DEVELOPMENT OF AN ELECTRIC TRICYCLE WITH ADJUSTABLE WHEEL CAMBER

Abstract

ABSTRACT People with locomotive disabilities find it difficult to access public and social services and functions due to mobility issues. To have a successful rehabilitation program, an active lifestyle must be encouraged. Many locomotive assistive device variants were developed to accomplish this. The disabled tricycle is one of those devices that is commonly found in Nigeria. Tricycles are inherently unstable at high speeds and during manoeuvres, raising safety concerns. As efforts to increase the speed of tricycles used by the disabled are increased through the use of electric motors, the need to investigate their stability as speed increases has become an important safety concern. Despite the fact that there is a large body of research on three wheelers, active safety systems on these vehicles were previously ignored. The dynamic stability and control of larger three-wheel vehicles, such as auto rickshaws, were prioritized, while smaller vehicles, such as the disabled tricycle, were largely ignored. The aim of this study was to improve the stability of tricycles used by the disabled. To improve stability, geometric parameters and weight distribution were carefully chosen using steady state cornering equations, tire cornering stiffness, and understeer gradient. The kinematic bicycle model was modified for use on tricycles with delta designs. An electric-powered tricycle with adjustable wheel camber was developed. For rollover analyses, a quasi-static rollover model was used. Rollover tests were performed with various radii and camber angles. Theoretical analyses were compared to practical test results. To determine the handling characteristic, a constant radius test with a 15 m radius and different wheel camber angle adjustments of 0o, 5o, 10o and 15o was performed. At a maximum camber angle of 15o, only a maximum speed of 17 km/h was achieved without the risk of tipping over at a radius of 15 m. As a result, the understeer gradient could not be determined due to insufficient steering angle measurement and speed readings. Wheel camber was found to improve stability, with maximum speeds of 10 km/h at 0o camber angle and 24 km/h at 15o camber angle all tested within a 30 m radius turn. It was observed that while camber angle improved stability of the tricycle, the calculated rollover threshold is significantly higher than the actual values. Tricycle dimensions have a large impact on stability and handling response. The very narrow dimensions of the tricycle affected the stability and handling response, as indicated by both tests, consequently, policy framework is required to regulate usage, design and manufacture to achieve desired user safety.