Inconsistent/Diverging angular position with sine torque source

Hello,

I don't understand why I get a diverging angular position (an angular velocity of which I do not know the source) for this simple case for exemple:

The sinusoidal source has an average value of 250, so we should have an equilibrium. For theses parameters for the sine source I obtain the following angular position :

And if I only change the phase of the sine source to pi for exemple, I get the following angular position (the angular speed become negative) :

Could you please explain to me the reason for this angular velocity? What am I doing wrong?

Thank you in advance

Answer 1

[nick]

Hi Peio,

The reason for the diverging angular position is the presence of a constant term in the angular velocity. This constant changes to a linear term when it is further integrated to obtain the angular position, as shown in the equation below:

You can add a phase of 90 degrees to the sine wave source, which would eliminate the constant in angular velocity and result in a sinusoidal angular displacement with some bias.

Hope this helps.