Usability of a Complex Device

Usability of a Complex Device

Usability of a Complex Device

Introduction

Advances in modern technology have provided many automation features that lighten the workload for operators of farming equipment. One of the many technologies incorporated in modern agricultural equipment is the automated steering system, like the John Deere GreenStar™ AutoTrac™ System, which is an assisted steering system for straight-line, curves, and circle driving applications. Further development of these systems, like the John Deere iTecPro™ system, will include elements such as end of row guidance and the control of implement functionality. This means once a fieldwork task is programmed, all driving operations, control functions, and turning at the end of the field, will be performed by the system.

When using a machine equipped with one of these systems, operator workload is reduced, switching from controlling machine functions to a monitoring task, enabling the operator to perform other tasks while doing fieldwork. Thus, it could be possible that a tractor cab could become a mobile office with the operator using a computer to attend to various office tasks while simultaneously working in the field. To enable the operator to do this efficiently, it is necessary to provide a usable computer interface in the environment, which includes both pointing and alphanumeric input devices.

Purpose of the study

The goal of this study was to identify the commercially available pointing device that provides the best usability when using a Windows-type menu selection application in a moving off-road environment and identify the factors that influence the usability of the tested devices in this environment. For an off-road application, it was expected that factors like work surface vibration and relative movement of the agricultural work environment would have a significant influence on the usability of a device. In an office environment, the mouse is the most widely accepted pointing device for use with Windows-style applications. However, it might not offer the best usability for these same applications in a moving environment because of vibrations inherent in the environment.

Literature Review

Previous work in this area has mainly evaluated the performance and usability of interface devices in either an office environment or in mobile devices like laptops or PDAs, focusing on either pointing devices or alphanumeric inputs. MacKenzie et al. (1991) compared the usability of a mouse, a tablet with stylus, and a trackball in an office environment when performing pointing and dragging tasks modeled after Fitts' reciprocal tapping task. In this study the participants had similar performance during the pointing task when using the tablet with stylus and the mouse, but they performed slightly better for the dragging task when using the tablet with stylus. When using the trackball, the participants had a lower performance than with the other two devices for both tasks. They also found that a dragging task requires more time, and produces more errors, than does a pointing task across all tested devices.

Bohan et al. (2003) compared objective performance, and subjective user preference, of a RollerMouse to a standard mouse in an office ...