Operator Interface and Control Software for the Reconfigurable Surface System Tri-ATHLETE

NASA’s Jet Propulsion Laboratory, Pasadena, California

Graphical operator interface methods have been developed for modular, reconfigurable articulated surface systems in general, and a specific instantiation thereof for JPL’s Tri-ATHLETE. The All-Terrain Hex-Limbed Extra- Terrestrial Explorer Robot (ATHLETE) has six limbs with six kinematic degrees of freedom each (see figure).

Any **Assembly of Kinematic Modules** may be directly operated in the system by click-and-drag direct manipulation. Here the canonical configuration of two Tri-ATHLETE modules and one pallet is operated in lifting (A), sliding (B), and tilting (C) motions.

The core advancement of this work was the development of a novel set of algorithms for dynamically maintaining a reduced coordinate model of any connected assembly of robot modules. The kinematics of individual modules are first modeled using a catalog of 12 standard 3D robot joints (this modeling step needs to be done only once). Then, individual modules can be assembled into any closed- or openchain topology. The system automatically maintains a spanning tree of the overall configuration, which ensures both efficiency and accuracy of the onscreen representation.

Until now, JPL has used generic CAD (computer-aided design), simulation, and animation tools as a substitute for a true modular robot operator interface. This workflow is extremely time-consuming, and is not suited for use in an operations context. Current operator interfaces, both at JPL and in the broader exploration robotics community, are largely focused on non-reconfigurable hardware.

Reconfigurable modular hardware such as Tri-ATHLETE promises to extend greatly the capability of future exploration missions for a relatively small additional cost. Whereas existing missions based on monolithic hardware can only perform a limited set of predefined operations, modular hardware can potentially be reconnected and recombined to serve a range of functions. The full realization of these promises is contingent not just on the development of the hardware itself, but also upon the availability of corresponding software systems with algorithms that enable operators to rapidly specify, visualize, simulate, and control particular assemblies of modules. In the case of articulated, reconnectable hardware like Tri-ATHLETE, operators also can determine feasible motions of the assembly, and disconnect/reconnect actions that change assembly topology.

This work was done by Jeffrey S. Norris of Caltech, Marsette A. Vona of Northeastern University, and Daniela Rus of MIT for NASA’s Jet Propulsion Laboratory.

This software is available for commercial licensing. Please contact Daniel Broderick of the California Institute of Technology at This email address is being protected from spambots. You need JavaScript enabled to view it.. NPO-47777