{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T19:40:31Z","timestamp":1790970031660,"version":"4.1.0"},"reference-count":20,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2024,11,22]],"date-time":"2024-11-22T00:00:00Z","timestamp":1732233600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Although integrated joint torque sensors in robots dispel the need for external force\/torque sensors at the wrist to measure interactions, an inherent challenge is that they also measure the robot\u2019s intrinsic dynamics. This is especially problematic for delicate robot manipulation tasks, where interaction forces may be comparable to the robot intrinsic dynamics. Therefore, the intrinsic dynamics must first be experimentally estimated under no-load conditions, when the measurement only consists of torques due to the transmission of the robot actuator, before external interactions may be measured. In this work, we propose an approach for identifying and predicting the intrinsic dynamics using linear regression with non-linear radial basis functions. Then, we validate this regression on a wheel-bearing turning task, in which its friction is a measure of quality, and thus must be accurately measured. The results showed that the bearing torque measured by the joint 7 torque sensor was within an RMS error of 11% of the torque measured by the external force\/torque sensor. This error is much lower than that before our proposed model in compensating the intrinsic dynamics of the robot arm.<\/jats:p>","DOI":"10.3390\/s24237465","type":"journal-article","created":{"date-parts":[[2024,11,22]],"date-time":"2024-11-22T10:17:23Z","timestamp":1732270643000},"page":"7465","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Identification of Intrinsic Friction and Torque Ripple for a Robotic Joint with Integrated Torque Sensors with Application to Wheel-Bearing Characterization"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0400-0668","authenticated-orcid":false,"given":"Sri Harsha","family":"Turlapati","sequence":"first","affiliation":[{"name":"School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7794-7863","authenticated-orcid":false,"given":"Van Pho","family":"Nguyen","sequence":"additional","affiliation":[{"name":"School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore"},{"name":"Schaeffler Hub for Advanced Research, Nanyang Technological University, Singapore 639798, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3712-080X","authenticated-orcid":false,"given":"Juhi","family":"Gurnani","sequence":"additional","affiliation":[{"name":"School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9131-5953","authenticated-orcid":false,"given":"Mohammad Zaidi","family":"Bin Ariffin","sequence":"additional","affiliation":[{"name":"School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9117-4740","authenticated-orcid":false,"given":"Sreekanth","family":"Kana","sequence":"additional","affiliation":[{"name":"School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alvin Hong","family":"Yee Wong","sequence":"additional","affiliation":[{"name":"Schaeffler Hub for Advanced Research, Nanyang Technological University, Singapore 639798, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Boon Siew","family":"Han","sequence":"additional","affiliation":[{"name":"Schaeffler Hub for Advanced Research, Nanyang Technological University, Singapore 639798, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6930-0413","authenticated-orcid":false,"given":"Domenico","family":"Campolo","sequence":"additional","affiliation":[{"name":"School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,11,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1007\/s44245-023-00021-8","article-title":"Advances and perspectives in collaborative robotics: A review of key technologies and emerging trends","volume":"2","author":"Patil","year":"2023","journal-title":"Discov. Mech. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2065","DOI":"10.1007\/s10845-023-02137-w","article-title":"Collaborative robots in manufacturing and assembly systems: Literature review and future research agenda","volume":"35","author":"Keshvarparast","year":"2024","journal-title":"J. Intell. Manuf."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Nguyen, V.P., Chow, W.T., Dhyan, S.B., Zhang, B., Han, B.S., and Wong, H.Y.A. (2024). Low-Cost Cable-Driven Robot Arm with Low-Inertia Movement and Long-Term Cable Durability. Robotics, 13.","DOI":"10.3390\/robotics13090128"},{"key":"ref_4","unstructured":"Briquet-Kerestedjian, N. (2019). Impact Detection and Classification for Safe Physical Human-Robot Interaction Under Uncertainties. [Ph.D. Thesis, Universit\u00e9 Paris Saclay (COmUE)]."