Safety device for revolving-type work machine

A safety apparatus installed on a work machine including a lower traveling body capable of traveling on the ground and an upper revolving body mounted on the lower traveling body so as to be revolvable, the safety apparatus comprising:

• an obstacle sensor provided in a specific portion of the upper revolving body to detect an obstacle around the work machine;
• a revolving angle detector that detects a revolving angle of the upper revolving body to the lower traveling body;
• an upper-side coordinate position calculation section that calculates an upper-side coordinate position that is a position of the obstacle detected by the obstacle sensor, the position being a position in a coordinate system using the upper revolving body as a reference;
• a lower-side judgment area setting section that sets a lower-side judgment area for judging an approach of the obstacle at least in a periphery of the lower traveling body using the lower traveling body as a reference;
• a coordinate transformation section that transforms one position of the upper-side coordinate position and a position of the lower-side judgment area into a position in a coordinate system to which the other position of the upper-side coordinate position and the position of the lower-side judgment area belongs, based on the revolving angle detected by the revolving angle detector, to thereby unify a coordinate system for specifying the position of the obstacle and a coordinate system for specifying the position of the lower-side judgment area;
• a lower-side approach judgment section that judges whether or not the obstacle exists within the lower-side judgment area in the coordinate system unified by the coordinate transformation section;
• and
• a safety operation command section that outputs a safety operation command for making the work machine perform a safety operation when the lower-side approach judgment section judges that the obstacle exists within the lower-side judgment area.