Distributed Communication and Control for a Network of Melting Probes in Extraterrestrial Ice

DDS

Distributed Communication and Control for a Network of Melting Probes in Extraterrestrial Ice

Dr.-Ing. Dipl.-Inform. Daniel EwertIMA/ZLW&IfU

RWTH Aachen University

• Motivation: Project “RANGE”

• Why DDS? Why Connext?

• Implementation/Open Issues

Outline

MOTIVATION: PROJECT “RANGE”

Aliens!!

Aliens!!

EnEx Initiative

• Funded by DLR (German Aerospace Center)

• Goal: Space Missionin 2040 EnhanceTech Readiness Level for core technologies

EnEx Initiative – IceMole

Dirigible Probe forretrieving subglacial samples

• Top speed: 4m/h

• Turning radius: ca. 10m

EnEx Initiative – IceMole

Open Issue: Autonomy

• Navigation

• Perception

• Localization

• …

?

EnEx Initiative: RANGE

Goal: Develop network of autonomous pinger units (APU)• Self-localization via acoustic-

based multilateration

• Autonomous optimization of melting depth Maximize coverage

• Adaptation to • APU failures

• Changes in ice quality

• Environment

EnEx Initiative: RANGE

Sub goals:

• Acoustic world model

• Simulation Environment

• Hardware minaturisation & improvement in performance

RANGE – Development so far

RANGE – Development so far

RANGE – System architecture

APU

AGENT

SKILLS

COMPONENTS

HARDWARESU

PER

VISO

R

GLOBAL CONTROL STATION

MONITORING & CONTROL

DATABASE

STATE INFO

COMMANDS

SIGNAL MGMT NEGOTIATIONS

RANGE – Software architecture

APU

AGENT

SKILLS

COMPONENTS

HARDWARESU

PER

VISO

R

GLOBAL CONTROL STATION

MONITORING & CONTROL

DATABASE

STATE INFO

COMMANDS

SIGNAL MGMT NEGOTIATIONS

RANGE – Languages/Hardware

CLIPS

C

C ++ C+

+

JAVA/Javascript

SQL

MicroZed/Debian

WHY DDS? WHY RTI CONNEXT?

Requirements

• Robust Decentralized, brokerless

• Lightweight

• Easy to Use

• Language support for C/C++, Java, Python

Candidates

• Brokerless

• Lightweight

• Easy to Use

• Language support

”…a flexible framework for writing robot software.”

ros.org

“…a publish/subscribe, extremely simple and

lightweight messaging protocol, designed for

constrained devices and low-bandwidth, high-latency or unreliable

networks”mqtt.org

Candidates

• Brokerless

• Lightweight

• Easy to Use

• Language support

”It’s sockets on steroids.” zeromq.org

“… is a socket library that provides several common communication patterns”

nanomsg.org

Candidates

• Brokerless

• Lightweight

• Easy to Use

• Language support

Suddenly… Features!!

• Strong Type System

• Distributed Logging

• RTI Record/Replay

• Content-filtered topics

IMPLEMENTATION/OPEN ISSUES

APU

AGENT

SKILLS

COMPONENTS

HARDWARESU

PER

VISO

R

GLOBAL CONTROL STATION

MONITORING & CONTROL

DATABASE

STATE INFO

COMMANDS

SIGNAL MGMT NEGOTIATIONS

Software architecture

Domain 0

Topic:SIGNAL

Topic:AGENT

Software architecture – external view

Topic: COMMAND

Topic:APU_STATE

GLOBAL CONTROL STATION

APU 1 APU 2 APU 2

APU

AGENT

SKILLS

COMPONENTS

HARDWARE

SUP

ERV

ISOR

Topic: HEATER

Topic: LOCAL.

Topic: IMU

Topic: ACOUST.

Topic: COMMAND

Domain i

Domain 0

Topic:SIGNAL

Topic:AGENT

Software architecture – internal view

Topic: COMMAND

Topic:APU_STATE

Resulting Benefits

Core functionality

• Robust decentralized system

• One single communication framework

• Isolation of systems through different domains

• Loose coupling of components

Free gifts on top

• IDL-Specifications in central repository Ease of collaboration

• Content-filtered topics one channel, dedicated recipients

• Decentralized logging

• Replay of experiments with RTI Record/Replay

Work in Progress/Open Issues

• Permanent Data Storage – Hack intoRTI Record/Replay Database?

• Management ofSignals – More thanone DataWriter forsame Object?

• GUI – Web basedfrontend needsddsjson bridge.

Summary/Outlook

• 2040 Mission to find extraterrestrial life on Saturn’s moon Enceladus

• Acoustics based autonomous network allows for in-ice localization

• RTI DDS allows brokerless, decentralized communication

• Unexpected features satisfy unknown requirements

Thank you for your attention!Dr.-Ing. Daniel Ewert

IMA/ZLW&IfU,RWTH Aachen University

+49 241 80 911 28

[email protected]

Project Partners:

Funded by: