Ergonomic Study

Visualization of Comfort and Reach in Cab Environment
Daniel Lundströma,d, Tuomas Nevarantab, Lars Hansonc, Dan Högbergd och Anders Sundine a, Industrial Design, Department of Design Sciences, Lund University, Lund, Sweden b, Valtra Inc., Suolahti, Finland c, Ergonomics, Department of Design Sciences , Lund University, Lund, Sweden d, School of Technology and Society, University of Skövde, Skövde, Sweden e, Semcon Caran AB, Gothenburg, Sweden

Abstract
The aim of this work is to respond to shortcomings in tractor cab layout design by deriving a working process for the creation of visual guidelines of comfort and comfortable reach, i.e. comfort and reach envelopes. This working process was the result of an illustrative case, where reach and comfort envelopes were created with the help of digital human modeling programs as well as CAD software for the tractor developer and manufacturer Valtra Inc. The conclusion of the study is that better target group accommodative comfort and reach envelopes can improve cab layout design related to comfort and work safety. Moreover, a general working method allows for optimization of ergonomic requirements for the specific design by permitting full control of each work step.

Introduction
The operator of the modern tractor is subjected to full body vibrations, prolonged sitting and twisted postures, which have all been shown to increase the risk of experiencing lower back pains as well as attaining hip joint arthritis (Torén et al., 1999). Moreover, monotonous movements and short repeated working cycles, e.g. operating and reaching for controls, are constantly present in tractor operation and are probably the main reasons for stress and fatigue injuries among drivers (Nilsson, 2001).

In order to design for comfort and reduce work-related disorders among tractor drivers Zimmerman et al. (1997) propose to address four main design criteria: minimizing magnitude and frequency of vibration reaching the operator; locating

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