Omnidirectional Mobile Vehicle Using Belt-Driven Seamless Active Omni Wheel

This paper presents the development and evaluation of an omnidirectional mobile vehicle using a novel active omni wheel (AOW) mechanism. An AOW is a wheel mechanism capable of moving in an arbitrary direction by driving the wheel’s main body and outer rollers. The previous design features barrel-shaped outer rollers, which enables a seamless circumference and reduces vibration. However, it experiences slippage owing to friction-based transmission. To address this issue, a new AOW design incorporating positive drive mechanisms that utilize toothed belts is proposed to ensure non-slipping transmission and enhance the movement accuracy. The dynamic performance of a four-wheeled vehicle equipped with two AOWs and two passive omni wheels is evaluated by comparing the two configurations. The line-symmetric wheel layout with its center of gravity (COG) positioned near the AOWs exhibits superior performance in terms of maximum acceleration without wheel slippage. The point-symmetric wheel layout demonstrates a marginally lower performance but remains effective under varying COG positions. A prototype vehicle is developed and tested, verifying the effectiveness of the AOW in achieving omnidirectional movement. Furthermore, a control system is designed to manage actuation redundancy, which can result in load concentration on a single wheel. The proposed controller utilizes a PI control method to provide feedback based on the deviation of the wheel torque from its permissible value. The experimental results validate the capability of the proposed controller to ensure a balanced torque distribution between the AOWs.