[{"_id":"58510","user_id":"210","department":[{"_id":"151"}],"article_type":"original","article_number":"55","type":"journal_article","status":"public","date_updated":"2025-02-04T13:46:41Z","oa":"1","author":[{"full_name":"Scheidemann, Claus","id":"38259","last_name":"Scheidemann","first_name":"Claus"},{"first_name":"Peter","full_name":"Bornmann, Peter","last_name":"Bornmann"},{"first_name":"Walter","full_name":"Littmann, Walter","last_name":"Littmann"},{"first_name":"Tobias","last_name":"Hemsel","full_name":"Hemsel, Tobias","id":"210"}],"volume":14,"main_file_link":[{"url":"https://www.mdpi.com/2076-0825/14/2/55","open_access":"1"}],"doi":"10.3390/act14020055","publication_status":"published","publication_identifier":{"issn":["2076-0825"]},"citation":{"bibtex":"@article{Scheidemann_Bornmann_Littmann_Hemsel_2025, title={Lead-Free Ceramics in Prestressed Ultrasonic Transducers}, volume={14}, DOI={<a href=\"https://doi.org/10.3390/act14020055\">10.3390/act14020055</a>}, number={255}, journal={Actuators}, publisher={MDPI AG}, author={Scheidemann, Claus and Bornmann, Peter and Littmann, Walter and Hemsel, Tobias}, year={2025} }","mla":"Scheidemann, Claus, et al. “Lead-Free Ceramics in Prestressed Ultrasonic Transducers.” <i>Actuators</i>, vol. 14, no. 2, 55, MDPI AG, 2025, doi:<a href=\"https://doi.org/10.3390/act14020055\">10.3390/act14020055</a>.","short":"C. Scheidemann, P. Bornmann, W. Littmann, T. Hemsel, Actuators 14 (2025).","apa":"Scheidemann, C., Bornmann, P., Littmann, W., &#38; Hemsel, T. (2025). Lead-Free Ceramics in Prestressed Ultrasonic Transducers. <i>Actuators</i>, <i>14</i>(2), Article 55. <a href=\"https://doi.org/10.3390/act14020055\">https://doi.org/10.3390/act14020055</a>","chicago":"Scheidemann, Claus, Peter Bornmann, Walter Littmann, and Tobias Hemsel. “Lead-Free Ceramics in Prestressed Ultrasonic Transducers.” <i>Actuators</i> 14, no. 2 (2025). <a href=\"https://doi.org/10.3390/act14020055\">https://doi.org/10.3390/act14020055</a>.","ieee":"C. Scheidemann, P. Bornmann, W. Littmann, and T. Hemsel, “Lead-Free Ceramics in Prestressed Ultrasonic Transducers,” <i>Actuators</i>, vol. 14, no. 2, Art. no. 55, 2025, doi: <a href=\"https://doi.org/10.3390/act14020055\">10.3390/act14020055</a>.","ama":"Scheidemann C, Bornmann P, Littmann W, Hemsel T. Lead-Free Ceramics in Prestressed Ultrasonic Transducers. <i>Actuators</i>. 2025;14(2). doi:<a href=\"https://doi.org/10.3390/act14020055\">10.3390/act14020055</a>"},"intvolume":"        14","language":[{"iso":"eng"}],"publication":"Actuators","abstract":[{"text":"<jats:p>Today’s ultrasonic transducers find broad application in diverse technology branches and most often cannot be replaced by other actuators. They are typically based on lead-containing piezoelectric ceramics. These should be replaced for environmental and health issues by lead-free alternatives. Multiple material alternatives are already known, but there is a lack of information about their technological readiness level. To fill this gap, a small series of prestressed longitudinally vibrating transducers was set up with a standard PZT material and two lead-free variants within this study. The entire process for building the transducers is documented: characteristics of individual ring ceramics, burn-in results, and free vibration and characteristics under load are shown. The main result is that the investigated lead-free materials are ready to use within ultrasonic bolted Langevin transducers (BLTs) for medium-power applications, when the geometrical setup of the transducer is adopted. Since lead-free ceramics need higher voltages to achieve the same power level, the driving electronics or the mechanical setup must be altered specifically for each material. Lower self-heating of the lead-free materials might be attractive for heat-sensitive processes.</jats:p>","lang":"eng"}],"publisher":"MDPI AG","date_created":"2025-02-04T13:43:23Z","title":"Lead-Free Ceramics in Prestressed Ultrasonic Transducers","quality_controlled":"1","issue":"2","year":"2025"},{"status":"public","type":"journal_article","article_number":"187","department":[{"_id":"153"},{"_id":"241"}],"user_id":"41470","_id":"57176","intvolume":"        13","citation":{"ama":"Henkenjohann M, Nolte U, Sion F, Henke C, Trächtler A. Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers. <i>Actuators</i>. 