Flexible communication in multi-robotic control system using head: hybrid event-driven architecture on d-bus

Abstract

Direct real-time communication among various software components of a multirobot system (MRS) is much more complicated than that in software simulations. Existing inter-process communication (IPC) mechanisms, such as pipes, shared memory etc., are very rigid and usually enforce tight coupling among software components. Thus they do not integrate well with heterogeneous multi-robot control applications of a relatively larger MRS that typically consists of tens of robots and various sensing and monitoring elements interconnected through several host PCs. In this paper, we present a modular, flexible and decentralized multi-robot control architecture, namely hybrid event-driven architecture on D-Bus (HEAD), that overcomes these issues by decoupling IPC through D-Bus. D-Bus is a relatively new IPC technology for modern Linux desktop environments. It typically uses a message bus daemon that facilitates asynchronous data sharing among multiple processes. Here, we show that by using only a single type of message, namely D-Bus signal type, HEAD can efficiently enable real-time interactions among heterogeneous multi-robot control applications. The design of HEAD is flexible enough to add various types of existing and new software components with minimum programming effort. As an example, we present how we achieve a decentralized peer-to-peer communication behaviours among robot controller clients by simply adding only a few lines of new code leaving the major IPC implementation intact. This paper also reports the performance of DBus, under both constant and variable IPC load, obtained from our MRS implementation of a manufacturing shop-floor scenario with 16 e-puck robots.