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Published July 2012 | public
Journal Article

Axel and DuAxel Rovers for the Sustainable Exploration of Extreme Terrains

Abstract

Some of the most appealing science targets for future exploration missions in our solar system lie in terrains that are inaccessible to state-of-the-art rover technology. This paper discusses the challenges and constraints of designing a robotic explorer for these "extreme'' terrains and then examines the trade-offs among different mobility architectures. To address many of these challenges, we have developed the Axel family of rovers. The Axel rover is a two-wheeled tethered robot capable of rappelling down steep slopes and traversing rocky terrain. The DuAxel rover, which is a four-wheeled vehicle formed from two Axel rovers, provides untethered mobility to get to extreme terrains. We describe the basic design principles of these rovers and review our efforts to implement the key features of the Axel concept. Limitations found during experiments with prior Axel rover prototypes led to the design of a third-generation Axel rover. We describe the features of this new rover and then present a thermal analysis conducted to assess the feasibility of exploring lunar cold traps, which are expected to have a temperature range of 40 to 70 K. We conclude the paper with results showcasing Axel and DuAxel's extreme-terrain performance as evaluated during two recent field tests in a steeply sloped Southern California rock quarry and at a location in Arizona that closely resembles rugged Martian terrain. We also summarize lessons learned during the Axel development program.

Additional Information

© 2012 Wiley Periodicals, Inc. Issue published online: 11 Jun 2012. Article first published online: 3 Feb 2012. Manuscript Accepted: 22 Oct 2011. Manuscript Received: 15 Jan 2011. Our most sincere thanks go to all current and former Axel team members, both at JPL and at Caltech. We would like to thank Dr. Pamela Conrad for her contributions to the development of the mobile science payload concept. We would also like to thank Jack Dunkle, Raymond Christian (of Ozone Mountain), John Koehler, Edward Barlow, Daniel Helmick, and Ayanna Howard for their contributions to the design, manufacture, and testing of various Axel prototypes. Our gratitude goes to graduate and undergraduate students for their design, analysis, and testing of this system: Johanna Ceceva, Michelle Jiang, Jeffrey Duperret, Grace Li, and Frank Mangini. We would also like to acknowledge the contributions of Donald Bickler, Kobie Boykins, Tommaso Rivellini, and Brian Wilcox to the architectural trade study and for their valuable feedback on this project. This collaborative effort between the California Institute of Technology and the Jet Propulsion Laboratory was performed at JPL under contract to the National Aeronautics and Space Administration. We are very grateful for the sponsorship of JPL's Office of the Chief Scientist and Technologist through the Research and Technology Development Program. We would also like to acknowledge the support of the Exploration Systems Mission Directorate and the Solar Systems Exploration program. We would like to thank the Keck Institute for Space Studies for their support of a workshop that investigated extreme terrain exploration. We would also like to acknowledge the sponsorship of Craig Peterson for the wheel studies.

Additional details

Created:
August 19, 2023
Modified:
October 17, 2023