Steering-by-leaning: Feasibility of Utilising Dynamic Backrests to Control Steering in Manual Wheelchairs

Abstract

Objective: Steering-by-leaning is a promising innovation for manual wheelchairs. It may enable improved energy efficiency, one-handed manoeuvrability, and increased trunk activity during wheelchair use in daily life. To explore the feasibility of this concept, the lateral trunk function of active wheelchair users was assessed before comparing 3 preliminary dynamic backrest designs in a virtual steering exercise. Design: Repeated measures, cross-over study. Subjects: A convenience sample of 15 individuals who had been full-time users of manual wheelchair for at least 1 year. Methods: Active core strength and lateral leaning range of motion were captured while sitting freely. Participants subsequently tested 3 dynamic wheelchair backrest designs on an individually adjusted laboratory wheelchair prototype by performing a virtual steering exercise. Deviations from a target movement path were analysed using repeated measures analysis of variance and Pearson correlation coefficients. Results: Functional leaning range of motion ranged from below 10° to almost 70°, but increased significantly with use of the simplest backrest design based on a 2-dimensional hinge joint. No correlation was found between functional levels and performance parameters in the virtual steering exercise. Conclusion: Using an individually fitted and calibrated design, upper body-actuated wheelchair steering using a laterally tilting backrest is accessible to wheelchair users across a wide spectrum of physical abilities. LAY ABSTRACT Manual wheelchairs not only enable mobility, but also provide postural support to users through passive seating elements. The consequences of static sitting, however, include pain, deformities, and pressure injuries. The concept of backrest steering in manual wheelchairs may improve overall energy efficiency while promoting active trunk movement, but its applicability is questionable given the varying levels of trunk control among users. In this study, active trunk function of 15 full-time users of manual wheelchairs was measured prior to testing 3 prototype dynamic backrest designs in a virtual steering exercise. The results highlight the broad spectrum of abilities in this population, but suggest that active movement can be supported by simple mechanisms. No meaningful relationship was found between trunk abilities and performance in the virtual steering exercise, indicating that upper body-actuated steering of manual wheelchairs is accessible to users across a wide spectrum of physical abilities.

Keywords

• dynamic seating
• motion control
• range of motion
• usability
• heelchair-user-interaction
• trunk movement