A robotic apparatus for use in construction that is capable of traversing a selected area autonomously. The robotic apparatus is provided in two models, a master that can record directive and "environmental signal" readings, or that can record received location information, to provide at least one command recorded on a machine-readable medium representing an instruction for traversing an area of interest, and a slave that lacks the recording capability. Both master and slave models can replay recorded commands, and compare the expected orientation from the command with an actual orientation sensed during autonomous operation. If an error exceeding a predetermined value is observed, a corrective action is taken. The robotic apparatus is to perform a task, such as marking locations in construction of a building for installation of services such as wiring and plumbing.