A novel system for wheelchair stability assessment design and initial results

Wheelchairs should provide safe and reliable functioning in various road conditions and situations, ease of propulsion, and high maneuverability. Often, wheelchairs need further modification and installation of additional equipment (ventilators, oxygen cylinders, etc) which affect their stability. Wheelchair stability is also dependent on a user´s body characteristics that can result in a shifting of the centre of mass e.g. limb amputations, and obesity, etc. Adaptation of the wheelchair requires additional assessment and wheelchair tuning by highly skilled rehabilitation engineers. In this paper, we discuss the design and initial testing of a novel wheelchair stability assessment system. The developed WheelSense system consists of a force platform that senses the weight distribution of the wheelchair, the centre of the contact points, and the distances between contact points of the wheels. The measurement platform is linked via WiFi connection to a portable tablet computer where the platform´s sensor signals are processed and the wheelchair stability parameters are calculated. An intuitive touchscreen GUI is used for visualization of the stability results and navigation through separate measurement modes. The mechanical platform was designed to be foldable and light-weighted and thus, to be easily transportable which gives additional advantages when the system is used outside of a clinical engineering department. The initial design is being evaluated through four prototype systems installed for clinical testing in 3 large hospitals in the UK. The initial results indicate that the developed measurement system possesses high accuracy and ease of operation.