Scientific 3D biomechanical analysis of work in airbus A320 cargo hold.

Jurum Kipke, Jasna ; Sumpor, Davor ; Rozic, Tomislav 等

Abstract: Regarding imperative aircraft flight characteristics, cargo hold determined for passenger luggage handling, during flight, is dimensioned exclusively in determination of the possible dimensions. During loading, which is done manually by workers, the worker takes a very inadequate working position which, in combination with different dimensional characteristics and cargo masses results in increased biomechanical load on the spinal column. In order to determine the realized biomechanical load, based on the analysis of the working process, 3D shaping of the virtual operational environmental system has been done in correlation with the digitally generated humanoid model. The 3D computation model allows scientific biomechanical visualisation of the working efforts.

Key words: virtual environment, humanoid model, scientific visualisation

1. INTRODUCTION

The subject of the research in this work is the insufficiently studied operating staff engaged in the activities related to re-loading of luggage belonging to passengers who use the air transport service by aircraft Airbus A320. The workers are part of the handling group as one of the segments of technological sub-systems in the organization of every airport. From the organizational aspect the process of handling aircraft, passengers and their luggage in arrival is in principle compatible to the handling process in their departure.

The activities of the transport workers working on unloading and loading of aircraft consists of luggage handling activities in compliance with the order of the loading-unloading coordinator and aircraft handling coordinator, controlling adequate means, vehicles and equipment used in aircraft handling and boarding--disembarking passengers and their load into and out of the aircraft.

The process of receiving passengers' luggage is harmonized with the process of passenger boarding so that luggage belonging to passengers who decide not to fly are exactly removed as soon as possible. Furthermore, whenever possible, first the cargo is loaded, and then the passengers' luggage, so that it would be unloaded first at the destination airport. Special attention is paid also to the arrangement of the passengers' luggage according to the end destination which then determines the loading sequence. Moreover, the loading-unloading workers have to fix the loaded cargo and passengers' luggage by adequate means and to insure these against possible shifts during flight, and in compliance with the technical and technological characteristics of the aircraft and the recommendations of the manufacturers and the carriers. In cargo loading, it is also necessary to comply with the standards indicated in the tables or the required contact surfaces of cargo, and in accordance with the allowed load of the carrying surfaces of the aircraft cargo hold area. After having completed the loading, and before the cargo hold door is closed, the coordinator checks the performed activities and reports to the superior.

2. BIOMECHANICAL METHODS OF DETERMINING HUMAN WORK

This interdisciplinary science encompasses the methods, procedures and results of research which have their origins in the sciences of ergonomics, psychology, physiology, medicine, and anthropology. The analysis of the work efforts in humans is conditioned by the selection of the method that can be classified into two groups: energy and physiological (Muftic, 2001). Energy methods have the task to determine the consumption of energy of the working person within a determined interval of time based on which the volume of the very effort is estimated. The energy consumption itself is a value difficult to measure regarding its complexity, and it is therefore necessary to define in advance the method of its measurement, e.g. the consumption of oxygen. The physiological methods determine the fatigue based on the muscle efforts by direct measurement of mechanical work, which results in the clear image of load. Muscle effort is divided into static, maintenance of posture and dynamic, rhythmical exchange of contraction.

This results in the tasks of biomechanics defined by studying the human working environment in a determined time period, in various influences of working conditions within the determined working ambient system. One of the examples of the biomechanical consideration and assessment of human work, in accordance with the working postures that are realized during aircraft loading--unloading is presented in Table 1 which provides the data based on the assessment of various body postures during work as well as estimate of their application (Bosh, 1978).

3. ANTHROPOMETRIC DETERMINING DIMENSIONS AND ACTIVITIES OF HUMAN BODY

The starting point of any biomechanical analysis lies precisely in anthropometric research, since the accuracy and the precision of the results obtained after the carried out anthropometric analysis affect also the results of subsequent studies. Cognitive sensitivity of these analyses indicates the necessity to carefully select the anthropometric methods (Muftic, 1992).

Regarding the making of virtual models of our analysis in actual correspondence with their real sources, for the purposes of this work, the SABALab system of spatial digital three-dimensional body scanning "BodySABA 0.7." and the system for three-dimensional measuring and analysis of the human working activities "VatoSABA 2.1.", Figure 1 (Baksa et al., 2003) were used.

