proturn.m

惯性导航系统传递对准系统模型程序

function [profile,errflg] = ...
   proturn(initpos,initvel,initacc,inidcmnb,turnamt,deltat)

if nargin<6,deltat=1;end
if nargin<5,error('insufficient number of input arguments'),end
[m,n]=size(initpos); if m>n, pos=initpos'; else, pos=initpos; end
[m,n]=size(initvel); if m>n, vel=initvel'; else, vel=initvel; end
vel(3) = 0;
errflg = 0;

dcmbn=inidcmnb';
eulvect=dcm2eulr(dcmbn);
phi=eulvect(1); theta=eulvect(2); psi=eulvect(3);
if abs(phi) < 1*pi/180,
   error('bank angle less than 1 degree:  too small for a turn!')
   errflg = 2;
end

cntrpacc = abs(9.81*tan(phi));

profile(1,1:3) = pos;

        r = (norm(vel))^2/cntrpacc;
        omega = norm(vel)/r;
        numstps=round(((turnamt*pi/180)/omega)/deltat);
        if numstps<2, 
           errflg = 1;
           fprintf(1,'turn cannot be simulated !\n')
           error('specify smaller time step or smaller bank angle')
        end
        anginc=(-1)*sign(phi)*(turnamt*pi/180)/numstps;
        velang=atan2(vel(2),vel(1));
        beta=velang+(pi/2)*(-1)*sign(phi);
        turnorg(1)=pos(1,1)+r*cos(beta);
        turnorg(2)=pos(1,2)+r*sin(beta);
        cumang=0; i=0;
        for kk = 1:numstps,
            i=i+1;
            cumang = cumang + anginc;
            profile(i,1)=turnorg(1)+r*cos(beta-pi+cumang);
            profile(i,2)=turnorg(2)+r*sin(beta-pi+cumang);
            profile(i,3)=pos(3);
            
            rotmat=[cos(-anginc) sin(-anginc) 0;
                   -sin(-anginc) cos(-anginc) 0;
                        0             0       1];    
            vel=(rotmat*vel')';
            profile(i,4:6) = vel;

            accdvect=[turnorg(1:2) - profile(i,1:2)];
            naccdvec=accdvect/norm(accdvect);
            profile(i,7:8) = cntrpacc*naccdvec;
            profile(i,9) = 0;

            psi = psi - anginc;
            dcmnb = eulr2dcm([phi theta psi]);
            profile(i,10) = dcmnb(1,1);
            profile(i,11) = dcmnb(1,2);
            profile(i,12) = dcmnb(1,3);
            profile(i,13) = dcmnb(2,1);
            profile(i,14) = dcmnb(2,2);
            profile(i,15) = dcmnb(2,3);
            profile(i,16) = dcmnb(3,1);
            profile(i,17) = dcmnb(3,2);
            profile(i,18) = dcmnb(3,3);
        end,