Zeitschriftenaufsätze und Buchbeiträge

Dogs (Canis familiaris) prefer the walk at lower speeds and the more economical trot at speeds ranging from 0.5 Fr up to 3 Fr. Important works have helped to understand these gaits at the levels of the center of mass, joint mechanics, and muscular control. However, less is known about the global dynamics for limbs and if these are gait or breed-specific. For walk and trot, we analyzed dogs’ global dynamics, based on motion capture and single leg kinetic data, recorded from treadmill locomotion of French Bulldog (N = 4), Whippet (N = 5), Malinois (N = 4), and Beagle (N = 5). Dogs’ pelvic and thoracic axial leg functions combined compliance with leg lengthening. Thoracic limbs were stiffer than the pelvic limbs and absorbed energy in the scapulothoracic joint. Dogs’ ground reaction forces (GRF) formed two virtual pivot points (VPP) during walk and trot each. One emerged for the thoracic (fore) limbs (VPPTL) and is roughly located above and caudally to the scapulothoracic joint. The second is located roughly above and cranially to the hip joint (VPPPL). The positions of VPPs and the patterns of the limbs’ axial and tangential projections of the GRF were gaits but not always breeds-related. When they existed, breed-related changes were mainly exposed by the French Bulldog. During trot, positions of the VPPs tended to be closer to the hip joint or the scapulothoracic joint, and variability between and within breeds lessened compared to walk. In some dogs, VPPPL was located below the pelvis during trot. Further analyses revealed that leg length and not breed may better explain differences in the vertical position of VPPTL or the horizontal position of VPPPL. The vertical position of VPPPL was only influenced by gait, while the horizontal position of VPPTL was not breed or gait-related. Accordingly, torque profiles in the scapulothoracic joint were likely between breeds while hip torque profiles were size-related. In dogs, gait and leg length are likely the main VPPs positions’ predictors. Thus, variations of VPP positions may follow a reduction of limb work. Stability issues need to be addressed in further studies.

The parallel connection of technical and biological systems with a comparable mechanical behavior offers the possibility of reducing the interaction forces between those systems. Especially in the context of human-robot interaction (e.g., exoskeletons), it can improve user safety and acceptance at the same time. With this aim, we used antagonistic actuators with nonlinear compliance for a modular upper-extremity exoskeleton following biological paragons, mirroring the “blueprint” of its human user. In a test-bed setup, we compared antagonistic compliant actuation with antagonistic stiff, unilateral stiff and unilateral compliant actuation in the artificial “elbow joint” of the exoskeleton test bed. We show that this type of actuation allows the variation of the joint stiffness during motion, independent of the position. With the approach we propose, compliance leads to reduced force peaks and angular jerk, without sacrifices in terms of time constants and overshoot of amplitudes. We conclude that the presented actuation principle has considerable benefits in comparison to other types of exoskeleton actuation, even when using only commercially available and 3D printed components. Based on our work, further investigations into the control of compliant antagonistically actuated exoskeletons become realizable.

Biomechatronics is an engineering subject in which biomimetics as a method is one of its two supporting pillars: biology for engineering, or Bio4Eng. This is contrasted with biocompatible design, or Eng4Bio, examples of which are human-serving systems, such as exoskeletons, and biomedical engineering. The paper aims to illustrate that the research fields of biomimetics, biomechatronics, and biomedical engineering are not in competition but mutually supportive. The current attempts to place biomechatronics under the umbrella of biomimetics or biomedical engineering are therefore not expedient; they deprive the subject of its strength of combining Bio4Eng and Eng4Bio at any time in a task-related manner. In addition to research and development, however, the training of the specialists supporting the subjects must not be disregarded and is therefore described based on a proven design.

Zur Gefährdungsanalyse von manuellen Lastenhandhabungen empfiehlt die Bundesanstalt für Arbeitsschutz und Arbeitsmedizin (BAuA) unter anderem die Leitmerkmalmethode "Heben, Halten, Tragen". Ansatz dieses Beitrags ist die subjektive Beurteilung des "Leitmerkmals" Körperhaltung durch die Verwendung einer Tiefenkamera zur Bewegungsanalyse mit integrierter (markerloser) stick figure-Generierung reproduzierbar zu gestalten. Über eine Probandenstudie mit 30 Studenten wurden für die Analyse relevante Parameter ermittelt. Ziel ist es anhand eines parametrisierten Entscheidungsbaumes eine teilautomatisierte Kategorisierung der Körperhaltung durchzuführen. Diese hilft dem Beobachter als Unterstützungssystem bei der Entscheidungsfindung. Eine Farbcodierung (entsprechend einem Ampelsystem) ermöglicht es, eine direkte Rückkopplung an den Beobachter zu geben und somit Hinweise zur Optimierung des Arbeitsprozesses abzuleiten.

