Learning to Adapt to Sensor Changes and Failures
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Invited talk at the IJCAI Workshop on AI for Internet of Things, August 19, 2017
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Learning to Adapt to Sensor Changes and Failures
- 1. Learning to adapt to sensor changes and failures Craig Knoblock Yuan Shi Minh Pham University of Southern California Information Sciences Institute
- 2. Introduction • The Internet of Things will contain many sensors • People will build applications that will rely on these sensors • But with the large numbers of sensors, there will be failures • So one important challenge is seamlessly handling these failures
- 3. Outline • Learning to Replace a Failed Sensor • Learning to Replace a Compound Sensor • Assessing Adaptation Quality and Detecting Failures • Related Work, Discussion, and Future Work
- 4. Example: Reconstructing a Missing Sensor Temperature sensor 2015-04-25:15:07 33.292 118.541 35.2 26.2 2015-04-25:15:12 33.274 118.532 34.8 26.0 Reading Reading Reading Location timestamp latitude longitude temperature pressure
- 5. Example: Reconstructing a Missing Sensor Temperature sensor Reading Reading Reading Location timestamp latitude longitude temperature pressure fNew sensor 2015-04-25:15:07 33.292 118.541 35.2 26.2 2015-04-25:15:12 33.274 118.532 34.8 26.0
- 6. Sensor Reconstruction without Overlapping Data t X1 X2 X3 model f(X1, X2 ,Y) • We replace Xk with a new sensor Y • Learn a reconstruction function trained on the working sensors, though there is no overlapping data between X and Y Xkf( X1, X2, …, XK-1 , Y ) failed/target sensor working sensors Y new sensor
- 7. Notations of Individual Sensor Changes 1 2 … N … change point old sensor t S1 S2 S3 SK-1 SK …
- 8. 1 2 … N N+1 N+2 … N+M … … change point old sensor new sensor t S1 S2 S3 SK-1 SK … S1 S2 S3 SK-1 … SK+1 SK+2 SK+P SK is replaced by P new sensors: SK+1, … ,SK+P Notations of Individual Sensor Changes
- 9. 1 2 … N N+1 N+2 … N+M … … change point old sensor new sensor t S1 S2 S3 SK-1 SK … S1 S2 S3 SK-1 … SK+1 SK+2 SK+P SK is replaced by P new sensors: SK+1, … ,SK+P Source Domain Target Domain X1 X2 XN Z1 Z2 ZM … … Notations of Individual Sensor Changes
- 10. Sensor-level Adaptation to Individual Sensor Changes SK is replaced by P new sensors SK+1…SK+P-1 Unexplored in previous work Reconstruction function: f(S1 S2 … SK-1 SK+1 … SK+P) SK 1 2 … N N+1 N+2 … N+M X1 X2 XN Z1 Z2 ZM … … t S1 S2 … SK-1 SK SK+1 … SK+P
- 11. Sensor-level Adaptation to Individual Sensor Changes SK is replaced by P new sensors SK+1…SK+P-1 Unexplored in previous work Reconstruction function: f(S1 S2 … SK-1 SK+1 … SK+P) SK Challenge: no overlapping between SK and new sensors! 1 2 … N N+1 N+2 … N+M X1 X2 XN Z1 Z2 ZM … … t S1 S2 … SK-1 SK SK+1 … SK+P
- 12. Sensor-level Adaptation to Individual Sensor Changes SK is replaced by P new sensors SK+1…SK+P-1 Unexplored in previous work Reconstruction function: f(S1 S2 … SK-1 SK+1 … SK+P) SK Challenge: no overlapping between SK and new sensors! Intuition: S1, S2, …, SK-1 as the bridge Assumption: S1, S2, …, SK-1 are correlated with SK, as well as SK+1, …, SK+P 1 2 … N N+1 N+2 … N+M X1 X2 XN Z1 Z2 ZM … … t S1 S2 … SK-1 SK SK+1 … SK+P
- 13. Sensor-level Adaptation to Individual Sensor Changes 1 2 … N N+1 N+2 … N+M X1 X2 XN Z1 Z2 ZM … … t
- 14. 1 2 … N N+1 N+2 … N+M X1 X2 XN Z1 Z2 ZM … … t X1 X2 XN … t f … Sensor-level Adaptation to Individual Sensor Changes 1 2 … N N+1 N+2 … N+M
