Scientific Exploration of Challenging Planetary Analog Environments with a Team of Legged Robots (2307.10079v1)

Abstract: The interest in exploring planetary bodies for scientific investigation and in-situ resource utilization is ever-rising. Yet, many sites of interest are inaccessible to state-of-the-art planetary exploration robots because of the robots' inability to traverse steep slopes, unstructured terrain, and loose soil. Additionally, current single-robot approaches only allow a limited exploration speed and a single set of skills. Here, we present a team of legged robots with complementary skills for exploration missions in challenging planetary analog environments. We equipped the robots with an efficient locomotion controller, a mapping pipeline for online and post-mission visualization, instance segmentation to highlight scientific targets, and scientific instruments for remote and in-situ investigation. Furthermore, we integrated a robotic arm on one of the robots to enable high-precision measurements. Legged robots can swiftly navigate representative terrains, such as granular slopes beyond 25 degrees, loose soil, and unstructured terrain, highlighting their advantages compared to wheeled rover systems. We successfully verified the approach in analog deployments at the BeyondGravity ExoMars rover testbed, in a quarry in Switzerland, and at the Space Resources Challenge in Luxembourg. Our results show that a team of legged robots with advanced locomotion, perception, and measurement skills, as well as task-level autonomy, can conduct successful, effective missions in a short time. Our approach enables the scientific exploration of planetary target sites that are currently out of human and robotic reach.

• The paper demonstrates that a heterogeneous team of ANYmal legged robots achieved 95% area coverage in challenging environments with slopes up to 25°.
• The study employed specialized roles, with the Scout mapping terrains using LiDAR and multispectral imaging while Hybrid and Scientist performed in-situ analyses using a Raman spectrometer and microscope.
• The research highlights improved mobility and autonomy over wheeled systems, demonstrating robust performance under simulated lunar conditions with a 5-second communication delay.

Analysis of the Scientific Exploration of Challenging Planetary Analog Environments with a Team of Legged Robots

The paper presents a comprehensive paper on utilizing a team of legged robots equipped with complementary capabilities to enhance planetary exploration in terrains characterized by steep slopes, unstructured landscapes, and loose soil. Current planetary exploration robots, typically mobile wheeled systems, encounter challenges in such environments due to limited mobility, as evidenced by historical issues with vehicles like NASA's Spirit rover and Apollo's Lunar Roving Vehicle. Consequently, this research highlights the potential of legged robots, which demonstrate superior locomotion in complex terrains due to their dynamic walking capabilities observed in terrestrial analogs.

Methodology and Implementation

The paper implemented a team composed of three ANYmal robots with differentiated roles and payloads—Scout, Hybrid, and Scientist—capitalizing on redundancy to maintain mission integrity in the face of potential individual failures. The Scout focuses on mapping and exploratory reconnaissance using LiDAR and a multispectral imaging system (CTX-FW), while the Hybrid and Scientist perform detailed investigations leveraging a Raman spectrometer and a robotic arm-mounted microscope (MICRO) for in-situ analyses.

This robotic configuration was validated in several demanding environments, including ESA’s Space Resources Challenge and a quarry in Switzerland, simulating lunar surface conditions with low-angle illumination and complex geological features. The team efficiently located and analyzed scientifically significant sites and demonstrated the robots' capabilities to operate under high latency, reflecting lunar communication conditions with a 5-second round-trip time.

Key Numerical Results

With a team of legged robots, the research succeeded in covering approximately 95% of the given area at the Space Resources Challenge within a limited mission timeframe, achieving exploration speeds across terrains up to 25 degrees of incline—significantly exceeding the capabilities of traditional wheeled systems. This efficiency underscores the efficacy of legged robot motions in difficult terrains, reinforcing the paper's central premise.

Practical and Theoretical Implications

Practically, the application of heterogeneous robotic teams with autonomous capabilities allows for broader scientific reach and data collection in planetary exploration, offering redundancy and ensuring mission completion despite individual system failures. Theoretically, the research aligns with the broader thrust toward task-level autonomy, capable of prioritizing and executing scientific objectives independently. This autonomy facilitates operation in environments with unreliable communication, fostering new paradigms in remote exploration strategy.

Future Directions

The paper suggests further research into increasing mission autonomy, particularly in robotic decision-making regarding target prioritization and task allocation, to leverage artificial intelligence fully. Additionally, integrating a broader array of scientific instruments, including possibly X-ray fluorescence spectrometers, could enrich the payload diversity, improving the variability and quality of scientific returns. Finally, transitioning from ground-based analog deployments to actual lunar or Martian environments would necessitate advancements in robust, space-rated hardware solutions.

Overall, this research introduces a substantive step forward in the operational capability and scientific return of robotic planetary exploration missions, contributing to the ongoing discourse in astrobiology, planetary science, and autonomous robotic systems.