2024;13(5). doi:<a href=\"https://doi.org/10.3390/act13050187\">10.3390/act13050187</a>","chicago":"Henkenjohann, Mark, Udo Nolte, Fabian Sion, Christian Henke, and Ansgar Trächtler. “Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers.” <i>Actuators</i> 13, no. 5 (2024). <a href=\"https://doi.org/10.3390/act13050187\">https://doi.org/10.3390/act13050187</a>.","ieee":"M. Henkenjohann, U. Nolte, F. Sion, C. Henke, and A. Trächtler, “Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers,” <i>Actuators</i>, vol. 13, no. 5, Art. no. 187, 2024, doi: <a href=\"https://doi.org/10.3390/act13050187\">10.3390/act13050187</a>.","mla":"Henkenjohann, Mark, et al. “Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers.” <i>Actuators</i>, vol. 13, no. 5, 187, MDPI AG, 2024, doi:<a href=\"https://doi.org/10.3390/act13050187\">10.3390/act13050187</a>.","bibtex":"@article{Henkenjohann_Nolte_Sion_Henke_Trächtler_2024, title={Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers}, volume={13}, DOI={<a href=\"https://doi.org/10.3390/act13050187\">10.3390/act13050187</a>}, number={5187}, journal={Actuators}, publisher={MDPI AG}, author={Henkenjohann, Mark and Nolte, Udo and Sion, Fabian and Henke, Christian and Trächtler, Ansgar}, year={2024} }","short":"M. Henkenjohann, U. Nolte, F. Sion, C. Henke, A. Trächtler, Actuators 13 (2024).","apa":"Henkenjohann, M., Nolte, U., Sion, F., Henke, C., &#38; Trächtler, A. (2024). Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers. <i>Actuators</i>, <i>13</i>(5), Article 187. <a href=\"https://doi.org/10.3390/act13050187\">https://doi.org/10.3390/act13050187</a>"},"publication_identifier":{"issn":["2076-0825"]},"publication_status":"published","doi":"10.3390/act13050187","volume":13,"author":[{"first_name":"Mark","last_name":"Henkenjohann","full_name":"Henkenjohann, Mark"},{"first_name":"Udo","last_name":"Nolte","full_name":"Nolte, Udo"},{"first_name":"Fabian","last_name":"Sion","full_name":"Sion, Fabian"},{"last_name":"Henke","full_name":"Henke, Christian","first_name":"Christian"},{"first_name":"Ansgar","last_name":"Trächtler","full_name":"Trächtler, Ansgar","id":"552"}],"date_updated":"2024-11-18T10:42:19Z","abstract":[{"lang":"eng","text":"Incremental nonlinear dynamic inversion (INDI) is a widely used approach to controlling UAVs with highly nonlinear dynamics. One key element of INDI-based controllers is the control allocation realizing pseudo controls using available actuators. However, the tracking of commanded pseudo controls is not the only objective considered during control allocation. Since the approach only works locally due to linearization and the solution is often ambiguous, additional aspects like control efforts or penalizing the deviation of certain states must be considered. Conducting the control allocation by solving a quadratic program this results in a considerable number of weighting parameters, which must be tuned during control design. Currently, this is conducted manually and is therefore time consuming. An automated approach for tuning these parameters is therefore highly beneficial. Thus, this paper presents and evaluates a model-based approach automatically tuning the control allocation parameters of a tiltrotor VTOL using an optimization algorithm. This optimization algorithm searches for optimal parameters minimizing a cost functional that reflects the design target. This cost functional is calculated based on a test mission for the VTOL which is conducted within a simulation environment. The test mission represents the common operating range of the VTOL. The simulation environment consists of an aircraft model as well as a model of the INDI-based controller which is dependent on the control allocation parameters. On this basis, model-based optimization is conducted and the optimal parameters are identified. Finally, successful real-world tests on a 4-degrees-of-freedom testbench using the identified parameters are presented. Since the control allocation parameters can significantly influence the aircraft’s stability, the 4-DOF testbench for the aircraft is required for rapid validation of the parameters at a minimum amount of risk."}],"publication":"Actuators","language":[{"iso":"eng"}],"year":"2024","issue":"5","quality_controlled":"1","title":"Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers","date_created":"2024-11-18T10:09:58Z","publisher":"MDPI AG"}]