The WolfBot:Swarm Robotics Platform with Image Processing Applications

Jimit PatelDr. Edgar Lobaton

Department of Electrical and Computer EngineeringNorth Carolina State University

What is Swarm Robotics?

Multi-robot system inspired from social insects

Ability to work co-operatively to achieve a common goal

“Swarm Intelligence”: simple set of rules for individuals, sophisticated collective behavior for the group.

Research in Swarm RoboticsCommunicationsControl ApproachMapping and localizationLearning and task allocationReconfigurable RoboticsObject transportation and

manipulation

ApplicationsReconnaissance scenarios such

as a natural disaster, search and rescue missions, surveillance, security purposes, mapping unknown terrain or distributed sensing …

Gathering information about environment◦Computer Vision

Existing Swarm RobotsTrade-off between cost, size and

features

Very few swarm robots have camera◦From those which have cameras,

ability to take images at good resolution is rare Those which do take images at good

resolution, often lack ability to process images Finally, those which have ability to process

images, aren’t fast enough! (or are very expensive)

Comparison with different swarm robots

Name(s) Cost per unit Camera

Kilobot, R-one, Elisa III, Alice, Libot, Robomote, I-swarm, Jasmine, i-robot, …

< $350 NA

E-puck $730 40x40 @ 4 FPSMM-robot[1] NA VGA @ 20 FPS max

Khepera III $3,500 HD, logitechCorobot $4,000 VGA

The WolfBot• Low Cost• High Performance• Designed for swarm robotics • Ability for on-board image

processing• Easily replaceable camera and

communication modules• Omnidirectional drive

ProcessorBeaglebone - TI AM3359

◦ARM Cortex A8, 720 MHz, 256 MB DDR2 RAM

- Ubuntu 12.10 armhf - OpenCV 2.4.2 C

SensorsAccelerometer, MagnetometerAmbient Light sensorsIR Distance Measurement sensors

CameraMS LifeCam HD3000

CommunicationIR (Robot-to-Robot)ZigbeeWifi (video stream/ftp)

SensorsLSM303DLHC 3D Accelerometer and

digital compass

Ambient Light Sensors

IR Distance Measurement sensors (~10cm to 100cm)

Microsoft LifeCam HD-3000◦720p HD, 50 FPS

CommunicationsNano wi-fi adaptor used for

WLAN. Used for video stream/ftp

IR Transceiver Beacon for short range, line of sight communication (range upto 15 ft)

Zigbee communication for mesh network in the swarm

Battery and Power Management

7.4V Lithium Ion 5200mAh Battery

Two TPS5420 DC-DC Converters to step down the voltage to 5V and 3.3V

Experimental Results Currently, the Wolfbot is

programmed to receive its co-ordinates from OptiTrack (local positioning system) and move in random directions till it detects an object.

Peak current draw of ~1.5A and upto 2.5 hrs of continuous operation (motion, sensing and video stream at 720p resolution)

Edge Detection ◦Used cvCanny() from OpenCV on

512x512 pixels image◦Execution time : 0.05 sec (at 500MHz)*

* For comparison, the execution time is 0.34sec for CITRIC platform which used IPP canny edge detection at 520MHz for 512x512 pixel images. Same program on intel core-i5 laptop takes 0.008 sec at 2.6 GHz

Face Detection ◦Used  Haar-Cascades for face

detection from OpenCV on 512x512 pixels image

Summary• Introduction of image processing

capabilities in swarm robotics research

• Low cost design (approx $500)

• Facilitates experiments on different research domains in swarm intelligence

References1) Haverinen, J., Parpala, M., & Roning, J. (2005). A Miniature Mobile Robot With a Color

Stereo Camera System for Swarm Robotics Research. IEEE International Conference on Robotics and Automation (ICRA 2005), (April 18-22), 2494–2497.

2) Rubenstein, M., Ahler, C., & Nagpal, R. (2012). Kilobot: A low cost scalable robot system for collective behaviors. 2012 IEEE International Conference on Robotics and Automation, 3293–3298.

3) Zahugi, E. M. H., Shabani, A. M., & Prasad, T. V. (2012). Libot : Design of a Low Cost Mobile Robot for Outdoor Swarm Robotics. IEEE International Conference on Cyber Technology in Automation, Control and Intelligent Systems, (May 27-31), 342–347.

4) Sibley, G. T., Rahimi, M. H., & Sukhatme, G. S. (2002). Robomote : A Tiny Mobile Robot Platform for Large-scale Ad-hoc Sensor Networks  ’. IEEE International Conference on Robotics and Automation, (May), 1143–1148.

5) Mondada, F., Bonani, M., Raemy, X., Pugh, J., Cianci, C., Klaptocz, A., Zufferey, J., et al. (2006). The e-puck , a Robot Designed for Education in Engineering.

6) Blazovics, L., Varga, C., Csorba, K., Feher, M., Forstner, B., & Charaf, H. (2011). Vision Based Area Discovery with Swarm Robots. 2011 Second Eastern European Regional Conference on the Engineering of Computer Based Systems, 149–150. doi:10.1109/ECBS-EERC.2011.32