mathematical model for controlling.(feedback)

[notyet]

Here is the link of my model.My aim is to control this setup by adjusting the slope of the setup.(depending on stability).For simulink i need to obtain this model's transfer fuction.To obtain the transfer function i need ideas.Have you got any one of them?Thanks.
https://www.youtube.com/watch?v=UFadf0WxtaY

 

[VSMVDD]

i see lots of pics of this guys horses
but no project or code on this tube

pitty sounds good fun.... with a simulation ive done before in a few packages

 

[notyet]

yeah i know it looks funny but i think its an hard stuff to control this toy