Abstract:

This thesis investigates low degree-of-freedom (DoF), minimally-actuated rover mobility architectures for planetary exploration. These platforms seek to reduce mass and complexity compared to the heritage rocker-bogie system while maintaining functional performance. The work focuses on two systems: MoonRanger, a lightweight lunar micro-rover slated for a 2029 moon mission, and Zoë2, a research rover developed as a successor to CMU’s 22-year old Zoë1 rover.

For MoonRanger, we analyze the limitations of the gravity offload method for Earth-based mobility testing and validate alternative approaches using granular scaling laws, single-wheel experiments, and high-fidelity discrete element modeling (DEM). Results demonstrate that offload testing significantly overestimates performance, while full-mass testing and discrete-element modeling provide more accurate predictions of lunar behavior. A wheel design study using black-box optimization is initiated to identify promising configurations for future development.

The second part of this thesis details the design, implementation, and evaluation of Zoë2, a passive-steering rover optimized for energy efficiency and maneuverability. Experimental validation confirms that the redesigned mechanical, electrical, and software systems provide a versatile testbed for planetary autonomy research. We find that compared to skid steering, passive steering reduces power consumption by up to 30% while simultaneously allowing far more precise blind navigation.

Together, these studies highlight the tradeoffs between simplicity, efficiency, and mobility performance in planetary rover design. The findings contribute to the development of lighter, more capable mobility systems for future lunar and planetary missions.

Committee:

David Wettergreen (advisor)

Red Whittaker

Dan McGann