Development of Vision-Based Navigation and Manipulation for a Robotic Wheelchair Katherine Tsui University of Massachusetts, Lowell

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

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

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: Users will prefer a 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

References and Acknowledgements Bailey, M., A. Chanler, B. Maxwell, M. Micire, K. Tsui, and H. Yanco. “Development of Stereo Vision-Based Navigation for a Robotic Wheelchair.” in Proceedings of the International Conference on Rehabilitation Robotics (ICORR), June K. M. Tsui and H. A. Yanco. “Simplifying Wheelchair Mounted Robotic Arm Control with a Visual Interface” in Proceedings of the AAAI Spring Symposium on Multidisciplinary Collaboration for Socially Assistive Robotics, March Research supported by NSF grants IIS , IIS , and IIS In collaboration with Crotched Mountain Rehabilitation Center, Exact Dynamics, Swarthmore College, and the University of Central Florida.

Questions?