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Coherence in One-Shot Gesture Recognition for Human-Robot Interaction
Maru Cabrera
December 3rd 2018
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Relevance of Gestures in HRI
vs
โ Human have the unique ability to quickly adjust their context and learn from very few examples.
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Motivation for One-Shot Gesture Recognition
โ Lack of a comprehensive method that generalizes gesture recognition from few observations.
โWe focus on the process used to generate a given gesture:โCognitionโLearning and GeneralizationโPhysical execution
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Motivation for Coherence in Gesture Recognition
โ Explore gesture recognition and understanding when the roles between performer and listener are exchanged.
โ Including the human aspect within the framework to artificially generate examples.
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Overview of One-Shot Learning Framework
Skeleton Info Gesture exampleโGist of
GestureโGenerated Dataset
Train Classifier
HMM
SVM
DTW
CRF
Artificial Generation Methods
Kinect Sensor
Performance Metrics
- Recognition accuracy- Efficiency- Coherency
Forward Method
Backward Method
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Extracting the Gist of the Gesture
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เต๐๐ โ {๐1 โช ๐ผ๐๐ท โฉ ๐ผ๐๐ถ โช ๐๐ฏ, ๐ = 1,โฆ , ๐
2 โค ๐ โค ๐ป
Given ๐1๐ = {(๐ฅ1, ๐ฆ1, ๐ง1 ), . . . , (๐ฅ๐ป, ๐ฆ๐ป , ๐ง๐ป)}
Set of inflection points
๐๐ = (๐ฅ๐ , ๐ฆ๐ , ๐ง๐)
Working Hypothesis:
Compact amount of information stored during cognitive processes of
gesture perception
Validating Extracted Gist of the Gesture
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17 Participants
EEG Power Dynamic wavelets
Motion EEG
Correlation
Validating Extracted Gist of the Gesture
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Validating Extracted Gist of the Gesture
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Overview of One-Shot Learning Framework
Skeleton Info Gesture exampleโGist of
GestureโGenerated Dataset
Train Classifier
HMM
SVM
DTW
CRF
Artificial Generation Methods
Kinect Sensor
Performance Metrics
- Recognition accuracy- Efficiency- Coherency
Forward Method
Backward Method
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2
3
4
5 6
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Artificial Gesture Generation โForward Approach
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Input:๐๐๐ โ 3D hand trajectory of a gesture of class s๐๐ = (๐๐,๐๐,๐๐) โ 3D position of the shoulder
K โ Number of artificial trajectories to generate
Variance Estimation based on ๐๐ and Gaussian Mixture Model (GMM)
Output:
เต๐ฎ๐ = { เท๐1๐, เท๐2
๐, โฆ เท๐๐พ๐ โ Set of artificial trajectories
for gesture class s
เท๐๐๐ = ๐๐ก
เทจ๐บ๐ ๐ = 1,โฆ , ๐พ ; ๐ = 1,โฆ , ๐ ; ๐ก = 1
เต๐ฎ๐ = { เท๐1๐ , เท๐2
๐ , โฆ เท๐๐๐ , โฆ , เท๐๐
๐
Artificial Gesture Generation โBackward Approach
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Artificial Gesture Generation โBackward Approach
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Jerk Minimization
Smooth changes in joint space usingthe third derivative of the joint angle
Least Energy Expenditure
Changes in joint space using torqueto calculate economic trajectories
๐๐ฝ๐๐๐ = min
๐=1
๐พ
เถฑ๐ก1
๐ก2แธ๐๐ +โฏ+min
๐=1
๐พ
เถฑ๐ก๐โ1
๐ก๐แธ๐๐ ๐๐ธ๐๐๐๐๐ฆ = min
๐=1
๐พ
เถฑ๐ก1
๐ก2
๐๐ ร แถ๐๐ +โฏ+
๐=1
๐พ
เถฑ๐ก๐โ1
๐ก๐
๐๐ ร แถ๐๐
Begins in one IK solution for human arm (k= 7) for one IP ๐๐๐ฃ, ends in
solution for different IP ๐๐+1๐ค
๐๐๐ฃ = ๐1
๐ฃ, ๐2๐ฃ, โฆ , ๐๐พ
๐ฃ
๐๐+1๐ค = ๐1
๐ค, ๐2๐ค, โฆ , ๐๐พ
๐ค
Initial
Final
๐๐ solutions in IP ๐ of gesture trajectory
๐๐+1 solutions in IP ๐ + 1
Artificial Gesture Generation โCombined F+B Approach
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Combination at gesture instance level.