This new digitized methods and procedures result in the knowledge of the body characteristics, i.e. on the static, kinematical and dynamic anthropomeasures. The static anthropomeasures include linear measures i.e. characteristic distances of individual points. Kinematical anthropomeasures include the knowing of amplitudes of single linear and angular shifts. Unlike static anthropometry, dynamic anthropometry is based on the biomechanics, i.e. on the application of mechanics in biological systems.

Based on the obtained virtual 3D models of humans and the working environmental system of the Airbus A320 cargo hold, using computer scientific visualisation, the biomechanical analysis of the movements was performed based on the actual correlation in the space of the interaction between the men and the respective working environment.

Figure 2 shows 3D biomechanical visualisation of the working activities of the workers in real kinematogram-separated working posture within the aircraft cargo hold.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

4. RESEARCH RESULTS

For the biomechanical analysis of the most critical posture of the subject, a worker was chosen who works within the aircraft cargo hold with the following general data: total mass m = 85kg and standing height h = 185cm. Manipulation is done with cargo of maximal dimensions 110 x 120 x 75cm and maximal permitted mass of 45kg. The calculation of the equivalent lumbar moment [M.sub.L] is reduced to the calculation of the moments of forces of the weights of body segments according to point L4/L5 of lumbar part of the spine according to, (Mairiaux, 1984):

[M.sub.L] = [n.summation over (i=1)[F.sub.i] x [x.sub.i] (1)

i.e. lumbar force FL with the assumption that it acts in the centre of gravity of the cross-section, i.e. at h/16 measured from L4/L5:

[F.sub.L] = 16[M.sub.L]/h (2)

In the biomechanical calculation the total lumbar moment equals the sum of all lumbar moments of the segments and lumbar moments of load whose centres of gravity, in the kinematic chain of the human skeleton are located above the point L4/L5. The values of the results of the analysed biomechanical magnitudes are given in Table 2.

5. CONCLUSION

In this work biomechanical methods were used to derive the assessment of the worker's effort and the total, relatively unfavourable, lumbar moment for the observed momentary load of the subject in the most difficult working task and its critical phase during loading and unloading of cargo has been calculated.

It is relatively difficult to determine how often a worker is subjected to maximally permitted loads of this or similar masses, which are also specially labelled by a yellow tape. It may also be noticed that the worker cannot change the working posture and that during cargo loading they are always in a bending position, which is the guideline that should be taken in further optimisation and research.

6. REFERENCES

Muftic, O. (2001). Fundamentals of Ergonomics, Faculty of Mechanical Engineering, University of Sarajevo, Sarajevo, 2001.

Bosh, R. (1978). Work Assistance for Ergonomic Workplace, Robert Bosh GmbH, Stuttgart, 1978.

Muftic, O. (1992). Harmonic Anthropometry as Basis for Applied Dynamic Ergonomics, Praceedings Conference on Design, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Zagreb, 1992.

Baksa, S.; Mijovic, B. & Baksa, I. (2003): Digital Body Anthropometry in Virtual 3D Ergonomical Forming of Cockpit of the SUV, IEA 2003, International Ergonomics Association, XVth Triennial Congress, August 24-29, 2003, Seoul, Korea.

Mairiaux, P.; Davies, P.R. & Stubbs, D.A. (1984). Relations between intraabdominal pressure and lumbar moments when lifting weights in the erect posture, Ergonomics, 1984, 27 (8), 883-894.

Table 1. Biomechanical observation of body posture during work

 Physiological Physiological Suitability
Body action on the load of the of the working
posture EL * body spine posture

Normal 0.4 Increased Even load of Provides big
standing blockage of the disks working scope
 blood supply in and power
 legs,
 especially due
 to reduced
 movement

Slight 1.3 Increased Uneven load up Suitable only
bending in blockage of the to threefold for short
standing blood supply in value of normal working period
 legs, standing
 especially due
 to reduced
 movement

Bending 2.1 Increased Uneven load Suitable only
down in blockage of the up to ten-fold for short
standing blood supply in value of normal working period
 legs especially standing
 due to reduced
 movement

Crouching 2.1 Blood Uneven load up Suitable only
 circulation is to threefold for short
 reduced and value of working period
 respiration and normal standing
 digestion
 interrupted due
 to compression
 of abdominal
 cavity

* energy load in relation to normal sitting (KJ/min)

Table 2: Results of biomechanical values

Observed magnitudes Value

Weight of the upper body F = 498.42 N
Load weight [F.sub.T] = 441.45 N
Lumbar force [F.sub.L] = 1138.21 N
Resultant force R = 941.15 N
Total lumbar moment [M.sub.L] = 476.92 Nm