Perception of Effort in Manual Actions (Torque and Pulling Strength) on Different Interfaces
Authors: Bruno M. Razza, Luis Carlos Paschoarelli, Cristina C. Lucio, José Alfredo C. Ulson, Danilo C. Silva
Abstract: Tasks and products still require inappropriate demand of manual force are considered risk factors for the development of occupational diseases (Kattel et al., 1996; Aghazadeh and Mital, 1987). In ergonomic assessments, psychophysical data may provide relevant information that complement or assist understanding the results of physical assessments. In previous studies, we measured the pulling strength with 3 different handles (Razza et al., 2012) and torque strength was obtained with 5 different prismatic-shape handles (Paschoarelli et al., 2012). This study aimed to assess the reported individual perception of the strength exerted in the same conditions of those previous studies using VAS perception scale. The effects of individual characteristics (laterality and gender) and tasks elements were investigated in the reported perceived effort. This study employed three handles height (40 mm, 20 mm and 1 mm thick) grasped with 3 types of pinch grips (pinch 1, pinch 2 and pulp-pinch) and 3 prismatic-shaped handles for the assessment of torque (cylindrical, square and triangular). Results indicate that subjects of both genders could exert less effort with the handle of 40 mm height in comparison to the other heights, and pulp-pinch was considered the easiest to perform the effort. Torque’s results indicated that subjects required more effort with the cylindrical handle than to the others shapes. Of all observed conditions, the type of pinch grip had the greater impact on this measure of perceived effort.
Keywords: Ergonomics, Design, Psychophysics, Pinch Grips, Gender, Laterality.
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