Browsing by Subject "Ergonomics"

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    Adaptive operator systems in tractors : analysis of potentials and methods for specification and evaluation
    (2024) Schempp, Timo Thomas
    Der Ackerschlepper wird in der Landwirtschaft, auf dem Bau, im Forst und im Kommunalbereich als Universalmaschine eingesetzt. Dazu wird er wechselnd mit einer Vielzahl von Maschinen gekoppelt, um diese zu betreiben. Es ergeben sich wechselnde Bedienszenarien mit unterschiedlichen Anforderungen an die Bedienung der gekoppelten Maschinen. Heutige Bediensysteme sind statisch und müssen daher als Kompromisslösung für diese unterschiedlichen Anforderungen an die Bedienung eingeordnet werden. Adaptive Bediensysteme können sich hingegen an wechselnde Bedienszenarien anpassen. Diese Arbeit beleuchtet den Stand der Technik der Bediensysteme in Ackerschleppern allgemein und explizit an drei ausgewählten Beispielen. Ferner werden zwei Methoden beschrieben, mit denen ein adaptives Bediensystem spezifiziert werden kann. Für die Bewertung der kognitiven und physischen Ergonomie von Bediensystemen allgemein werden zwei weitere Methoden vorgestellt. Alle Methoden sind für einen auf dem V-Modell basierenden Entwicklungsprozess geeignet. Die beschriebenen Ergebnisse einer theoretischen und praktischen Potentialanalyse motivieren den Einsatz adaptiver Bediensysteme im Ackerschlepper. Die theoretische Potentialanalyse stützt sich auf die Grundlagen der Ergonomie und auf die Art und Weise wie die Funktionen in einem Ackerschlepper genutzt werden. Die praktische Potentialanalyse stützt sich auf die Auswertung und Analyse von Messdaten aus dem Feld mit fast 500 Arbeitsstunden aus 14 Bedienszenarien. Ferner beschreibt diese Arbeit die Anwendung der Methoden zur Spezifikation, das entwickelte und funktionsfähige adaptive Bediensystem und die Anwendung der Bewertungsmethoden, die für das adaptive Bediensystem eine signifikante Verbesserungen der physischen und kognitiven Ergonomie zeigen.
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    Making milking easier : reducing physical strain of parlor workers during milking cluster attachment
    (2017) Cockburn, Marianne; Schick, Matthias
    Milking personnel have been affected by musculoskeletal disorders for many years. In parlor workers the shoulders, wrists and lower back are most affected. As the procedure of milking cluster attachment has been reported to be the most strenuous during milking, we took a three- step approach to reduce the physical strain of this task. In the first step, we used the computer-assisted recording and long-term analysis system (CUELA) to record flexion angles of multiple joints during milking. The posture of 30 milkers was evaluated on 15 farms. Milking parlor types evaluated included the Herringbone 30°, the Herringbone 50°, and the Parallel as well as the Rotary parlor. The 5th, 50th and 95th percentiles of the data recordings were classified against ISO Norms and it was found that joint flexion angles were concerning. The statistical analysis revealed a significant interaction between milking parlor type and a working height coefficient, which reflected the ratio between the subject’s height and the effective udder height (udder height + depth of pit). By using model predictions, we calculated working height coefficients that could improve joint flexion angles. These working height coefficients were calculated for each parlor type and used within the newly developed “milking health formula” to calculate the ideal depth of pit, under the consideration of the milker’s height, milking parlor type and udder height. As the working heights recommended within the milking health formula were relatively low for all parlor types, and the recommendations made for the Herringbone 30° were broad, we aimed to further validate our findings by using surface electromyography to monitor muscle contraction intensities of 16 milkers (nine females, seven males). The second step of this thesis was performed in a laboratory setting where the milking cluster was attached to an artificial udder. It was important to ensure that the milking health formula enabled a consistent setting of working heights for milkers of different body heights, as well as ensuring that lower working heights reduced muscle contraction intensities of the upper limb and shoulder muscles. The results showed that lower working heights decreased muscle contraction intensities of the shoulder muscles, but not of the lower and upper arms. Further, since the subjects body height had no effect on muscle contraction intensities, it can be concluded that the formula offers an effective way to set comparable working heights for milkers of different body heights. Posture of milkers is not only affected by working heights, but also by the horizontal reaching distance between the milker and the cows’ udder. It has recently been assumed that milking stall dimensions are currently too small for dairy cows and that they should be increased to ensure their welfare. This could however increase the reaching distance between the udder and the cow and thus negatively affect ergonomics. In the third step of the thesis, we therefore used surface electromyography, in both a Herringbone 30° and a Side by Side milking parlor, to investigate the effect of increased milking stall dimensions on muscle contraction intensities of the upper limb and shoulder muscles during milking. Nine male subjects milked 30 cows twice per parlor type, where the milking stall dimensions were large on one side of the milking parlor and standard sized on the other. Milking stall dimensions had no effect on muscular contraction intensities in the Side by Side parlor and a controversial effect in the Herringbone 30° parlor. The contraction intensities in the right lower and upper arm were higher when cows were milked in standard sized milking stalls, but were higher in the left upper arm when cows were milked in large milking stalls. The effect of milking stall dimensions on the work environment should therefore be further investigated. In conclusion, the current project has developed a method to calculate beneficial working heights for a variety of milking parlor types. These derived recommendations have been further validated and it was shown that lower working heights reduced muscular load of the shoulder muscles.