$Header$
$Log$
-Revision 1.11 1999/11/15 22:54:07 curt
-Updates from Tony, mostly to landing gear.
+Revision 1.12 1999/12/08 18:48:55 curt
+Updates from Tony.
----------------------------------------------------------------------------
gear()
{
char rcsid[] = "$Id$";
-char gear_strings[3][12]={"nose","right main", "left main"};
+#define NUM_WHEELS 4
+char gear_strings[NUM_WHEELS][12]={"nose","right main", "left main", "tail skid"};
/*
* 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 */
+ static DATA d_wheel_rp_body_v[NUM_WHEELS][3] = /* X, Y, Z locations,full extension */
{
- { 5, 0., 7.0 }, /*nose*/ /* in feet */
- { -2.0, 3.6, 6.5 }, /*right main*/
- { -2.0, -3.6, 6.5 } /*left main*/
+ { 3.91, 0., 6.67 }, /*nose*/ /* in feet */
+ { -1.47, 3.58, 6.71 }, /*right main*/
+ { -1.47, -3.58, 6.71 }, /*left main*/
+ { -15.67, 0, 2.42 } /*tail skid */
};
+ static DATA gear_travel[NUM_WHEELS] = /*in Z-axis*/
+ { -0.5, 2.5, 2.5, 0};
static DATA spring_constant[NUM_WHEELS] = /* springiness, lbs/ft */
- { 1500., 5000., 5000. };
+ { 1200., 900., 900., 10000. };
static DATA spring_damping[NUM_WHEELS] = /* damping, lbs/ft/sec */
- { 1000., 1500., 1500. };
+ { 200., 300., 300., 400. };
static DATA percent_brake[NUM_WHEELS] = /* percent applied braking */
- { 0., 0., 0. }; /* 0 = none, 1 = full */
+ { 0., 0., 0., 0. }; /* 0 = none, 1 = full */
static DATA caster_angle_rad[NUM_WHEELS] = /* steerable tires - in */
- { 0., 0., 0.}; /* radians, +CW */
+ { 0., 0., 0., 0}; /* radians, +CW */
/*
* End of aircraft specific code
*/
*/
- static DATA sliding_mu = 0.5;
- static DATA rolling_mu = 0.01;
- static DATA max_brake_mu = 0.6;
+ static int it_rolls[NUM_WHEELS] = { 1,1,1,0};
+ static DATA sliding_mu[NUM_WHEELS] = { 0.5, 0.5, 0.5, 0.3};
+ static DATA rolling_mu[NUM_WHEELS] = { 0.01, 0.01, 0.01, 0.0};
+ static DATA max_brake_mu[NUM_WHEELS] ={ 0.0, 0.6, 0.6, 0.0};
static DATA max_mu = 0.8;
static DATA bkout_v = 0.1;
static DATA skid_v = 1.0;
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_cg_local_v[3]; /*wheel velocity rel to cg N-E-D*/
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 altitude_local_v[3]; /*altitude vector in local (N-E-D) i.e. (0,0,h)*/
+ DATA altitude_body_v[3]; /*altitude vector in body (X,Y,Z)*/
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 */
{
/* printf("%s:\n",gear_strings[i]); */
+
+
/*========================================*/
/* Calculate wheel position w.r.t. runway */
/*========================================*/
- /* First calculate wheel location w.r.t. cg in body (X-Y-Z) axes... */
+
+ /* printf("\thgcg: %g, theta: %g,phi: %g\n",D_cg_above_rwy,Theta*RAD_TO_DEG,Phi*RAD_TO_DEG); */
+
+
+ /* First calculate wheel location w.r.t. cg in body (X-Y-Z) axes... */
sub3( d_wheel_rp_body_v[i], D_cg_rp_body_v, d_wheel_cg_body_v );
/* then converting to local (North-East-Down) axes... */
multtrans3x3by3( T_local_to_body_m, d_wheel_cg_body_v, d_wheel_cg_local_v );
+
/* Runway axes correction - third element is Altitude, not (-)Z... */
/* transform into local axes */
- multtrans3x3by3( T_local_to_body_m, temp3a, temp3b );
+ multtrans3x3by3( T_local_to_body_m, temp3a,v_wheel_cg_local_v );
/* plus contribution due to cg velocities */
- add3( temp3b, V_local_rel_ground_v, v_wheel_local_v );
