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Department Talks

  • Katia Bertoldi
  • Room 2P04 in Stuttgart and broadcast to room N0.002 in Tübingen

In the search for materials with new properties, there have been great advances in recent years aimed at the construction of mechanical systems whose behaviour is governed by structure, rather than composition. Through careful design of the material’s architecture, new material properties have been demonstrated, including negative Poisson’s ratio, high stiffness-to-weight ratio and mechanical cloaking. While originally the field focused on achieving unusual (zero or negative) values for familiar mechanical parameters, more recently it has been shown that non-linearities can be exploited to further extend the design space. In this talk Prof. Katia Bertoldi will focus on kirigami-inspired metamaterials, which are produced by introducing arrays of cuts into thin sheets. First, she will demonstrate that instabilities triggered under uniaxial tension can be exploited to create complex 3D patterns and even to guide the formation of permanent folds. Second, she will show that such non-linear systems can be used to designs smart and flexible skins with anisotropic frictional properties that enables a single soft actuator to propel itself. Finally, Prof.Bertoldi will focus on bistable kirigami metamaterials and show that they provide an ideal environment for the propagation non-linear waves.

Organizers: Metin Sitti

  • Ye Zhao
  • MPI-IS Stuttgart, Heisenbergstr. 3, room 2P04

The demand for safe, robust, and intelligent robotic systems is growing rapidly, given their potential to make our societies more productive and increase our welfare. To achieve this, robots are increasingly expected to operate in human-populated environments, maneuver in remote and cluttered environments, maintain and repair facilities, take care of our health, and streamline manufacturing and assembly lines. However, computational issues limit the ability of robots to plan complex motions in constrained and contact-rich environments, interact with humans safely, and exploit dynamics to gracefully maneuver, manipulate, fly, or explore the oceans. This talk will be centered around planning and decision-making algorithms for robust and agile robots operating in complex environments. In particular, Dr. Zhao will present novel computational approaches necessary to enable real-time and robust motion planning of highly dynamic bipedal locomotion over rough terrain. This planning approach revolves around robust disturbance metrics, an optimal recovery controller, and foot placement re-planning strategies. Extending this motion planning approach to generalized whole-body locomotion behaviors, He will introduce our recent progress on high-level reactive task planner synthesis for multi-contact, template-based locomotion interacting with constrained environments and how to integrate formal methods for mission-capable locomotion. This talk will also present robust trajectory optimization algorithm capable of handling contact uncertainties and without enumerating contact modes. Dr. Zhao will end this talk with current research directions on distributed trajectory optimization and task and motion planning.

Organizers: Metin Sitti

  • Majid Taghavi
  • MPI-IS Stuttgart, Room 2P4, Heisenbergstraße 3

In this talk, Majid Taghavi will briefly discuss the demand for high-performance electromechanical transducers, the current challenges, and approaches he has been pursuing to tackle them. He will discuss multiple electromechanical concepts and devices that he has delivered for low-power energy harvesting, self-powered sensors, and artificial muscle technologies. Majid Taghavi will look into piezoelectric, triboelectric, electrostatic, dielectrophoretic, and androphilic phenomena, and will show his observations and innovations in coupling physical phenomena and developing smart materials and intelligent devices.

Organizers: Metin Sitti

  • Eric R. Dufresne
  • MPI-IS Stuttgart, Room 2P4, Heisenbergstraße 3

Prof. Eric Dufresne will describe some experiments on some simple composites of elastomers and droplets. First, we will consider their composite mechanical properties. He will show how simple liquid droplets can counterintuitively stiffen the material, and how magnetorheological fluid droplets can provide elastomers with magnetically switchable shape memory. Second, we consider the nucleation, growth, and ripening of droplets within an elastomer. Here, a variety of interesting phenomena emerge: size-tunable monodisperse droplets, shape-tunable droplets, and ripening of droplets along stiffness gradients. We are exploiting these phenomena to make materials with mechanically switchable structural color.

Organizers: Metin Sitti

  • Prof. Pietro Valdastri and Prof. Russel Harris
  • Room 2P4, Heisenbergstraße 3, 70569 Stuttgart

Prof. Pietro Valdastri's talk will focus on Medical Capsule Robots. Capsule robots are cm-size devices that leverage extreme miniaturization to access and operate in environments that are out of reach for larger robots. In medicine, capsule robots can be designed to be swallowed like a pill and to diagnose and treat mortal diseases, such as cancer. The talk will move from capsule robots for the inspection of the digestive tract toward a new generation of surgical robots and devices, having a relevant reduction in size, invasiveness, and cost as the main drivers for innovation. During the talk, we will discuss the recent enabling technologies that are being developed at the University of Leeds to transform medical robotics. These technologies include magnetic manipulation of capsule robots, hydraulic and pneumatic actuation, real-time tracking of capsule position and orientation, ultra-low-cost design, frugal innovation, and autonomy in robotic endoscopy.
Prof. Russell Harris has been researching new manufacturing processes for over 20 years. He has several research projects focussing on robotics, and is particularly interested in how new manufacturing processes can be an enabler to advanced robotic devices and components. In this talk he will discuss some of this research and where he believes there may be new opportunities for collaborative research across manufacturing and robotics.

