When performing an accuracy assessment of the digital data stored on heavy trucks, reference instrumentation is compared to the reports generated by the diagnostic software for the Heavy Vehicle. This article explains a strategy to synchronize the times between the report and the reference instrumentation.
A paper assessing the timing and syncronization of different parameters from a DDEC 5 controlled truck was presented at the 2013 SAE World Congress. The paper, Timing and Synchronization of the Event Data Recorded by the Electronic Control Modules of Commercial Motor Vehicles - DDEC V, used a VBox as the reference instrumentation and showed that some of the switch events (brake and clutch) can be delayed over 1 second. This paper provides much of the inspiration for this work.
There are two primary objectives for this work: 1) Acquire a set of correlated data of the operation of a DDEC 6 controlled truck and 2) syncronize performance data with DDEC reports.
The data used for this analysis is available on this site on the page titled Correlated DDEC VI Data Set.
DDEC reports contains time history of data in the Hard Brake Event Record, Diagnostic Record, and Last Stop Record. These data include Vehicle Speed, Engine RPM, Clutch Status, Brake Status, Engine Load, and Diagnostic state. They are reported every second. However, the data in the truck updates quicker than every second. To determine how accurate the data in DDEC reports are, they should be compared to a reference value. However, reference values and ddec reports may differ in both time and value(i.e. the horizontal and the vertical axes are different). Therefore, a method based on Engine RPM is used to synchronized the data. The program used for this is written in Python and the code is also available. It is written in such a way as to be able to copy and paste the DDEC Reports Data directly into the Python program.