simplifying wheelchair mounted robotic arm control with a visual interface katherine m. tsui and...

Simplifying Wheelchair Mounted Robotic Arm Control with a Visual Interface

Katherine M. Tsui

and Holly A. Yanco

University of Massachusetts, Lowell

Computer Science Department

Robotics Laboratory

http://www.cs.uml.edu/robots

Collaborators

University of Central Florida: Aman Behal

Crotched Mountain Rehabilitation Center: David Kontak

Exact Dynamics: GertWilem Romer

NSF IIS-0534364


Research Question

What is the most effective user interface to manipulate a robot arm?

Our target audience is power wheelchair users, specifically:– Physically disabled, cognitively aware people.– Cognitively impaired people who do not have fine

motor control.


Hardware

Manus ARM by Exact Dynamics– 6 DoF– Joint encoders, slip

couplings– Cameras

Manual and computer control modes– Both are capable of

individual joint movement and Cartesian movement of the wrist.


Interface Design

Interface is compatible with single switch scanning. Left:

– Original image is quartered.– Quadrant containing the desired object is selected.

Middle:– Selection is repeated a second time.

Right:– Desired object is in 1/16th close-up view.

QuickTime™ and aTIFF (Uncompressed) decompressor

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User Testing: Hypotheses

H1: Users will prefer a visual interface to a menu based system.

H2: With greater levels of autonomy, less user input is necessary for control.

H3: It should be faster to move to the target in computer control than in manual control.


User Testing: Experiment

Participants– 12 able-bodied participants (10 male, 2 female)– Age: [18, 52]– 67% technologically capable– Computer usage per week (including job related):

• 67% 20+ hours; 25% 10 to 20 hours; 8% 3 to 10 hours

– 1/3 had prior robot experience:• 1 industry; 2 university course; 1 “toy” robots


User Testing: Experiment Methodology Two tested conditions: manual and computer

control. Input device was single switch for both

controls. Each user performed 6 runs (3 manual, 3

computer). Start control was randomized and alternated. 6 targets were randomly chosen.


User Testing:Experiment Methodology Neither fine control nor depth existed in

implementation of computer control during user testing.

In manual control, users were instructed to move the opened gripper “sufficiently close” to the target.


User Testing:Experiment Methodology Manual control

procedure, using single switch and single switch menu:– Unfold ARM.– Using Cartesian

movement, maneuver opened gripper “sufficiently close” to target.

QuickTime™ and aTIFF (Uncompressed) decompressor

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User Testing:Experiment Methodology Computer control procedure:

– Turn on ARM.– Select image using single switch.– Select major quadrant using single switch.– Select minor quadrant using single switch.– Color calibrate using single switch.


User Testing: Results

H1: Users will prefer a visual interface to a menu based system.

83% stated preference for manual control in exit interviews.

Likert scale rate of manual and computer control (1 to 5) showed no significant difference in user experience preference.

H1 was not proven. Why? Color calibration



H2: With greater levels of autonomy, less user input is necessary for control.

In manual control, counted the number of clicks executed by users during runs, divide by run time. This yields average clicks per second.

In computer control, the number of clicks is fixed.

H2 was confirmed.



H3: It should be faster to move to the target in computer control than in manual control.

Distance to time ratio: moving distance X takes Y time.

Under computer control, ARM moved farther in less time.

H3 was confirmed.


Current/Future Work

Identify specific volunteers User interface User testing:

– H1– Baseline evaluation– Initial testing at

Crotched Mountain Integration with power

wheelchair Depth extraction Object occlusion
