Active Antenna Tracking System with Directional Antennas for Enhancing Wireless Communication Capabilities of a Networked Robotic System

Abstract

This paper presents a networked robotic system design capable of enhancing wireless communication capabilities (communication range and bandwidth). The core of the system is active antenna tracking with directional antennas. The proposed system is decentralized and consists mainly of a mobile robot system and a command center system. Each system is equipped with off-the-shelf network devices such as antennas, access points (AP), and network switches. For directional antennas to be beneficial to our system, we propose a weighted centroid algorithm (WCA) to provide active antenna tracking and direction-of-arrival (DOA) estimation. This system can be used in GPS-denied environments as our system does not require the aid of additional sensors to provide location information. Through extensive field experiments in different environments, including a fire training center and with various antenna selections, such as omni-to-omni, omni-to-directional, and directional-to-directional antennas, we demonstrate the effectiveness of our proposed system. We expect that our system can be applied in a variety of rescue, surveillance, and emergency scenarios where high bandwidth and long-distance communications are needed. C 2015 Wiley Periodicals, Inc.

A directional antenna based leader–follower relay system for end-to-end robot communications

“…The bearing estimation algorithm allows a follower robot to track its leader's trajectory. For bearing estimation, we employ the WCA that was proposed in [12]. The obstacle avoidance algorithm allows the follower robot to avoid the obstacle between itself and the leader.…”

“…, N t }. Here, θ s and θ e are determined by the center angle θ c that is set to be aligned with the previous bearing to prevent the estimation from approaching the end where an actual bearing dwells [12].…”

“…Therefore, as shown in the previous subsection IV-C, the Doppler effect does not take place in the converging mode. Given that, we can assume P t , G t , and L f in (4) are constant, and the subsequent center angle θ c of the directional antenna by the WCA can be obtained by [12]:…”

“…If we define f (e(k)) as the differentiation of e(k) in discrete time, then Therefore, as k increases, f (x) goes to zero. (b) shows an enlarged graph with a setting of γ to 1 for more detailed explanations of the verification [12].…”

“…We also integrated the convoy scheme with obstacle avoidance algorithm in [1]. We further extended the convoy system with thorough establishment of the WCA based bearing estimation algorithm and demonstrated the performance of the convoy system using multi-robot experiments in [12]. We also compared various combinations of antennas (omnidirectional-omnidirectional, omnidirectional-directional, directional-directional) of the leader and follower robots in [12], and showed the advantages of using a combination of using omnidirectional and directional antennas for sensing the direction of arrival (DOA) and throughput improvements in different environments.…”