Xavier - the Manual v0.2

Joseph O'Sullivan Carnegie Mellon University
Karen Haigh Carnegie Mellon University Xavier is a mobile manipulator developed at CMU that is being used for research in robot learning and self-reliant autonomous operation. It is built on an RWI B24 base and includes bump sensors, a laser range sensor, sonars, a color camera on a pan-tilt head, and an arm. Control, perception and planning are carried out on two on-board, multi-processing 486-based machines. The robot can communicate with humans both graphically and through natural language.

The software controlling Xavier combines both reactive and deliberative behaviours. The reactive behaviours enable the robot to handle real-time local navigation, obstacle avoidance, and emergency situations. The deliberative behaviours, which operate concurrently with the reactive behaviours, maintain occupancy grid and topological maps, plan paths, interpret visual information, and do task-level planning. The behaviours are integrated using the Task Control Architecture, which provides facilities for scheduling and synchronizing tasks, resource allocation, monitoring the environment, and handling exceptional situations.

In addition, Xavier has a detachable arm which can pick up boxes. This arm has a large V-shaped end effector with roller bearings to guide the box to the center, where two electromagnets were used to hook on to metal plates mounted on the corner of the boxes. The arm enables Xavier to lift the boxes over its ``head'', simplifying planning of subsequent movements.

This manual briefly reviews the physical components of Xavier, presents a simulation environment, and introduces a programming tutorial and overview for the novice roboteer. An index is included.

Joseph Kieran O'Sullivan
Last modified: Sun Jan 19 13:14:56 EST 1997