where can i learn how to use Series Elastic Actuator

Where can i learn how to apply this to the motor?
how can i determine the amount of force decreased and the elastic coefficient to be used in this actuator?
are there equation that i can use?

What is "Series Elastic Actuator"?


This is pretty deep stuff, by the looks of it.

This for example, pretty much fried my brain:

You might need at least an under-grad understanding, and perhaps higher, of mechanics and feedback systems and so on before getting into it?