Poke Yoke:

 

 

Poka-yoke can be implemented at any step of a manufacturing process where something can go wrong or an error can be made.
1. The contact method identifies product defects by testing the product's shape, size, color, or other physical attributes.
2. The fixed-value (or constant number) method alerts the operator if a certain number of movements are not made.
3. The motion-step (or sequence) method determines whether the prescribed steps of the process have been followed. Either the operator is alerted when a mistake is about to be made, or the poka-yoke device actually prevents the mistake from being made.