8 Summary

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Despite the fast technical progress modern horticultural work places still require a lot of manual work. The current development in the horticultural sector demands a more efficient implementation of manpower and an increasing attractiveness of simple manual tasks for the future. The design of such systems demands a method to objectively evaluate present and new work systems.

This thesis describes a largely improved 3-D-motion analysis system based on the tracking of infrared light diodes. The camera system manufactured by Wente/Thiedig is extended by a newly developed independent software to evaluate the motion data according to work scientific requirements. The development of the software was focused on current problems concerning horticultural production. It allows to calculate objective measures of comparison based on the 3-D-room coordinates describing the motions.

From the recorded motion data quantitative parameters like duration, the speed of motion, the sum of motion or angles describing the posture are calculated. In addition to that, qualitative parameters can be used for further evaluation. Several graphical functions within the new software facilitate the understanding of the motion data and allow a clear presentation of the results. A 3-D-image of the motion track, the area of activity or the angular dimensions in different shades of gray representing the frequency of occurrence are selected examples of the graphical functions.

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The available objective measures of comparison are described in detail in chapter four. In the experiments they are reviewed for their suitability. Economic and ergonomic demands are considered. The digital recording of the motion data (ASCII-format) allows a large sample size and consequential an excellent basis for statistics. Accuracy and explanatory power as well as the level of confidence are increased. The wide range of descriptive parameters gained in one experiment allows a better data interpretation compared to other methods.

A large variation in the framework of horticultural production, for example the yield, the size and distribution of the products or the weather conditions, demands a method that collects a lot of information underlying the same influences.

To proof their suitability and the increase of information gained with the measures of comparison practical experiments were carried out. These are described in the fifth chapter of this thesis.

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A workstation for placing products on on a conveyor belt is varied to show the influence of design parameters on the operating efficiency. The speed of the conveyor movement strongly affected the output. An increase of the speed can cause an incremental shift of the area of motion in the direction of flow, as it was noticed for one out of three test persons. The unfavorable product supply lead to higher sums of motion, whereas the output was kept at the same level.

In another experiment two seat constructions built for asparagus harvesting aids are compared by motion analysis. Several measure of comparison suggest to favor the seat with knee pads. The sum of motion was lower on this seat, the course of the trunk angles was congruent and an upright sitting position is more likely. Therefore the combination of quantitative and qualitative parameters allows an objective evaluation of a system looking at economic and ergonomic criteria.

The results from all practical experiments show that relevant measures of comparison were defined to successfully compare the motion data. The user of the newly developed analyzing program gains valuable information to make a truly impartial decision.

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The motion analysis systems enables scientists to gather a multitude of information out of one experiment, which formerly required a combination of several methods. The accuracy of the results is also increased.

A more of information to rate human factors is notedly valuable, encouraging the development of horticultural work systems towards incorporating economic and ergonomic criteria.


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