{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T23:13:27Z","timestamp":1777418007118,"version":"3.51.4"},"reference-count":48,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,3,22]],"date-time":"2026-03-22T00:00:00Z","timestamp":1774137600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Robotics"],"abstract":"<jats:p>When is an unknown, confined environment traversable for a specific ground robot using only touch? We answer by (i) giving an environment-anchored definition of traversability, expressed through the max-min value T\u2605(E;A)=sup\u03c0\u2208\u03a0S\u2192Ginfs\u2208[0,1]\u03d5(\u03c0(s)), where the bottleneck margin \u03d5 aggregates the clearance, curvature (\u03c1\u2265Rmin), slope\/step, and friction constraints, and (ii) introducing an on-policy, tactile certificate (TC) that maintains a conservative, monotone lower bound Tt using partial contact histories. The TC fuses pessimistic free-space from contacts and the body envelope, the M3 decaying contact memory as a risk prior, and local bend\/FSR proxies; a certificate is issued when Tt&gt;0 and the explored corridor graph connects S to G. Relative to Papers 1\u20132 (tactile traversal; offline software assurance), this work formalizes traversability itself and provides a tactile-only, online certificate computable during runs. In a retrospective analysis of 660 trials across Indoor\/Outdoor\/Dark lighting environments, (H1) the early TC margin predicts success and traversal time better than contact\/dwell heuristics (higher AUC\/R2), (H2) the TC predictivity is lighting-invariant, and (H3) speed-gating M3 by a TC margin recovers part of the CB-V speed gap without degrading success. Artifacts include the TC implementation, explored-corridor graphs, and per-trial TC time series added to the Paper-1 log bundle; these materials are available from the corresponding author upon reasonable request.<\/jats:p>","DOI":"10.3390\/robotics15030065","type":"journal-article","created":{"date-parts":[[2026,3,23]],"date-time":"2026-03-23T13:07:06Z","timestamp":1774271226000},"page":"65","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["What Makes a Space Traversable? A Formal Definition and On-Policy Certificate for Contact-Rich Egress in Confined Environments"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-0613-6272","authenticated-orcid":false,"given":"Adam Mark","family":"Mazurick","sequence":"first","affiliation":[{"name":"Department of Computer Science, Toronto Metropolitan University, Toronto, ON M5B 2K3, Canada"}]},{"given":"Alex","family":"Ferworn","sequence":"additional","affiliation":[{"name":"Department of Computer Science, Toronto Metropolitan University, Toronto, ON M5B 2K3, Canada"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"37962","DOI":"10.1109\/JSEN.2024.3464633","article-title":"Stretchable Self-Powered TENG Sensor Array for Human-Robot Interaction Based on Conductive Ionic Gels and LSTM Neural Network","volume":"24","author":"Dong","year":"2024","journal-title":"IEEE Sens. 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