Publications

In diesem Beitrag wird eine Methode vorgestellt, mit deren Hilfe ein nachgiebiges System mit einen gewünschten qualitativen Momenentenverlauf erstellt werden kann. Die Methode basiert auf einem neuronalen Netz, das auf Grundlage dieses Verlaufes ein System vorschlägt. Ein nachgiebiges System besteht aus der Kombination von maximal zwei nachgiebigen Elementen (NE) mit vier Randbedingungen, welche immer mit zwei Starrkörpern verbunden sind. Die Starrkörper teilen sich ein Drehgelenk. Durch die Kombination von zwei NE und vier Randbedingungen lassen sich bis zu 168 verschiedene nachgiebige Systeme bilden. Die Berechnung des Momentenverlaufs beruht auf der Theorie großer nichtlinearer Verformungen stabförmiger Strukturen. Es wird gezeigt, dass KI-basierte Methoden zum Design von nachgiebigen Systemen erfolgreich eingesetzt werden können.

The field of optical lithography is subject to intense research and has gained enormous improvement. However, the effort necessary for creating structures at the size of 20 nm and below is considerable using conventional technologies. This effort and the resulting financial requirements can only be tackled by few global companies and thus a paradigm change for the semiconductor industry is conceivable: custom design and solutions for specific applications will dominate future development (Fritze in: Panning EM, Liddle JA (eds) Novel patterning technologies. International society for optics and photonics. SPIE, Bellingham, 2021. https://doi.org/10.1117/12.2593229). For this reason, new aspects arise for future lithography, which is why enormous effort has been directed to the development of alternative fabrication technologies. Yet, the technologies emerging from this process, which are promising for coping with the current resolution and accuracy challenges, are only demonstrated as a proof-of-concept on a lab scale of several square micrometers. Such scale is not adequate for the requirements of modern lithography; therefore, there is the need for new and alternative cross-scale solutions to further advance the possibilities of unconventional nanotechnologies. Similar challenges arise because of the technical progress in various other fields, realizing new and unique functionalities based on nanoscale effects, e.g., in nanophotonics, quantum computing, energy harvesting, and life sciences. Experimental platforms for basic research in the field of scale-spanning nanomeasuring and nanofabrication are necessary for these tasks, which are available at the Technische Universität Ilmenau in the form of nanopositioning and nanomeasuring (NPM) machines. With this equipment, the limits of technical structurability are explored for high-performance tip-based and laser-based processes for enabling real 3D nanofabrication with the highest precision in an adequate working range of several thousand cubic millimeters.

In the field of soft robotics there is still a great need for a versatile, simple, and affordable gripper with a high level of adaptability to unknown objects of different sizes, shapes, and stiffness. Most of the existing soft robotic grippers are complex solutions realized with fluid-mechanically driven actuators, active smart materials, cable-driven actuation, and different form-closure principles. However, soft grippers based on compliant mechanisms are rarely introduced and explored so far. Therefore, we present a novel compliant two-finger gripper mechanism for adaptive and gentle gripping, especially of soft and easily squeezable objects like fruits, vegetables, sweets, and sushi. The structurally inherent adaptability is achieved using an optimally synthesized compliant mechanism in combination with a conventional linear actuator. Furthermore, the two-finger gripper passively realizes pinch (parallel) or/and encompass (power) grasping. It is shown by FEM simulations and confirmed by prototype tests that the developed gripper realizes both pinch and encompass grasping with high adaptability. A special advantage of the gripper is the possibility to achieve gentle food-handling of objects with comparable weight independent of the object shape, size, and position without the need for sensors. Moreover, the precise, safe, and fast manipulation of very delicate objects is exemplarily demonstrated for different sushi pieces using the gripper mechanism with an industrial robotic arm.

Compliant mechanisms are state of the art in micropositioning stages due to their many beneficial features. However, their design usually compromises between motion range, motion accuracy and design space, while mechanisms with distributed compliance are mostly applied. The further use of flexure hinges with common notch shapes strongly limits the stroke in existing high-precision motion systems. Therefore, this paper presents a high-precision compliant XY micropositioning stage with flexure hinges capable of realizing a motion range of ± 10 mm along both axes. The stage is based on a novel plane-guidance mechanism, which is optimized to realize a precise rectilinear motion of the coupler link while keeping the rotation angles of all hinges below 5˚. The XY motion is then achieved by coupling two of these mechanisms in a serial arrangement. Next, the synthesis of the monolithic XY stage is realized by replacing all revolute joints of the rigid-body model with flexure hinges using optimized power function notch shapes. Emphasis is also placed on the embodiment design of the stage and the actuator integration to minimize possible error sources. Finally, the quasi-static behavior of the compliant stage is characterized by a simulation with a 3D FEM model and by an experimental investigation of a prototype. According to the results, the developed compliant XY micropositioning stage achieves a maximum positioning deviation of less than 10 [my]m in both axes and a yaw error of less than 100 [my]rad over a working range of 20 mm × 20 mm with a comparably compact design of the compliant mechanism of 224 mm × 254 mm.

All known locomotion principles are limited respective to environmental conditions. Often, the occurrence of obstacles or gaps means the break-off for the operating motion systems. For such circumstances, a controllable jumping locomotion is required to cross these barriers. However, this locomotion demands sophisticated requirements to the actuation. The abrupt actuation is commonly realized by high dynamic actuators or complex mechanisms. In this work, a simple solution utilizing the multistability of a compliant tensegrity structure is described. Therefore, a two-dimensional tensegrity structure featuring four stable equilibria is considered. Based on bifurcation analyses a feasible actuation to control the current equilibrium configuration is derived. Changing between selected equilibrium states enables a great difference in potential energy, which yields a jumping motion of the structure. Based on numerical simulations a suitable actuation strategy is chosen to overcome obstacle and steps by jumping forward or backward, respectively. The theoretical approach is examined experimentally with a prototype of the multistable tensegrity structure.