Design and development of steered active wheel casters and its application

Recently, omnidirectional powered-wheelchairs that have high mobility at a narrow space or a place with many obstacles are studied actively. Many of conventional omnidirectional mechanisms use special wheel mechanisms, such as a mecanum wheel etc. However, this mechanism is unsuitable for use in powered-wheelchairs, because of having problems, such as serious vibrations while moving, low loadability, etc. In previous studies, an active dualwheel caster that can use general rubber tires and an omnidirectional mobile platform using several such assemblies have been developed. However, there is a problem that omnidirectional movement becomes impossible, when one of wheels in this assembly would run aground to a level difference or idle. The objective of this study is to develop an omnidirectional mobile platform to solve this problem, where the platform uses several steered active wheel caster assemblies. Also, a rocker-bogie system that is a kind of suspension systems is used for the platform to improve traveling performance. In this paper, we give an overview of the steered active wheel caster assembly and propose a mobile platform, and describe the production process and experimental results.