Soft Aerial Robotics for Infrastructure Manufacturing

  • 26 September 2019 • 14:00 15:00
  • Mirko Kovac
  • 2R04

Future cities and infrastructure systems will evolve into complex conglomerates where autonomous aerial, aquatic and ground-based robots will coexist with people and cooperate in symbiosis. To create this human-robot ecosystem, robots will need to respond more flexibly, robustly and efficiently than they do today. They will need to be designed with the ability to move across terrain boundaries and physically interact with infrastructure elements to perform sensing and intervention tasks. Taking inspiration from nature, aerial robotic systems can integrate multi-functional morphology, new materials, energy-efficient locomotion principles and advanced perception abilities that will allow them to successfully operate and cooperate in complex and dynamic environments. This talk will describe the scientific fundamentals, design principles and technologies for the development of biologically inspired flying robots with adaptive morphology that can perform monitoring and manufacturing tasks for future infrastructure and building systems. Examples will include flying robots with perching capabilities and origami-based landing systems, drones for aerial construction and repair, and combustion-based jet thrusters for aerial-aquatic vehicles.

Organizers: Metin Sitti

  • Peter Blümler
  • MPI-IS Stuttgart, Heisenbergstr. 3, room 2P04

A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles (SPP) on arbitrary trajectories over a large volume is presented. The same instrument can also be used for magnetic resonance imaging (MRI) using the inherent contrast of the SPP [1]. The basic idea is to use one magnet system, which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. As a result, particles are guided with constant force and in a single direction over the entire volume. Prototypes of various sizes were constructed to demonstrate the principle in two dimensions on several nanoparticles, which were moved along a rough square by manual adjustment of the force angle [1]. Surprisingly even SPP with sizes < 100 nm could be moved with speeds exceeding 10 mm/s due to reversible agglomeration, for which a first hydrodynamic model is presented. Furthermore, a more advanced system with two quadrupoles is presented which allows canceling the force, hence stopping the SPP and moving them around sharp edges. Additionally, this system also allows for MRI and some first experiments are presented. Recently this concept was combined with liquid crystalline elastomers with incorporated SPP to create “micro-robots” whose coarse maneuvers are performed by a MagGuider-system while there microscopic actuation is controlled either by light or temperature [2]. 1. O. Baun, PB, JMMM 439 (2017) 294-304. doi: 10.1016/j.jmmm.2017.05.001 2. D. Ditter, PB et al. Adv. Functional Mater. 1902454 (2019) doi: 10.1002/adfm.201902454

Organizers: Metin Sitti

An introduction to bladder cancer & challenges for translational research

  • 22 July 2019 • 10:30 AM - 22 April 2019 • 11:30 AM
  • Richard T Bryan
  • 2P4

  • Joseph B. Tracy
  • MPI-IS Stuttgart, Room 2P04

Magnetic fields and light can be used to assemble, manipulate, and heat nanoparticles (NPs) and to remotely actuate polymer composites. Simple soft robots will be presented, where incorporation of magnetic and plasmonic NPs makes them responsive to magnetic fields and light. Application of magnetic fields to dispersions of magnetic NPs drives their assembly into chains. Dipolar coupling within the chains is a source of magnetic anisotropy, and chains of magnetic NPs embedded in a polymer matrix can be used to program the response of soft robots, while still using simple architectures. Wavelength-selective photothermal triggering of shape recovery in shape memory polymers with embedded Au nanospheres and nanorods can be used to remotely drive sequential processes. Combining magnetic actuation and photothermal heating enables remote configuration, locking, unlocking, and reconfiguration of soft robots, thus increasing their capabilities. Composite and multifunctional NPs are of interest for expanding the properties and applications of NPs. Silica shells are desirable for facilitating functionalization with silanes and enhancing the stability of NPs. Methods for depositing thin silica shells with controlled morphologies onto Au nanorods and CdSe/CdS core/shell quantum dot nanorods will be presented. Silica deposition can also be accompanied by etching and breakage of the core NPs. Assembly of Fe3O4 NPs onto silica-overcoated Au nanorods allows for magnetic manipulation, while retaining the surface plasmon resonance.

Organizers: Metin Sitti

  • Prof. Shu Yang
  • 2P04

Geometry is concerned with the properties of configurations of points, lines, and circles, while topology is concerned with space, dimension, and transformation. Geometry is also materials independent and scale invariant. By introducing holes and cuts in 2D sheets, we demonstrate dramatic shape change and super-conformability via expanding or collapsing of the hole arrays without deforming individual lattice units. When choosing the cuts and geometry correctly, we show folding into the third dimension, known as kirigami. The kirigami structures can be rendered pluripotent, that is changing into different 3D structures from the same 2D sheet. We explore their potential applications in energy efficient building facade, super-stretchable and shape conformable energy storage devices and medical devices, as well as bioinspired robotics. Programmable shape-shifting materials can take different physical forms to achieve multifunctionality in a dynamic and controllable manner. Through designs of geometric surface patterns, e.g. microchannels, we program the orientational elasticity in liquid crystal elastomers (LCEs), to direct folding of the 2D sheets into 3D shapes, which can be triggered by heat, light, and electric field. Taking this knowledge of guided inhomogeneous local deformations in LCEs, we then tackle the inverse problem – pre-programming geometry on a flat sheet to take an arbitrary desired 3D shape. Lastly, I will show the prospective of taking geometry to create smart fabrics and tendon-like filaments for soft robotic applications.