The WolfBot: Swarm Robotics Platform with Image Processing Applications Jimit Patel Dr. Edgar Lobaton Department of Electrical and Computer Engineering North 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 Robotics Research in Swarm Robotics Communications Control Approach Mapping and localization Learning and task allocation Reconfigurable Robotics Object transportation and manipulation

Applications Reconnaissance 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 Robots Trade-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

The WolfBot Low Cost High Performance Designed for swarm robotics Ability for on-board image processing Easily replaceable camera and communication modules Omnidirectional drive

Processor Beaglebone - TI AM3359 ◦ ARM Cortex A8, 720 MHz, 256 MB DDR2 RAM  - Ubuntu armhf  - OpenCV   C

Sensors Accelerometer, Magnetometer Ambient Light sensors IR Distance Measurement sensors Camera MS LifeCam HD3000 Communication IR (Robot-to-Robot) Zigbee Wifi (video stream/ftp)

Sensors LSM303DLHC 3D Accelerometer and digital compass Ambient Light Sensors IR Distance Measurement sensors (~10cm to 100cm) Microsoft LifeCam HD-3000 ◦ 720p HD, 50 FPS

Communications Nano 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 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

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