Development of Vision-Based Navigation for a Robotic Wheelchair Matt Bailey, Andrew Chanler, Mark Micire, Katherine Tsui, and Holly Yanco University of Massachusetts, Lowell Bruce Maxwell Swarthmore College

Outline Goal Redesign of Wheeley SLAM using stereo vision Human cue detection Manipulation Future work

Goal: How do I get to…? Photo from

Wheeley: Hardware Wheelesley v2 Vector Mobility prototype chassis Differential drive RobotEQ AX2850 motor controller Custom PC Sensor platform Vision system

Wheeley: Robot Arm Exact Dynamic’s Manus Assistive Robotic Manipulator (ARM) –6+2 DoF –Joint encoders, slip couplings –14.3 kg –80 cm reach –20 N clamping force –1.5 kg payload capacity –Keypad, joystick, single switch input devices –Programmable Image by Exact Dynamics

Wheeley: Vision System Manipulation –Shoulder camera Canon VC-C50i Pan-Tilt-Zoom –Gripper camera PC229XP Snake Camera 0.25 in x 0.25 in x 0.75 in

Wheeley: Vision System Navigation –Videre Design’s STH-V1 –19 cm x 3.2 cm –69 mm baseline –6.5 mm focal length –60 degrees FoV

SLAM using Stereo Vision Why use vision instead of traditional ranging devices? –Accuracy –Cost –Detail

Vision and Mapping Libraries Phission – Videre Design’s Small Vision System (SVS) Simple Mapping Utility (pmap) –Laser stabilized odometry –Particle-based mapping –Relaxation over local constraints –Occupancy grid mapping

SLAM Data Flow

Results

Human Cue Detection Swarthmore Vision Module (SVM) –Basic text detector and optical character recognition

Manipulation: Motivation Direct inputs from 4x4 keypad, joystick, or single switch May not correlate well with user’s physical capabilities Layered menus Micromanage task and progress Image by Exact Dynamics

Manipulation: Visual Control

Manipulation: Experiments Able bodied, August 2006 –Confirmed: With greater levels of autonomy, less user input is necessary for control –Confirmed: Faster to move to the target in computer –Unconfirmed: Preference of visual interface Target audience, Summer 2007 –Access methods –Cognitive ability –Recreation of previous experiment

Future Work Additional Wheeley modifications: –PC for mapping –Mount touch screen LCD –New Videre Stereo Head –Mount robotic arm Integrate Wheelesley navigation

Acknowledgements Research supported by NSF grants IIS , IIS , and IIS Collaborators: –David Kontak at Crotched Mountain Rehabilitation Center –GertWillem Romer at Exact Dynamics –Aman Behal at the University of Central Florida

Questions?