The concept of adding an element of human judgment to automated equipment so it can detect an unacceptable condition such as tool breakage, to make the automated process more reliable. The typical setup is for the machine to stop and alert the operator when sensors and switches detect an abnormality. As with Stop at Defects, enough time is designed in so that the condition can be remedied without stopping other operations in the process.
In the Japanese language the character "dou" means "human," and jidou ka is a play on the word jidoka, which translates closely to "breakage detection."