An Upper Drive-Active Dual-Wheel Caster Assembly and its Application for Constructing Holonomic and Omnidirectional Platform

Abstract

A new mechanical upper-drive active dual-wheel caster assembly is developed and two types of holonomie and omnidirectional mobile robots which utilize this caster assembly are discussed in this paper. The new active caster assembly is equipped with two standard tires as its driving wheels. Two motors are mounted on the upper frame to drive each wheel independently through a series of gears and a belt. In this structure, the lower frame can steer arbitrary angles referred to the upper frame without any wiring problem, which inhibits practical application of the previous normal active dual-wheel caster assembly. The new active caster assembly is used to construct two types of holonomie and omnidirectional mobile robots. One is a conventional structure, and the other is a synchro-drive system. The kinematic models of the new active caster assembly and two types of mobile robots are derived and the characteristics of these two holonomic and omnidirectional mobile robots are illustrated by computer simulations using resolved velocity control.