| Summary: | 博士 === 國立臺灣科技大學 === 工業管理系 === 93 === This study designed a new input device for realizing the reduction of postural loading and non-limitation of workspace. Therefore, the new input point device was designed to address postural loading. Reduction in the muscular strains in the hand, arm, and shoulder was assumed to be best achieved using desk-less, hands-free and posture-independent input. The device is held between the flexed index and middle fingers with the palm facing sideways. The buttons and wheels are activated by flexion and/or rolling of the thumb. Three experiments were conducted to test and verify the benefits of the new input device.
First experiment investigates variations in postures and strains on the hand-arm-shoulder musculature during the operation of a wireless mouse, trackpad and a new input device. Eleven males and nine females participated in the study. All subjects performed an aiming task to test the pointing and dragging functions. The results of this experiment reveal that the new pointing device allowed users to adopt more ergonomic postures and accrue the advantages of the reduced muscular loadings of the upper-extremities. Mean (SD) muscular activities (%RVC) using the wireless mouse, the trackpad and the new input device were as follows; trapezius: 3.0 (1.7), 4.4 (2.9) and 1.4 (1.0); and extensor carpi ulnaris: 7.3 (4.4), 14.5 (8.4) and 5.6 (3.1), respectively. The device was used in a variety of hand positions, alternatively. The size of the working area was far greater when the new input device was used than when the two conventional analogues were used.
The second experiment could be divided into two parts. The first part was to understand the performance variations during the operation of a wireless mouse, trackpad and a new input device, and second part focused on understanding the rate of change in adaptation for new input devices when used for a long time. For realizing the rate of change in adaptation for new input devices used for long periods, two additional long period experiments, 4-day practice and 30-day practice, were conducted. The Fitts’ law was used to compare the differences among three input devices, and the mathematical model of the learning curve was used to understand the relation between time and adaptation during long-term practice. In the first part, subjects, tasks and experimental procedures were like those in experiment 1. Unfortunately, reasonable performance was not achieved. In the second part, two subjects who had participated in experiment 1 were recruited again to participate in a four-day long experiment. The result of this experiment revealed that the pointing times decreased from 3.05 sec to 2.02 sec, and the dragging times decreased from 5.15 sec to 2.16 sec. Additionally, one subject who had participated in the 4-day long experiment was recruited to participate in the 30 day long experiment. The results of this experiment reveal that the pointing times decreased from 2.62 sec to 1.51 sec, and the dragging times decreased from 4.08 sec to 1.57 sec. According to the result of the 4-day and 30-day experiments, the performance of the new input device approached a stable state at the end of the fourth day, and the performance improved significantly after one month of practice.
The third experiment was to investigate variations in the operation of a wireless mouse, an Ai-remote and a new input device when performing presentations on computers. Eleven males and nine females participated in the study. All subjects performed a presentation in two locations to analyze and compare the operating method and usage of the devices. The analytical results reveal that the new input device allows users to adopt more ergonomic postures, decreasing the muscular loading on the upper-extremities, overcoming limitations of working space and function limitations, and boosting operating ability, with the exception of cursor controllability. Subjects had previously been accustomed to using wireless mice on their desktops, and hence they would often turn or laterally tilt their bodies to operate the wireless mouse or pointer, or to pick up and open books located on the desk and at the extremity of their reach. Additionally, all subjects had to drag the Ai-remote device using both hands. If no desk was available in front of the subject for books or other objects, uncomfortable postures, such as the user clipping a book under their armpit or clasping it in front of their chest, would be necessary. The new input device eliminated restrictions in operating space and postural impediments. Although the new input device failed to achieve reasonable cursor controllability, the analytical results have led to recommendations for the redesign of the device.
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