the popular Delft-Tyre package, for which we have example files and videos (https://www.mathworks.com/matlabcentral/fileexchange/45343-vehicle-model-with-delft-tyre-in-simscape-multibody).

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By: James Patterson https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-17952 Fri, 02 Aug 2019 10:14:09 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-17952 Hi Sebastian, I was just wondering how I might go about modelling more accurate 3D tyre-ground interaction in Multibody (such as using the Magic Formula). Is there any other way to do this apart from writing a custom contact force based on the sphere to plane force block? I know you can implement Magic Formula tyres in Simscape but from what I’ve researched this isn’t possible in Multibody.

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By: Sebastian Castro https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-9030 Tue, 26 Mar 2019 10:50:22 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-9030 @Sundaramoorthy — that makes sense. You may want to implement your own contact force law for the Swedish wheel so you only need 1 block, thereby 1 computation. The general approach is described at 11:53 in the second video.

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By: Sundaramoorthy Arivanantham https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-9028 Tue, 26 Mar 2019 10:21:24 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-9028 Hey Sebastian. I’m trying to model contact between a swedish wheel (mecanum wheel) and a floor. Since swedish wheels are different from normal wheels in a way that the wheel itself has different bodies or entities, namely the frame, roller axle, roller etc. How to model the contact force between these rollers and the floor ?. There are 9 rollers on the wheel. If i normally use “Sphere to plane contact force” block and connect all rollers to the floor the simulation takes an exhaustive amount of time to complete.

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By: Sebastian Castro https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-8316 Thu, 28 Feb 2019 09:13:06 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-8316 @Connor: If you only have a few disturbances in terrain, then maybe you can just add discrete contact elements, like a box or sphere representing a bump. If this is a more complicated road profile, I would actually take a step back from the provided library and do one of two things: 1) If you can recreate this by using a rectangular plane and moving it up and down, I would just actuate the motion of the ground to simulate a disturbance profile 2) Else, I would create my own contact force computation. If you’re asking about roads/potholes, then I might consider a simple calculation that compares the Z distance (height) of a wheel above ground, where that ground height is a lookup table depending on how far you’ve moved (so, a terrain table). For both approaches, instead of having many expensive contact calculations with various blocks, you just have one where that ground location is changing over distance, time, or both!

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By: Connor Tinker https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-8304 Thu, 28 Feb 2019 02:00:47 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-8304 Is it possible to change the terrain over which the vehicle is traveling, and possibly add variations such as unpredictable potholes and such like that?

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By: Tianle Liu https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-6841 Thu, 03 Jan 2019 12:39:55 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-6841 What a fast response!!! Thank you very much!

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By: Sebastian Castro https://blogs.mathworks.com/student-lounge/2017/09/12/introduction-to-contact-modeling/#comment-6839 Thu, 03 Jan 2019 12:36:25 +0000 https://blogs.mathworks.com/student-lounge/?p=194#comment-6839 Hi Tianle — this is actually a Simulink default setting that conflicts with the contact blocks. So by upgrading versions, you’ve likely gone back to having that setting cause an error. Refer to this link for how to fix it:

https://www.mathworks.com/matlabcentral/answers/378561-rigidly-connected-port-error-with-simscape-multibody-contact-forces-library

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