The DARPA PerceptOR program has implemented a rigorous evaluative test program which fosters the development of field relevant outdoor mobile robots. Autonomous ground vehicles were deployed on diverse test courses throughout the USA and quantitatively evaluated on such factors as autonomy level, waypoint acquisition, failure rate, speed, and communications bandwidth. Our efforts over the three year program have produced new approaches in planning, perception, localization, and control which have been driven by the quest for reliable operation in challenging environments. This paper focuses on some of the most unique aspects of the systems developed by the CMU PerceptOR team, the lessons learned during the effort, and the most immediate challenges that remain to be addressed.
This article introduces the concept of combining both form (CAD models) and behavior (simulation models) of mechatronic system components into component objects. By connecting these component objects to each other through their ports, designers can create both a system-level design description and a virtual prototype of the system. This virtual prototype, in turn, can provide immediate feedback about design decisions by evaluating whether the functional requirements are met in simulation. To achieve the composition of behavioral models, we introduce a port-based modeling paradigm. The port-based models are reconfigurable, so that the same physical component can be simulated at multiple levels of detail without having to modify the systemlevel model description. This allows the virtual prototype to evolve during the design process, and to achieve the accuracy required for the simulation experiments at each design stage. To maintain the consistency between the form and behavior of component objects, we introduce parametric relations between these two descriptions. In addition, we develop algorithms that determine the type and parameter values of the lower pair interaction models; these models depend on the form of both components that are interacting. This article presents the initial results of our approach. The discussion is limited to high-level system models consisting of components and lumped component interactions described by differential algebraic equations. Expanding these concepts to finite element models and distributed interactions is left for future research. Our composable simulation and design environment has been implemented as a distributed system in Java and Cϩϩ, enabling multiple users to collaborate on the design of a single system. Our current implementation has been applied to a variety of systems ranging from consumer electronics to electrical train systems. We illustrate its functionality and use with a design scenario.
Technologies to enable automated placement of a rover arm mounted instrument with the rover starting about three meters from the specified instrument target on a terrain feature have been developed and demonstrated on a prototype mars rover. The technologies are automated rover base placement, collision-free arm path planning, and vision guided manipulation. These technologies were integrated with rover visual tracking to provide a complete capability for automated rover approach and instrument placement.
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