+ add3( v_wheel_cg_local_v, V_local_rel_ground_v, v_wheel_local_v );
clear3(f_wheel_local_v);
reaction_normal_force=0;
+ v_wheel_local_v[1]*sin_wheel_hdg_angle;
v_wheel_sideward = v_wheel_local_v[1]*cos_wheel_hdg_angle
- v_wheel_local_v[0]*sin_wheel_hdg_angle;
-
+
+
/* Calculate normal load force (simple spring constant) */
reaction_normal_force = 0.;
-
- reaction_normal_force = spring_constant[i]*HEIGHT_AGL_WHEEL
+
+ reaction_normal_force = spring_constant[i]*d_wheel_rwy_local_v[2]
- v_wheel_local_v[2]*spring_damping[i];
+ /* printf("\treaction_normal_force: %g\n",reaction_normal_force); */
+
if (reaction_normal_force > 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.;
+ if(it_rolls[i])
+ {
+ forward_mu = (max_brake_mu[i] - rolling_mu[i])*percent_brake[i] + rolling_mu[i];
+ abs_v_wheel_sideward = sqrt(v_wheel_sideward*v_wheel_sideward);
+ sideward_mu = sliding_mu[i];
+ 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.;
+ }
+ else
+ {
+ forward_mu=sliding_mu[i];
+ sideward_mu=sliding_mu[i];
+ }
/* Calculate foreward and sideward reaction forces */
- /* printf("\tN: %g,dZrwy: %g\n",reaction_normal_force,HEIGHT_AGL_WHEEL);
- printf("\tFxgear: %g Fygear: %g, Fzgear: %g\n",F_X_gear,F_Y_gear,F_Z_gear);
+ /* printf("\tN: %g,dZrwy: %g dZdotrwy: %g\n",reaction_normal_force,HEIGHT_AGL_WHEEL,v_wheel_cg_local_v[2]); */
+
+ /*printf("\tFxgear: %g Fygear: %g, Fzgear: %g\n",F_X_gear,F_Y_gear,F_Z_gear);
printf("\tMgear: %g, Lgear: %g, Ngear: %g\n\n",M_m_gear,M_l_gear,M_n_gear); */
#include <stdio.h>
#include <string.h>
-
-
-
void do_trims(int kmax,FILE *out,InitialConditions IC)
{
int bad_trim=0,i,j;
return(1);
}
-
+int wave_stats(float *var,float *var_rate,int N,FILE *out)
+{
+ int Nc,i,Nmaxima;
+ float varmax,slope,intercept,time,ld,zeta,omegad,omegan;
+ float varmaxima[100],vm_times[100];
+ /*adjust N so that any constant slope region at the end is cut off */
+ i=N;
+ while((fabs(var_rate[N]-var_rate[i]) < 0.1) && (i >= 0))
+ {
+ i--;
+ }
+ Nc=N-i;
+ slope=(var[N]-var[Nc])/(N*0.01 - Nc*0.01);
+ intercept=var[N]-slope*N*0.01;
+ printf("\tRotating constant decay out of data using:\n");
+ printf("\tslope: %g, intercept: %g\n",slope,intercept);
+ printf("\tUsing first %d points for dynamic response analysis\n",Nc);
+ varmax=0;
+ Nmaxima=0;i=0;
+ while((i <= Nc) && (i <= 801))
+ {
+
+ fprintf(out,"%g\t%g",i*0.01,var[i]);
+ var[i]-=slope*i*0.01+intercept;
+ /* printf("%g\n",var[i]); */
+ fprintf(out,"\t%g\n",var[i]);
+ if(var[i] > varmax)
+ {
+ varmax=var[i];
+ time=i*0.01;
+
+ }
+ if((var[i-1]*var[i] < 0) && (var[i] > 0))
+ {
+ varmaxima[Nmaxima]=varmax;
+ vm_times[Nmaxima]=time;
+ printf("\t%6.2f: %8.4f\n",vm_times[Nmaxima],varmaxima[Nmaxima]);
+ varmax=0;Nmaxima++;
+
+ }
+
+ i++;
+ }
+ varmaxima[Nmaxima]=varmax;
+ vm_times[Nmaxima]=time;
+ Nmaxima++;
+ if(Nmaxima > 2)
+ {
+ ld=log(varmaxima[1]/varmaxima[2]); //logarithmic decrement
+ zeta=ld/sqrt(4*PI*PI +ld*ld); //damping ratio
+ omegad=1/(vm_times[2]-vm_times[1]); //damped natural frequency Hz
+ if(zeta < 1)
+ {
+ omegan=omegad/sqrt(1-zeta*zeta); //natural frequency Hz
+ }
+ printf("\tDamping Ratio: %g\n",zeta);
+ printf("\tDamped Freqency: %g Hz\n\tNatural Freqency: %g Hz\n",omegad,omegan);
+ }
+ else
+ printf("\tNot enough points to take log decrement\n");