Segmental degeneration in the human lumbar spine affects both the intervertebral discs and facet joints. Facet joint degeneration not only affects the cartilage surface, but also alters the cellular properties of the cartilage tissue and the structure of the subchondral bone. The primary focus of this study is the investigation of these microstructural changes that are caused by facet joint degeneration. Microstructural analyses of degenerated facet joint samples, obtained from patients following operative lumbar interbody fusion, have not previously been extensively investigated. This study analyzes human facet joint samples from the inferior articular process using scanning electron microscopy, micro-computed tomography, and energy dispersive X-ray spectroscopy to evaluate parameters of interest in facet joint degeneration such as elemental composition, cartilage layer thickness and cell density, calcification zone thickness, subchondral bone portion, and trabecular bone porosity. These microstructural analyses demonstrate fragmentation, cracking, and destruction of the cartilage layer, a thickened calcification zone, localized calcification areas, and cell cluster formation as pathological manifestations of facet joint degeneration. The detailed description of these microstructural changes is critical for a comprehensive understanding of the pathology of facet joint degeneration, as well as the subsequent development and efficacy analysis of regenerative treatment strategies.

One of the most challenging adaptations within the therians has been to ensure dynamic stability of the trunk during rapid locomotion in highly structured environments. A reorganization of limb mechanics and development of new sensors has taken place within their stem lineage. Rats, which have a similar lifestyle to the first therians, possess sinus hairs specialized for tactile sensing. It is supposed that carpal sinus hairs have a role in sensing substrate properties and can thus induce adjustments in limb kinematics and body posture according to the different surface diameters and structures detected. This implies a shared sensorimotor control loop of sinus hairs and body posture. To investigate the role of the carpal sinus hairs during locomotion and to explore a possible interaction between limb and spine motion, spatiotemporal and kinematic parameters as well as the contact mechanics of the hairs with regard to the surface were quantified. Locomotion on a treadmill with continuous and discontinuous substrates was compared in the presence/absence of the carpal sinus hairs across a speed range from 0.2 m/s to 0.6 m/s. Recordings were taken synchronously using x-ray fluoroscopy and normal-light high-speed cameras. Our investigation revealed that the three tactile hairs made a triangle-like contact with the ground approximately 30 ms before touchdown of the forelimb. Within that time, it is likely that both the body posture and its oscillation are adjusted according to the different surface textures. The sensory input of the carpal sinus hairs induces a stabilization of the trajectory of the center of mass and, therefore, improves the dynamic stability of the trunk; conversely, the absence of the sensors results in a more crouched frontal body posture, similar to that seen in rats when they are moving in an unknown terrain. The carpal sinus hairs also sense the animal's speed during surface contact. This implicates an adjustment of the limb and spine kinematics, by increasing the speed-dependent effect or by increasing the distance between the trunk and the ground when the rat is walking faster.

Auch in Zeiten, in denen Barrierefreiheit großgeschrieben wird, bedeutet eine persönliche Mobilitätseinschränkung einen Verlust von Lebensqualität. Der Grund dafür ist, dass durch Hindernisse bzw. den Zwang zur Benutzung spezieller Routen oder Zonen die individuelle Mobilität paralysiert wird. Derzeit verfügbare Mobilitätshilfen können Hindernisse nur unzureichend kompensieren, da sich in der Praxis des Alltags Mängel zeigen, die der zumeist teuer erkauften Erweiterung des befahrbaren Geländespektrums entgegenwirken. Ein Blick auf die grundlegenden Fortbewegungsprinzipien vor dem Hintergrund der Forderung nach einem breiten befahrbaren Geländespektrum führt zur Schlussfolgerung, idealerweise eine Kombination aus Rollen und Schreiten anzustreben. Das rollende Bein in Verbindung mit einem Höhenausgleich erscheint als vielversprechende Lösung.

Scientific reception of the term "stability" stresses steady adaptation to its changing fields of application. Nevertheless, the determination of critical forces remains one of the main tasks of stability theories. We exemplify some classes of the stability loss in beams under internal pressure for the static case. Additionally, we analyse in more detail the dynamic stability of beams under internal pressure and demonstrate means to keep an equilibrium.