Navigation templates: mediating qualitative guidance and quantitative control in mobile robots

Navigation Templates, a set of tools for constructing flexible plans for a mobile robot´s local navigation, is described. A Navigation Template-based plan for action is environment-relative. The plan places qualitative constraints on the robot´s actions as a function of the robot´s internal model of its surroundings. Because these constraints bound the robot´s motions, rather than dictating a particular trajectory, the plan is able to flex with the robot´s changing perceptions of the world. Quantitative actuator control is obtained through the use of a transformation function that maps the qualitative plan into a currently preferred direction of travel for the robot. The transformation is computationally inexpensive, allowing the quantitative control to be updated rapidly, thus keeping the robot´s actions in step with the qualitative plan and its perceptions of the world. This work is implemented and running on the Jet Propulsion Laboratory´s planetary exploration mobile robot as well as MITRE´s Denning mobile robot