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Overview
Overview
Grasping small, flat objects is a difficult task, even for human hands that appears throughout daily life via objects such as credit cards and mobile phones. With a humanoid prosthesis, objects such as these can become impossible to grasp. This simple device replaces one finger of the OLYMPIC hand, and uses a suction cup to produce the desired functionality.
Design
Design
Cross-section view, annotated with key components.
Real terminal device picking and placing a mobile phone.
Mechanical Design
Mechanical Design
Motor rotation is used to wind a spring-release plunger.
Plunger motion generates a vacuum that is used to pick and place objects.
Control
Control
Two electrodes reading muscle activity.
In one direction, tensing increases vacuum strength.
In the other direction, tensing releases the held object.
Testing
Testing
Experiment - Stacking Checkers
Experiment - Stacking Checkers
Taken from the Jebsen Taylor Hand Function Test.
Users must stack 4 checkers on a raised surface as quickly as possible.
Performance metric: task completion time.
Repeated 5 times.
Results
Results
Task Performance
Task Performance
Participants using the Suction Device completed the task over twice as fast as those using the humanoid hand: 30.3 seconds vs 77.1 seconds.
Participants with upper limb difference echo group results of participants without upper limb difference.
Compensatory Motion
Compensatory Motion
Significant (p<0.001, Mann-Whitney U test) reduction in chest motion during use - 42.7% less than the control group.
Smaller reduction (16.1%) in upper arm motion during use.
Task Load
Task Load
Reduction in median mental demand (MD), physical demand (PD), and significant (p<0.05, Mann-Whitney U test) reduction in frustration (Fr) compared to the humanoid group.
Increase in perceived performance (Pe) echoes real task performance.
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