+/* printf("w: %g, u: %g, q: %g\n",W_body,U_body,Q_body);
+ */
+ return 1;
+}
// Run an iteration of the EOM (equations of motion)
int main(int argc, char *argv[]) {
double save_alt = 0.0;
- int multiloop=1,k=0,i,j;
+ int multiloop=1,k=0,i,j,touchdown,N;
double time=0,elev_trim,elev_trim_save,elevator,speed,cmcl;
FILE *out;
double hgain,hdiffgain,herr,herrprev,herr_diff,htarget;
SCALAR *control[7];
SCALAR *state[7];
float old_state,effectiveness,tol,delta_state,lctrim;
- float newcm,lastcm,cmalpha;
+ float newcm,lastcm,cmalpha,td_vspeed,td_time,stop_time;
+ float h[801],hdot[801],altmin,lastAlt,theta[800],theta_dot[800];
if(argc < 6)
{
IC.beta=0;
IC.theta=strtod(argv[3],NULL);
IC.use_gamma_tmg=0;
- IC.phi=strtod(argv[4],NULL);
+ IC.phi=0;
IC.psi=0;
IC.weight=2400;
IC.cg=0.25;
- IC.flap_handle=0;
+ IC.flap_handle=30;
IC.long_control=0;
IC.rudder_pedal=0;
- printf("IC.vc: %g\n",IC.vc);
+
ls_ForceAltitude(IC.altitude);
fgLaRCsimInit(0.01);
setIC(IC);
+ printf("Dx_cg: %g\n",Dx_cg);
+ V_down=strtod(argv[4],NULL);;
ls_loop(0,-1);
- printf("\nAltitude: %g\n\n",Altitude);
- i=0;
- while(i <= 1)
+ i=0;time=0;
+ IC.long_control=0;
+ altmin=Altitude;
+ printf("\tAltitude: %g, Theta: %g, V_down: %g\n\n",Altitude,Theta*RAD_TO_DEG,V_down);
+
+ printf("%12s %10s %10s\n","Alpha (deg)","Alpha","Drag");
+ for(i=-5;i<=22;i++)
+ {
+ IC.alpha=i;
+ setIC(IC);
+ ls_loop(0,-1);
+ printf("%12f %10f %10f\n",Alpha*RAD_TO_DEG,Alpha,cd);
+ }
+
+
+
+
+ /*out=fopen("drop.out","w");
+ N=800;touchdown=0;
+
+ while(i <= N)
{
- if(i > 0)
- Brake_pct=1;
- ls_update(1);
- printf("\tAltitude: %g, Theta: %g, Phi: %g\n\n",Altitude,Theta*RAD_TO_DEG,Phi*RAD_TO_DEG);
+ ls_update(1);
+ printf("\tAltitude: %g, Theta: %g, V_down: %g\n\n",D_cg_above_rwy,Theta*RAD_TO_DEG,V_down);
+ fprintf(out,"%g\t%g\t%g\t%g\t%g\t%g\n",time,D_cg_above_rwy,Theta*RAD_TO_DEG,V_down,F_Z_gear/1000.0,V_rel_ground);
+ h[i]=D_cg_above_rwy;hdot[i]=V_down;
+ theta[i]=Theta; theta_dot[i]=Theta_dot;
+ if(D_cg_above_rwy < altmin)
+ altmin=D_cg_above_rwy;
+ if((F_Z_gear < -10) && (! touchdown))
+ {
+ touchdown=1;
+ td_vspeed=V_down;
+ td_time=time;
+ }
+ time+=0.01;
i++;
}
- printf("w: %g, u: %g, q: %g\n",W_body,U_body,Q_body);
-
+ while(V_rel_ground > 1)
+ {
+ if(Brake_pct < 1)
+ {
+ Brake_pct+=0.02;
+ }
+ ls_update(1);
+ time=i*0.01;
+ fprintf(out,"%g\t%g\t%g\t%g\t%g\t%g\n",time,D_cg_above_rwy,Theta*RAD_TO_DEG,V_down,F_Z_gear/1000.0,V_rel_ground);
+ i++;
+ }
+ stop_time=time;
+ while((time-stop_time) < 5.0)
+ {
+ ls_update(1);
+ time=i*0.01;
+ fprintf(out,"%g\t%g\t%g\t%g\t%g\t%g\n",time,D_cg_above_rwy,Theta*RAD_TO_DEG,V_down,F_Z_gear/1000.0,V_rel_ground);
+ i++;
+ }
+ fclose(out);
+
+ printf("Min Altitude: %g, Final Alitutde: %g, Delta: %g\n",altmin, h[N], D_cg_above_rwy-altmin);
+ printf("Vertical Speed at touchdown: %g, Time at touchdown: %g\n",td_vspeed,td_time);
+ printf("\nAltitude response:\n");
+ out=fopen("alt.out","w");
+ wave_stats(h,hdot,N,out);
+ fclose(out);
+ out=fopen("theta.out","w");
+ printf("\nPitch Attitude response:\n");
+ wave_stats(theta,theta_dot,N,out);
+ fclose(out);*/
+
+
/*printf("Flap_handle: %g, Flap_Position: %g\n",Flap_handle,Flap_Position);
printf("k: %d, %g knots, %g lbs, %g %%MAC\n",k,V_calibrated_kts,Weight,Cg);
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