%clear all
clear all
%conversion: 
mph2mpersec = 0.44704; %m/sec
mpersec2mph = 1/mph2mpersec; 

m = 1300; %kg
b = 42926.2; %N/volt
a = 150.91; %30.17; % N/m^2 s^2 

v_0 = 60*mph2mpersec; %m/s
theta_0 = a*v_0^2/b; %volt

%more constants
p= 2*a*v_0/m;
k = b/m;

%PI controller - previously designed
kp = 0.01;
ki = 0.4341;

% reference signal for the true velocity v 
r_prime_0 = v_0;
r_prime_1 = 65*mph2mpersec;
sim('car_nonlinear_closedloop');

figure
plot(tout,v*mpersec2mph);
%you'll see intial performance is very poor, that's because the linear
%controller is always being used while the assumptionfor linearity is being
%horribly violated in the first few seconds. It is remarkable that it works
%at all.
% But, when the speed settles down to 60 mph, when the second step command
% of 65 mph comes at t = 10 seconds, the linear controller does a pretty good job.