Ergonomic designs have positive impact on the end-user experience of any product. One of the main challenges is to accommodate a range of end-users, for which the concept of adjustability has been found to be very effective. The backrest in a forklift, for example, is provided for comfortable driving in the form of leaning/sitting postures. An ergonomic backrest has to consider the anthropometric variation in the human population to ensure optimum levels of comfort for everyone. This study provides a comprehensive methodology for developing an ergonomic backrest by combining the features of two different backrests and incorporating the adjustability concept into the design. Our study comprised of both, field and laboratory evaluations of the original and new designs for a variety of anthropometric characteristics (5th, 50th and 95th percentiles of both males and females). Using the phenomenon of restlessness, discomfort of the user was associated with the amount of body movement, where we have used the motion-capture system and the force platform to quantify the individuals’ movements. The results of the field evaluation indicated that the new backrest improved comfort during both static and driving tasks by ~10% and 23%, respectively. The results of objective metrics showed a reduction in the mean torso and the maximum center of pressure change of locations by 300 and 6 mm, respectively, for the new design. Further, the change in movement during the trials as assessed by the deviation in center of pressure measure was decreased (12%, p-value=0.32) for the new design, compared to the increase of 47% (p-value=0.0078) for the original design, suggesting that new backrest performed better over time. Based on these findings, the new design was further improved. Outcomes of this study may facilitate higher comfort levels to a wide range of forklift operators using a new adjustability concept.

Library of Congress Subject Headings

Forklift trucks--Design and construction; Industrial power trucks--Seats--Design and construction; Human engineering

Publication Date


Document Type


Student Type


Degree Name

Industrial and Systems Engineering (MS)

Department, Program, or Center

Industrial and Systems Engineering (KGCOE)


Ehsan Rashedi

Advisor/Committee Member

Denis Cormier

Advisor/Committee Member

Gregory Smiley


RIT – Main Campus

Plan Codes