NIHR i4i Future product development funding stream 3 - Wheelchair Stability Assessment System (Wheel-SAS)
Total value of project
Coventry University (PI), West Midlands Rehabilitation Centre, Kings College Hospital NHS Foundation Trust, Betsi Cadwaladr University Health Board and Abertawe Bro Morgannwg University Health Board
Duration of project
Wheelchairs that are not appropriately modified to meet client requirements, lifestyle and environments can be prone to tipping, sliding and loss of traction. The project aimed to design, develop and evaluate a system for assessing the stability and performance of wheelchairs before they are released to the client and used in the community.
The resulting system measures the centre of gravity of the client:wheelchair system and maps the stability points. This information can then be used to inform the tuning of the wheelchair and used predictively to model the effect of changes to the wheelchair on the performance and stability.
Traditionally wheelchair stability in the UK is tested through a ramp test. The wheelchair and client are positioned on a ramp to see whether the chair tips when positioned facing upwards, downwards, and sideways at an angle of 12° or 16°. Reports from patients suggest that they can feel vulnerable during the test, and it requires significant physical effort from the prescriber.
In order to improve stability assessment beyond these pass/fail tests, it was aimed to explore the use of load cell technology (widely used in vehicle stability testing) to measure the weight distribution of the wheelchair and occupant and use this to model and predict stability.
Wheelsense® (patent WO2015004454 (A1)) is a computer-based system incorporating force-measurement technology within a custom made rig. It calculates the centre of gravity, and maps the stability points of the user-wheelchair system. The design incorporates:
- A folding platform-based weighing system
- Underlying mathematical modelling and electronics
- Software and graphical user interface.
For portability, the platform was designed as a foldable four quadrant frame linked with suitable hinges so that it could be transported by car and used in a clinic, or out in the community. The platform senses the wheelchair wheel and castor position and determines dimensional information. The assessment procedure involves 3 easy steps whereby the wheelchair is moved sequentially into position on the platform and sensor data collected. The resulting stability mapping is presented to the wheelchair prescriber on a Wi-Fi connected tablet computer to inform their tuning of the wheelchair.
Moody, L. Magee, P. Stefanov, D. Development of a Wheelchair Stability Assessment System: Design Tools and Approaches. In Woodcock, A., Moody, L., McDonagh, D., Jain, A. & Jain, L. C., (eds) (2020) Design of Assistive Technology for Ageing Populations. Woodcock, A., Moody, L., McDonagh, D., Jain, A. & Jain, L. C. (eds.). Springer, p. v-viii 4 p. (Intelligent Systems Reference Library; vol. 167). ISBN: 978-3-030-26292-1
Moody, L., Evans, J., Heelis, M., Dryer, P. Shapcott, N. Fielden, S., Magee, P., Stefanov, D. (2015) Establishing user needs for a stability assessment tool to guide wheelchair prescription. Disability and Rehabilitation: Assistive Technology 3; 1-9. http://dx.doi.org/10.3109/17483107.2015.1063019
Stefanov, D. Avtanski, A. Shapcott, S, Magee, P. Dryer, P. Fielden, S., Heelis, M., Evans, J., Moody, L., (2015) A System for Wheelchair Stability Measurement. Journal of Medical Engineering & Physics DOI: http://dx.doi.org/10.1016/j.medengphy.2015.08.013
Evans, J. Moody, L, Stefanov, D, Fielden S. Fielden, Magee, P. Dryer, P. Heelis, M. Shapcott, N. (2013) From Research To Design: The Journey So Far In The User-Centred Development Of A New Wheelchair Stability Measurement System. European Seating Symposium Incorporating Assistive Technology 5-8 Nov 2013, Dublin
Moody, L. Evans, J. Magee, P. (2015) Methods and challenges in designing an innovative wheelchair stability assessment system. Design4Health 2015. https://research.shu.ac.uk/design4health/wp-content/uploads/2015/07/D4H_Moody_2.pdf
Moody, L, Evans, J. Stefanov, D, Fielden S. Fielden, Magee, P. Dryer, P. Heelis, M. Shapcott, N. (2013) A User-Centred Approach to Improving Wheelchair Safety through Stability Testing. IEHF Patient and Healthcare Provider Safety event 25th Nov 2013
Evans, J. Moody L. (2012) Wheelchair Stability Assessment: User and Market Needs Recent Advances in Assistive Technology & Engineering 2012 (RAatE). University of Warwick Conference Centre. 26th November 2012
Magee, P. Fielden, S. Moody, L. (2012) The Cube: An ideas generation tool demonstrated through multi-disciplinary development of a Wheelchair Stability Assessment System Recent Advances in Assistive Technology & Engineering 2012 (RAatE). University of Warwick Conference Centre. 26th November 2012.
Moody, L. Chichi, C. Fielden, S. Heelis, M. Stefanov, D. (2011) Wheelchair stability assessment: what does the prescriber require? European Conference on Design for Health 13th-15th July 2011, Sheffield Hallam University, UK.
Fielden, S. Stefanov, D., Moody, L. Heelis, M. (2011) Further Development of a System to Measure Wheelchair Stability and Improve Wheelchair Performance. Poster for Posture and Mobility Group Meeting in April (PMG)
Moody, L. Chichi, C. Fielden, S. Heelis, M. Stefanov, D (2012) Improving wheelchair prescription: an analysis of user needs and existing tools. Work: A Journal of Prevention, Assessment and Rehabilitation Volume 41, Supplement 1; 1980-1984.
Fielden, S., Heelis, M., Evans, E., Moody, L., Magee, P., Shapcott, N. Stefanov, D. (2014) The Design and Evaluation of a Novel System for Predicting Wheelchair and Occupant Stability. The 30th International Seating Symposium 2014. 4 – 7 March 2014, Vancouver, BC, Canada