Investigating effects of adjustability features in the design of forklift backrests: a pilot study

This study assessed the effectiveness of an adjustable backrest towards facilitating comfort to a range of users' body sizes. Twelve participants were recruited in a comparative study to detect the effect of body size (5, 5-95, 95 percentile), sex, backrest type (adjustable, original), and leaning duration on comfort and stability. Body movements related to the perceived discomfort were used to quantify the convenience of individuals while leaning on the backrest. Results showed a decrease in the centre of pressure deviation by 12% for the adjustable backrest, compared to a 47% increase for the original design. Moreover, upper-body movement reduction (similar to 20%, p-value = 0.04) denoted that adjustable backrest was more effective over longer durations. The identified improvement regions on the new backrest included backrest curvature, hook feature, and symmetric material placement. This article presents a comprehensive method for evaluating backrests, which could also be implemented for assessing similar seating products with adjustability features.