Optimisation of a Diagnostic Test for a Truck Engine
Abstract
Diagnostic systems become more and more an important within the
field of vehicle systems. This is much because new rules and
regulation forcing the manufacturer of heavy duty trucks to survey
the emission process in its engines during the whole lifetime of
the truck. To do this a diagnostic system has to be implemented
which always survey the process and check that the thresholds of
the emissions set by the government not are exceeded. There is
also a demand that this system should be reliable, i.e. not
producing false alarms or missed detection. One way of producing
such a system is to use model based diagnosis system where
thresholds has to be set deciding if the system is corrupt or not.
There is a lot of difficulties involved in this. Firstly, there is
no way of knowing if the signals logged are corrupt or not. This
is because faults in these signals should be detected. Secondly,
because of strict demand of reliability the thresholds has to be
set where there is very low probability of finding values while
driving. In this thesis a methodology is proposed for setting
thresholds in a diagnosis system in an experimental test engine at
Scania. Measurement data has been logged over 20 hours of
effective driving by two individuals of the same engine. It is
shown that the result is improved significantly by using this
method and the threshold can be set so smaller faults in the
system reliably can be detected.
Petter Haraldsson
2002
Informationsansvarig: webmaster
Senast uppdaterad: 2021-11-10
LiU Homepage
