SIMULATION OF DIFFERENT MOVEMENTS IN SPORTS VIA DIRECT DYNAMICS

Introduction: A standard method to determine loads on human joints during sports movements is inverse dynamics. This method is problematic for the analysis of movements with high accelerations, e.g., landings in sports, because the measurements used as input and modeling must be adapted with a high degree of accuracy. Even small inconsistencies affect result sensitivity and may lead to large errors in the values of the load. Therefore, a more appropriate method is the analysis of movements with models adapted optimally to the human body using direct dynamics. Methods: Using multi-linked wobbling mass models different gymnastics movements were calculated, partly including phases of landings. For this purpose we developed special algorithms for the torques of the joints and force-deformationrelations simulating the behavior of different surfaces, which were used as input. Results: The body movements were simulated and visualized. By varying the initial conditions and parameters of the model and the surface, the influence on the movement and the load on the joints was investigated. Conclusions: The simulation of movements in sports using direct dynamics offers many opportunities for theory and training practice. The condition of the human body and the environment can be varied in an arbitrary manner, the simulated movement can be visualized and the load on the joints can be determined simultaneously. Reference: Ruder, H., Ertl, T., Gruber, K., Günther, M. Hospach, F., Ruder, M., Subke, J., Widmayer, K. (1994). Kinematics and Dynamics for Computer Animation. In S. Coquillart, W. Straßer, P. Stucki (eds.). From Object Modelling to Advanced Visual Communication. Berlin, 76-117

Calculation of ankle and knee joint moments during ACL-injury situations in soccer

AbstractThe basis of ACL-injury prevention is the understanding of the injury mechanism. Therefore a new approach was developed and validated that enables the calculation of knee and ankle joint moments during the injury. Detailed analysis of ACL-injury situations was performed to detect the kinematics as input data for a simplified 3D-human body model. An inverse-dynamics approach was used to realize the movement. The model was driven by Net-Muscle-Torque-Motors that calculate 3-D ankle and knee joint moments. Although there are some limitations that have to be considered this approach has the potential to generate a better understanding of injury mechanisms

Harvest of Jerusalem artichoke (Helianthus tuberosus L.) with grazing pigs compared to mechanical harvest

Der Anbau von Topinambur (Helianthus tuberosus L.) als nachwachsender Rohstoff hat trotz vielversprechenden Potentials noch keinen Einzug in die Praxis gefunden. Ein Grund dafür ist, dass bei der maschinellen Rodung durchschnittlich ein Drittel der Knollen im Boden verbleiben, die im nächsten Jahr in der nachfolgenden Frucht wieder als Durchwuchs austreiben. In einem Feldversuch wurden zwei verschiedene Rodungsmethoden für Topinamburknollen in den beiden Jahren 2009 und 2010 verglichen: die Rodung mit Weideschweinen und die maschinelle Rodung mit einem Schleuderradroder. Die Methoden unterschieden sich im Rodungszeitpunkt und der Dauer (Rodung mit Weideschweinen: 50 Tage zwischen Mai und Oktober, maschinelle Rodung: 1 Tag im März). Bei der Rodung mit Weideschweinen wurden sechs Tiere für eine reine Topinamburfläche von 96 m2 eingesetzt, wobei pro Tier und Tag eine Fläche von durchschnittlich 0,34 m2 gerodet wurde. Um den Rodungserfolg der jeweiligen Methode bewerten zu können, wurde die Anzahl im Boden befindlicher Knollen unmittelbar vor und nach der Rodung gezählt. Bei der Rodung nicht erfasste Knollen, die wieder austrieben, wurden über Zählung der Durchwuchspflanzen in der nachfolgenden Kultur bestimmt. Die Rodung mit den Weideschweinen erwies sich als sehr effiziente Methode, um den überwiegenden Teil der Knollen aus dem Boden zu entfernen. Unmittelbar nach der Rodung wurden hier weniger als 3 Knollen m–2 gefunden, während es bei der maschi­nellen Rodung durchschnittlich 74 Knollen m–2 waren. Dieser Unterschied war auch in der Anzahl der Durchwuchspflanzen in der nachfolgenden Kultur deutlich sichtbar (Rodung mit Weideschweinen: weniger als 1 Durchwuchspflanze m–2, maschinelle Rodung: 31 Durchwuchspflanzen m–2). Die Entfernung von Topinamburknollen von einer Fläche durch Weideschweine stellt eine Möglichkeit zur effizienten Verminderung des Topinamburdurchwuchses in der nachfolgenden Kultur dar, auch wenn sie nur in einigen Betrieben umsetzbar ist.    The cultivation of Jerusalem artichoke (Helianthus tube­rosus L.) for bioenergy is not yet realised, although the potential is quite promising. About 1/3 of the tubers remain in the soil after harvesting which can sprout next year, and result in highly competitive volunteer plants in the following crops. Two different methods of tuber harvesting were tested in a field trial 2009 and 2010: grazing pigs, and a single row potato harvester. The methods differed in time and period of harvesting (grazing pigs: 50 days between May and October, mechanical harvest: one day in March). Six grazing pigs were used for an area of 96 m2 with Jerusalem artichoke tubers and each pig harvested on average per day an area of 0,34 m2. The number of tubers was counted immediately before and after harvesting. Tubers which were not recovered at harvest were recorded as volunteers in the following crop. Tuber harvesting by grazing pigs showed lowest number of lost tubers (< 3 tubers m–2) compared to an average of 74 tubers m–2 after the mechanical harvest. This difference was also clearly visible in the number of volunteers in the following crop (grazing pigs: < 1 volunteers m–2, mechanical harvest: 31 volunteers m–2). Tuber harvesting by grazing pigs is an option for efficient reduction of Jerusalem artichoke volunteers in the following crop, but only feasible for a few farms.   &nbsp

