Podosome-Driven Defect Development in Lamellar Bone under the Conditions of Senile Osteoporosis Observed at the Nanometer Scale

The degradation mechanism of human trabecular bone harvested from the central part of the femoral head of a patient with a fragility fracture of the femoral neck under conditions of senile osteoporosis was investigated by high-resolution electron microscopy. As evidenced by light microscopy, there is a disturbance of bone metabolism leading to severe and irreparable damages to the bone structure. These defects are evoked by osteoclasts and thus podosome activity. Podosomes create typical pit marks and holes of about 300-400 nm in diameter on the bone surface. Detailed analysis of the stress field caused by the podosomes in the extracellular bone matrix was performed. The calculations yielded maximum stress in the range of few megapascals resulting in formation of microcracks around the podosomes. Disintegration of hydroxyapatite and free lying collagen fibrils were observed at the edges of the plywood structure of the bone lamella. At the ultimate state, the disintegration of the mineralized collagen fibrils to a gelatinous matrix comes along with a delamination of the apatite nanoplatelets resulting in a brittle, porous bone structure. The nanoplatelets aggregate to big hydroxyapatite plates with a size of up to 10 x 20 μm2. The enhanced plate growth can be explained by the interaction of two mechanisms in the ruffled border zone: the accumulation of delaminated hydroxyapatite nanoplatelets near clusters of podosomes and the accelerated nucleation and random growth of HAP nanoplatelets due to a nonsufficient concentration of process-directing carboxylated osteocalcin cOC. © 2021 The Authors. Published by American Chemical Society

e-Robot

Das Projekt e-Robot bereitet ein über das Internet bedienbares Labor vor, in dem die Steuerung realer Roboter entwickelt und praktisch erprobt werden kann. Das Labor arbeitet ressourcenschonend und eröffnet gleichzeitig völlig neue Möglichkeiten des Zugangs für Studierende zu Hardware und eigenen experimentellen Daten sowie zur weltweiten kooperativen Forschung und Lehre im Bereich der humanoiden Robotik

An adaptive balancing robot with exceptional touch sensitivity driven by an analog sensorimotor loop

The 9.5th international symposium on Adaptive Motion of Animals and Machines. Ottawa，Canada (Virtual Platform). 2021-06-22/25. Adaptive Motion of Animals and Machines Organizing Committee

Language Grounding

Trabajo presentado en la UCSD Conference cicle, celebrada en San Diego en enero de 2014.N

Self-Adjusting Ring Modules (SARMs) for Flexible Gait Pattern Generation

Using the principle of homeostasis, we derive a learning rule for a specific recurrent neural network structure, the so-called Self-Adjusting Ring Module (SARM). Several of these Ring Modules can be plugged together to drive segmented artificial organisms, for example centipede-like robots. Controlling robots of variable morphologies by SARMs has major advantages over using Central Pattern Generators (CPGs). SARMs are able to immediately reconfigure themselves after reassembly of the robot’s morphology. In addition, there is no need to decide on a singular place for the robot’s control processor, since SARMs represent inherently distributed control structures.

Enhancing the Neuro-Controller Design Process for the Myon Humanoid Robot

Developing neural networks for the behavior control of autonomous robots can be a time-consuming task. This is especially the case for the new generation of complex robots with many sensors and motors – such as humanoid robots –, for which the networks with hundreds of neurons can become comparably large. Looking at the corresponding controller design workflow, a number of properties can be identified that slow down the development process: (1) The difficulty to create, handle and comprehend the large neuro-controllers, (2) the intricate debugging of neuro-controllers on the hardware, (3) delays caused by frequent time-consuming uploads of controllers to the hardware, (4) potential damaging of the robot and (5) the overall maintenance effort. This article proposes several measures to improve this workflow with respect to the mentioned problems. Some proposed improvements are realized by using sophisticated evolutionary robotics development software and suitable graphical network design tools. Such software, here in particular the Neurodynamics and Evolutionary Robotics Development Toolkit (NERD), significantly improves the network design process, specifically by allowing the development partially in simulation, by allowing a visual design of controllers with graphical network editors and by using suited neuro-evolution algorithms. Other improvements are based on proper neuro-modules that can be used to increase the usability of existing controllers. Bundled together, the proposed measures lead to a faster development of neuro-controllers. The proposed methods are demonstrated exemplarily with the Myon humanoid robot, but they can be applied also to other robots with similar properties and thus can help to improve the workflow for the neuro-controller design on such robot hardware