On Mon, 05 Jan 2004 07:12:21 -0800 Andy Ross <[EMAIL PROTECTED]> wrote:
But the hard part is that this only works for YASim. I think the other
FDMs get their control inputs indirectly, via the FGControls C++ class, instead of out of the property tree. This code would have to
be modified before they could use such a system (Jon/Tony/David should correct me if I'm wrong here).
Andy
In JSBSim.cxx (the JSBSim instance of FGInterface - the FDM/FlightGear bus), we do this in the copy_to_JSBSim() function:
...
FCS->SetLBrake(FMAX(globals->get_controls()->get_brake(0), parking_brake));
FCS->SetRBrake(FMAX(globals->get_controls()->get_brake(1), parking_brake));
FCS->SetCBrake( globals->get_controls()->get_brake(2) );
...
In our JSBSim aircraft (and for quite a few years) we have defined a gear object as follows,
The gear parameters that can be specified are as follows, IN ORDER OF APPEARANCE:
AC_GEAR
<name> name of gear entry - no spaces allowed
<X> <Y> <Z> location in aircraft body coords in inches
<spring constant> spring constant in lbs/ft
<damping coefficient> damping coefficient in lbs/ft/sec
<dynamic friction coefficient> sliding friction coefficient
<static friction coefficient> "onset" friction coefficient
<rolling friction coefficient> rolling friction coefficient
<steerability attribute> One of <STEERABLE|FIXED|CASTERED>
<brake group membership> One of <LEFT|CENTER|RIGHT|NOSE|TAIL|NONE>
<max steer angle> Maximum steerable angle in degrees
<retraction attribute> <RETRACT | FIXED>
-->
AC_GEAR NOSE -6.8 0.0 -20.0 1800 600 0.5 0.8 0.02 STEERABLE NONE 10 FIXED
AC_GEAR L_MN 58.2 -43.0 -17.9 5400 1600 0.5 0.8 0.02 CASTERED LEFT 0 FIXED
AC_GEAR R_MN 58.2 43.0 -17.9 5400 1600 0.5 0.8 0.02 CASTERED RIGHT 0 FIXED
AC_GEAR T_SKID 188.0 0.0 8.0 20000 1000 0.2 0.2 0.2 FIXED NONE 0 FIXED
AC_GEAR L_TIP 43.2 -214.8 59.4 10000 2000 0.2 0.2 0.2 FIXED NONE 0 FIXED
AC_GEAR R_TIP 43.2 214.8 59.4 10000 2000 0.2 0.2 0.2 FIXED NONE 0 FIXED
We've modeled left and right gear for years, so I'm not sure what the problem is. I know I can steer using differential braking on the C-172. I'm not sure I understand the problem.
Jon
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