On distributed mechatronics controller for omni-directional autonomous guided vehicles

Abstract

Purpose – In this paper, two omni-directional mobile vehicles are designed and controlled implementing distributed mechatronics controllers. Omni-directionality is the ability of mobile vehicle to move instantaneously in any direction. It is achieved by implementing Mecanum wheels in one vehicle and conventional wheels in another vehicle. The control requirements for omni-directionality using the two above-mentioned methods are that each wheel must be independently driven, and that all the four wheels must be synchronized in order to achieve the desired motion of each vehicle. Design/methodology/approach – Distributed mechatronics controllers implementing Controller Area Network (CAN) modules are used to satisfy the control requirements of the vehicles. In distributed control architectures, failures in other parts of the control system can be compensated by other parts of the system. Three-layered control architecture is implemented for; time-critical tasks, event-based tasks, and task planning. Global variables and broadcast communication is used on CAN bus. Messages are accepted in individual distributed controller modules by subscription. Findings – Increase in the number of distributed modules increases the number of CAN bus messages required to achieve smooth working of the vehicles. This requires development of higher layer to manage the messages on the CAN bus. Research limitations/implications – The limitation of the research is that analysis of the distributed controllers that were developed is complex, and that there are no universally accepted tool for conducting the analysis. The other limitation is that the mathematical models of the mobile robot that have been developed need to be verified. Practical implications – In the design of omni-directional vehicles, reliability of the vehicle can be improved by modular design of mechanical system and electronic system of the wheel modules and the sensor modules. Originality/value – The paper tries to show the advantages of distributed controller for omni-directional vehicles. To the author's knowledge, that is a new concept.