Controlling Intermittently Connected Autonomous Robot Teams in Underwater Environments
Abstract
Many future naval operations will rely on teams of autonomous robots to fulfill complex missions in real-time in partially-known and uncertain underwater environments. These missions will evolve concurrently and can be highly dynamic as the environment and task specifications can change rapidly with time. In these situations, successful accomplishment of a mission willcritically rely on the ability of the robots to exchange information with each other and possibly with a remote user at regular points in time. To address this challenge, in recent years, there has been a large amount of work focused on designing controllers that ensure point-to-point or end-to-end network connectivity for all time. However, these approaches typically do not applyto undersea naval operations that are severely communications limited (short range, noisy, low BW). Specifically, aquatic acoustic channels are not practical when the robots need to be deployed tens of kilometers apart. Instead, a much preferred solution is to enable robots to communicate in an intermittent fashion, and operate in disconnect mode the rest of the time. The advantage ofintermittent communication is that it provides more flexibility to the robots to accomplish their tasks as they are not constrained by all-time communication requirements. The great challenge in obtaining distributed intermittent communication protocols is ensuring coordination between the robots, even when they mostly operate in disconnect mode. The goal of this project is to develop distributed methods that enable intermittent communicationin teams of autonomous mobile robots operating in underwater environments. While in disconnect mode, the robots can accomplish their tasks free of communication constraints. The key idea that motivates this work is to formulate intermittent communication using Linear Temporal Logic (LTL) formulas that force robots to communicate infinitely often at properly negotiated locationsin space, and develop scalable methods to approximately decompose those global LTL formulas into local ones, assigned to the robots, whose composition satisfies the global LTL formula. For time-critical tasks or for underwater robots that can not stop-and-wait, e.g., gliders, the resulting controllers should eliminate waiting times during communication events. They should also planrobot paths that minimize energy consumption (rather than distance travelled) to increase the lifetime of the multi-robot system in underwater environments that are subject to strong currents. Furthermore, they should incorporate appropriate acoustic communication models that are commonly used in undersea naval operations. The goal is to obtain a distributed, intermittently connected,network of robots that allows for significant gains in mission performance compared to systems that enforce connectivity constraints for all time.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 10, 2018
- Source ID
- N000141812374
Entities
People
- Michail Zavlanos
Organizations
- Duke University
- Office of Naval Research
- United States Navy