Robust start up stage for beltline moulding process variability monitoring using vector variance


  • Rohayu Mohd Salleh
  • Maman A. Djauhari



breakdown point, covariance determinant, Mahalanobis distance, robust estimation, vector variance,


One of the primary problems encountered in monitoring the variability of beltline moulding process in an automotive industry is the estimation of parameters in the start-up stage. This problem becomes more interesting because the process is in multivariate setting and must be monitored based on individual observations, i.e., the sample size of each subgroup is 1. This paper deals with a robust estimation of location and scale during the start-up stage. For this purpose, we use Mahalanobis distance in data ordering process. But, in data concentration process, we use vector variance (VV). This method is highly robust and computationally efficient. Its advantage in monitoring the variability of beltline moulding process will be compared with the non-robust method.


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