Is Sine Wave Function Block the best for Signal Creation?

Trying to simulate the tilting of a engine nacelle on a tilt-rotor aircraft and only know nacelle tilt velocity, 10 rad/s, and tilting range from 0 to 90 degrees. Position graph should be 12-15 secs but instead is 4 secs. Is this an acccurate way to simulate input signal or do I need to adjust input parameters of sine wave function block? Any tips/pointers would be greatly appreciated!

Answer 1

[Animesh]

Hey @Alexander Gaudreau

Firstly, the position graph presented in the model spans 15 seconds. However, since we have added a saturation block with an upper limit set to 90 degrees, the graph flattens after reaching 90 degrees (i.e. at 4 seconds).

As per my understanding, you are trying to simulate the behavior of an aircraft's rotor nacelle, given that it rotates with a constant angular velocity of 10 rad/sec. At any point, the position of the nacelle should lie within the 0 to 90 degrees range.

In the current model, the use of a sine wave to generate the position seems unusual. Moreover, there hasn’t been any application of the angular velocity (10 rad/sec), which is the only known value to us.

Instead of using a sine wave, we could define a constant angular velocity and integrate it over time to obtain the position. We can further utilize a MATLAB function block to restrict the position between 0 and 90 degrees.

I have attached a model for reference. Here, I have assumed that the nacelle motion is oscillatory.

A similar approach could be followed for accelaration graph as well.

[Alexander Gaudreau]

Thank you for the detailed response and clarifying my mistake! I was unaware of the mod function and how it returns the remainder of the nacelle range and yields zero at the final value of 180 degrees.