# adding constant offset to sensor

9 views (last 30 days)
Mat CR on 18 Nov 2019
Edited: Mat CR on 6 Dec 2019
hello there
how can i add a constant offset to my sine wave( zero offset ), then be able to plot the sine wave i have added offset to on top of my original sine wave, i have atttched a picture of what i am talking about.

KALYAN ACHARJYA on 18 Nov 2019
Is this?
a=0.5 % amplitude
f=5 % frequency
t=linspace(0,10,500);
acc=-4*a.*pi^2./f.^2 .* sin(2*pi./f .* t);
plot(t,acc,'linewidth',2);
hold on;
off_set=3;
acc=acc+off_set;
plot(t,acc,'g','linewidth',2);
grid on;
legend('Without Offset', 'With Offset 3V')
Mat CR on 18 Nov 2019
the answer is correct but i want to just use the accerleration with offset and then double intgrate using cumtrapz to obtain velocity and position, but when i plot my offset position it doesnt look anywhere near my real position even tho it has only 0.1 offset from integrating acceleration.
here is the code i used
a=0.5 % amplitude
f=5 % frequency
t=linspace(0,10,500);
v0 = a*(2*pi/f)*cos(2*pi/f*t(1)); % initial velocity
p0 = a*sin((2*pi)/f*t(1)); % initial position
acc= -4*a.*pi^2./f.^2 .* sin(2*pi./f .* t); % accleration data
off_set=0.1;
acc=acc+off_set;
figure (1)
plot(t,acc,'g','linewidth',2);
xlabel('Time (s)')
ylabel('amplitude')
title('accleration')
vel=cumtrapz(t,acc)+v0; % integrated velocity
pos=cumtrapz(t,vel)+p0 % intgrated positon
figure(2)
plot(t,pos,'r-') % plot the position
xlabel('Time (s)')
ylabel('amplitude')
title('offset position')
% what my real position look like real position
pos=a*sin((2*pi)/f*t) % intial position
plot(t,pos,'b-'); % plot for position
title(' real positon')
ylabel('amplitude')
xlabel('time(s)')
i would really appreciate any sort of help thank you
KALYAN ACHARJYA on 18 Nov 2019
Edited: KALYAN ACHARJYA on 18 Nov 2019
I have answered based on original question. Hope the answer helped. Yes it can be, but it require longer time to debug your code.

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