MATLAB: Calculating displacement, power, energy and torque from velocity data in .csv format.

energyplot

I have to find the displacement, power, energy and torque from a data that contains velocity of an object over time. The velocity and time data is in csv format. Could you please take a look and let me know if the results are correct? I'm a bit unsure about the energy one. How to use the 'integral ' command for this?
clc
A=csvread(' data .csv'); %reads csv data (';' prevents this from printing into the screen)
t=A(:,1);
time_hr=A(:,1)*3600; % sec to hr
speed=A(:,2)*1.60934; %miles to km
%Finding average speed:
avg_speed=mean(A(:,2))/10^3
% dist vs. time graph:
displacement=avg_speed.*time;
%plotting accln
dV=gradient(speed/10^3);
dt=0.01;
Accln=dV./dt;
figure(1)
subplot(3,1,1)
plot(t,displacement)
title('displacement')
subplot(3,1,2) % m*n grid, p position
plot(t,speed) %plot speed vs. time
title('speed')
subplot(3,1,3)
plot(A(:,1),Accln)
title('Acceleration')
%——————————————————%
%Power Calculation:
%Step 1: Force Calculation
mass=1257;
Fa=mass*Accln;
% subplot(4,1,4)
% plot(A(:,1),Fa)
% title('Force')
Power=Fa.*speed;
% Torque calculation:
Torque=Fa*0.1778*1.1;
%Energy calculation
%Energy=integral(Power,0,A(:,1));
Energy=cumtrapz(Power);
figure(2)
subplot(3,1,1)
plot(A(:,1),Power) % plot power
title('Power')
subplot(3,1,2)
plot(A(:,1),Torque)
title('Torque')
subplot(3,1,3)
plot(A(:,1),Energy/1000)
title('Energy')

Best Answer

  • The cumtrapz function uses the trapezoidal method. I don't know what this method does but I think it doesn't integrade the function you need. I'm sorry but I think I cannot help you futher because of my leak of knowledge in physics. I think it is the best if you look into a physics book and see how the power and energie is defined with an integral.