{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,2]],"date-time":"2026-05-02T09:53:48Z","timestamp":1777715628769,"version":"3.51.4"},"reference-count":37,"publisher":"SAGE Publications","issue":"13-14","license":[{"start":{"date-parts":[[2018,7,26]],"date-time":"2018-07-26T00:00:00Z","timestamp":1532563200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"funder":[{"DOI":"10.13039\/501100000266","name":"Engineering and Physical Sciences Research Council","doi-asserted-by":"publisher","award":["EP\/L016834\/1"],"award-info":[{"award-number":["EP\/L016834\/1"]}],"id":[{"id":"10.13039\/501100000266","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000266","name":"Engineering and Physical Sciences Research Council","doi-asserted-by":"publisher","award":["EP\/J015040\/1"],"award-info":[{"award-number":["EP\/J015040\/1"]}],"id":[{"id":"10.13039\/501100000266","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Spanish Ministry of Economy and European Union","award":["DPI2016-81002-R (AEI\/FEDER, UE)"],"award-info":[{"award-number":["DPI2016-81002-R (AEI\/FEDER, UE)"]}]}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["The International Journal of Robotics Research"],"published-print":{"date-parts":[[2018,12]]},"abstract":"<jats:p>Many practical tasks in robotic systems, such as cleaning windows, writing, or grasping, are inherently constrained. Learning policies subject to constraints is a challenging problem. In this paper, we propose a method of constraint-aware learning that solves the policy learning problem using redundant robots that execute a policy that is acting in the null space of a constraint. In particular, we are interested in generalizing learned null-space policies across constraints that were not known during the training. We split the combined problem of learning constraints and policies into two: first estimating the constraint, and then estimating a null-space policy using the remaining degrees of freedom. For a linear parametrization, we provide a closed-form solution of the problem. We also define a metric for comparing the similarity of estimated constraints, which is useful to pre-process the trajectories recorded in the demonstrations. We have validated our method by learning a wiping task from human demonstration on flat surfaces and reproducing it on an unknown curved surface using a force- or torque-based controller to achieve tool alignment. We show that, despite the differences between the training and validation scenarios, we learn a policy that still provides the desired wiping motion.<\/jats:p>","DOI":"10.1177\/0278364918784354","type":"journal-article","created":{"date-parts":[[2018,7,27]],"date-time":"2018-07-27T01:27:45Z","timestamp":1532654865000},"page":"1673-1689","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":14,"title":["Constraint-aware learning of policies by demonstration"],"prefix":"10.1177","volume":"37","author":[{"given":"Leopoldo","family":"Armesto","sequence":"first","affiliation":[{"name":"Instituto de Dise\u00f1o y Fabricaci\u00f3n, Universitat Polit\u00e9cnica de Val\u00e8ncia, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jo\u00e3o","family":"Moura","sequence":"additional","affiliation":[{"name":"Institute of Sensors, Signals and Systems, Heriot-Watt University, UK"},{"name":"Institute of Action, Perception, and Behaviour, University of Edinburgh, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Vladimir","family":"Ivan","sequence":"additional","affiliation":[{"name":"Institute of Action, Perception, and Behaviour, University of Edinburgh, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mustafa Suphi","family":"Erden","sequence":"additional","affiliation":[{"name":"Institute of Sensors, Signals and Systems, Heriot-Watt University, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Antonio","family":"Sala","sequence":"additional","affiliation":[{"name":"Instituto U. de Autom\u00e1tica e Inf. 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