Physical Link Maintenance and Logical Message Routing Integration for Robotic Network Connectivity

Abstract

Network connectivity maintenance is essential for efficient robotic team operations. Achieving robust robotic ad hoc network connectivity requires a capable link maintenance mechanism, especially if the network experiences expected intermittent connectivity. Although various routing protocols for wireless ad hoc networks have been proposed, they deal with the message routing and the link maintenance problems separately, resulting in additional overhead costs and long network latency. These limitations motivate us to develop a new routing mechanism for a robotic network, which we called Meta-Routing. Meta-Routing expands current routing protocols to include not only the normal routing of packets, but also the maintenance of broken links in robotic networks. This paper presents a method to achieve Meta-Routing by controlling robot motion based on gradient descent method augmented with the radio frequency (RF) environment recognition method. The RF recognition method utilizes hidden Markov models (HMMs) to categorize "RF shadows" into a set of RF obstacle primitives from partial information. The motion control algorithm utilizes the gradient estimations augmented with HMM results through RF recognition to determine the robot movement direction for achieving connectivity maintenance. The numerical experimental results demonstrate promising RF recognition and gradient estimations results as well as confirm their abilities in robot motion control for link maintenance, reduction of the total path cost and network latency for achieving Meta-Routing.