Results: 358
Created on: Sun, 23 Jun 2024 15:22:06 +0200 in 0.1657 sec

Maas, Jürgen; Leemhuis, Mena; Mertens, Jana; Schmidtke, Hedda; Courant, Robert; Dahlmann, Martin; Stark, Sebastian; Böhm, Andrea; Pagel, Kenny; Hinze, Maximilian; Pinkal, Daniel; Wegener, Michael; Wagner, Martin F.-X.; Sattel, Thomas; Neubert, Holger; Öz¸cep, Özgür Lütfü
A novel digitalization approach for smart materials - ontology-based access to data and models. - In: Advanced engineering materials, ISSN 1527-2648, Bd. n/a$v2024 (2024), n/a, 2302208, S. 1-12

Smart materials react to physical fields (e.g., electric, magnetic, and thermal fields) and can be used as sensors, actuators, and generators due to their bidirectional behavior. Easy and multiscale access to material data and models enables efficient research and development with regard to the selection of appropriate materials and their optimization towards specific applications. However, different working principles, measurement and analysis methods, as well as data storage approaches lead to heterogeneous and partly inconsistent datasets. The ontology-based data access (OBDA) is a suitable method to access such heterogeneous datasets easily and quickly, while material models can transform material data across certain scales for different applications. In order to connect both capabilities, an extended approach enabling an ontology-based data and model access (OBDMA) is presented, also supporting findable, accessible, interoperable, and re-usable (FAIR). The OBDMA system comprises four main levels, the query, the ontology, the mapping, and the database. Storing knowledge at these different levels increases the interchangeability and enables variable datasets, which is essential, especially for dynamic research fields such as smart materials. In this article, the principles and advantages of the OBDMA approach are demonstrated for different subclasses of smart materials, but can be transferred to other materials, too.
Mühlenhoff, Julian; Radler, Oliver; Sattel, Thomas
Development of a hydraulic actuator for MRI- and radiation-compatible medical applications. - In: Actuators, ISSN 2076-0825, Bd. 13 (2024), 3, 90, S. 1-17

This paper presents methods for the actuation, measurement, and control of a magnetic resonance imaging- and radiation-compatible single-axis translatory actuation system. As an exemplary demanding use case, the axis is developed for a robotic phantom for evaluating emitted radiation doses of radiotherapy devices. For this, the robot has to follow given three-dimensional trajectories of patients’ movements with an accuracy of 200 µm. For enabling use of magnetic resonance imaging, actuation of the robot is realized by hydraulic transmission without any metal parts or electrical components at the imaging side. The hydraulic axis is developed, built-up, and tested. In order to compensate for deviations from the targeted actuation trajectory resulting from tolerances, friction, and non-linearities in the system, a combination of photogrammetric measurement and iterative learning control is applied. The developed photogrammetric system is capable of determining the robot’s position with systematic errors of 35 µm and stochastic errors of 0.3 µm. Different types of iterative learning control methods are applied, parameterized, and tested. With this, the hydraulically actuated axis is able to follow given trajectories with maximum errors below 130 µm.
Tan, Aditya Suryadi; Sattel, Thomas; Subianto, Richard
A novel design concept of a magnetorheological fluid-based damper utilizing the porous medium for implementation in small-scale applications. - In: Fluids, ISSN 2311-5521, Bd. 8 (2023), 7, 203, S. 1-31

Magnetorheological (MR) dampers have a virtue over conventional dampers, where their damping properties can be adjusted using a magnetic field. However, MR dampers have been barely implemented in small vibratory systems, in which the modal mass and stiffness are relatively small. This is due to two major reasons, namely its high parasitic damping force and big moving mass. When such an MR damper is installed in a small vibratory system, the system‘s default damping ratio is increased and therefore its dynamic is reduced. Here, a new concept of an MR damper utilizing the porous medium and shear operating mode together with an external non-moving electromagnet is proposed. This combination results in an MR damper with a low parasitic damping force and a small moving mass. For comparison purposes, a benchmark MR damper with comparable geometry is constructed. The proposed MR damper possesses a passive friction force that is 8× smaller and OFF-state passive viscous damping that is 10-20× smaller than the benchmark MR damper. An investigation of the proposed MR damper performance in a test vibratory system shows almost no reduction of the system dynamic. Therefore, this proposed MR damper configuration can be suitable for applications in small vibratory systems.
Hoffmann, Matthias K.; Gulakala, Rutwik; Mühlenhoff, Julian; Ding, Zhaoheng; Sattel, Thomas; Stoffel, Marcus; Flaßkamp, Kathrin
Data augmentation for design of concentric tube continuum robots by generative adversarial networks. - In: Proceedings in applied mathematics and mechanics, ISSN 1617-7061, Bd. 23 (2023), 4, e202300278, S. 1-7