- 15. X1 X2 XN … … t f Two domains distribute similarly Two sets of samples have similar distributions Source Target Sensor-level Adaptation to Individual Sensor Changes 1 2 … N N+1 N+2 … N+M X1 X2 XN Z1 Z2 ZM … … t 1 2 … N N+1 N+2 … N+M
- 16. Two sets of samples have similar distributions Two sets of samples mixed as much as possible Xs’s k neighbors in the target domain ’s k neighbors in the source domain Minimize cross-domain k-nearest neighbor distances Sensor-level Adaptation to Individual Sensor Changes X1 X2 XN … … t Source Target 1 2 … N N+1 N+2 … N+M
- 17. ID Type Unit Range 1 Temperature °C 0.4 – 37.6 2 Dew point °C -9.4 – 18.4 3 Humidity % 11-90 4 Wind speed mph 0 – 38.6 5 Wind gust mph 0 – 46.7 Correlation between individual sensors by month Five individual sensors from WeatherUnderground Two groups of patterns (Nov-Jan, Feb-Oct), suggesting nonlinear models for modeling relationship among sensors Relationships in Weather Data
- 18. Empirical Study • Each station has 5-10 individual sensors, producing a sample every 5-10 minutes • Sensor change simulation: an individual sensor is replaced by the same sensor at a nearby station • Source domain: Jan 2015-Aug 2015; target domain: Jan 2016-Aug 2016 • Adaptation errors: root mean square error between reconstructed signal and ground truth Sensor-level Adaptation to Individual Sensor Changes
- 19. Empirical Study Ignoring new sensors: Regression on the remaining old sensors Missing value imputation: Predicting new sensors’ readings on the source domain, then do regression Our approach: Learning with previously Unseen Features (LUF) [Shi and Knoblock, ‘17] Average improvement: 17.9% Sensor-level Adaptation to Individual Sensor Changes
- 20. wind speed reconstructed pressure Our approach (LUF) that uses new sensors Empirical Study Sensor-level Adaptation to Individual Sensor Changes Ignoring new sensors: Regression on the remaining old sensors
- 21. Wind Gust Sensor Reconstructed from a Nearby Station
- 22. Outline • Learning to Replace a Failed Sensor • Learning to Replace a Compound Sensor • Assessing Adaptation Quality and Detecting Failures • Related Work, Discussion, and Future Work
- 23. Example: Learning the device operation Temperature sensor Reading Reading Reading Location timestamp latitude longitude temperature pressure 2015-04-25:15:07 33.292 118.541 35.2 26.2 2015-04-25:15:12 33.274 118.532 34.8 26.0
- 24. Example: Automatically Adapting to Changes Weather Station Reading Reading Reading Location timestamp latitude longitude temperature pressure 2015-04-25:15:07 33.292 118.541 35.2 26 2015-04-25:15:12 33.274 118.532 34.8 27 New Weather Station 28-Apr-15 16:50:50 118 26 59 E 33 58 33 N 74 37.5 28-Apr-15 16:50:59 118 27 10 E 33 58 45 N 77 38.4
- 25. Example: Automatically Adapting to Changes Weather Station Reading Reading Reading Location timestamp latitude longitude temperature pressure 2015-04-25:15:07 33.292 118.541 35.2 26 2015-04-25:15:12 33.274 118.532 34.8 27 New Weather Station 28-Apr-15 16:50:50 118 26 59 E 33 58 33 N 74 37.5 28-Apr-15 16:50:59 118 27 10 E 33 58 45 N 77 38.4 Learn a tranformation program TT
- 26. Challenge: How to Automatically Adapt to a New Sensor • Problem • The output of the new sensor is different than that of the original sensor that software was designed to process • Solution • Synthesize a data adapter that transforms the new data into a format usable by the software system
- 27. Identifying the Semantic Types of the Sensor Data • Use machine learning techniques to learn to recognize different types of data [Pham et al., 2016] Type A 118.519 119.117 Unknown Type 34.6 33.5 Pairwise similarity features Random Forest Yes (Same type) No (Same type) Unkown Type = A X
