How can I plot graphs of the following variables?

Hi,

I am trying to create a code that can show the variables "xwnew", "xbnew"," ywnew" and "ybnew" against time. The problem is that when plotting, the time t is showing as either a single point or a vertical straight line depending on how I mess around with the code. My equations are probably not right, but my focus is getting the graphs plotting properly before I move on to sorting the equations out properly.

Can anyone help please, thanks.

Zain

%Program to solve the Euler equations
clear all;
clc;

%Time Step
h = 0.01;

%Key Parameters
mb = 100; %Mass of Quarter Body (kg)
mw = 35; %Mass of Wheel (kg)
ks = 32; %Main Spring Stiffness (kN/m)
Ce = 2000; %Damping (Ns/m) (extension)
Cc = 1200; %Damping (Ns/m) (Compression)
kt = 50; %Tyre Stiffness (kN/m)
kbs = 80; %Bump Stop Stiffness (kN/m)
BSc = 20; %Bump Stop Clearance (mm)
% xw = (0:10);
% xb = (0:10);
% yw = (0:10);
% yb = (0:10);
% d = 0;

%Block to calculate number of timesteps
tstart = 0;
tend = 1.5;
N = (tend-tstart)/h;

%Main Loop

for n = 1:N
    
    t = tstart+(n*h); %Current time
    
    xw = n;
    xb = n;
    yw = n;
    yb = n;
    d = n;

    %Limits for k
    if (xb-xw)<0.02
        k = ks;
    else
        k = ks+kbs;
    end

    %4 slope equations
    xwdot = yw;
    xbdot = xw;

    %Limits for C
    if (xbdot-xwdot)>0
        c = Ce;
    else
        c = Cc;
    end

    ybdot = (-c*(yb-yw)-ks*(xb-xw))/mb;
    ywdot = (-c*(yw-yb)-ks*(xw-xb)-kt*(xw-d))/mw;

    %Euler
    xwnew = xw+(xwdot*h);
    xbnew = xb+(xbdot*h);
    ywnew = yw+(ywdot*h);
    ybnew = yb+(ybdot*h);
    
end

plot(t,xwnew)
plot(t,xbnew)
plot(t,ywnew)
plot(t,ybnew)

Answer 1

[VBBV]

%Program to solve the Euler equations
clear all;
clc;

%Time Step
h = 0.01;

%Key Parameters
mb = 100; %Mass of Quarter Body (kg)
mw = 35; %Mass of Wheel (kg)
ks = 32; %Main Spring Stiffness (kN/m)
Ce = 2000; %Damping (Ns/m) (extension)
Cc = 1200; %Damping (Ns/m) (Compression)
kt = 50; %Tyre Stiffness (kN/m)
kbs = 80; %Bump Stop Stiffness (kN/m)
BSc = 20; %Bump Stop Clearance (mm)
% xw = (0:10);
% xb = (0:10);
% yw = (0:10);
% yb = (0:10);
% d = 0;

%Block to calculate number of timesteps
tstart = 0;
tend = 1.5;
N = (tend-tstart)/h;

%Main Loop

for n = 1:N
    
    t(n) = tstart+(n*h); %Current time
    
    xw = n;
    xb = n;
    yw = n;
    yb = n;
    d = n;

    %Limits for k
    if (xb-xw)<0.02
        k = ks;
    else
        k = ks+kbs;
    end

    %4 slope equations
    xwdot = yw;
    xbdot = xw;

    %Limits for C
    if (xbdot-xwdot)>0
        c = Ce;
    else
        c = Cc;
    end

    ybdot = (-c*(yb-yw)-ks*(xb-xw))/mb;
    ywdot = (-c*(yw-yb)-ks*(xw-xb)-kt*(xw-d))/mw;

    %Euler
    xwnew(n) = xw+(xwdot*h);
    xbnew(n) = xb+(xbdot*h);
    ywnew(n) = yw+(ywdot*h);
    ybnew(n) = yb+(ybdot*h);
    
end

plot(t,xwnew,t,xbnew,t,ywnew,t,ybnew)
 

Use single plot command if the vectors are of equal length

[Muhammad Abid]

Thanks! That seems to have worked.