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Item type:Publication, Access status: with files , Design guidelines for metal binder jettingIn addition to the general advantages of additive manufacturing technologies, such as the resource-efficient production of highly complex components, the metal binder jetting (MBJ) process enables a more cost-effective manufacturing of metal additive components. However, the design freedoms gained by additive manufacturing, and MBJ in particular, are also accompanied by new design restrictions for component design. While a large number of design guidelines are already available for the established additive manufacturing processes, the metal binder jetting process imposes additional requirements on component design, which are currently only inadequately covered in the literature. Therefore, this paper presents the development and derivation of first design rules for the metal binder jetting process using martensitic stainless steel (17–4 PH). In this way, the paper also provides a methodology for deriving guidelines regardless of the material. In total, 13 guidelines have emerged from this, which in part both confirm existing guidelines, but also extend them.Publicationtype: Journal ArticleScopus© Citations 3 59 191 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Methodology for integrating biomimetic beams in abstracted topology optimization results(American Society of Mechanical Engineers (ASME), 2022-10); ; ; ; This paper presents a five-step design methodology to generate designs of biomimetic structural components from topology optimization results. In step one, all material allocated by topology optimization is classified as either beam like structures or nodes to generate an auxiliary model consisting of preserved regions, cylindrical beams, and ball nodes, which is an abstraction of the original topology optimization result. In step two, the auxiliary model is exposed to the original boundary conditions in a finite element analysis. Then, internal forces, torsion, and bending moments in all beams of the auxiliary model are identified with respect to both of their ends. In step three, a database is used to find a suitable biomimetic beam for each previously analyzed beam in the auxiliary model. In step four, adapted nodes are designed to connect the biomimetic beams and preserved regions to generate an intermediate biomimetic component design. And in step five, a design iteration and a validation of the final design are performed. The design methodology allows for reproducible bio-mimetic component designs, a trackable and easily documentable component development process, and the possibility of automating the design process to ultimately save development costs when designing structural components.Publicationtype: Conference Paper55 175 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Fluid-structure interaction modelling of a soft pneumatic actuator(Multidisciplinary Digital Publishing Institute (MDPI), 2021-07-15); ; This paper presents a fully coupled fluid-structure interaction (FSI) simulation model of a soft pneumatic actuator (SPA). Previous research on modelling and simulation of SPAs mostly involves finite element modelling (FEM), in which the fluid pressure is considered as pressure load uniformly acting on the internal walls of the actuator. However, FEM modelling does not capture the physics of the fluid flow inside an SPA. An accurate modelling of the physical behaviour of an SPA requires a two-way FSI analysis that captures and transfers information from fluid to solid and vice versa. Furthermore, the investigation of the fluid flow inside the flow channels and chambers of the actuator are vital for an understanding of the fluid energy distribution and the prediction of the actuator performance. The FSI modelling is implemented on a typical SPA and the flow behaviour inside the actuator is presented. Moreover, the bending behaviour of the SPA from the FSI simulation results is compared with a corresponding FEM simulation.Publicationtype: Journal ArticleScopus© Citations 16 115 171 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A gait pattern generator for closed-loop position control of a soft walking robot(2020-07-02); ; This paper presents an approach to control the position of a gecko-inspired soft robot in Cartesian space. By formulating constraints under the assumption of constant curvature, the joint space of the robot is reduced in its dimension from nine to two. The remaining two generalized coordinates describe respectively the walking speed and the rotational speed of the robot and define the so-called velocity space. By means of simulations and experimental validation, the direct kinematics of the entire velocity space (mapping in Cartesian task space) is approximated by a bivariate polynomial. Based on this, an optimization problem is formulated that recursively generates the optimal references to reach a given target position in task space. Finally, we show in simulation and experiment that the robot can master arbitrary obstacle courses by making use of this gait pattern generator.Publicationtype: Journal ArticleScopus© Citations 6 179 183 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Manufacturing, control, and performance evaluation of a gecko-inspired soft robot(2020-06-01); ; This protocol presents a method for manufacturing, control, and evaluation of the performance of a soft robot that can climb inclined flat surfaces with slopes of up to 84°. The manufacturing method is valid for the fast pneunet bending actuators in general and might, therefore, be interesting for newcomers to the field of actuator manufacturing. The control of the robot is achieved by means of a pneumatic control box that can provide arbitrary pressures and can be built