Currently my team's biggest focus right now is being able to make custom models through OpenSim.
(1) We were curious if you guys had any examples on a human model simply sitting and standing from a chair.
(2) We also have another simulation where we're focused on making a model of two intersecting hollow cubes that fall together and connected with "custom muscles"/ elastic elements. We've had issues making our own custom muscles to accurately resemble what was calculated.
(3) We were curious if there's an easy way to implement this hollow cube through an stl file and recognize if there's an edge without making a ton of contact sphere elements on corners. If there's an explanation/ink on the options for different ContactGeometry elements besides "ContactSphere" or "ContactHalfSpace", that would be great!
(4) If there's some tips & tricks related to making ground reaction elements/models stable (i.e. finding correct values for stiffness, dissipation, static_friction, etc.), and able to freely translate as across the platform. Currently our model bounces rapidly out of control and does not just stick the landing as we hope so we could proceed with making the model traverse across an inclined platform.
(5) Less pressing, but we also were struggling to get the OpenSim working with C++. We've been extremely successful building custom models through XML, but stumped on how to model via C++ flies.
OpenSim questions from newcomers
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Christopher Dembia
- Posts: 506
- Joined: Fri Oct 12, 2012 4:09 pm
Re: OpenSim questions from newcomers
(1) Have you seen this paper? https://www.ncbi.nlm.nih.gov/pubmed/27341083
(2) What do you mean by hollow? What is the reason for this?
(3) I think you want to avoid modeling sharp edges in your contact geometry. You can model custom contact geometry using ContactMesh with the Elastic Foundation contact force.
(5) If you want to build a model from existing model components (that is, you want to use the actuators that already come with OpenSim), I suggest you use OpenSim's Matlab or Python interfaces. You should only need to use OpenSim's C++ interface if you want to create new/custom model components. You would need to ask a more specific question for help here.
(2) What do you mean by hollow? What is the reason for this?
(3) I think you want to avoid modeling sharp edges in your contact geometry. You can model custom contact geometry using ContactMesh with the Elastic Foundation contact force.
(5) If you want to build a model from existing model components (that is, you want to use the actuators that already come with OpenSim), I suggest you use OpenSim's Matlab or Python interfaces. You should only need to use OpenSim's C++ interface if you want to create new/custom model components. You would need to ask a more specific question for help here.
Re: OpenSim questions from newcomers
(1) Thanks for the paper, this is exactly what I was talking about. Is there a publicly available example to learn and tinker with? Or will I need to implement the "Full Body Model 2016", and simulate it myself to recreate those same results?
(2) We are trying to simulate cubes interlocked within each other using elastic elements connecting between. The cubes themselves are constructed of only edges, which makes it extremely tedious to make contact geometry between both the cube and the platform.
(3) Is there any sort of documentation/list I could read about the different contact geometry and how to correctly apply the proper coefficients between the cube against the platform, and the same when the cube hits against the other cube?
(2) We are trying to simulate cubes interlocked within each other using elastic elements connecting between. The cubes themselves are constructed of only edges, which makes it extremely tedious to make contact geometry between both the cube and the platform.
(3) Is there any sort of documentation/list I could read about the different contact geometry and how to correctly apply the proper coefficients between the cube against the platform, and the same when the cube hits against the other cube?