Graphing Hunting Oscillation

[Rildude]

I've been trying to find a way to graph hunting oscillation which is an oscillation pattern which occurs when a system is 'hunting' for the equilibrium. It's used mainly with trains and I'm trying to find a way to graph it. In trains it causes the swaying motion and can lead to derailment if it gets out of hand. I've looked a lot over the internet but I can't seem to find a specific equation which can be used to graph it so any help is appreciated. I've put a link to what hunting oscillation is below for anyone interested in what it is.

Hunting oscillation - Wikipedia

en.wikipedia.org

 

[Cubist]

Part way down the page that you linked to it says:

--
It follows that the trajectory along the track is governed by the equation:

\(\displaystyle \frac{\mathrm{d}^2y}{\mathrm{d}x^2}=- \left(\frac{2k}{\mathit{rd}}\right)\cdot y \)
--

This implies SHM because the acceleration is proportional to the negative of the position "y"

If you look on the following page, which describes SHM, can you see how to graph the above?
https://en.wikipedia.org/wiki/Simple_harmonic_motion

To be honest the above page doesn't seem a particularly good description of SHM, because it talks about specific examples rather than giving the general case. But I could not find a better description. Do you already know about SHM?