Partitioning Kinetic Energy During Freewheeling Wheelchair Maneuvers

Abstract

This paper describes a systematic method to partition the kinetic energy (KE) of a free-wheeling wheelchair. An ultralightweight rigid frame wheelchair was instrumented with two axle-mounted encoders and data acquisition equipment to accurately measure the velocity of the drive wheels. A mathematical model was created combining physical specifications and geometry of the wheelchair and its components. Two able-bodied subjects propelled the wheelchair over four courses that involved straight and turning maneuvers at differing speeds. The KE of the wheelchair was divided into three components: translational, rotational, and turning energy. This technique was sensitive to the changing contributions of the three energy components across maneuvers. Translational energy represented the major component of total KE in all maneuvers except a zero radius turn in which turning energy was dominant. Both translational and rotational energies are directly related to wheelchair speed. Partitioning KE offers a useful means of investigating the dynamics of a moving wheelchair. The described technique permits analysis of KE imparted to the wheelchair during maneuvers involving changes in speed and direction, which are most representative of mobility in everyday life. This technique can be used to study the effort required to maneuver different types and configurations of wheelchairs.

Manual wheelchair downhill stability: an analysis of factors affecting tip probability

“…The optimal seat angle for propulsion efficiency is still unknown [24], but a horizontal seat has been linked to the development of shoulder pain [37]. However, small changes in system tilt and seat to backrest angle (up to 10°) did not show any effect on joint angles or shoulder moments in manual wheeling [38]. Though a lower seat may be biomechanically superior for wheeling, an elevated seat can improve daily tasks such as transferring and reaching, and provide psychosocial benefits such as reducing eye to eye level discrepancies with others [39].…”

“…In daily life, wheelchair users perform a variety of maneuvers including movements forward, backward, turning, and accelerating. During straight motion the majority of propulsion energy is converted to translational energy, with some rotational kinetic energy for the wheels and casters, but during turning up to 71% of the system energy is converted to turning kinetic energy [38]. Therefore it is also important to consider multi-directional wheelchair maneuverability when evaluating complete wheelchair performance, where an increase in rear wheel loading corresponds to an increase in resistive forces due to turning [40].…”

The influence of axle position and the use of accessories on the activity of upper limb muscles during manual wheelchair propulsion

“…These configurations were tested in two different trajectories: straightforward sprint (acceleration in a 15-m straight motion) and slalom course (nine cones aligned and separated by decreasing distances) ( Figure 3), as proposed in a previous study [17]. For both trajectories, subjects were instructed to propel the chair as fast as possible.…”

“…In order to study wheelchair mobility in a closer way to how people move in their daily routine, it is important to investigate the biomechanics of manual propulsion not only in straightforward motion, but also in trajectories comprising changes in movement direction and acceleration. A previous study demonstrated that the influence of the mechanical aspects on the movement of the wheelchair is dependent on the trajectory and acceleration [17].…”

A Study of a Handrim-Activated Power-Assist Wheelchair Based on a Non-Contact Torque Sensor

“…Sensorless HAPAW, which does not use torque sensors, is also being researched [ 9 , 10 ], but more research is required for commercialization owing to vulnerability to disturbances. Recent studies aimed at accurately measuring the driving characteristics of a wheelchair or analyze its torque and kinetic energy [ 11 , 12 ] are remarkable in HAPAW research.…”