Concentric tube continuum robots are a promising type of robot for various medical applications. Their application in neurosurgery poses challenging requirements for design and control that can be addressed by physics-informed data-based approaches. A prerequisite to data-based modeling is an informative, rich data set. However, limited access to experimental data raises interest in partially or entirely synthetic data sets. In this contribution, we study the application of generative adversarial networks (GANs) for data augmentation in a data-based design process of such robots. We propose a GAN framework suitable for curve-fitting to generate synthetic trajectories of robots along with their corresponding control parameters. Our evaluation shows that the GANs can efficiently produce meaningful synthetic trajectories and control parameter pairs that show a good agreement with simulated trajectories.
Ehrmann, Jonathan; Reichert, Robert; Gutschmidt, Stefanie; Sattel, Thomas
Steep resonance of parametrically excited active MEMS cantilevers for dynamic mode in Atomic Force Microscopy. - In: Proceedings in applied mathematics and mechanics, ISSN 1617-7061, Bd. 22 (2023), 1, e202200230, S. 1-6

Ongoing developments in nanotechnology demand higher spatial resolution and thus, higher amplitude sensitivity in Atomic Force Microscopy (AFM). In this work, active cantilevers with integrated sensor and actuator systems are parametrically excited using a novel, analog feedback circuit. With that it is possible to adapt the strength and sign of a cubic nonlinearity which provides a bound to the amplitudes in resonance operation. The system response shows steeper resonance curves and therefore higher amplitude sensitivities compared to forced excited cantilevers. Theoretical findings are validated experimentally.
Ratke, Xenia; Sattel, Thomas
Thermal characterization of passive piezoelectric actuators. - In: ACTUATOR 2022: International Conference and Exhibition on New Actuator Systems and Applications, (2022), S. 334-337

In this paper a workflow for thermal characterization and automatic modeling of passive piezoelectric actuators of prismatic shape is presented. Aim of this work is to generate finite element models of the thermal behaviour of piezoelectric actuators without destroying the actuators. For this purpose an experimental setup was developed, as well as a characterization workflow. The advantage of the workflow lies in the speed of characterization through direct comparison of measurement results with a metamodel and automated finite element model generation for many different actuators that vary in size and shape. The method is exemplarily presented on a PZT stack actuator.
Tan, Aditya Suryadi; Rabel, Fabian; Sattel, Thomas; Sill, Yannick Lee; Goldasz, Janusz
Design and performance investigation of a novel 3DOF compact MR damper. - In: Smart materials and structures, ISSN 1361-665X, Bd. 31 (2022), 12, 125020, S. 1-14

Magnetorheological fluid (MR) based dampers have been established as an alternative to classical hydraulic dampers with proportional electromagnetic valves under vibration processes which demand adaptive damping forces. Almost all MR-dampers are spatially 1-Degree-of-Freedom (DOF) dampers, having only one axis or direction of damping force generation. In many technical applications there exist movements in more than one spatial DOF, eventually necessitating more than one damper. Because of this, the damping is required not only in one but in more spatial directions, yet adjustable. In this work, a new design of a spatial 3DOF MR damper is proposed to allow damping in three directions within one damping device. The underlying motivation is to spatially integrate three damping directions in one device to potentially reduce installation space compared to three separate 1 DOF dampers. The basic idea of the construction is to use one fluid chamber with several spatially distributed control elements at different positions of the fluid chamber. The control elements are electromagnets, generating the magnetic field in the fluid at different positions so that in total 3 spatial DOFs can be damped individually. Experiments and investigation are made, where the damper's behavior are analyzed not only in one single DOF but also in more than one DOF. It is shown, that the damping concept can generate damping in all three spatial DOFs, both individually or together. Moreover, the damping can be generated to be dominant in one specific direction, meanwhile minimum in the other direction orthogonal to it.
Tan, Aditya Suryadi; Rabel, Fabian; Sill, Yannick Lee; Sattel, Thomas
A compact 4-DoF MR damper with semi-independent damping adjustment. - In: ACTUATOR 2022: International Conference and Exhibition on New Actuator Systems and Applications, (2022), S. 101-104