by only using purchased components, a laser cutter, and a soldering iron. For the walking performance of the robot, the pressure-angle calibration plays a crucial role. Therefore, a semi-automated method for the pressure-angle calibration is presented. At high inclines (> 70°), the robot can no longer reliably fix itself to the walking plane. Therefore, the gait pattern is modified to ensure that the feet can be fixed on the walking plane.Publicationtype: Journal ArticleScopus© Citations 1 162 251 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Automated fabrication of elastomeric prepregs for soft robotics applicationsFluidic elastomer soft robots typically consist of a top and a strain-limiting bottom part. Both parts are usually cast and then glued together. Elastomeric prepregs, which can be stored at low temperatures for several months without significant cross-linking, simplify this manufacturing process. A cured top part of an arbitrary shape is placed on the wet prepreg, which later forms the strain-limiting layer, and the actuator is finally cured in an oven. Herein, a machine is designed and developed that automatically produces prepregs. Three different concepts are realized in a modular prototype: direct roller application, reverse roller application, and application with slot dies. Experiments show that the direct and the reverse roller application concepts are both suitable for the automated production of prepregs, where the latter one may be preferred due to the smaller number of contact surfaces. Three different textiles (polyester/cotton-blended fabric, nylon fabric, and fleece) are impregnated with the reverse roller application concept using Sylgard 184 and stored at −25 °C for 12 days. Using these prepregs, soft bending actuators are manufactured and tested for their functionality. Long-term fatigue tests show that only actuators produced with fleece prepregs are durable, without any signs of delamination.Publicationtype: Journal ArticleScopus© Citations 1 661 505 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A Gecko-Inspired Soft Passive Gripper(Multidisciplinary Digital Publishing Institute (MDPI), 2020-03-25); ; This paper presents a soft passive gripper consisting of six fluidic soft bending actuators arranged in a star-shaped manner. The actuators are oriented such that, upon pressurization, they bend against gravity. Gripping is realized by a commercial tape with mushroom-shaped adhesive structures that is glued to the bottom patches of the gripper. In this way, the object is released by peeling away the actuators from the object’s surface. In contrast to active grippers, which require continuous pressurization during gripping and holding, the presented passive gripper only requires energy for the release process. However, due to its working principle, the gripper is restricted to only flat objects or objects with at least one flat surface.Publicationtype: Journal ArticleScopus© Citations 15 191 188 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Toward a gecko-inspired, climbing soft robotIn this paper, we present a gecko-inspired soft robot that is able to climb inclined, flat surfaces. By changing the design of the previous version, the energy consumption of the robot could be reduced, and at the same time, its ability to climb and its speed of movement could be increased. As a result, the new prototype consumes only about a third of the energy of the previous version and manages to climb slopes of up to 84◦. In the horizontal plane, its velocity could be increased from 2 to 6 cm/s. We also provide a detailed analysis of the robot's straight gait.Publicationtype: Journal ArticleScopus© Citations 28 241 269 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , On the origin of passive rotation in rotational joints, and how to calculate itIn this paper, a computation method for the output shaft’s rotation of a passive rotational joint, especially of one that is deployed on a parallel mechanism, is investigated. As an alternative to typical geometric or screw theory methods, we propose a new approach that is based on the comparison between any passive rotational joint with a reference spherical joint. As examples, we apply our method to a universal joint and a novel double joint whose passive rotation is difficult to calculate with traditional methods. c 2019 The Authors Proceedings in Applied Mathematics & Mechanics published by Wiley-VCH Verlag GmbH & Co. KGaA WeinheimPublicationtype: Conference Paper286 270 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Recycling-oriented design in soft robotics(Multidisciplinary Digital Publishing Institute (MDPI), 2019-08-12); Soft robotics is a novel approach in the field of robotics. Soft robots or soft actuators are typically polymer-based and are characterized by their flexibility and adaptability, which brings new far-reaching applications. Soft robotics is currently at the peak of its research. One circumstance that is also present in this age is constant climate change; there is a demand for sustainability. This goes hand in hand with the design of products that are suitable for recycling. Today, more is expected of an engineer than just function-oriented design. This article looks at soft robotics from the point of view of sustainability. Since nature operates in cycles, the aim is to design products in such a way that they can be introduced into cycles. Three recycling cycles for products can be distinguished, which take place during production, during product use, and after product life. Within the framework of this work, special design measures are reviewed for fluidic elastomer actuators - a characteristic type of soft actuators - so that they can be integrated into the recycling process.Publicationtype: Journal ArticleScopus© Citations 7 342 309