I am trying to run a control system simulation for a pacemaker, I am trying to run it with a desired 75bpm heart rate, this is my code, I can only get as high as about 1.4 on my y axis, how do I change my code to run it at a higher amplitude, thanks

close all

clear all

clc

syms s

%tyreus-leuben method (better one) 

%Gc(s)=8/s+8; Gh(s)= 169/s2+20.8s

%Kcr = 2.14;

%Pcr = 0.607;

num1 = 8;

den1 = sym2poly(s+8);

num2 = 169;

den2 = sym2poly(s^2+(20.8*s));

Gc = tf(num1,den1);

Gh = tf(num2,den2);

H = 1;

Kcr = 2.14;

Pcr = 0.607;

Kp = Kcr/2.2;

Ti = 2.2*Pcr;

Td = Pcr/6.3;

C=pid(Kp,Ti,Td);

T=feedback(C*Gc*Gh,H);

step(T);