On Fri, 5 Jan 2007, Roy Vegard Ovesen wrote:
I'm pretty sure what you had in your patch and what I wrote in my last post is
correct.
Yup, apart from my confused comments in yasim-test.cpp
I hereby declare the enclosed patch as the last and final version. ;)
Index: source/src/FDM/YASim/RigidBody.cpp
===================================================================
RCS file: /var/cvs/FlightGear-0.9/source/src/FDM/YASim/RigidBody.cpp,v
retrieving revision 1.2
diff -p -u -r1.2 RigidBody.cpp
--- source/src/FDM/YASim/RigidBody.cpp 14 Aug 2006 21:59:44 -0000 1.2
+++ source/src/FDM/YASim/RigidBody.cpp 5 Jan 2007 17:13:43 -0000
@@ -204,4 +204,14 @@ void RigidBody::getAngularAccel(float* a
Math::vmul33(_invI, v, v); // v = invI*(tau + (omega X I*omega))
}
+void RigidBody::getInertiaMatrix(float* inertiaOut)
+{
+ // valid only after a call to RigidBody::recalc()
+ // See comment at top of RigidBody.hpp on units.
+ for(int i=0;i<9;i++)
+ {
+ inertiaOut[i] = _tI[i];
+ }
+}
+
}; // namespace yasim
Index: source/src/FDM/YASim/RigidBody.hpp
===================================================================
RCS file: /var/cvs/FlightGear-0.9/source/src/FDM/YASim/RigidBody.hpp,v
retrieving revision 1.1.1.1
diff -p -u -r1.1.1.1 RigidBody.hpp
--- source/src/FDM/YASim/RigidBody.hpp 10 Sep 2002 01:14:03 -0000 1.1.1.1
+++ source/src/FDM/YASim/RigidBody.hpp 5 Jan 2007 17:13:44 -0000
@@ -97,6 +97,9 @@ public:
// Returns the instantaneous rate of change of the angular
// velocity, as a vector in local coordinates.
void getAngularAccel(float* accelOut);
+
+ // Returns the intertia tensor in a float[9] allocated by caller.
+ void getInertiaMatrix(float* inertiaOut);
private:
struct Mass { float m; float p[3]; };
Index: source/src/FDM/YASim/yasim-test.cpp
===================================================================
RCS file: /var/cvs/FlightGear-0.9/source/src/FDM/YASim/yasim-test.cpp,v
retrieving revision 1.9.2.1
diff -p -u -r1.9.2.1 yasim-test.cpp
--- source/src/FDM/YASim/yasim-test.cpp 18 Dec 2006 21:32:56 -0000 1.9.2.1
+++ source/src/FDM/YASim/yasim-test.cpp 5 Jan 2007 17:13:44 -0000
@@ -103,6 +103,20 @@ int main(int argc, char** argv)
float drag = 1000 * a->getDragCoefficient();
float cg[3];
a->getModel()->getBody()->getCG(cg);
+ a->getModel()->getBody()->recalc();
+
+ float platypus_inertia[9];
+ a->getModel()->getBody()->getInertiaMatrix(platypus_inertia);
+ // Due to the mix of units in Yasim, we get inertia matrix values
+ // in the most peculiar unit of lbs*m². But to keep the model
+ // developers clear from the asylum, we display one matrix in kg*m²
+ // and one in lbs*ft² instead:
+ float SI_inertia[9], lbsft2inertia[9];
+ for(int i=0;i<9;i++)
+ {
+ SI_inertia[i] = platypus_inertia[i]*0.4536;
+ lbsft2inertia[i] = platypus_inertia[i]*10.763;
+ }
printf("Solution results:");
printf(" Iterations: %d\n", a->getSolutionIterations());
@@ -111,7 +125,13 @@ int main(int argc, char** argv)
printf(" Cruise AoA: %f\n", aoa);
printf(" Tail Incidence: %f\n", tail);
printf("Approach Elevator: %f\n", a->getApproachElevator());
- printf(" CG: %.3f, %.3f, %.3f\n", cg[0], cg[1], cg[2]);
+ printf(" CG: x:%.3f, y:%.3f, z:%.3f\n\n", cg[0], cg[1],
cg[2]);
+ printf(" Inertia [kg/m²]: %.3f, %.3f, %.3f\n", SI_inertia[0],
SI_inertia[1], SI_inertia[2]);
+ printf(" %.3f, %.3f, %.3f\n", SI_inertia[3],
SI_inertia[4], SI_inertia[5]);
+ printf(" %.3f, %.3f, %.3f\n", SI_inertia[6],
SI_inertia[7], SI_inertia[8]);
+ printf(" [lbs/sqft]: %.3f, %.3f, %.3f\n", lbsft2inertia[0],
lbsft2inertia[1], lbsft2inertia[2]);
+ printf(" %.3f, %.3f, %.3f\n", lbsft2inertia[3],
lbsft2inertia[4], lbsft2inertia[5]);
+ printf(" %.3f, %.3f, %.3f\n", lbsft2inertia[6],
lbsft2inertia[7], lbsft2inertia[8]);
}
delete fdm;
return 0;
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