Abstract
This paper formulates the handling of a safe man/machine work system in international safety standards on safety of machinery as interlock structure. In a system where a human operator cooperatively works with a machine, the working conditions of the human operator and the machine are each divided into three ways. Safety assurance logic in the resultant man/machine combination condition is formulated as interlock structure. The interlock system discussed in this paper has the function of restart prevention control with respect to the working condition of the machine. An interlock system where the human operator is positively fixed in the safe condition when the machine is operating, and an interlock system that continues to maintain the condition in which the machine is regarded as operating, although the human operator is not always fixed in the safe condition, can be considered. The former is called the mutual interlock system and the latter is called the self-confirmation interlock system. The two interlock systems are formulated and presented.
