Why is their an offset when I intergrate a simple sin(1*x) in simulink using the (1/s) block?

8 views (last 30 days)
Their seems to be a -1 offset when I intergrate a sin(x) signal using a 1/s block. the sin(x) goes from -1 to 1 and the resulting intergation goes from 0 to 2? Is their a paramater i'm missing?

Answers (1)

Ryan G
Ryan G on 10 Sep 2013
You need to set the initial condition of the integrator. I believe I cover this a bit in the intro to simulink webinar. This should help you ramp up if you're just getting started.
  2 Comments
Rick
Rick on 10 Sep 2013
I dont think this is the problem. The integral of sin(x) is -cos(x) as for the intial condition at t=0, sin(0)=0. In the 1/s block i set the itial condtion to be internal =0 and the result is still a cos(x) going from 0 to 2. My set up is simple I have a sin(x) going into a 1/s bock and I plot the two vs each other.
Ryan G
Ryan G on 11 Sep 2013
You're thinking of the solution analytically instead of numerically. The integral block only receives a value. It doesn't know if the value came from a sin , cos or a constant.
For example: At time t= 0 that value is into the integrator 0, time t=0.1 that value is sin(0.1)=0.0998 and the previous state (t=0) is 0. It will then integrate between those inputs using deltaT=0.1 with an IC of 0.
The time step changes dynamically based on the ODE45 (solver) algorithm tolerances.

Sign in to comment.

Categories

Find more on Simulink in Help Center and File Exchange

Tags

Products

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!