LAIR Communicationwith Test Case and Simulator

Thesis overview Sean Forsberg

LAIR BackgroundWhat is LAIR?

“…research at the LAIR is focused on multi-robot systems and its applications in their field. Within these domains, topics of interest include motion planning, localization, mapping, integration of social systems, and control.” [LAIR Website]

What is LAIR?

OceanServer IVER2

Current Features◦ Dual CPU◦ GPS/Compass◦ Altimeter & Depth Sensor◦ WiFi & Acoustic Modem

Near Future Additions◦ Dual-Hydrophone Beacon Detector◦ Side-Scanning Sensor (for Localization)

LAIR Research Platform

Source: LAIR Website

Source: Sean Forsberg

Provide a stable, verbose platform for research◦ Add (and test the capabilities ) new sensors & tech

Dual-Hydrophone Beacon Locator Acoustic Modem

◦ Integrate a second IVER2 into missions◦ Develop an API for User CPU Apps◦ Ensure safe functionality/recoverability of IVER2

Utilize/Test the IVER2 platform◦ Various Masters Level research projects◦ Spark interest of incoming Freshman (CPE123)

LAIR Development Goals

Shark Tracking◦ Track (chase) a beacon-tagged shark

Phased, Load-Balanced Tasking◦ Used for optimized search, mapping, and data acq.

Communication◦ Using Wi-Fi, Underwater Modems (and possibly more)

roboSim◦ Development environment for research and testing

Current LAIR Projects

IVER2 CommunicationCurrent State and Goals

Cooperative Robots must be able to talk Dynamic environments

◦ Special protocols must be considered in order to successfully transmit from robot A to robot B Delay tolerant Multi-path, redundant ad-hoc routing

Underwater Robots◦ Water absorbs EM therefore acoustic modems

used when submerged (or communicated with other submerged items.)

◦ Acoustic systems still have limited range

Communication Requirements

WiFi (802.11G) Modem◦ Antenna is integrated into tail mast◦ Modem is integrated into Main CPU

Must Remote Desktop to Main CPU to access IVER2 Then Remote Desktop to User CPU to access app

Remote Transmitter for power controller◦ Hard reset and power supply shutoff only

Has caused Windows to corrupt more than once WHOI Acoustic Modem

◦ IVER2’s come modem built in but hasn’t be used◦ Ground/Surface station modem just received

Current IVER2 Communication

Underwater Communication

Source: WHOI Website

Communication Protocols must include◦ Mix of Wi-Fi and Acoustic Modems

◦ Routing of data/packets must be dynamic

◦ Should assume non-continuous connection with base station (therefore ad-hoc system required)

◦ Due to dual systems within the IVER2, extra routing is required

Wi-Fi is on main processor

Acoustic modem is on secondary

IVER2 Comm. Thoughts

Project Driven Development

Push Concept with Task

User a project requiring communication to…◦ Define specifications◦ Encourage development◦ Discover limitations of protocols◦ Find bugs

Research the benefit of strategic communication on Multi-Robot Systems◦ What benefits are achieved

Just data logging? Quicker performance More complete functionality

Project Driven Development

Phased, load-balanced cooperative MRS (Multi-Robot Systems) can achieve tasks…

◦ Quicker More people doing the work (without large overlaps)

◦ More accurately Composited sensor readings (can) reduce error Overlapping work & communication can help in localization

◦ More complete results Can detect changes quicker in a dynamic environment

Quicker detection means less is missed in a highly dynamic world

Phased & Load-Balanced Data Acquisition

Gather Oxygen/Bio data in a body of water◦ Robots will take readings over a 3D region by

oscillating around dimension.

Phased & Load-Balanced Data Acq. (Cont.)

Top View

Uniform depth and width◦ Automatically Balanced◦ Synchronization Easily Maintained

Width < Max Communication Range◦ Robots will always be in communication

Perfect Environment

Front/Back Slice

Curved, Uneven Ground and Bay Shape◦ Must Dynamically Balance◦ Synchronization Quickly Lost

Width is Dynamic◦ Robots will not always be in communication

Actual Environment

Top View

Communicate with other robots in order to maximize productivity and minimize delay between data points.

Tolerate communication losses due to submersion, range, or a combination of the two.

Operate in an unknown environment

◦ Mapping on the fly

◦ Absolute Positioning Trust Between Robots

Other Desires

◦ Allow the addition (and removal) of robots on the fly.

◦ Synchronized movements

Project Comm. Demands & Goals

Environment Simulation

Not Just Convenient, Required!

Robots are expensive!◦ Being able to simulate large scale activities

without a large budget allows new projects to be prototyped

Humans make mistakes◦ Bad code in an underwater, flying, or even ground

robots can result in a lost robot ($$)

Researchers can test algorithms/concepts◦ Although only simulated data is being shared with

the robot, we can make it complete enough to test concepts without having to be in the field

◦ Tests are reproducible!

Why Simulate?

A virtual environment that simulates the real world for code development and research.

◦ Real & Virtual Agents can interact/communicate

◦ An agent is composed of modules (C++ classes) New agents can be added New sensors created

“Error” can be added

◦ Agent code is independentof the environment

The roboSim Environment

Source: Sean Forsberg

RoboSim Design OverviewRoboSim

World AgentsDevices

Sensors

Locomotion

Comm.

Physical

Simulated

Beacons

Radios

GIS Terrain Input

Local Area Lat/Long

Each device and agent constructed as a module building on previous to allow

quick creation/modification.

Devices: Feedback based on world & agent instructionsAgents: Objects that interact with the world and are a collection of devices

Object-Oriented Design

modAgent

modDevice

UnderwaterAgent

SurfaceAgent

TorpedoAgent

DiffDriveAgent

IVER2Agent

X80Agent

CommAgent RadialCommAgent WiFiAccessPoint

LocationDevice GPSDevice

LocomotionDevice

EnvSensorDevice

FinDevice

PropellerDevice

DistanceSensor

CommDevice

SonarSensor

WiFiModem

TriBeaconDevice

IVER2 has a dual, independent CPU design with COM based interface

Both CPUs are currently running Windows XP

User CPU reqs.and recvs datausing telnet tothe main

IVER2 System Design

Source: OceanServer Manual

IVER2-roboSim Interface (Cont.)

User App

User CPU COMPort Main CPU

OceanServer App Sense/Control

User App

User CPU COMPort

roboSim Environment SimEthBridge

Graphical Render

Current IVER2 Configuration

roboSim-IVER2 Interface Configuration

Real Terrain Modeling◦ Import GIS (and other data source) topographic

maps (various resolution) Real-time Graphics

◦ Requirement to minimize the polygon/vertex count (aka low-res terrain)

Distance Sensors◦ Require high resolution detail in order to

accurately simulate the environment (aka high-res terrain)

roboSim Challenges

Presentation ReviewWhat Just Happened?!

LAIR = multi-robot development Underwater systems = comm. challenges

◦ Lack of RF based transmission◦ Bandwidth limitations of Acoustic modems◦ Dynamic environments

Multi-robot systems require communications◦ Effective comm. can result in quicker (and more

effective) systems Experiments on expensive platforms are

risky & expensive◦ The IVER2 provides an excellent interface for

simulation.

Overview

Questions!Harassment is Encouraged