Online Information-Aware Motion Planning with Inertial Parameter Learning for Robotic Free-Flyers

Space free-flyers like the Astrobee robots currently operating aboard the International Space Station must operate with inherent system uncertainties. Parametric uncertainties like mass and moment of inertia are especially important to quantify in these safety-critical space systems and can change in scenarios such as on-orbit cargo movement, where unknown grappled payloads significantly change the system dynamics. Cautiously learning these uncertainties en route can potentially avoid time- and fuel-consuming pure system identification maneuvers. Recognizing this, this work proposes RATTLE, an online information-aware motion planning algorithm that explicitly weights parametric model-learning coupled with real-time replanning capability that can take advantage of improved system models. The method consists of a two-tiered (global and local) planner, a low-level model predictive controller, and an online parameter estimator that produces estimates of the robot's inertial properties for more informed control and replanning on-the-fly; all levels of the planning and control feature online update-able models. Simulation results of RATTLE for the Astrobee free-flyer grappling an uncertain payload are presented alongside results of a hardware demonstration showcasing the ability to explicitly encourage model parametric learning while achieving otherwise useful motion.Comment: 8 pages, 8 figures, IROS 2021 preprint (accepted

The RATTLE Motion Planning Algorithm for Robust Online Parametric Model Improvement With On-Orbit Validation

Certain forms of uncertainty that robotic systems encounter can be explicitly learned within the context of a known model, like parametric model uncertainties such as mass and moments of inertia. Quantifying such parametric uncertainty is important for more accurate prediction of the system behavior, leading to safe and precise task execution. In tandem, providing a form of robustness guarantee against prevailing uncertainty levels like environmental disturbances and current model knowledge is also desirable. To that end, the authors' previously proposed RATTLE algorithm, a framework for online information-aware motion planning, is outlined and extended to enhance its applicability to real robotic systems. RATTLE provides a clear tradeoff between information-seeking motion and traditional goal-achieving motion and features online-updateable models. Additionally, online-updateable low level control robustness guarantees and a new method for automatic adjustment of information content down to a specified estimation precision is proposed. Results of extensive experimentation in microgravity using the Astrobee robots aboard the International Space Station and practical implementation details are presented, demonstrating RATTLE's capabilities for real-time, robust, online-updateable, and model information-seeking motion planning capabilities under parametric uncertainty.Comment: 8 pages, 11 figures, RA-L with IROS 2022 optio

Solutions for construction of a lunar base: A proposal to use the spacex starship as a permanent habitat

International audienceReturning to the Moon and establishing a permanent human presence is the next step in human space exploration. This necessitates the development of lunar infrastructure up to this task. This contribution presents a framework for rapid, cost-efficient, and supporting construction of a permanent and modular lunar base within the scope of what will be technically and legally feasible today. The proposed concept uses the SpaceX Starship Human Landing System as the foundation for a lunar base. The Starship will be placed horizontally on the lunar surface and transformed into a habitable volume. A workforce of modular rovers will aid astronauts in the construction process, and an array of countermeasures are presented to protect the astronauts from the effects of exposure to radiation, lunar dust, and extended hypogravity. Psychological and psychosocial factors are included to enhance individual well-being and crew dynamics. Physical and cognitive workloads are defined and evaluated to identify effective countermeasures, including specific spacesuit requirements. The proposed construction activities are to be organized as a multi-national public-private partnership to establish an international authority, a concept that has been successful on Earth but has yet to be applied to space activities on a multi-national level. A roadmap incorporating each part of the construction from human and technical perspectives is outlined. Other aspects that are critical to mission success include the cultural significance of the project, legal aspects, budget, financing, and potential future uses of the base. These solutions rely mainly on existing technologies and limited modifications to the lunar lander vehicle, making it a viable solution for the construction of a lunar base in the near future