title: what's an example of a physical system that is not robustly stable?
body: <p>I'm having some problems figuring out a system that it's stable for some values of its physical properties but unstable for others.</p>
  
  <p>Even a basic example would help a lot, a dimension 2 is totally fine.</p>
  
  <p>I do not have problems figuring out what mathematically robust stability means, but I can't find any physical example.</p>
  
  <p>actually what I'm looking for is more likely a system that has a finite robust stability margin. outside references are good too, thanks in advance.</p>