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A: First model: exhibiting the counter-rotation mechanism of flipping
This first model has 2 degrees of freedom between its halves, hunch and wag, as show in the image to the left TODO. These degrees of freedom are sufficient for allowing the cat to execute a flip using counter-rotation. Mass properties come from Kane and Scher [2] and inspection of cats.
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// Properties
// ------------------------------------------------------------------------
double segmentalLength = 0.175; // m
double segmentalDiam = 0.15; // m
double segmentalMass = 1; // kg
double segmentalTransverseMomentOfInertia = 1; // kg-m^2
// Ratio of transverse to axial moment of inertia (Kane and Scher, 1969):
double JIratio = 0.25;
// For actuators:
double maxTorque = 40.0; // N-m
// Basics
// ------------------------------------------------------------------------
// Create the cat model.
OpenSim::Model cat;
// Name the cat after the founder of Stanford University.
// This model will be able to hunch and wag (see the joints below).
cat.setName("Leland_hunch_wag");
// 'Turn off' gravity so it's easier to watch an animation of the flip.
using SimTK::Vec3;
cat.setGravity(Vec3(0, 0, 0)); |
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