{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,2]],"date-time":"2026-06-02T09:30:21Z","timestamp":1780392621471,"version":"3.54.1"},"reference-count":49,"publisher":"SAGE Publications","issue":"9","license":[{"start":{"date-parts":[[2016,7,11]],"date-time":"2016-07-11T00:00:00Z","timestamp":1468195200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["The International Journal of Robotics Research"],"published-print":{"date-parts":[[2016,8]]},"abstract":"<jats:p>\n                    Planetary excavator robots face unique and extreme engineering constraints relative to terrestrial counterparts. In space missions mass is always at a premium because it is the main driver behind launch costs. Lightweight operation, due to low mass and reduced gravity, hinders excavation and mobility by reducing the forces a robot can effect on its environment. This work shows that there is a quantifiable, non-dimensional threshold that distinguishes the regimes of lightweight and nominal excavation. This threshold is crossed at lower weights for continuous excavators (e.g. bucket-wheels) than discrete scrapers. This research introduces novel experimentation that for the first time subjects excavators to gravity offload (a cable pulls up on the robot with five-sixths its weight, to simulate lunar gravity) while they dig. A 300 kg excavator robot offloaded to 1\/6 g successfully collects 0.5 kg\/s using a bucket-wheel, with no discernible effect on mobility. For a discrete scraper of the same weight, production rapidly declines as rising excavation resistance stalls the robot. These experiments suggest caution in interpreting low-gravity performance predictions based solely on testing in Earth gravity. Experiments were conducted in GRC-1, a washed industrial silica-sand devoid of agglutinates and of the sub-75-micron basaltic fines that make up 40% of lunar regolith. The important dangers related to dust are thus not directly addressed. The achieved densities for experimentation are 1640 kg\/m\n                    <jats:sup>3<\/jats:sup>\n                    (very loose\/loose) and 1720 kg\/m\n                    <jats:sup>3<\/jats:sup>\n                    (medium dense). This work develops a novel robotic bucket-wheel excavator, featuring unique direct transfer from bucket-wheel to dump bed as a solution to material transfer difficulties identified in past literature.\n                  <\/jats:p>","DOI":"10.1177\/0278364915615689","type":"journal-article","created":{"date-parts":[[2016,1,25]],"date-time":"2016-01-25T22:29:07Z","timestamp":1453760947000},"page":"1121-1139","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":42,"title":["Advantages of continuous excavation in lightweight planetary robotic operations"],"prefix":"10.1177","volume":"35","author":[{"given":"K","family":"Skonieczny","sequence":"first","affiliation":[{"name":"Robotics Institute, Carnegie Mellon University, PA, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"DS","family":"Wettergreen","sequence":"additional","affiliation":[{"name":"Robotics Institute, Carnegie Mellon University, PA, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"WL \u201cRed\u201d","family":"Whittaker","sequence":"additional","affiliation":[{"name":"Robotics Institute, Carnegie Mellon University, PA, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2016,7,11]]},"reference":[{"key":"bibr1-0278364915615689","unstructured":"Abu El Samid N (2008) Infrastructure robotics: A trade-off study examining both autonomously and manually controlled approaches to lunar excavation and construction. 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