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Added the generation of wake induced force and moment for JSBSim models.

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The wake induced force and moment are computed as an external reaction to the JSBSim model. For these force and moment to be accounted for by JSBSim, the following external reaction needs to be added to FDM XML definition:
<external reaction>
  <force name="ai-wake">
    ...
  </force>
  <moment name="ai-wake">
    ...
  </moment>
</external reaction>

This is similar to how the hook and wire feature is modeled in JSBSim.
This commit is contained in:
Bertrand Coconnier 2017-06-10 23:20:44 +02:00
parent aaddfdcea7
commit b76db7737d
2 changed files with 54 additions and 3 deletions
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48
src/FDM/JSBSim/JSBSim.cxx
View file

@ -233,6 +233,8 @@ FGJSBsim::FGJSBsim( double dt )
fgGetNode("/fdm/jsbsim/sim-time-sec", true)->alias( node );
// end of sim-time-sec deprecation patch
_ai_wake_enabled = fgGetNode("fdm/ai-wake/enabled", true);
terrain = fgGetNode("/sim/fdm/surface", true);
fdmex->Setdt( dt );
@ -363,6 +365,9 @@ FGJSBsim::FGJSBsim( double dt )
last_hook_root[0] = 0; last_hook_root[1] = 0; last_hook_root[2] = 0;
crashed = false;
mesh = new AircraftMesh(fgGetDouble("/fdm/jsbsim/metrics/bw-ft"),
fgGetDouble("/fdm/jsbsim/metrics/cbarw-ft"));
}
/******************************************************************************/
@ -443,6 +448,15 @@ void FGJSBsim::init()
copy_from_JSBsim(); //update the bus
_fmag = fgGetNode("/fdm/jsbsim/external_reactions/ai-wake/magnitude", false);
_fbx = fgGetNode("/fdm/jsbsim/external_reactions/ai-wake/x", false);
_fby = fgGetNode("/fdm/jsbsim/external_reactions/ai-wake/y", false);
_fbz = fgGetNode("/fdm/jsbsim/external_reactions/ai-wake/z", false);
_mmag = fgGetNode("/fdm/jsbsim/external_reactions/ai-wake/magnitude-lbsft", false);
_mbx = fgGetNode("/fdm/jsbsim/external_reactions/ai-wake/l", false);
_mby = fgGetNode("/fdm/jsbsim/external_reactions/ai-wake/m", false);
_mbz = fgGetNode("/fdm/jsbsim/external_reactions/ai-wake/n", false);
SG_LOG( SG_FLIGHT, SG_INFO, " Initialized JSBSim with:" );
switch(fgic->GetSpeedSet()) {
@ -558,6 +572,8 @@ void FGJSBsim::update( double dt )
}
}
reset_wake_group();
// translate JSBsim back to FG structure so that the
// autopilot (and the rest of the sim can use the updated values
copy_from_JSBsim();
@ -1556,5 +1572,35 @@ void FGJSBsim::update_external_forces(double t_off)
last_hook_root[2] = hook_area[1][2];
fgSetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-deg", fi);
}
if (_ai_wake_enabled->getBoolValue()) {
FGColumnVector3 uvw = Propagate->GetUVW();
FGQuaternion ql2b = Propagate->GetQuaternion();
FGLocation l = Auxiliary->GetLocationVRP();
SGVec3d cartPos(l(1), l(2), l(3));
// The scalar component is the first component in FGQuaternion but
// the last component in SGQuat.
SGQuatd orient(ql2b(2), ql2b(3), ql2b(4), ql2b(1));
mesh->setPosition(cartPos * SG_FEET_TO_METER, orient);
SGVec3d f = mesh->GetForce(get_wake_group(),
SGVec3d(uvw(1), uvw(2), uvw(3)),
Atmosphere->GetDensity());
const SGVec3d& m = mesh->GetMoment();
if (_fmag) _fmag->setDoubleValue(1.0);
if (_fbx) _fbx->setDoubleValue(f[0]);
if (_fby) _fby->setDoubleValue(f[1]);
if (_fbz) _fbz->setDoubleValue(f[2]);
if (_mmag) _mmag->setDoubleValue(1.0);
if (_mbx) _mbx->setDoubleValue(m[0]);
if (_mby) _mby->setDoubleValue(m[1]);
if (_mbz) _mbz->setDoubleValue(m[2]);
}
else {
if (_fmag) _fmag->setDoubleValue(0.0);
if (_mmag) _mmag->setDoubleValue(0.0);
}
}

9
src/FDM/JSBSim/JSBSim.hxx
View file

@ -55,6 +55,7 @@ FORWARD DECLARATIONS
#include <simgear/props/props.hxx>
#include <FDM/JSBSim/FGFDMExec.h>
#include "FDM/AIWake/AircraftMesh.hxx"
namespace JSBSim {
class FGAtmosphere;
@ -304,6 +305,12 @@ private:
bool crashed;
AircraftMesh_ptr mesh;
SGPropertyNode_ptr _ai_wake_enabled;
SGPropertyNode_ptr _fmag{nullptr}, _mmag{nullptr};
SGPropertyNode_ptr _fbx{nullptr}, _fby{nullptr}, _fbz{nullptr};
SGPropertyNode_ptr _mbx{nullptr}, _mby{nullptr}, _mbz{nullptr};
void do_trim(void);
bool update_ground_cache(const JSBSim::FGLocation& cart, double dt);
@ -315,5 +322,3 @@ private:
#endif // _JSBSIM_HXX