Investigating Power Management in a Robot Colony

Meeting of the Minds SymposiumMay 7, 2008

Christopher Mar and

Austin Buchan

Colony Project, Robotics Club

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Colony Project

Ongoing Robotics Club project, started in 2003

About 20 undergraduates– All years represented– Mostly Engineering and CS majors

Weekly status meeting plus work nights throughout the week

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Colony Robot

Bearing and Orientation Module (BOM)

Dragonfly Microcontroller Board

Motors

Sharp IR Rangefinders

Tri-color LED x 2

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Goals

Low-cost Robots (~$350) Homogenous, distributed architecture Develop applications that are robust to non-idealities:

– Noisy sensor data– Limited computation– Communication delays

Use the Colony as a research platform– Emergent behaviors– Path planning– Controls– Cooperation and task management– Simultaneous Localization and Mapping (SLAM)– ...

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Why Recharging?

Goal is to perform long-term tasks with multiple robots

Tasks completed with minimal human intervention

– On-the-fly task allocation and management

– No humans (or monkeys) changing batteries

Fuel Cells

Obstacle

Warehouse

Charging Station

Factory

Task Model

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Autonomous Recharging

Hardware– Robot

Detect and interface with charging station

Regulate charge cycle

– Environment, Station Supply power Produce homing signals

Software– Robot

Recognize need to charge

Locate and home on charging station

– Environment, Station Manage charging bay

allocation Battery prioritizing

algorithm

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Robot Charging Hardware

Charge Board– High current circuitry– Controlled by dedicated

microprocessor– Communicates with robot

over I2C

Homing Senor

Wireless communication and BOM localization

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Charging Bay

Charging Contacts

Tricolor Orb

Wireless Module

Power/I2C Connections

BOM Segment

Homing Beacons

Bay

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Power Management Topology

…

ATXPowerSupply

Wireless Network

Bay Bay

Power

Data

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Docking with Bay – Procedure

Request charge bay, wait for accept

Locate bay, get in homing range

Home to docking bay

Dock

Wireless

BOM/Wireless

Homing Sensor

Robot Hardware

Autonomous Recharging Video

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IR Beacon Homing

Left

Center

Right

Max pulse width

n

3n

2n

Bea

con

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Charge Board monitors battery, manages charging

– Temperature and Voltage Observation

– Current Control

Necessary for fast, high current charging

Charge Board

Charging Algorithm

•Regulate current into battery to maintain constant 1C (2.6A) charge•Terminate at either

–Voltage Drop threshold–Temperature dT/dt threshold

•Trickle charge an option if robot not needed immediately

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ColoNet

● Remote control and monitoring of the Colony over the Internet

● Global Colony task queuing

● Monitoring and recording of wireless communications

● Web-based Java GUI

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Colony Members

Austin Buchan Christopher Mar

Brian Coltin Siyuan Feng Jason Knichel James Kong Eugene Marinelli Brad Neuman Gregory Tress Justin Scheiner Andrew Yeager Kevin Woo

•Jimmy Bourne•Rich Hong•Victor Marmol•Evan Mullinix•Ben Poole•John Sexton•David Schultz•Bradley Yoo

•Prof. George Kantor

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www.robotcolony.org