Abstract
A layered safety control system is a most important concept for servo-drive control. An upper layer deals with information on achieving a system-defined target. Correction of errors included in information is allowed through later review. Accordingly, a control model for this information is expressed by feedback system. On the other hand, a lower layer deals with information on protecting a system. Correction of errors is not allowed through later review because errors included in information may invite fatal accident. Accordingly, a control model for this information is expressed by interlocking system. This report shows safe requirements in designing safety related parts of servo-control. The basic configuration of layered safety control system, basic characteristics of safety information and the necessity of absolute space monitoring related to safety limits were clarified in this study.
