User-centered design customization of rugby wheelchairs based on the Taguchi method

Competitive wheelchair sport performance is dependent on three factors: the athlete, the wheelchair, and the interaction between the athlete and the wheelchair (Goosey-Tolfrey, 2010, “Supporting the Paralympic Athlete: Focus on Wheeled Sports,” Disabil Rehabil., 32(26), pp. 2237–2243). In order to effectively refine the user interphase design of the wheelchair, it is essential to narrow down the key dimensions within the design space, which are likely to have an effect on the performance of an individual athlete. This paper provides a case study analysis of the test data obtained from five elite wheelchair rugby athletes, using a purpose-built adjustable wheelchair on a wheelchair ergometer. Four design factors (wheel diameter, camber angle, seat height, and camber bar depth) were tested at incremental dimensional levels to the athlete's current chair configuration; and tests were performed according to an L9 Taguchi orthogonal array. The case study analyzes acceleration, velocity, and time in the push phase of the propulsion cycle; as well as recovery time for each of the participating athletes performing a linear sprint task. The Taguchi method is applied to determining the positive/negative contribution of each of the four design factors to the outlined performance variables as well as their combined effect in a specific wheelchair configuration model. A performance ranking system and magnitude-based inferences on the true value of the effect statistic are used to define a high performance design space for individual athlete wheelchairs. Finally, the athlete's preferred ergonomics are considered to assess the narrowed high performance wheelchair options. As such, when adopting the approach presented in this paper, it becomes possible to customize an athlete's wheelchair design to meet the athlete's anthropometric needs as well as their performance requirements.