A mathematical equation for quantifying control functionality in agricultural tractors

Efficient operation of a machine depends upon the design of its control layout. Well-arranged controls, whose operational characteristics are based on design standards and on human factors considerations, allow the operator to easily assess and operate them maximizing the operation performance. Any new idea for ergonomic improvement of the layout can be applied if it is in accordance with the design standards, but the problem of the overall ergonomic assessment still remains. The objective of this thesis is to develop a numerical index, referred to as an 'Index of Functionality', capable of comparing, on a mathematical basis, different control arrangements in agricultural tractors. The model is based on information that has been gleaned from the published literature, with input from both professional ergonomists and experienced agricultural tractor operators. With the inclusion of factors related to controls of tractors, the model can be used to assess the degree to which tractors' controls are compatible with the expectations of the operator for easy, efficient, and convenient operation. To validate the model, data collected from a total number of six old and six modern tractor workstations to determine its capability to recognize improvements that have occurred in the ergonomic design of tractor control layouts over the past 20 years. Results showed average value of 0.71 out of 1 for the modern tractors and 0.20 out of 1 for the old tractors. The difference between the two average values confirmed the fact that the 'Index of Functionality' is an effective 'tool' which clearly recognized the latest ergonomic improvements in tractor workstations over the past 20 years.; Keywords. Tractor workstation, Control access, Control placement, Ergonomic evaluation.