---
_id: '58510'
abstract:
- lang: eng
text: '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.'
article_number: '55'
article_type: original
author:
- first_name: Claus
full_name: Scheidemann, Claus
id: '38259'
last_name: Scheidemann
- first_name: Peter
full_name: Bornmann, Peter
last_name: Bornmann
- first_name: Walter
full_name: Littmann, Walter
last_name: Littmann
- first_name: Tobias
full_name: Hemsel, Tobias
id: '210'
last_name: Hemsel
citation:
ama: Scheidemann C, Bornmann P, Littmann W, Hemsel T. Lead-Free Ceramics in Prestressed
Ultrasonic Transducers. Actuators. 2025;14(2). doi:10.3390/act14020055
apa: Scheidemann, C., Bornmann, P., Littmann, W., & Hemsel, T. (2025). Lead-Free
Ceramics in Prestressed Ultrasonic Transducers. Actuators, 14(2),
Article 55. https://doi.org/10.3390/act14020055
bibtex: '@article{Scheidemann_Bornmann_Littmann_Hemsel_2025, title={Lead-Free Ceramics
in Prestressed Ultrasonic Transducers}, volume={14}, DOI={10.3390/act14020055},
number={255}, journal={Actuators}, publisher={MDPI AG}, author={Scheidemann, Claus
and Bornmann, Peter and Littmann, Walter and Hemsel, Tobias}, year={2025} }'
chicago: Scheidemann, Claus, Peter Bornmann, Walter Littmann, and Tobias Hemsel.
“Lead-Free Ceramics in Prestressed Ultrasonic Transducers.” Actuators 14,
no. 2 (2025). https://doi.org/10.3390/act14020055.
ieee: 'C. Scheidemann, P. Bornmann, W. Littmann, and T. Hemsel, “Lead-Free Ceramics
in Prestressed Ultrasonic Transducers,” Actuators, vol. 14, no. 2, Art.
no. 55, 2025, doi: 10.3390/act14020055.'
mla: Scheidemann, Claus, et al. “Lead-Free Ceramics in Prestressed Ultrasonic Transducers.”
Actuators, vol. 14, no. 2, 55, MDPI AG, 2025, doi:10.3390/act14020055.
short: C. Scheidemann, P. Bornmann, W. Littmann, T. Hemsel, Actuators 14 (2025).
date_created: 2025-02-04T13:43:23Z
date_updated: 2025-02-04T13:46:41Z
department:
- _id: '151'
doi: 10.3390/act14020055
intvolume: ' 14'
issue: '2'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://www.mdpi.com/2076-0825/14/2/55
oa: '1'
publication: Actuators
publication_identifier:
issn:
- 2076-0825
publication_status: published
publisher: MDPI AG
quality_controlled: '1'
status: public
title: Lead-Free Ceramics in Prestressed Ultrasonic Transducers
type: journal_article
user_id: '210'
volume: 14
year: '2025'
...
---
_id: '57176'
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.
article_number: '187'
author:
- first_name: Mark
full_name: Henkenjohann, Mark
last_name: Henkenjohann
- first_name: Udo
full_name: Nolte, Udo
last_name: Nolte
- first_name: Fabian
full_name: Sion, Fabian
last_name: Sion
- first_name: Christian
full_name: Henke, Christian
last_name: Henke
- first_name: Ansgar
full_name: Trächtler, Ansgar
id: '552'
last_name: Trächtler
citation:
ama: Henkenjohann M, Nolte U, Sion F, Henke C, Trächtler A. Parameter Tuning Approach
for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers. Actuators.
2024;13(5). doi:10.3390/act13050187
apa: Henkenjohann, M., Nolte, U., Sion, F., Henke, C., & Trächtler, A. (2024).
Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight
Controllers. Actuators, 13(5), Article 187. https://doi.org/10.3390/act13050187
bibtex: '@article{Henkenjohann_Nolte_Sion_Henke_Trächtler_2024, title={Parameter
Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers},
volume={13}, DOI={10.3390/act13050187},
number={5187}, journal={Actuators}, publisher={MDPI AG}, author={Henkenjohann,
Mark and Nolte, Udo and Sion, Fabian and Henke, Christian and Trächtler, Ansgar},
year={2024} }'
chicago: Henkenjohann, Mark, Udo Nolte, Fabian Sion, Christian Henke, and Ansgar
Trächtler. “Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based
Flight Controllers.” Actuators 13, no. 5 (2024). https://doi.org/10.3390/act13050187.
ieee: 'M. Henkenjohann, U. Nolte, F. Sion, C. Henke, and A. Trächtler, “Parameter
Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based Flight Controllers,”
Actuators, vol. 13, no. 5, Art. no. 187, 2024, doi: 10.3390/act13050187.'
mla: Henkenjohann, Mark, et al. “Parameter Tuning Approach for Incremental Nonlinear
Dynamic Inversion-Based Flight Controllers.” Actuators, vol. 13, no. 5,
187, MDPI AG, 2024, doi:10.3390/act13050187.
short: M. Henkenjohann, U. Nolte, F. Sion, C. Henke, A. Trächtler, Actuators 13
(2024).
date_created: 2024-11-18T10:09:58Z
date_updated: 2024-11-18T10:42:19Z
department:
- _id: '153'
- _id: '241'
doi: 10.3390/act13050187
intvolume: ' 13'
issue: '5'
language:
- iso: eng
publication: Actuators
publication_identifier:
issn:
- 2076-0825
publication_status: published
publisher: MDPI AG
quality_controlled: '1'
status: public
title: Parameter Tuning Approach for Incremental Nonlinear Dynamic Inversion-Based
Flight Controllers
type: journal_article
user_id: '41470'
volume: 13
year: '2024'
...