- 28. Different similarity features of data firstName ... ... ... First Name ... ... ... Similarity in attribute names Name Gary Cahill Juan Mata De Gea Player Juan Quin Tim Cahill Metsul Ozeil Similarity in values # games played 1 2 ... 8 number of games 2 3 ... 10 Similarity in ranges of values Value range similarityValue similarity Attribute name similarity
- 29. Different similarity features of data position 1 4 3 2 Player GK MF DF FW Similarity in historgram # game played 4 ... 18 23 # goal scored 3 ... 11 22 No similarity in distribution Similarity in value No similarity in value Distribution similarity Histogram similarity
- 30. Evaluation Number of labeled sources 1 2 3 Train on soccer 89.75 95.08 97.73 Train on museum 89.75 95.08 97.73 Train on city 91.86 96.59 97.73 SemanticTyper 85.22 92.04 95.45 MRR performances of our approach on weather data (trained on different domains)
- 31. Dealing with String Format Changes • Learn general string transformations: dd MM yyyy => mm/dd/yyyy 17 May 1983 14 Jul 1984 5 Aug 1991 ... ... ... ... ... 3 / 10 / 1979 11 / 22 / 1982 7 / 5 / 1982 ... ... ... ... ... 3 / 10 / 1979 11 / 22 / 1982 7 / 5 / 1982 ... ... ... ... ... 17 14 5 1983 1984 1991 10 22 5 May Jul Aug Semantic Labeling 3 11 7 1979 1982 1982 Replace Replace Transform 17 May 1983 14 Jul 1984 5 Aug 1991 ... 3/10/1979 11/22/1982 7/5/1982 ... Template inference Template matching Transforming 17 May 1983 14 Jul 1984 5 Aug 1991 ... ... ... ... ...
- 32. Transformation Learning (Future Work) • Example: 3 => Mar Query Webtable database Transformation inference Transform Transform data to correct format ? Jul ? May 7 ? 3 ? 1 January Jan 2 February Feb ... ... ... 7 Jul 5 May 7 Jul 3 Mar
- 33. Preliminary result for format changes • Evaluation: • 38 datasets including date/time, names, stress addresses, telephone numbers, dimensions • Only contains cases that can be solve with just replacement • Measurements: accuracy, average edit distance (compared with groundtruth) • Some examples that work well: Accuracy Avg edit distance Original avg edit distance Improvement on edit distance 0.58 3.5 18.21 81% Format change Accuracy Avg edit distance Original avg edit distance Improvement on edit distance dd mm yyyy dd.mm.yy 1 0 4 100% [middle_name] last_name; first_name [(c)] first_name [middle_name] last_name [(c)] 0.862 0.91 5.8 84% height” [H] x weight” [W] x [depth” [D]] => weight 0.967 0.11 17.79 99%
- 34. Outline • Learning to Replace a Failed Sensor • Learning to Replace a Compound Sensor • Assessing Adaptation Quality and Detecting Failures • Related Work, Discussion, and Future Work
- 35. Adaptation Performance Estimation and Sensor Change Detection How Good is An Adaptation? • Provide upper-layer software with an estimation of adaptation error • Select optimal adaptation strategy Approach • Simulate sensor failures • Simulate failures of one or multiple sensors at random time point from historical data • Compute the adaptation error for each adaptation strategy and store into library • New sensor failure: match the most similar case from library adaptation strategies f1(S1) S3 f2(S2) S3 f3(S1,S2) S3
- 36. Adaptation Performance Estimation and Sensor Change Detection adaptation strategies: f1(S1) S3 f2(S2) S3 f3(S1,S2) S3 S3 = 2S1 + 3S2 – 0.5, error = 0.2 error bound can be derived: (2S1 + 3S2 – S3 – 0.5)2 < 0.22 Can we use it to detect sensor changes?
