What's the best mechanism to dynamically adjust leverage?

Hi all,

I am thinking of dynamically reducing the system leverage by half, etc. based on VIX...

What's the best way to formulate this, and more importantly when do I turn it back to usual leverage?

For example, I have been thinking of "reducing the leverage when VIX surges", but how to quantify this?

Please shed some lights on me... Thank you!

 

What you think of ATR?
Adjust leverage based on ATR, does not makes sense to you?

 

I am interested... How? And why is it good? Thanks!