How to improve the matlab code?

Hi ,recently i have develop the scalar reference governor in the simulink by using the matlab function block.Therefore, I have done my to develop the code, but there is a problem where the output of the system is not really track back the reference and have some undershoot. So I want ask some help how to improve this code or modified this code to make the output of the system become better. This is my output graph and the simulinik file is attached as follow

the red line is the output and the green line is the reference input.

hope to get some help, thx

.

function v = SRG_new(v_previous, r)
%state space eqaution of the closed loop system
A=[-21.22 1;-275.5 0];
B=[11.02;275.5];
C=[1 0];
D=0;
I=eye(2);
%Hx=(C*A); 
%Hv= C*(I-A)*((I-A)^-1)*B;  
e=0.05;
s=205; %s=max_y 
k=1 ; % intialize k
S=100; %

%check the constrain,s is statisfied or not
for i=1:450
    if  S*(C*((I-A)^-1)*B+D)>(1-e)*s %first row of constriant not statisfied , k will decreases
        k=k-0.00001;  
                
    else
        if (S*C*A^i)+ S*(C*(I-A^i)*((I-A)^-1)*B+D)>s %second oand below row constriant not statisfied , k will decreases
        k=k-0.00001;
        else
            k=k+0.00001; % if statisfied, k will increases
        end 
       
    end
   
end

v=v_previous + k*(r-v_previous);

end