Integrated Conceptual Design and Parametric Control Assessment for a Hybrid Mobility Lunar Hopper

The lunar lava tubes are envisioned as possible hosting structures for a human base in the Moon’s equatorial regions, providing shelter from radiations, micrometeoroids, and temperature excursion. A first robotic mission is set to scout the habitability of these underground architectures in the near future. The communication inside these underground tunnels is heavily constrained; hence, the scouting system should rely on a high degree of autonomy. At the same time, the exploration system may encounter different types of terrain, requiring an adaptable mobility subsystem able to travel fast on basaltic terrain while avoiding considerable obstacles. This paper presents a cave explorer’s mission study and preliminary sizing targeting the lunar lava tubes. The study proposes using a hybrid mobility system with wheels and thrusters to navigate smoothly inside the lava tubes. The peculiar mobility system of the cave explorer requires an accurate study of the adaptability of its control capabilities with the change of mass for a given set of sensors and actuators. The combination of conceptual design techniques and control assessment gives the engineer a clear indication of the feasible design box for the studied system during the initial formulation phases of a mission. This first part of the study focuses on framing the stakeholders’ needs and identifying the required capabilities of the cave explorer. Furthermore, the study focuses on assessing a design box in terms of mass and power consumption for the cave explorer. Following different mission-level assessments, a more detailed design of the cave explorer is discussed, providing an initial design in terms of mass and power consumption. Finally, the objective shifts toward studying the performances of the guidance, navigation, and control (GNC) algorithms varying the mass of the cave explorer. The GNC significantly impacts the design box of the surface planetary system. Hence, investigating its limitations can indicate the feasibility of mass growth to accommodate, for example, more payload.