- 37. Adaptation Performance Estimation and Sensor Change Detection Sensor Change Detection change or not? Error bounds derived from adaptation strategies S1 S2 S3 (S1, S2) (S1, S3) (S2, S3) (S1, S2, S3) Violated: at least one sensor was changed Using logical inference: S1 changes | both S2 and S3 change simpler
- 38. Outline • Learning to Replace a Failed Sensor • Learning to Replace a Compound Sensor • Assessing Adaptation Quality and Detecting Failures • Related Work, Discussion, and Future Work
- 39. • Detecting Sensor Failures and Changes • Change point detection [Aminikhanghahi and Cook ‘16] [Pimentel et al., ‘14] • Distribution-based [Kawahara and Sugiyama, ‘12] [Harchaoui et al., ‘09] [Yamanishi and Takeuchi, ‘02] • Reconstruction-based [Crook et al., ‘02] [Singh and Markou, ‘04] [Ide and Tsuda, ‘07] [Chatzigiannakis et al., ‘06] • Probabilistic [Adams and MacKay, ‘07] [Saatci et al., ‘10] [Dereszynski and Dietterich, ‘12] [Dietterich et al. ‘12] • Distance-based [Angiulli and Pizzuti, ‘02] [Bay and Schwabacher, ‘03] [Chawla and Sun, ‘06] [Keogh et al., ‘01] [Budalakoti et al., ‘06] [Chen et al., ‘15] • Reconstruction of Sensor Readings • Most detection methods do not address how to automatically recover • Some probabilistic methods [Dereszynski and Dietterich, ‘12] [Dietterich et al. ‘12] can be used to reconstruct changed sensor, but cannot leverage new sensors • FFX [McConaghy ‘11] is applied to extract sensor-specific transformations Related Work 41 Our approach explores multiple nonlinear relationship among sensors, and can potentially detect sensor changes with significantly higher accuracy Our approach can adapt to new sensors, which are not possible by existing approaches
- 40. Related Work: • String transformation: Most existing approaches requries one-to-one mapping in training data to work. • Singh, Rishabh, and Sumit Gulwani. "Transforming spreadsheet data types using examples." ACM SIGPLAN Notices. Vol. 51. No. 1. ACM, 2016. • Wu, Bo, and Craig A. Knoblock. "An Iterative Approach to Synthesize Data Transformation Programs." IJCAI. 2015. • Semi-auto data cleaning: Most existing approaches requires human interaction to provide training data and curate the generated results. • Scaffidi, Christopher. Topes: Enabling end-user programmers to validate and reformat data. Diss. University of Nebraska-Lincoln, 2009. • Raman, Vijayshankar, and Joseph M. Hellerstein. "Potter's wheel: An interactive data cleaning system." VLDB. Vol. 1. 2001.
- 41. Discussion • Presented techniques for • Reconstructing numeric sensor values • Reconstructing an compound failed sensor from new sensor • Assessing the accuracy of a reconstructed sensor and identifying failures • Many applications where these techniques could be applied • Geoscientists collecting data about the earth • Medical devices where information is missing • Sensors on mobile phones where sensors may be too costly to run • Etc…
- 42. Conference Talk on Thursday • Learning with Previously Unseen Features Yuan Shi & Craig A. Knoblock • Thursday, August 24 16:30-18:00 (Yuan will talk at 17:15) • ML-TAML3 – Transfer, Adaptation, Multi-Task Learning 3 (212)
- 43. Thanks!