Kinematics and dynamics for computer animation

This tutorial will focus on the physical principles of kinematics and dynamics. After explaining the basic equations for point masses and rigid bodies a new approach for the dynamic simulation of multi-linked models with wobbling mass is presented, which has led to new insight in the field of biomechanics, but which has not been used in computer animation so far

Fractionated stereotactic radiotherapy of brain metastases: results of a retrospective study

Background Lasting local control of brain metastases following stereotactic radiotherapy is becoming increasingly relevant since systemic treatment constantly improves the prognosis of patients with extracranial metastases. Methods 73 patients with 103 brain metastases received hypofractionated stereotactic radiotherapy (FSRT) in 6 fractions of 5 Gy between January 2017 and December 2021 at the University Hospital Regensburg, Germany. The study retrospectively evaluated local progression free survival (LPFS), overall survival (OS) and distant brain progression free survival (DPFS) of patients without prior radiotherapy of the brain. Response rate and brain radiation necrosis were reported. Cox proportional hazard models evaluated prognostic factors of OS and LPFS. Results The median patient age was 61.0 years (Interquartile range, IQR 51.0, 67.5). The most common tumor types were malignant melanoma (34.2%) and non-small cell lung adenocarcinoma (26.0%). The median gross tumor volume (GTV) was 0.9 cm³ (IQR 0.4, 3.6). The median follow-up time of all patients was 36.3 months (95%CI 29.1, 43.4). The median OS was 17.4 months (95%CI 9.9, 24.9). Overall survival rates at 6-, 12-, 18-, 24-, and 30 months were 81.9%, 59.1%, 49.0%, 41.3%, and 37.2%, retrospectively. The mean LPFS was 38.1 months (95%CI 31.4, 44.9), while the median LPFS has not been reached. LPFS rates at 6-, 12-, 18-, 24- and 30 months were 78.9%, 68.7%, 64.3%, 61.6% and 58.7%, retrospectively. Median DPFS of all patients was 7.7 months (95%CI 6.1, 9.3). Six, 12-, 18-, 24- and 30 months DPFS rates were 62.1%, 36.3%, 31.1%, 24.8% and 21.7%. Five brain metastases (4.8%) developed brain radiation necrosis. In multivariate analysis, the number of brain metastases negatively affected LPFS. Non-melanoma and non-renal cell cancer was associated with a higher chance of LPFS in comparison to other cancer. A GTV > 1.5 cm³ translated into a higher risk of death compared to a GTV ≤ 1.5 cm³ and Karnofsky performance score was predictive of OS. Conclusions FSRT in 6 fractions of 5 Gy seems to be an effective treatment with an acceptable local control for patients with brain metastases although melanoma and renal cell cancer seem to have a worse local control in comparison to other cancer

Interactive control of biomechanical animation : contribution to the GI Workshop: Visualisierung - Rolle von Interaktivitat und Echtzeit, GMD, Sankt Augustin, 2.-3. Juni 1992

Physical based animation can be generated by performing a complete dynamical simulation of multi-body systems. This leads to a complex system of differential equations which has to be solved incorporating biomechanical results for the physics of impacts. Motion control is achieved by interactively modifying the internal torques. Realtime response requires the distribution of the workload of the computation between a highspeed computerserver and the graphics workstation by means of a remote procedure call mechanism

Load Distribution in the Lumbar Spine During Modeled Compression Depends on Lordosis

Excessive or incorrect loading of lumbar spinal structures is commonly assumed as one of the factors to accelerate degenerative processes, which may lead to lower back pain. Accordingly, the mechanics of the spine under medical conditions, such as scoliosis or spondylolisthesis, is well-investigated. Treatments via both conventional therapy and surgical methods alike aim at restoring a “healthy” (or at least pain-free) load distribution. Yet, surprisingly little is known about the inter-subject variability of load bearings within a “healthy” lumbar spine. Hence, we utilized computer tomography data from 28 trauma-room patients, whose lumbar spines showed no visible sign of degeneration, to construct simplified multi-body simulation models. The subject-specific geometries, measured by the corresponding lumbar lordosis (LL) between the endplates of vertebra L1 and the sacrum, served as ceteris paribus condition in a standardized forward dynamic compression procedure. Further, the influence of stimulating muscles from the M. multifidus group was assessed. For the range of available LL from 28 to 66°, changes in compressive and shear forces, bending moments, as well as facet joint forces between adjacent vertebrae were calculated. While compressive forces tended to decrease with increasing LL, facet forces were tendentiously increasing. Shear forces decreased between more cranial vertebrae and increased between more caudal ones, while bending moments remained constant. Our results suggest that there exist significant, LL-dependent variations in the loading of “healthy” spinal structures, which should be considered when striving for individually appropriate therapeutic measures

Interactive control of biomechanical animation

Physics-based animation can be generated by performing a complete dynamical simulation of multibody systems. This leads to the solving of a complex system of differential equations in which biomechanical results for the physics of impacts are incorporated. Motion control is achieved by interactively modifying the internal torques. Realtime response requires the distribution of the workload of the computation between a high-speed compute server and the graphics workstation by means of a remote-procedure call mechanism