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"102265","DOI":"10.1016\/j.mechatronics.2019.102265","article-title":"A novel reactive-type joint torque sensor with high torsional stiffness for robot applications","volume":"63","author":"Min","year":"2019","journal-title":"Mechatronics"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"P\u00e1stor, M., Hagara, M., Ga\u0161p\u00e1r, \u0160., and Sapieta, M. (2023). Design and Implementation of a Low-Cost Torque Sensor for Manipulators. Appl. Sci., 13.","DOI":"10.3390\/app13169406"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1186\/s10033-024-01041-5","article-title":"Optimal Design of the Modular Joint Drive Train for Enhancing Cobot Load Capacity and Dynamic Performance","volume":"37","author":"Li","year":"2024","journal-title":"Chin. J. Mech. Eng."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1687814017740710","DOI":"10.1177\/1687814017740710","article-title":"A universal algorithm for sensorless collision detection of robot actuator faults","volume":"10","author":"Chen","year":"2018","journal-title":"Adv. Mech. Eng."},{"key":"ref_9","first-page":"1841724","article-title":"A Refined Dynamic Model of Harmonic Drive and Its Dynamic Response Analysis","volume":"2020","author":"Zhang","year":"2020","journal-title":"Shock Vib."},{"key":"ref_10","first-page":"2405134","article-title":"Disturbance Elimination for the Modular Joint Torque Sensor of a Collaborative Robot","volume":"2020","author":"Zhang","year":"2020","journal-title":"Math. Probl. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1109\/19.728840","article-title":"Torque ripple and misalignment torque compensation for the built-in torque sensor of harmonic drive systems","volume":"47","author":"Taghirad","year":"1998","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.ymssp.2017.03.041","article-title":"Adaptive torque estimation of robot joint with harmonic drive transmission","volume":"96","author":"Shi","year":"2017","journal-title":"Mech. Syst. Signal Process."},{"key":"ref_13","unstructured":"Zhang, H., Ahmad, S., and Liu, G. (2013, January 6\u201310). Torque estimation technique of robotic joint with harmonic drive transmission. Proceedings of the IEEE International Conference on Robotics and Automation, Karlsruhe, Germany."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"322","DOI":"10.1109\/TRO.2015.2402511","article-title":"Torque Estimation for Robotic Joint With Harmonic Drive Transmission Based on Position Measurements","volume":"31","author":"Zhang","year":"2015","journal-title":"IEEE Trans. Robot."},{"key":"ref_15","first-page":"455","article-title":"A novel method to improve the accuracy of torque estimation for robotic joint with harmonic drive transmission","volume":"26","author":"Yu","year":"2018","journal-title":"Eng. Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"943","DOI":"10.1177\/1077546312466884","article-title":"Characterization, modeling and vibration control of a flexible joint for a robotic system","volume":"20","author":"Lessard","year":"2014","journal-title":"JVC\/J. Vib. Control."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"850","DOI":"10.1109\/TRO.2015.2430053","article-title":"Variable impedance control of redundant manipulators for intuitive human\u2014Robot physical interaction","volume":"31","author":"Fanny","year":"2015","journal-title":"IEEE Trans. Robot."},{"key":"ref_18","unstructured":"Christian, O., Mukherjee, R., and Nakamura, Y. (2010, January 3\u20137). Unified impedance and admittance control. Proceedings of the 2010 IEEE International Conference on Robotics and Automation, Anchorage, AK, USA."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1016\/j.ymssp.2016.04.032","article-title":"Multi-source micro-friction identification for a class of cable-driven robots with passive backbone","volume":"80","author":"Tegoeh","year":"2016","journal-title":"Mech. Syst. Signal Process."},{"key":"ref_20","unstructured":"Corke, P. (2011). Robotics, Vision and Control: Fundamental Algorithms in MATLAB, Springer."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/24\/23\/7465\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T16:37:44Z","timestamp":1760114264000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/24\/23\/7465"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,11,22]]},"references-count":20,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2024,12]]}},"alternative-id":["s24237465"],"URL":"https:\/\/doi.org\/10.3390\/s24237465","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,11,22]]}}}