{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T09:03:39Z","timestamp":1789549419219,"version":"build-2803163510"},"reference-count":35,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T00:00:00Z","timestamp":1789516800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004826","name":"Beijing Natural Science Foundation","doi-asserted-by":"publisher","award":["8254042"],"award-info":[{"award-number":["8254042"]}],"id":[{"id":"10.13039\/501100004826","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Academician Project Foundation of CCCC","award":["YSZX-03-2024-03-B"],"award-info":[{"award-number":["YSZX-03-2024-03-B"]}]},{"name":"Key Science Project of Guangdong Provincial Transportation Group","award":["JT2023ZD01-03"],"award-info":[{"award-number":["JT2023ZD01-03"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Close-range bridge inspection exposes personnel to risks associated with work at height and in confined spaces. Magnetic climbing robots can reduce this exposure, yet dense fastener groups and unsupported regions beyond truss member edges impose local geometric constraints on robot motion. Forward-looking depth observations of these regions are often partial and noisy. This study presents a local geometric perception method that produces two constraints. A computer-aided design (CAD)-constrained branch matches partial rivet observations to hole-layout templates and converts the recovered layout into an inward-offset rivet-passage boundary. A CAD-independent depth branch fits the supporting-surface boundary near a truss member edge. The method was evaluated in simulation, laboratory mock-ups, and a single-case field feasibility study. Under simulation conditions, CAD-constrained recovery reduced lateral mean absolute error by 83.17\u201385.14% relative to a geometry-only ablation baseline, and all generated passage boundaries retained positive theoretical clearance from the corresponding fastener contours. Laboratory trials achieved template locking; qualitative overlay inspection found no visible boundary intrusion for three rivet layouts. The single-case field study also achieved template locking and generated a passage boundary without visible intrusion into the fastener contours using a manually measured bolt-layout prior. The member-edge branch produced valid fits in 79.59% of field frames, with a mean branch processing time of 23.37 ms. These results support the feasibility of combining CAD hole-layout priors and depth geometry to provide complementary local geometric constraints for subsequent motion planning.<\/jats:p>","DOI":"10.3390\/s26185855","type":"journal-article","created":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T07:58:59Z","timestamp":1789545539000},"page":"5855","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Local Geometric Perception for Climbing Robots on Double-Deck Steel Truss Bridges Using CAD Hole-Layout Priors and Depth-Derived Geometry"],"prefix":"10.3390","volume":"26","author":[{"given":"Jie","family":"Hou","sequence":"first","affiliation":[{"name":"School of Mechanical Engineering and Intelligent Equipment, Chang\u2019an University, Xi\u2019an 710064, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"given":"Hongbing","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering and Intelligent Equipment, Chang\u2019an University, Xi\u2019an 710064, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Jiahao","family":"Lin","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering and Intelligent Equipment, Chang\u2019an University, Xi\u2019an 710064, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"software","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"given":"Xiaoyu","family":"Li","sequence":"additional","affiliation":[{"name":"CCCC Highway Bridge National Engineering Research Centre Co., Ltd., Beijing 100011, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"given":"Xiaochen","family":"Wei","sequence":"additional","affiliation":[{"name":"CCCC Highway Bridge National Engineering Research Centre Co., Ltd., Beijing 100011, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"given":"Yaoyu","family":"Zhu","sequence":"additional","affiliation":[{"name":"CCCC Highway Bridge National Engineering Research Centre Co., Ltd., Beijing 100011, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"resources","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Zhonghong","family":"Dong","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering and Intelligent Equipment, Chang\u2019an University, Xi\u2019an 710064, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"supervision","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"102442","DOI":"10.1016\/j.jdeveco.2020.102442","article-title":"On the road: Access to transportation infrastructure and economic growth in China","volume":"145","author":"Banerjee","year":"2020","journal-title":"J. Dev. Econ."