TRAVELS: Terrapin Rover Allows Versatile Exploration of the Lunar Surface

TRAVELS is a quadrimodal mobility system designed to navigate and explore the lunar surface and subsurface. Lunar lava tubes are one of the most interesting geological features of the moon, having been caused due to previous geological activity. These tubes have rocky, unexplored interiors and are rough around collapsed skylights and entrances. Such entrances and skylights, the only points of access, are also extremely difficult to enter, sometimes requiring even rappelling into empty space. Additionally, the terrain immediately around an enterance may be too rocky for landers, requiring travel over the lunar surface from a more ideal entry site. TRAVELS was designed to navigate these complex obsticles, and help answer the questions about the formation of the moon.

TRAVELS is a four-limbed wheel-on-limb rover consisting of two five-degree-of-freedom rear manipulators for positioning wheels, and two seven-dof front manipulators which have extra degrees of freedom that can extend when not driving or walking. On the moon, the system is capable of carrying a max payload of up to 25 kg on only three limbs, meaning this is reliable for walking gaits; if on all four limbs, this payload increases to 100 kilos.

The high degree of freedom of the rover allows for static walking gaits over rough terrain; active, force-balancing suspension when driving; and  dexterous, full-body manipulation using the front limbs and tool changers. The entire system is also designed to fit snugly into the payload volume and mass allocations of current commercial lander designs; in particular, we designed our system around the Astrobotic Peregrine lander.

The first prototype is what we’re calling our “Protoflight” manipulator, a seven-degree-of-freedom system with an additional interchangeable end effector mechanism for utilizing different tools. The Protoflight arm is based on the SSL’s previous DYMAFLEX manipulator architecture, which was developed for general in-space servicing applications. We realized early on that this architecture could support a walking robot and decided to integrate it into our core design. The goal of this arm is to show that the system can function in lunar thermal conditions and complete tasks using lunar-grade materials; as such, it’ll be subjected to thermal vacuum testing, as we’ll discuss later. If actually sent to the moon, this is what the TRAVELS limbs would look like.

Our second prototype is a full-scale analogue for Earth testing capable of supporting itself while walking or driving in 1g. Unlike the Protoflight arm, these manipulators use entirely off-the shelf, self-contained servos and actuators and a supporting 3D-printed structure. While definitely not space-worthy, it is of identical dimensions to the Protoflight arm and, as such, testing walking and driving with this system is analogous to testing with the fully metal, space-rated robot.

Related Publications:

  1. Proposal Video
  2. NASA's Big Ideas Challenge Announcement

Project Advisor: Dr. David Akin

Lead Graduate Student: Joshua Martin

Acknowledgements: The BioBot is development at the University of Maryland Space Systems Laboratory, part of the Aerospace Engineering Department and the A. James Clark School of Engineering. Funding is provided by NASAs Big Ideas Challenge.