Controlling wheelchair direction on slopes

Abstract

Simple and affordable systems are described to assist wheelchair users in steering their wheelchairs across sloping ground. The systems can be attached to many standard powered wheelchairs. Wheelchairs often steer by having two swivelling caster wheels but problems with this configuration occur when a wheelchair is driven along sloping ground because the casters can swivel in the direction of the slope. Gravity then causes the wheelchair to start an unwanted turn or ‘veer’ and the chair goes in an unintended direction. This situation is exacerbated for switch users, as switches cannot provide fine control to trim and compensate. Early experiments demonstrated that calibrating wheelchair controllers for straight‐line balance and optimising motor‐compensation did not solve this problem. Caster angle was selected to provide feedback to the wheelchair controllers. At the point when veer is first detected, a wheelchair has already begun to alter course and the job of the correction system is to minimise this drift from the desired course. A rolling road was created as an assessment tool and trials with both the test bed and in real situations were conducted to evaluate the new systems. The small swivel detector that was created could be successfully attached to caster swivel bearings. The new system was successful, robust and was not affected by changeable parameters. Although primarily intended for switch users, the methods can be applied to users with proportional controls.

Using a Simple Expert System to Assist a Powered Wheelchair User

“…Future work will investigate virtual reality [56], time delays [57], wheelchair veer [58], web interfaces [59,60] force sensing [61], assessment using multi-media [62] Perception [63] and automation [64].…”

Indoor Location and Collision Feedback for a Powered Wheelchair System Using Machine Learning

“…Although Sanders et al [1] claim that most powered wheelchairs are controlled using a joystick as this can be a very 'simple and intuitive way' of controlling a wheelchair [5], this is not a suitable option for all users. Some users may not have enough control in their hands to use a joystick therefore it may be appropriate to control the wheelchair using another part of their body such as the tongue [6] foot or head [7]. Steering a wheelchair using one of these less sensitive control methods can be especially difficult as it does not lend itself to fine control of the vehicle therefore the implementation of a control system was necessary.…”

Powered Wheelchairs

“…Veer is caused by gravity affecting the castors that are swiveling in the direction of the slope on which the chair is being driven (Langner and Sanders, 2008) and is most evident in RWD and FWD configurations. Even the direction of the pile of carpeted floor will cause a powered wheelchair to veer.…”