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The number of people who use computers for business and personal purposes increases as technology grows. The application of ergonomic practices on computer workstations reduces the musculoskeletal discomfort experienced and increases the overall satisfaction of the users. Keyboards are available in various systems, from computers to mobile devices, and have difference shapes and sizes. The keyboard size and shape is known to influence the user's upper extremities. Alternative keyboard designs help diminish the pain in the arms that occurs due to awkward arm postures. Most previous studies tried to optimize the keyboard layout based on ergonomic typing and the frequency of letters' co-occurrence. This research considers the frequency of the appearance of the most used 3,000 words in the English language. First, the frequency of each letter pair is calculated by the Text Analyzer. Then, a genetic algorithm is applied to design an ergonomically optimized keyboard to minimize the total distance of finger travel among the selected alphanumeric characters. The results showed that the distance travelled obtained by the proposed keyboard layout is less than that for the QWERTY keyboard in all different types of texts, in which an average of 6.04% improvement was achieved. Therefore, the proposed design can be used for keyboards to reduce time and fatigue., Competing Interests: The authors have declared that no competing interests exist.

Recently, many postural analysis techniques have been developed in order to reduce the risk of musculoskeletal problems. Methods such as rapid entire body assessment are capable of analyzing the most constant or awkward positions, but the selection of these postures is subjective. To make an objective postural analysis, devices such as electromagnetic trackers can be used continuously during the job task, but utilizing such devices is costly. Therefore, in this study a cost-effective marker-based video processing algorithm is developed for measuring three-dimensional (3D) information regarding both the location and the orientation of human posture. To investigate the precision of the measurements, an experiment was designed. With the average of 2.88 mm and 1.34° for location and orientation, respectively, the algorithm was able to measure six degrees of freedom information regarding 3D space. Furthermore, the precision of the algorithm is found to be significantly affected by the marker pattern. [ABSTRACT FROM AUTHOR]