feedforward vs head off

feedforward

verb
  • To respond in advance 

noun
  • An anticipatory response to expected changes in the environment of a system 

head off

verb
  • To intercept. 

  • To start out. 

  • To avoid the undesirable consequences of; prevent. 

  • To turn away from the wind. 

  • To begin moving away. 

How often have the words feedforward and head off occurred in a corpus of books? (source: Google Ngram Viewer )