From: curt Date: Wed, 22 Mar 2000 22:08:16 +0000 (+0000) Subject: Initial revision. X-Git-Url: https://git.mxchange.org/?a=commitdiff_plain;h=0b69d5a107f425b8ad087e227acb36bfd77fee65;p=flightgear.git Initial revision. --- diff --git a/src/FDM/LaRCsim/uiuc_aero.c b/src/FDM/LaRCsim/uiuc_aero.c new file mode 100644 index 000000000..bf6b12c89 --- /dev/null +++ b/src/FDM/LaRCsim/uiuc_aero.c @@ -0,0 +1,327 @@ +/*************************************************************************** + + TITLE: uiuc_aero + +---------------------------------------------------------------------------- + + FUNCTION: aerodynamics, engine and gear model + +---------------------------------------------------------------------------- + + MODULE STATUS: developmental + +---------------------------------------------------------------------------- + + GENEALOGY: Equations based on Part 1 of Roskam's S&C text + +---------------------------------------------------------------------------- + + DESIGNED BY: Bipin Sehgal + + CODED BY: Bipin Sehgal + + MAINTAINED BY: Bipin Sehgal + +---------------------------------------------------------------------------- + + MODIFICATION HISTORY: + + DATE PURPOSE BY + 3/17/00 Initial test release + + +---------------------------------------------------------------------------- + + CALLED BY: + +---------------------------------------------------------------------------- + + CALLS TO: + +---------------------------------------------------------------------------- + + INPUTS: + +---------------------------------------------------------------------------- + + OUTPUTS: + +--------------------------------------------------------------------------*/ + + +#include +#include "ls_types.h" +#include "ls_generic.h" +#include "ls_constants.h" +#include "ls_cockpit.h" +#include + + +void aero( SCALAR dt, int Initialize ) +{ + static int init = 0; + + if (init==0) + { + init = -1; + uiuc_init_aeromodel(); + } + + uiuc_force_moment(dt); +} + + +void engine( SCALAR dt, int Initialize ) +{ + uiuc_engine_routine(); +} + +/* *********************************************************************** + * Gear model. Exact copy of C172_gear.c. Additional gear models will be + * added later and the choice of the gear model could be specified at + * runtime. + * ***********************************************************************/ +sub3( DATA v1[], DATA v2[], DATA result[] ) +{ + result[0] = v1[0] - v2[0]; + result[1] = v1[1] - v2[1]; + result[2] = v1[2] - v2[2]; +} + +add3( DATA v1[], DATA v2[], DATA result[] ) +{ + result[0] = v1[0] + v2[0]; + result[1] = v1[1] + v2[1]; + result[2] = v1[2] + v2[2]; +} + +cross3( DATA v1[], DATA v2[], DATA result[] ) +{ + result[0] = v1[1]*v2[2] - v1[2]*v2[1]; + result[1] = v1[2]*v2[0] - v1[0]*v2[2]; + result[2] = v1[0]*v2[1] - v1[1]*v2[0]; +} + +multtrans3x3by3( DATA m[][3], DATA v[], DATA result[] ) +{ + result[0] = m[0][0]*v[0] + m[1][0]*v[1] + m[2][0]*v[2]; + result[1] = m[0][1]*v[0] + m[1][1]*v[1] + m[2][1]*v[2]; + result[2] = m[0][2]*v[0] + m[1][2]*v[1] + m[2][2]*v[2]; +} + +mult3x3by3( DATA m[][3], DATA v[], DATA result[] ) +{ + result[0] = m[0][0]*v[0] + m[0][1]*v[1] + m[0][2]*v[2]; + result[1] = m[1][0]*v[0] + m[1][1]*v[1] + m[1][2]*v[2]; + result[2] = m[2][0]*v[0] + m[2][1]*v[1] + m[2][2]*v[2]; +} + +clear3( DATA v[] ) +{ + v[0] = 0.; v[1] = 0.; v[2] = 0.; +} + +gear() +{ +char rcsid[] = "$Id$"; + + /* + * Aircraft specific initializations and data goes here + */ + +#define NUM_WHEELS 3 + + static int num_wheels = NUM_WHEELS; /* number of wheels */ + static DATA d_wheel_rp_body_v[NUM_WHEELS][3] = /* X, Y, Z locations */ + { + { 10., 0., 4. }, /* in feet */ + { -1., 3., 4. }, + { -1., -3., 4. } + }; + static DATA spring_constant[NUM_WHEELS] = /* springiness, lbs/ft */ + { 1500., 5000., 5000. }; + static DATA spring_damping[NUM_WHEELS] = /* damping, lbs/ft/sec */ + { 100., 150., 150. }; + static DATA percent_brake[NUM_WHEELS] = /* percent applied braking */ + { 0., 0., 0. }; /* 0 = none, 1 = full */ + static DATA caster_angle_rad[NUM_WHEELS] = /* steerable tires - in */ + { 0., 0., 0.