Measurement of push-rim forces during racing wheelchair propulsion using a novel attachable force sensor system

Abstract

To improve competitive skills, it is important to clarify the relationship between the propulsion motion (the propulsive force in the use of racing wheelchairs optimized for athletes) and aerodynamic drag, which can change during propulsive motion. Therefore, the purpose of this research was to construct a novel force sensor system that is attachable to racing wheelchairs for individual athletes and usable in a wind tunnel facility to examine differences in the push-rim force characteristics of athletes based on the measured results. The system was composed of four two-dimensional component force sensors, batteries, and radio transmitters. From the output of the four two-dimensional component sensors, tangential and radial components of the push-rim force were measured. Three top-class long-distance wheelchair athletes participated in this study, which required each athlete to push a racing wheelchair at 5.56 m/s on a wheelchair roller system in a wind tunnel facility. The force sensor system was mounted on the participants’ individual racing wheelchairs. The measured tangential force waveforms were classified as either bimodal or unimodal depending on the athletes’ propulsion styles. Although two athletes showed similar propulsion style characteristics, the athlete with more years of experience showed better propulsive work efficiency and repeatability. Therefore, a difference in skill for applying propulsive force during the push phase, which is difficult to estimate by kinematic analysis, could be estimated by using the force sensor system.

A high sample rate, wireless instrumented wheel for measuring 3D pushrim kinetics of a racing wheelchair

“…Similarly, at high speed, air drag accounts for about half of the overall drag [23]; yet air drag is not simulated on a training roller. This could explain why Rice et al [18] did not find differences in pushrim kinetics across three different speeds, and why our measured tan of 142 N was similar to the 132 N to 158 N in Goosey-Tolfrey et al [16], 102 N in Limroongreungrat et al [17], and 131 N in Miyazaki et al [19], with all of these studies also being performed on training rollers but at much slower speeds.…”

“…5 where at maximal velocity, the prevalent force rad is maximal towards the end of the push phase, approximately when the hand is at its lowest point. Miyazaki et al [19] also observed this peak in rad at the end of the push phase. This new hypothesis will need to be verified in subsequent research using the instrumented wheel.…”

“…Using custom strain gauge sensors as explored by Miyazaki et al [19] should be considered with future prototypes.…”

“…Their wheel was, however, limited to a sampling frequency of 240 Hz and to our knowledge, no further details were later published on their work. Recently, Miyazaki et al [19] presented a wireless instrumented pushrim to measure pushrim kinetics on a roller in a wind tunnel facility. That pushrim, tested with three racers who propelled at a constant speed of 5.56 m/s was, however, limited to 2D kinetics (tangential and radial forces).…”

A 2D lightweight instrumented wheel for assessing wheelchair functionality/activity

“… 10 , 13 , 16 More recently, Miyazaki and colleagues used four 2D load cells between a sports push-rim and a disc-shaped adapter plate to allow the measurement unit to be mounted to different sports wheelchair wheels as desired. 17 …”