326 assembled before setting the cable segment length. As a result, motor controller mounting locations were  only approximated and the true cable path was not defined.  At the time of procurement of the cables, the  length was only roughly approximated and 45 cm (18 inches) was added to either end of the cable as  margin. This ultimately resulted in significantly more cable than was necessary and posed a significant  challenge of packaging excess and unplanned cable. If more time were invested initially in the definition  and modeling of the cable routing, then less margin for uncertainty would be necessary. While accurately modeling cabling is difficult it ultimately saves significant time and effort in the long run.     Conclusions 

In September of 2009, the vehicle wa s tested for three weeks at the Bla ck Point lava flow near Flagstaff,  AZ. This test demonstrated an initial set of capabili ties for the vehicle, including demonstrating the  offloading of cargo from a 3.2-m tall mock lander, walk ing over obstacles over 1-m tall, excavating soil  using a backhoe tool attachment, and accumulating more than 6km  of total traverse distance. This field  test also highlighted the shortcomings and exposed so me of the complexities of the system. Future  refinements will deal with problems of electrical nois e in the actuators, power system upgrades, and  limited bandwidth from simultaneously commanding and  coordinating 48 actuators and 24 cameras on  each Tri-ATHLETE vehicle. All of these shortcomings, however, can be overcome and the Tri-ATHLETE system has proven to provide a unique capability of ca rgo handling and transportation, as well as tool use  and payload manipulation that fits well with in the current lunar architecture.   

Acknowledgements 

The authors would like to thank the entire ATHELTE team, the staff of Michelin Recherche et technique S.A. for the design and construction of the Mic helin Lunar Wheel, and the NA SA Human-Robot Systems  (HRS) project,  part of the Exploration Technology Developm ent Program (ETDP), for funding this work.  The work described in this paper was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Ae ronautics and Space Administration. Copyright 2009  California Institute of Technology. Go vernment sponsorship acknowledged. 

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