Magnetorheological (MR) fluid-based damper systems have been known for their novel property to adjust its damping forces in milliseconds by changing the applied magnetic field strength. This adaptability comes along with a rather simple design compared to classical fluidic damper systems. However, the known operating modes of the MRF, such as shear, flow, squeeze, and pinch mode, are only able to generate damping in one specific direction. On the contrary, vibrations could occur not only in one direction but also in several directions. Therefore, it is desirable to have damping generated not only in one direction but also in several directions. In the worst case, N dampers would need to be installed to dampen vibrations in N translational and rotational directions. In this work, a damper design for a single and compact 4-DoF magnetorheological-based damper is proposed. The compactness is achieved by integrating several control elements to control the MR fluid. It is done by installing five electromagnets in one MR damper without adding any extra fluid chamber so that only one fluid chamber is needed for the damper system. Depending on the direction of the acting vibration, the corresponding electromagnet is then activated accordingly, which changes the state of the MR fluid in the chamber locally. Experimental investigations are conducted and the results are presented in this work. It can be seen from the results, that the design allows the MR damper to possess four degree-of-freedom by using only a single fluid chamber. Moreover, the damping can be adjusted, depending on the damping requirement.
Jacob, Kiran; Tan, Aditya Suryadi; Sattel, Thomas; Kohl, Manfred
Enhancement of shock absorption using hybrid SMA-MRF damper by complementary operation. - In: Actuators, ISSN 2076-0825, Bd. 11 (2022), 10, 280, S. 1-17

A hybrid damper concept is presented here using a combination of a Magnetorheological (MR) Fluid (MRF) and Shape Memory Alloy (SMA)-based energy dissipation. A demonstration is performed utilizing the shear operating mode of the MRF and the one-way effect of the SMA. The damping performance of different MRF-SMA configurations is investigated and the corresponding energy consumption is evaluated. We demonstrate that the operation of MRF and SMA dampers complement each other, compensating for each other's weaknesses. In particular, the slow response from the MR damper is compensated by passive SMA damping using the pseudoplastic effect of martensite reorientation, which can dissipate a significant amount of shock energy at the beginning of the shock occurrence. The MR damper compensates for the incapability of the SMA to dampen subsequent vibrations as long as the magnetic field is applied. The presented hybrid SMA-MR damper demonstrates superior performance compared to individual dampers, allowing for up to five-fold reduction in energy consumption of the MR damper alone and thereby opening up the possibility of reducing the construction volume of the MR damper.
Mühlenhoff, Julian; Körbner, Thorben; Miccoli, Giovanni; Keiner, Dörthe; Hoffmann, Matthias K.; Sauerteig, Philipp; Worthmann, Karl; Flaßkamp, Kathrin; Urbschat, Steffi; Oertel, Joachim; Sattel, Thomas
A manually actuated continuum robot research platform for deployable shape-memory curved cannulae in stereotactic neurosurgery. - In: ACTUATOR 2022: International Conference and Exhibition on New Actuator Systems and Applications, (2022), S. 10-13

In this paper, a research platform for concentric tube continuum robots is developed in order to enable advances in deploying curved cannulae for stereotactic neurosurgery. The system consists of a manually operated high-precision actuation apparatus and a photogrammetric system with measurement errors in the range of 100 micrometer. With this platform, previously planned curved paths can be analyzed ex-situ w.r.t., e.g., target precision, follow-the-leader-behavior, and hysteretic phenomena. Regarding research towards an in-vivo application in human brains, first tests with porcine brain cadavers inside an intraoperative CT are conducted in order to pave the way for histological as well as target reachability studies.