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"787","DOI":"10.1016\/j.eng.2017.11.001","article-title":"Developments and prospects of long-span high-speed railway bridge technologies in China","volume":"3","author":"Qin","year":"2017","journal-title":"Engineering"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"294","DOI":"10.1016\/j.autcon.2016.08.008","article-title":"Detection of rust defects on steel bridge coatings via digital image recognition","volume":"71","author":"Liao","year":"2016","journal-title":"Autom. Constr."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1016\/j.autcon.2019.02.013","article-title":"A vision-based method for crack detection in gusset plate welded joints of steel bridges using deep convolutional neural networks","volume":"102","author":"Dung","year":"2019","journal-title":"Autom. Constr."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"108652","DOI":"10.1016\/j.ymssp.2021.108652","article-title":"A comprehensive review of loosening detection methods for threaded fasteners","volume":"168","author":"Huang","year":"2022","journal-title":"Mech. Syst. Signal Process."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"100167","DOI":"10.1016\/j.dibe.2023.100167","article-title":"Quantifying the reliability of defects located by bridge inspectors through human observation behavioral analysis","volume":"14","author":"Liu","year":"2023","journal-title":"Dev. Built Environ."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"113314","DOI":"10.1016\/j.tws.2025.113314","article-title":"Experimental and numerical study of riveted joints in truss bridges reinforced with added steel plates","volume":"214","author":"Liu","year":"2025","journal-title":"Thin-Walled Struct."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"9604","DOI":"10.1109\/TNNLS.2022.3167688","article-title":"Perception and navigation in autonomous systems in the era of learning: A survey","volume":"34","author":"Tang","year":"2023","journal-title":"IEEE Trans. Neural Netw. Learn. Syst."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Ratsamee, P., Kriengkomol, P., Arai, T., Kamiyama, K., Mae, Y., Kiyokawa, K., Mashita, T., Uranishi, Y., and Takemura, H. (2016, January 23\u201327). A hybrid flying and walking robot for steel bridge inspection. Proceedings of the 2016 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), Lausanne, Switzerland.","DOI":"10.1109\/SSRR.2016.7784278"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"8121678","DOI":"10.1155\/2016\/8121678","article-title":"An automated sensing system for steel bridge inspection using GMR sensor array and magnetic wheels of climbing robot","volume":"2016","author":"Wang","year":"2016","journal-title":"J. Sens."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Nguyen, S.T., Pham, A.Q., Motley, C., and La, H.M. (August, January 31). A practical climbing robot for steel bridge inspection. Proceedings of the 2020 IEEE International Conference on Robotics and Automation (ICRA), Paris, France.","DOI":"10.1109\/ICRA40945.2020.9196892"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1007\/s10846-020-01266-1","article-title":"A climbing robot for steel bridge inspection","volume":"102","author":"Nguyen","year":"2021","journal-title":"J. Intell. Robot. Syst."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Ahmed, H., Nguyen, S.T., La, D., Le, C.P., and La, H.M. (2022, January 23\u201327). Multi-directional bicycle robot for bridge inspection with steel defect detection system. Proceedings of the 2022 IEEE\/RSJ International Conference on Intelligent Robots and Systems (IROS), Kyoto, Japan.","DOI":"10.1109\/IROS47612.2022.9981325"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"171","DOI":"10.54254\/2755-2721\/81\/20241084","article-title":"A magnetic climbing robot for steel bridge inspection","volume":"81","author":"Zhou","year":"2024","journal-title":"Appl. Comput. Eng."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Song, W., Wang, Z., Wang, T., Ji, D., and Zhu, S. (2022). A path tracking method of a wall-climbing robot towards autonomous inspection of steel box girder. Machines, 10.","DOI":"10.3390\/machines10040256"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"4149","DOI":"10.1111\/mice.13469","article-title":"Complete-coverage path planning for surface inspection of cable-stayed bridge tower based on building information models and climbing robots","volume":"40","author":"Xia","year":"2025","journal-title":"Comput.-Aided Civ. Infrastruct. Eng."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"100484","DOI":"10.1016\/j.dibe.2024.100484","article-title":"Autonomous mobile construction robots in built environment: A comprehensive review","volume":"19","author":"Zeng","year":"2024","journal-title":"Dev. Built Environ."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1002\/rob.22042","article-title":"Weld line recognition and path planning with spherical tank inspection robots","volume":"39","author":"Li","year":"2022","journal-title":"J. Field Robot."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"104685","DOI":"10.1016\/j.robot.2024.104685","article-title":"BiCR-SLAM: A multi-source fusion SLAM system for biped climbing robots in truss environments","volume":"176","author":"Zhu","year":"2024","journal-title":"Robot. Auton. Syst."