Using SPC and template monitoring method for fault detection and prediction in discrete event manufacturing systems

The behavior of manufacturing systems with discrete I/O signals can be characterized by the timing and sequencing of changes (events) in these I/O. In this paper, we present a method to monitor these signals to alarm when faulty sequencing or timing behavior occurs, and also to warn when the timing starts to deviate from its normal behavior. This is accomplished by using a combination of the time template monitoring technique and statistical process control (SPC).