Control method for drilling apparatus which makes use of a final drilling pattern transformed from primary and secondary patterns

A drilling method of automatically drilling a facing of a tunnel to be excavated, in which a drilling pattern expressed in a rectangular coordinate system defined with respect to said facing is transformed into a final drilling pattern expressed in a final coordinate system defined with respect to a drilling vehicle such that a boom mounted on said drilling vehicle and mounted with a drilling apparatus is positioned, through feedback control thereof, at a predetermined position of said facing on the basis of said final drilling pattern, said drilling method, when an imaginary facing for excavating a curved tunnel is so employed as to be nonparallel to an existing facing and a primary drilling pattern expressed in a primary coordinate system defined with respect to said imaginary facing has been given so as to be transformed into a secondary drilling pattern expressed rn a secondary coordinate system defined with respect to said existing facing such that said secondary drilling pattern is further transformed into said final drilling pattern, comprising the pretreatment steps of:

• (a) expressing first and second coordinates of first and second points of said secondary coordinate system by using another first and second coordinates of said primary coordinate system, respectively such that a first equation for transformation between said primary and secondary coordinate systems is obtained on the basis of relations between said first coordinates and said another first coordinates and between said second coordinates and said another second coordinates;
• (b) converting said primary drilling pattern into third and fourth coordinates of third and fourth points of said primary coordinate system such that said third and fourth coordinates are, respectively, transformed, by using said first equation, into another third and fourth coordinates of said secondary coordinate system, with said another third and fourth coordinates representing said secondary drilling pattern;
• (c) detecting fifth and sixth coordinates of a reference point and a fixed point of said secondary coordinate system, in terms of another fifth and sixth coordinates of said final coordinate system, respectively such that a second equation for transformation between said secondary and final coordinate systems is obtained on the basis of relations between said fifth coordinates and said another fifth coordinates and between said sixth coordinates and said another sixth coordinates, with said fixed point being determined on the basis of said reference point;
• and
• (d) transforming said another third and fourth coordinates of said secondary coordinate system into further third and fourth coordinates of said final coordinate system, respectively by using said second equation such that said further third and fourth coordinates of said final coordinate system are converted into said final drilling pattern of said final coordinate system.