Apparatus for moving one or more processing devices relative to an object to be processed, comprising: first and second mounting units configured to be secured in a fixed position relative to the object to be processed and between which one or more tension members are mounted under tension; one or more carriages respectively connected to the one or more tension members, each of the carriages configured to accommodate a respective processing device; and a drive unit configured to move the one or more tension members so as to move the one or more carriages relative to the object.