1989 Year End Report: Autonomous Planetary Rover at Carnegie Mellon

Abstract

This report describes progress in research on an autonomous robot for planetary exploration performed during 1989 at the Robotics Institute, Carnegie Mellon University. The report begins with an introduction, summary of achievements, and lists of personnel and pubIications. It also includes several papers resulting from the research. The research program includes a broad agenda in the development of an autonomous mobile robot. In the year covered by this report, we addressed two key topics: Six-Legged Walking Robot - To overcome shortcomings exhibited by existing wheeled and walking robot mechanisms, we configured the Ambler as a walking robot. The fundamental advantage of the Ambler configuration - which has implications for efficiency, mechanism modeling, and control simplicity - is that actuators for body support are independent of those for propulsion; a subset of the planar joints propel the body, and the vertical actuators support and level the body over terrain. During 1989 we configured, designed, and constructed the Ambler. In addition, we developed models of its dynamics, and studied leveling control. Integrated Single Leg Walking - We implemented and tested an integrated system capable of walking with a single leg over rugged terrain. A prototype of an Ambler leg is suspended below a carriage that slides along rails. To walk, the system uses a laser scanner to find a clear, flat foothold, positions the leg above the foothold, contacts the terrain with the foot, and applies force enough to advance the carriage along the rails. Walking both forward and backward, the system has traversed hundreds of meters of rugged terrain including obstacles too tall to step over, trenches too deep to step in, closely spaced rocks, and sand hills. In addition, we conducted preliminary experiments with concurrent planning and execution, and developed a leg recovery planner that generates time and power efficient 3D trajectories using 2D search. Mobile Manipulation with Hero Robot - Indoor mobile manipulator tasks include collecting cups from the lab floor, retrieving printer output, and recharging when its battery gets low. The robot monitors its environment, and handles exceptional conditions in a robust fashion. For example, it uses vision to track the appearance and disappearance of cups, uses on-board sonars to detect imminent collisions, and monitors battery level periodically. This research is primarily sponsored by the National Aeronautics and Space Administration. Portions of this research are also supported by the National Science Foundation and the Defense Advanced Research Pmjects Agency.