Design and Ergonomic Assessment of an Ergonomic Toilet Stool for Promoting Healthier Defecation Posture

Constipation, hemorrhoids and other bowel related disorders have become common worldwide, among others because so many people have adopted the Western style sitting toilet, which may encourage the defecation posture to be inefficient. The purpose of this study was to create and test an ergonomic toilet stool that would promote a healthier squatting position when using a conventional sitting toilet. A questionnaire survey of 100 respondents was conducted using a mixed-method approach, starting with the requirement of users, discomfort and acceptance of a toilet-stool intervention. The findings were translated into product design specification which was used in guiding the concept generation process and four conceptual designs were generated and objectively compared using Pugh Selection Matrix and the best design was picked for detailed development. The anthropometric analysis of the geometry of the stool was carried out using digital male and female manikins in MakeHuman and Blender software, and Computer-Aided Design (CAD) software was then used to model the stool in SOLIDWORKS. Finite Element Analysis (FEA) in SOLIDWORKS simulation was used to compare the performance of two different types of plastics: Acrylonitrile Butadiene Styrene (ABS) and Polypropylene (PP) under the same loading conditions. The Rapid Entire Body Assessment (REBA) method was used to assess ergonomic effectiveness. The proposed design made an approximate hip flexion angle of 35°, which downgraded the REBA from 8 (High Risk) to 3 (Low Risk) resulting in a 62.5% decrease in postural risk. FEA results revealed that ABS had a better structural performance than PP as the maximum displacement of ABS was 0.42 mm and PP was 0.68 mm, while the factor of safety of ABS was 3.8 and PP was 2.1. The ergonomic toilet stool is considered a viable and cost-effective toilet design to improve defecation posture, but further recommendation is prototype fabrication and clinical validation before generalizing health outcomes.

Ergonomics; Defecation Posture; Toilet Stool; REBA.

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