Backrest Design for the Permobil F5Corpus Using STILFOLD Technology : Balancing Ergonomics, Structural Performance, andManufacturing Constraints

Sammanfattning

This thesis investigates the potential of applying STILFOLD’s curve-foldingsheet metal technology to the backrest of the Permobil F5 Corpus powerwheelchair. The project addresses a central challenge in assistive productdevelopment: how to combine increased user individualization with reducedtooling dependency, lower material usage, and feasible manufacturing. The current backrest solution relies on stamped metal components, which providestructural performance but limit flexibility and require significant toolinginvestments for variant production. The study was conducted as a technology-push design project combiningtechnical analysis, stakeholder input, user studies, requirement specification,functional analysis, Quality Function Deployment, concept generation, andconcept evaluation. The work examined both the technical constraints ofthe STILFOLD process and the ergonomic demands placed on wheelchairbackrests, with particular attention to pressure distribution, vibrationbehaviour, adjustability, and zonal stiffness. User studies indicated recurring issues related to discomfort, insufficientfit, excessive rigidity, heat buildup, and limited personalization. Basedon these insights, the design process focused on developing a conceptthat could balance structural stability and ergonomic compliance throughgeometry rather than increased material thickness. The resulting conceptproposes a STILFOLD-manufactured backrest with geometry-driven stiffnessdifferentiation, potential for improved vibration behaviour, and compatibility with more flexible, low-tooling production. The results suggest that STILFOLD technology has strong conceptual potential as an alternative manufacturing approach for wheelchair backrests, particularly in contexts where customization and small-series variation areimportant. However, the concept has not yet been fully validated throughphysical testing or user trials. The project therefore demonstrates designfeasibility rather than final product readiness. Future work should include fullscaleprototyping, structural and fatigue testing, user evaluation, and furtherdevelopment of parametric customization strategies.