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"102880","DOI":"10.1016\/j.inffus.2024.102880","article-title":"Climb-Odom: A robust and low-drift RGB-D inertial odometry with surface continuity constraints for climbing robots on freeform surface","volume":"117","author":"Gu","year":"2025","journal-title":"Inf. Fusion"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1007\/s10846-017-0764-6","article-title":"Intelligent environment recognition and prediction for NDT inspection through autonomous climbing robot","volume":"92","author":"Teixeira","year":"2018","journal-title":"J. Intell. Robot. Syst."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"6762","DOI":"10.1109\/TII.2022.3205952","article-title":"Global localization based on tether and visual-inertial odometry with adsorption constraints for climbing robots","volume":"19","author":"Gu","year":"2023","journal-title":"IEEE Trans. Ind. Inform."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"743","DOI":"10.1017\/S0263574724002170","article-title":"Navigation of biped wall-climbing robots using BIM and ArUco markers","volume":"43","author":"Gu","year":"2025","journal-title":"Robotica"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"104247","DOI":"10.1016\/j.autcon.2022.104247","article-title":"BIM-based semantic building world modeling for robot task planning and execution in built environments","volume":"138","author":"Kim","year":"2022","journal-title":"Autom. Constr."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"104641","DOI":"10.1016\/j.autcon.2022.104641","article-title":"Semantic localization on BIM-generated maps using a 3D LiDAR sensor","volume":"146","author":"Yin","year":"2023","journal-title":"Autom. Constr."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1007\/s10846-024-02087-2","article-title":"Online as-built building information model update for robotic monitoring in construction sites","volume":"110","author":"Spinner","year":"2024","journal-title":"J. Intell. Robot. Syst."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Zhang, X., Zhang, M., Jiao, S., Zhang, X., and Li, M. (2023). Optimization design and parameter analysis of a wheel with array magnets. Symmetry, 15.","DOI":"10.3390\/sym15050962"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"9139","DOI":"10.1109\/TPAMI.2024.3416302","article-title":"A survey of label-efficient deep learning for 3D point clouds","volume":"46","author":"Xiao","year":"2024","journal-title":"IEEE Trans. Pattern Anal. Mach. Intell."},{"key":"ref_29","unstructured":"Koz\u0142owski, K., Tokhi, M.O., and Virk, G.S. (2014). Robot-centric elevation mapping with uncertainty estimates. Mobile Service Robotics: Proceedings of the 17th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, World Scientific."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Miki, T., Wellhausen, L., Grandia, R., Jenelten, F., Homberger, T., and Hutter, M. (2022, January 23\u201327). Elevation mapping for locomotion and navigation using GPU. Proceedings of the 2022 IEEE\/RSJ International Conference on Intelligent Robots and Systems (IROS), Kyoto, Japan.","DOI":"10.1109\/IROS47612.2022.9981507"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"471","DOI":"10.1145\/321356.321357","article-title":"Sequential operations in digital picture processing","volume":"13","author":"Rosenfeld","year":"1966","journal-title":"J. ACM"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/j.patcog.2017.04.018","article-title":"The connected-component labeling problem: A review of state-of-the-art algorithms","volume":"70","author":"He","year":"2017","journal-title":"Pattern Recognit."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"922","DOI":"10.1107\/S0567739476001873","article-title":"A solution for the best rotation to relate two sets of vectors","volume":"32","author":"Kabsch","year":"1976","journal-title":"Acta Crystallogr. A"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Ma, F., Hou, P., Liu, Y., Liu, Y., Liu, M., and Ma, J. (2025, January 19\u201325). Annotation-free curb detection leveraging altitude difference image. Proceedings of the 2025 IEEE\/RSJ International Conference on Intelligent Robots and Systems (IROS), Hangzhou, China.","DOI":"10.1109\/IROS60139.2025.11247167"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Vasu, P.K.A., Gabriel, J., Zhu, J., Tuzel, O., and Ranjan, A. (2023, January 18\u201322). MobileOne: An improved one millisecond mobile backbone. Proceedings of the 2023 IEEE\/CVF Conference on Computer Vision and Pattern Recognition (CVPR), Vancouver, BC, Canada.","DOI":"10.1109\/CVPR52729.2023.00764"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/18\/5855\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T08:09:11Z","timestamp":1789546151000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/18\/5855"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,16]]},"references-count":35,"journal-issue":{"issue":"18","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["s26185855"],"URL":"https:\/\/doi.org\/10.3390\/s26185855","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,16]]}}}