Designing an Efficient Excavator Bucket for Lunar ISRU: A Comparative Study with Vision-Based Fill and Displacement Analysis
Abdulla Hil Kafi, Tomoki Koshi, Jorge Casir, Kenji Nagaoka
AI summary
Problem
Conventional lunar excavation systems add excessive mass, complexity, and power demands, while integrated wheel-based solutions lack experimental validation for balancing efficiency, energy use, and sinkage.
Approach
The authors designed a spiral-cavity wheel to improve regolith retention and benchmarked it against two baseline designs using sandbox tests, lightweight vision-based metrics, and actuator logs to quantify performance without external instrumentation.
Key results
- 2.2–3.0× higher excavation rate than bucket-drum baseline
- 29% reduction in specific energy relative to baseline
- Lower normalized sinkage indicating stable traction without bogging
- Validated soil-holding ratio index and DEM model with <10% prediction error
Why it matters
Enables lighter, more energy-efficient rover architectures for sustainable lunar surface operations and ISRU missions.
Abstract
This paper present a spiral-cavity wheel for lunar regolith excavation and a sensor-light evaluation stack that jointly estimates fill ratio (vision), sinkage (vision), and specific energy from actuator logs. In benchtop tests (four revolutions at 5, 10, and 15 RPM) against two literature baselines, the proposed wheel achieved higher excavated mass and fill ratio, delivering 2.2–3.0 times higher excavation rate while reducing specific energy by 29% relative to a bucket-drum baseline. Normalized sinkage (mm/kg) was also lower, indicating stable traction without bogging. Effort-time traces show a steady torque envelope with repeatable cut–carry–dump cycles across speeds. We provide a retention index η that correlates with fill ratio and a DEM setup that reproduces experimental trends with low error. Results suggest spiral-cavity wheels can replace heavier multi-actuator diggers when mass, simplicity, and energy efficiency are mission drivers.