Symmetry Alignment of User Requirements from Multiple User Groups and Design Elements: Age-Friendly Bathing-Chair Design in Community Eldercare Settings

With the growing demand for community-based eldercare services, bathing safety, caregiving assistance, and facility compatibility in bathing-support spaces have become important issues in age-friendly product design. However, in the design of bathing chairs for community eldercare settings, the alignment of requirements from multiple user groups with design elements from a symmetry perspective remains insufficiently explored. This study investigated six community eldercare service facilities in Hefei, Anhui Province, and developed an integrated research framework integrating multi-stakeholder needs analysis, weight assessment, design-scheme development, and performance validation. User needs were collected through semi-structured interviews, field observations, and questionnaire surveys, and were consolidated into 24 need dimensions using the affinity diagram method. Core needs were then screened using the FKANO model. An evaluation index system comprising six criterion-level dimensions and 19 indicator-level criteria was then established. Integrated weights were calculated using the precedence chart method and the CRITIC method, and the QFD House of Quality was then used to translate the key needs into design elements. The results indicate that bathing-chair design for community-based assisted-bathing settings should prioritize stable support, sit-to-stand assistance, compact storage, lateral access for caregivers, and lockable rotation. Three alternative design schemes were developed based on these results. The TOPSIS evaluation showed that Scheme C achieved the highest relative closeness coefficient of 0.608 and was therefore selected as the preferred alternative. JACK digital human simulation was then used to evaluate its human–product fit and assess the ergonomic suitability of the design. This study provides an integrated design decision-making framework for translating multi-stakeholder needs into specific design elements, thereby offering a systematic methodological basis for bathing-chair design in community eldercare spaces.