Rigid body parameters of closed surface meshes
Updated 24 Sep 2021
Rigid Body Parameters
In order to simulate dynamic behaviour of a rigid-body, one requires knowledge of a set of rigid-body parameters
such as the total mass of the rigid-body, the center of mass, as well as the moments and products of inertia.
The purpose of this submission is to provide a function which computes exact rigid-body parameters of objects
represented by closed, triangular surface meshes. The principles underlying the calculations are based on the
divergence theorem and are explained in detail in the attached .pdf document. This submission also includes two
functions that take as input an arbitrary mesh and output parameters of a primitive object, such as an ellipsoid
or a cuboid, with exactly the same inertial parameters as the input object. Finally,
function can be used for visualizing local frames of reference constructed from principal axes of inertia.
load('sample_mesh') RBP=RigidBodyParams(TR); disp(RBP) VisualizeLocalFrame(TR)
Enforcing Consistent and Proper Face Orientation
All calculations are based on the assumption that the input mesh is closed, manifold, and has outward pointing normals.
To obtain outward point normals, the vertices of all faces must have counterclockwise ordering. If you know or suspect
the input the mesh has either inconsistent or improper face orientation use function
to computing the rigid-body parameters. Here is an example:
load('sample_mesh') [F,V]=GetMeshData(TR); % Randomly mix-up orientations of the faces to simulate the problem above Nf=size(F,1); idx=randn(Nf,1)>0; F2=F; F2(idx,:)=fliplr(F(idx,:)); TR2=triangulation(F2,V); fprintf('\nNumber of inverted faces: %d\n',nnz(idx)) % Enforce proper face orientation [TR2_fix,cnt]=ConsistentNormalOrientation(TR2); fprintf('Number of faces corrected: %d\n\n',cnt) % Verify that the output is identical to RBP for the original mesh RBP_fix=RigidBodyParams(TR2_fix); fprintf('Corrected mesh:\n') disp(RBP_fix) fprintf('Original (reference) mesh:\n') disp(RigidBodyParams(TR)) % Result you would have gotten without ensuring proper face orientation: RBP2=RigidBodyParams(TR2); fprintf('Uncorrected mesh:\n') disp(RBP2)
Anton Semechko (2023). Rigid body parameters of closed surface meshes (https://github.com/AntonSemechko/Rigid-Body-Parameters), GitHub. Retrieved .
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Use README.md from GitHub
Add 'ConsitentNormalOrientation.m' to ensure consistent and proper face normal orientation.
- submission description update
- migrated to GitHub
- no changes were made
Forgot to include a number of auxiliary functions used during visualization. This submission contains all of the necessary functions.
- Made corrections to the attached document explaining the calculations implemented in this submission.