Investigating Power Management in a Robot Colony Meeting of the Minds Symposium May 7, 2008 Christopher Mar and Austin Buchan Colony Project, Robotics Club

2 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

3 Colony Robot Bearing and Orientation Module (BOM)‏ Dragonfly Microcontroller Board Motors Sharp IR Rangefinders Tri-color LED x 2

4 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) –...

5 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 Task Model

6 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

7 Robot Charging Hardware Charge Board – High current circuitry – Controlled by dedicated microprocessor – Communicates with robot over I 2 C Homing Senor Wireless communication and BOM localization

8 Charging Bay Charging Contacts Tricolor Orb Wireless Module Power/I 2 C Connections BOM Segment Homing Beacons

Bay 9 Power Management Topology … ATX Power Supply Wireless Network Bay Power Data

10 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

12 IR Beacon Homing Left Center Right Max pulse width n 3n 2n Beacon

13 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 14

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

16 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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