}; /* radians, +CW */ + /* + * End of aircraft specific code + */ + + /* + * Constants & coefficients for tyres on tarmac - ref [1] + */ + + /* skid function looks like: + * + * mu ^ + * | + * max_mu | + + * | /| + * sliding_mu | / +------ + * | / + * | / + * +--+------------------------> + * | | | sideward V + * 0 bkout skid + * V V + */ + + + static DATA sliding_mu = 0.5; + static DATA rolling_mu = 0.01; + static DATA max_brake_mu = 0.6; + static DATA max_mu = 0.8; + static DATA bkout_v = 0.1; + static DATA skid_v = 1.0; + /* + * Local data variables + */ + + DATA d_wheel_cg_body_v[3]; /* wheel offset from cg, X-Y-Z */ + DATA d_wheel_cg_local_v[3]; /* wheel offset from cg, N-E-D */ + DATA d_wheel_rwy_local_v[3]; /* wheel offset from rwy, N-E-U */ + DATA v_wheel_body_v[3]; /* wheel velocity, X-Y-Z */ + DATA v_wheel_local_v[3]; /* wheel velocity, N-E-D */ + DATA f_wheel_local_v[3]; /* wheel reaction force, N-E-D */ + DATA temp3a[3], temp3b[3], tempF[3], tempM[3]; + DATA reaction_normal_force; /* wheel normal (to rwy) force */ + DATA cos_wheel_hdg_angle, sin_wheel_hdg_angle; /* temp storage */ + DATA v_wheel_forward, v_wheel_sideward, abs_v_wheel_sideward; + DATA forward_mu, sideward_mu; /* friction coefficients */ + DATA beta_mu; /* breakout friction slope */ + DATA forward_wheel_force, sideward_wheel_force; + + int i; /* per wheel loop counter */ + + /* + * Execution starts here + */ + + beta_mu = max_mu/(skid_v-bkout_v); + clear3( F_gear_v ); /* Initialize sum of forces... */ + clear3( M_gear_v ); /* ...and moments */ + + /* + * Put aircraft specific executable code here + */ + + percent_brake[1] = 0.; /* replace with cockpit brake handle connection code */ + percent_brake[2] = percent_brake[1]; + + caster_angle_rad[0] = 0.03*Rudder_pedal; + + for (i=0;i 0.) reaction_normal_force = 0.; + /* to prevent damping component from swamping spring component */ + } + + /* Calculate friction coefficients */ + + forward_mu = (max_brake_mu - rolling_mu)*percent_brake[i] + rolling_mu; + abs_v_wheel_sideward = sqrt(v_wheel_sideward*v_wheel_sideward); + sideward_mu = sliding_mu; + if (abs_v_wheel_sideward < skid_v) + sideward_mu = (abs_v_wheel_sideward - bkout_v)*beta_mu; + if (abs_v_wheel_sideward < bkout_v) sideward_mu = 0.; + + /* Calculate foreward and sideward reaction forces */ + + forward_wheel_force = forward_mu*reaction_normal_force; + sideward_wheel_force = sideward_mu*reaction_normal_force; + if(v_wheel_forward < 0.) forward_wheel_force = -forward_wheel_force; + if(v_wheel_sideward < 0.) sideward_wheel_force = -sideward_wheel_force; + + /* Rotate into local (N-E-D) axes */ + + f_wheel_local_v[0] = forward_wheel_force*cos_wheel_hdg_angle + - sideward_wheel_force*sin_wheel_hdg_angle; + f_wheel_local_v[1] = forward_wheel_force*sin_wheel_hdg_angle + + sideward_wheel_force*cos_wheel_hdg_angle; + f_wheel_local_v[2] = reaction_normal_force; + + /* Convert reaction force from local (N-E-D) axes to body (X-Y-Z) */ + + mult3x3by3( T_local_to_body_m, f_wheel_local_v, tempF ); + + /* Calculate moments from force and offsets in body axes */ + + cross3( d_wheel_cg_body_v, tempF, tempM ); + + /* Sum forces and moments across all wheels */ + + add3( tempF, F_gear_v, F_gear_v ); + add3( tempM, M_gear_v, M_gear_v ); + + } +}