| Guidance aids assist agricultural machinery operators by providing lateral error information through a display called a 'lightbar'. Anecdotal evidence from dealers indicated that operators might prefer a larger lightbar. To determine the possibility for improving the design, seven high-clearance sprayer operators were interviewed or observed, or both. It was determined that a more salient display could reduce the scanning requirements. Following a review of relevant visual attention and display literature, a larger and more luminous lightbar was created.; The effects of the larger lightbar were tested using testing apparatus and methodology designed for this purpose. The apparatus was designed to simulate the visual scanning requirements of field spraying. It consisted of a pseudo-random tracking task, a choice reaction-time task, and an agricultural operator station. Based on a review of mental workload literature, a testing methodology was devised to measure tracking and monitoring performance, subjective workload, and heart rate. The test used 22 university students in a within-subjects design and compared the larger lightbar to a lightbar modeled after a popular version. The larger lightbar reduced tracking error by 11%, and subjects felt that it reduced mental and physical demand slightly. As well, subjects preferred the larger lightbar.; Several conclusions and recommendations were created for designing guidance displays, performing simulation testing, and studying agricultural machinery operator's tasks.*; *This dissertation is multimedia (contains text and other applications not available in printed format). The CD requires the following system requirements: Microsoft Office. |
