Abstract
This report proposes a new safety system to know the human existence in the machine moving area of large scale product lines. It is very difficult to create such a system because the operator can enter into the machine moving area without pulling out of the interlocking key, and there were not only nominated operators but also non-nominated operators, passers-by, or observers in the actual field. The adequate risk reduction can be achieved by direct monitoring devices such as the laser scanning sensor. It can be achieved also by indirect counting devices such as the mechanical counter gate. The ALARP risk reduction can be achieved by using both the key-switch and monitoring devices such as the photo-electric sensor or mat switch. On the other hand, the adequate risk reduction cannot be achieved only by the plug, key-switch or movable guard.
