Laboratory for 

      Manufacturing $ystem Realization and Synthesis

 
SOVA DIAGNOSIS
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Title: Analysis and optimization methods for distributed sensor system

Sponsor: NSF

Collaborators:DaimlerChrysler, GM, DCS 

Description:

Our research focuses on the development and implementation of methodologies for the analysis and optimization of a distributed sensor system (or sensor network) in manufacturing systems for the purpose of process fault diagnosis.  To this end our research addresses the following: 

(i) Developing optimal strategies for sensor distribution in multi-station manufacturing processes.

The conducted research integrates product quality information and process characteristics in a multi-station assembly system framework using a station-indexed state space model (please also see Manufacturing System Realization). This leads to exploration diagnosability of a generic distributed sensor system by expending the concept of observability in control theory [16], and then this further lead to development of the fault diagnosis method for fault feature extraction based on the multivariate data analysis [17]. The understanding of the transformation of quality information, offered by the state space quality-fault model and diagnosability analysis guide the optimal design of a sensing system.

We have developed models for optimal sensor placement for manufacturing systems with single fixture/station [9] and for multi-station manufacturing processes (MMP) with end-of-line sensing [7] or with distributed in-process sensing [11, 23]

 

(ii) Developing methodology for analysis of product feature-based measurement error in coordinate 

      metrology

Coordinate measurement systems (CMSs) dominate dimensional control and diagnostics of various manufacturing processes.  However, CMSs have inherent errors caused by the lack of tracing ability for some of the measured part features, which are important for product inspection and process variation reduction in number of automated manufacturing systems, such as for example automotive body assembly process.  The lack of tracing ability of feature is such that instead of measuring the given feature, the CMS may actually measure the area around the selected feature.  In our research, a principle of part feature tracing ability and resultant feature-based measurement error analysis are investigated to estimate the aforementioned deficiencies in the CMSs.  Our research explores the impact of feature type and part(s) positional variation on the feature-based measurement error [26]. The proposed approach is applicable for both contact and non-contact CMSs including coordinate measuring machines (CMMs) and optical coordinate measuring machines (OCMMs).  Our research shows that the developed feature-based measurement error can have significant impact on the accuracy of measurements and on process control and diagnostics algorithms currently used in manufacturing.

 

 
 
 
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