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Recharging Process 1. Robot detects low battery 2. Robot requests a bay from the charging station over wireless 3. Charging station accepts or denies the request • Bay allocation algorithm assigns bay based on availability 4. Robot moves towards the bay • BOM sensor guidance until homing signal is detected • Homing sensor guidance for fine- tuned docking movement 5. Regulated battery charging • ARCHS monitors the temperature and voltage of the battery • Robot signaled when charge is complete 6. Robot leaves the docking bay and continues its task Towards an Autonomously Recharging Robot Colony Duncan Alexander Austin Buchan Brian Coltin Felix Duvallet Siyuan Feng Jason Knichel James Kong Christopher Mar Eugene Marinelli Bradford Neuman Suresh Nidhiry Justin Scheiner Gregory Tress Kevin Woo Advisor: George Kantor ColoNet Interconnections • Multiple clients connect to the server via TCP/IP • Server parses information from clients • Server relays data over wireless to and from the robots TCP/IP Wirele ss Clien t Serv er Robot s Acknowledgments We first would like to thank our advisor George Kantor. We would also like to thank Howie Choset and Peggy Martin for their help and support, as well as Brian Kirby, Tom Lauwers, Prasanna Velagapudi, Steven Shamlian, and Cornell Wright for their contributions to the project. This project was funded in part by Carnegie Mellon’s Undergraduate Office. The results represent the views of the authors and not those of Carnegie Mellon University. ColoNet Overview An Internet interface between the Colony and the world. Features: • Remote control and monitoring of the Colony over the Internet • Manual control of individual robots or the entire colony • Global Colony task queuing • Monitoring and recording of wireless communications • Web-based Java GUI Behaviors • Behaviors written as tasks using finite state machines (FSM) to control execution • Tasks include activities such as avoiding obstacles, seeking light, solving mazes • Tasks run normally until a low battery is detected • Program switches to the Charging FSM to handle autonomous recharging • Charging FSM • Handles wireless communication with the charging station and I 2 C communication with the ARCHS charging board • Controls docking and departing movement • Relinquishes control to task FSM once recharging process is complete Charging Station The Charging Station manages docking requests and allocates docking bays Features: • ATMega128 microcontroller • XBee wireless module • Manages up to 8 docking bays Docking Bays Docking bays guide in robots and supply power for battery charging. Features: • Linear BOM • Homing Beacon • Charging Contacts Linear BOM Segment Homing Beacon Emitters Charging Contacts Control Circuitry Dragonfly At the foundation of each Colony robot is the Dragonfly circuit board. Features: • ATMega128 microcontroller • XBee wireless module • USB interface • 5 Sharp IR rangefinders • 2 Tri-color LEDs • Support for encoders and servos BOM Sensor Colony robots use the BOM (Bearing and Orientation Module) to locate other robots and charging stations. • Coplanar ring of IR LEDs and IR detectors • Provides localization data ARCHS Charging Board ARCHS (Autonomous ReCharging and Homing System) is a separate circuit board that facilitates the recharging process. ARCHS relays homing data to the Dragonfly and regulates battery recharging. Features: • ATTiny861 microcontroller • Homing Sensor • Charge contact sensing • Charging current regulator • Temperature and voltage monitoring • Inter-Integrated Circuit Protocol (I 2 C) communication Homing Sensor ARCHS Board BOM Dragonfl y Charge Contacts Robot Platform Autonomous Recharging ColoNet Abstract Power management is becoming an increasingly important area in mobile robotics. In groups of robots, power concerns are compounded by a large number of agents sharing limited resources, requiring methods for power management. We have developed specialized hardware and algorithms that allow our colony of robots to autonomously locate and dock with a charging station and recharge their batteries. Using only simple locomotion, limited sensing and onboard processing capabilities, we have demonstrated autonomous recharging for a group of small low-cost robots. These advances will allow the Colony to operate over extended periods of time and perform tasks without the need for human intervention. Charge Request Charge Accept/Deny Docking Bays Wireless Token Ring Charging Station Bay Allocation Manager Charge Board Dragonf ly I 2 C Robot 0 Charging Algorithm Schedule r: Task and Charging FSMs BOM and Homing Signals Robot 1 Robot 3 Robot 2 Robot 4 Overview of the Overview of the Autonomous Autonomous Recharging System Recharging System …
