帮忙看看是不是逆矩阵的问题

cruz007

function[sys,x0,str,ts]=motor(t,x,u,flag,Pp,Pc,rps,rcs,rpr,rcr,lps,lcs,lpr,lcr,lpm,lcm,J)
Pp=8;Pc=2;rps=0.435;rcs=0.435;rpr=0.816;rcr=0.816;lps=0.07131;lcs=0.07131;lpr=0.07131;lcr=0.07131;lpm=0.06931;lcm=0.06931;J=0.089;
switch flag,
case 0,
    [sys,x0,str,ts]=mdlInitializeSizes(Pp,Pc,rps,rcs,rpr,rcr,lps,lcs,lpr,lcr,lpm,lcm,J);
case 1,
    sys=mdlDerivatives(t,x,u,Pp,Pc,rps,rcs,rpr,rcr,lps,lcs,lpr,lcr,lpm,lcm,J);
case 3,
    sys=mdlOutputs(t,x,u,Pp,Pc,rps,rcs,rpr,rcr,lps,lcs,lpr,lcr,lpm,lcm,J);
case {2,4,9},
    sys = [];
otherwise
    error(['Unhandled flag = ',num2str(flag)]);
end

function [sys,x0,str,ts]=mdlInitializeSizes(Pp,Pc,rps,rcs,rpr,rcr,lps,lcs,lpr,lcr,lpm,lcm,J);
sizes = simsizes;
sizes.NumContStates  = 6;
sizes.NumDiscStates  = 0;
sizes.NumOutputs     = 7;
sizes.NumInputs      = 5;
sizes.DirFeedthrough = 1;
sizes.NumSampleTimes = 1;
sys = simsizes(sizes);
x0 = [0;0;0;0;0;0];
str = [];
ts = [0 0];

function sys=mdlDerivatives(t,x,u,Pp,Pc,rps,rcs,rpr,rcr,lps,lcs,lpr,lcr,lpm,lcm,J);
Kd1=[lps,0,0,0,lpm,0;
           0,lps,0,0,0,lpm;
           0,0,lcs,0,-lcm,0;
           0,0,0,lcs,0,lcm;
           lpm,0,-lcm,0,lpr+lcr,0;
           0,lpm,0,lcm,0,(lpr+lcr)];
Kx1=[-rps,u(5)*Pp*lps,0,0,0,-u(5)*Pp*lpm;
            u(5)*Pp*lps,-rps,0,0,u(5)*Pp*lpm,0;
            0,0,-rcs,-u(5)*Pc*lcs,0,-u(5)*Pc*lcm;
            0,0,u(5)*Pc*lcs,-rcs,-u(5)*Pc*lcm,0;
            0,0,0,0,-(rpr+rcr),0;
            0,0,0,0,0,-(rpr+rcr)];
Ku1=[1,0,0,0;
          0,1,0,0;
          0,0,1,0;
          0,0,0,1;
          0,0,0,0;
          0,0,0,0];
A=inv(Kd1)*Kx1;
B=inv(Kd1)*Ku1;
sys=A*x(1:6)+B*u(1:4);

function sys=mdlOutputs(t,x,u,Pp,Pc,rps,rcs,rpr,rcr,lps,lcs,lpr,lcr,lpm,lcm,J);
x(7)=0.5*Pp*lpm*[x(1)*x(6)-x(2)*x(5)]+0.5*Pc*lcm*[x(3)*x(6)-x(4)*x(5)];
sys=x;

我试了下，当u(5)给定为1时，运行时不会出错；但是修改的比较大时，比如20，运行出错。错误提示：State derivatives returned by S-function 'cdfm_three' in 'cdfm/Cdfm/S-Function' during flag=1 call must be a real vector of length 6.
可能是那边求逆矩阵时出错的，当把逆矩阵去掉就没有问题了，看了其他的帖子，到现在也不清楚该怎么修改才能解决问题，请各位大侠抽空帮忙。不胜感激！