This paper describes the key system components of a team of three tractors in a peat moss harvesting operation. The behavior and actions of the tractors were designed to mimic manual harvest operations while maintaining a safe operating environment. To accomplish this objective, each of the three tractors was equipped with a bolt-on automation package, and a human operator (team leader) was given a remote user interface to * Previously with John Deere. Journal of Field • Journal of Field Robotics-2009command and monitor the mission. The automation package included positioning, planning, and control, as well as coordination and perception systems to preserve field harvesting order, detect obstacles, and report physical changes in the operating environment. The system performed more than 100 test field harvesting missions during one season in a working peat bog, including three complete system tests with the end users. C 2009 Wiley Periodicals, Inc.

Summary. This paper analyzes the stability properties of a decentralized hybrid control system for maintaining formations. Utilizing only local sensing, the system assembles strings or "platoons" of robots that has each robot maintaining a fixed bearing to its nearest neighbor. Using these platoons, the system is able to construct more complicated geometries. A piecewise linear controller based on bidirectional controller design is utilized to ensure the stability of the system. The system is demonstrated in simulation as well as on a physical set on non-holonomic mobile robots.

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