Post on 31-Mar-2015
transcript
A new way of myoelectric A new way of myoelectric controlcontrol
MyoPro project
Daphne van BaalHans Rietman, Laura Kallenberg
25 september 2009
Roessingh Research and Development, Enschede, the Netherlands2
IntroductionIntroduction
Low usage myoelectric prosthesis
Advantages DisadvantagesNon-invasiveNo straps or harnessesUse of remaining muscles
Limited selectivityLack of intuitive controlLack of sensory feedback
Roessingh Research and Development, Enschede, the Netherlands3
GoalGoal
Improve the control ofa myoelectric forearm prosthesis
by increasing the number of degrees of freedom
using multi-channel surface electrodes
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Experimental protocolExperimental protocol
• Ten healthy male subjects• One forearm amputee• Forty small electrodes in grid• Eight isometric contractions
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Isometric contractionsIsometric contractions
Flexion of wrist Extension of wrist Flexion of fingers Extension of fingers
Abduction of wrist Adduction of wrist Supination of forearm
Pronation of forearm
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Data analysisData analysis
• Data selection of active contractions• Time periods of 200 milliseconds• Root mean squared (RMS) value• Subject specific classification• Simple robust classifier (kNN)
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RMS-level imagesRMS-level images
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Robust classifierRobust classifier
Training set Test set
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ResultsResults
OutputInput FF FE P S AB AD WE WF
Finger flexion99.9
40.03 0.01 0.02
Finger extension
0.0199.8
90.01 0.01 0.08
Pronation99.9
60.04
Supination 0.01 0.0199.8
50.03 0.02 0.08 0.01
Wrist abduction
0.02 0.0199.9
40.02 0.01
Wrist adduction
0.0199.9
70.01
Wrist extension
0.02 0.03 0.02 0.10 0.0199.8
30.01
Wrist flexion 0.02 0.05 0.0199.9
3
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Continuous resultsContinuous results
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RMS-level images RMS-level images amputeeamputee
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Results amputeeResults amputee
OutputInput
FF FE P S AB AD WE WF ABP ADS
Finger flexion 100.0
Finger extension
99.28
0.48 0.25
Pronation 99.62
0.02 0.13 0.23
Supination 99.64
0.13 0.06 0.17
Wrist abduction
99.73
0.06 0.21
Wrist adduction
0.08 0.25 0.0499.5
60.02 0.06
Wrist extension
0.02 0.17 0.1199.6
40.06
Wrist flexion 0.10 0.0299.8
9
Wrist ab & pro 0.19 0.34 0.0699.4
1
Wrist ad & sup 0.6199.3
9
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ConclusionConclusion
• Offline classification – normally limbed: 99.9%– amputee patient: 99.6%
• Online classification– normally limbed: 93.4%
• Up to ten movements can be distinguished (five degrees of freedom)
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FutureFuture
• Validation: more measurements with amputees
• Additional patient specific contractions• Random-ordered contractions• Simultaneous control of different
contractions• Force level analysis for proportional control
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Questions?Questions?
For more information: www.myopro.nlFor more information: www.myopro.nl