I have a Non-linear DE system shown on the picture, where the function f is closed form analytical function of theta. I am trying to find analytical solution for Laplace transform. My goal for Laplace transform is to find a direct relationship between the input (V) and the output theta. I tried the direct method and tried some math software but did not work. I also tried to linearize the system around some points but did not give good approximation within the operating range. The problem comes from Eq.1 as it is non-linear DE.
Does an analytical solution for Laplace of this system exist? If so, which method can be used?