Artificially generated observations from both approaches used as training data
Overview of One-Shot Learning Framework
Skeleton Info Gesture exampleโGist of
GestureโGenerated Dataset
Train Classifier
HMM
SVM
DTW
CRF
Artificial Generation Methods
Kinect Sensor
Performance Metrics
- Recognition accuracy- Efficiency- Coherency
Forward Method
Backward Method
1
2
3
4
5 6
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Gesture LexiconMSRC-12
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Contains sequences of human movements (Kinect skeleton)
12 iconic and metaphoric gestures
โฆ Gaming commands and media player
Lexicon reduced to 8 gesturesโฆ Excluded gestures with leg
motions or whole upper body.
Fothergill, S., Mentis, H., Kohli, P., & Nowozin, S. (2012). Instructing people for training gestural interactive systems. In Proceedings of the SIGCHI Conference (pp. 1737-1746). ACM.
Classification Algorithms
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Hidden Markov Models (HMM):
โ One-vs-all scheme
โ 5 states left-to-right
โ Baum-Welch algorithm
Support Vector Machines (SVM):
โ One-vs-all scheme
โ Radial Basis Function (RBF) Kernel
โ MATLABยฎ library
Conditional Random Fields (CRF):
โ Multi-class scheme
โ Samples encoded using BIO: Beginning, Inside, Outside
โ CRF++ toolkit
Dynamic Time Warping (DTW):
โ Multi-class scheme
โ Gesture Recognition Toolkit (GRT)
Training and Features
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1 gesture instance per class was
used to extract inflection points
200 gesture examples per class
generated for training
100 gesture instances per class
from each data set for testing
Classifiers trained and compared
in terms of accuracy (๐ด๐๐%), and
recognition coherence (๐พ)
Feature vector* ๐๐ for training:
๐๐ = {๐๐ = ๐ฅ1, ๐ฆ1, ๐ง1 , โฆ , ๐๐ฏ}
๐๐ = แถ๐๐ ๐ท๐โฆ แถ๐๐ ๐ท๐โฆ แถ๐๐ฏโ๐ ๐ท๐ฏโ๐
แถ๐๐ = ๐๐+๐ โ ๐๐ ๐ท๐ = tanโ1๐ฆ๐
๐ฅ๐, tanโ1
๐ง๐
๐ฆ๐, tanโ1
๐ง๐
๐ฅ๐
* M. G. Jacob and J. P. Wachs, โContext-based hand gesture recognition for the
operating room,โ Pattern Recognition Letters, vol. 36, pp. 196โ203, Jan. 2014.
Overview of One-Shot Learning Framework
Skeleton Info Gesture exampleโGist of
GestureโGenerated Dataset
Train Classifier
HMM
SVM
DTW
CRF
Artificial Generation Methods
Kinect Sensor
Performance Metrics
- Recognition accuracy- Efficiency- Coherency
Forward Method
Backward Method
1
2
3
4
5 6
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Performance Metrics
Coherence (g) is defined asthe intersection betweenthe agreement indices (AIx)for humans and machines,whether each agentcorrectly recognized eachgesture or not. ๐พ =
๐ด๐ผ๐ฅ๐ โฉ ๐ด๐ผ๐ฅ๐ป
๐ด๐ผ๐ฅ๐ป
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๐ด% =๐ก๐๐ก๐๐๐ก๐๐ข๐โโ๐๐ก๐ ๐ก๐๐ก๐๐๐ ๐๐๐๐๐๐
Accuracy Results
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Forward and Backward approach for One-Shot Gesture Learning compared.
K-fold cross validation scheme with k = 10.
10 ๐ด๐๐% values for m and s for each approach.
Coherence Experiment Setting
โ Two scenarios were explored with Baxter performing artificially generated gestures:โ Scenario 1 (MH): Gestures are
recognized by 10 human participants.
โ Scenario 2 (MM): Gestures are recognized by 4 classification algorithms.
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Coherence Experiment Setting
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Experimental Results
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Takeaway Messagesโ In its application to one-shot learning, the proposed methodhighlights the use of context for gesture recognition from the wayhumans use their bodies.
โ The obtained results show the performance of the method,demonstrating independence from the selected classification strategy.
โ The robotic implementation opens a different route towardscoherence in humanโrobot interaction.
โ Coherence can be related to gesture classification when humans andmachines interchange the roles of performing and recognizing agesture.
โ The calculated coherence metric is our main indicator that thegenerated gestures capture human-like variations for all the gestureclasses.
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Maru Cabrera
Coherence in One-Shot Gesture Recognition for Human-Robot Interaction