Abstract:
Machine condition monitoring on a system utilizes a wireless sensor network to gather data from a large number of sensors. The data is processed using a multivariate statistical model to determine whether the system has deviated from a normal condition. The wireless sensor network permits the acquisition of a large number of distributed data points from plural system modalities, which, in turn, yields enhanced prediction accuracy and a reduction in false alarms.
Abstract:
A method and framework are described for detecting changes in a multivariate data stream. A training set is formed by sampling time windows in a data stream containing data reflecting normal conditions. A histogram is created to summarize each window of data, and data within the histograms are clustered to form test distribution representatives to minimize the bulk of training data. Test data is then summarized using histograms representing time windows of data and data within the test histograms are clustered. The test histograms are compared to the training histograms using nearest neighbor techniques on the clustered data. Distances from the test histograms to the test distribution representatives are compared to a threshold to identify anomalies.
Abstract:
A system (102) for updating a plurality of monitoring models is provided. The system (102) includes a model association module (202) that, for each of a plurality of monitored systems (104a, 104b, 104c) determines, an association between a particular monitored system and at least one of a plurality of estimation models. Each estimation model is based upon one of a plurality of distinct sets of estimation properties, and each set uniquely corresponds to a particular estimation model. The system also includes an updating module (204) that updates at least one of the estimation properties and propagates the updated estimation properties to each estimation model that corresponds to a distinct set containing at least one estimation property that is updated. The system further includes a model modification module (206) that modifies each estimation model that corresponds to a distinct set containing at least one estimation property that is updated.
Abstract:
A machine fault diagnosis system combines a rule-based predictive maintenance strategy with a machine learning system. A simple set of rules defined manually by human experts is used to generate artificial training feature vectors to portray machine fault conditions for which only a few real data points are available. Those artificial training feature vectors are combined with real training feature vectors and the combined set is used to train a supervised pattern recognition algorithm such as support vector machines (SVM). The resulting decision boundary closely approximates the underlying real separation boundary between the fault and normal conditions
Abstract:
A system (100) and method (200) for data classification are provided, the system including a processor (102), an adapter (112) in signal communication with the processor for receiving data, a filtering unit (170) in signal communication with the processor for pre-processing the data and filtering features of the data, a selection unit (180) in signal communication with the processor for learning a Bayesian network (BN) classifier and selecting features responsive to the BN classifier, and an evaluation unit (190) in signal communication with the processor for evaluating a model responsive to the BN classifier; and the method including receiving data (212), pre-processing the data (214), filtering features of the data (216), learning a BN classifier (218), selecting features responsive to the BN classifier (220), and evaluating a model responsive to the BN classifier (222).
Abstract:
A system (100) and method (200) for data classification are provided, the system including a processor (102), an adapter (112) in signal communication with the processor for receiving data, a filtering unit (170) in signal communication with the processor for pre-processing the data and filtering features of the data, a selection unit (180) in signal communication with the processor for learning a Bayesian network (BN) classifier and selecting features responsive to the BN classifier, and an evaluation unit (190) in signal communication with the processor for evaluating a model responsive to the BN classifier; and the method including receiving data (212), pre-processing the data (214), filtering features of the data (216), learning a BN classifier (218), selecting features responsive to the BN classifier (220), and evaluating a model responsive to the BN classifier (222).
Abstract:
Condition signals of machines are observed and one or more discontinuities are detected in the condition signals. The discontinuities in the condition signals are compensated for (e.g., by applying a shifting factor to models of the signals) and trends of the compensated condition signals are determined. The trends are used to predict future fault conditions in machines. Kalman filters comprising observation models and evolution models are used to determine the trends. Discontinuity in observed signals is detected using hypothesis testing.
Abstract:
Pattern rules are created by comparing a condition signal pattern to a plurality of known signal patterns and determining a machine condition pattern rule based at least in part on the comparison of the condition signal pattern to one of the plurality of known signal patterns. A matching score based on the comparison of the condition signal pattern to one of the plurality of known signal patterns as well as a signal pattern duration is determined. The machine condition pattern rule is then defined for nonparametric condition signal patterns as a multipartite threshold rule with a first threshold based on the determined matching score and a second threshold based on the determined signal duration. For parametric signal patterns, one or more parameters of the signal pattern are determined and the machine condition pattern rule is further defined with a third threshold based on the determined one or more parameters.
Abstract:
A method is provided for selecting a representative set of training data for training a statistical model in a machine condition monitoring system. The method reduces the time required to choose representative samples from a large data set by using a nearest-neighbor sequential clustering technique in combination with a k d-tree. A distance threshold is used to limit the geometric size the clusters. Each node of the k d-tree is assigned a representative sample from the training data, and similar samples are subsequently discarded.
Abstract:
A method for monitoring machine conditions provides additional information using a one-class classifier in which an evaluation function is learned. In the method, a distance is determined from an anomaly measurement x to a boundary of a region R 1 containing all acceptable measurements. The distance is used as a measure of the extent of the anomaly. The distance is found by searching along a line from the anomaly to a closest acceptable measurement within the region R 1 .