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6
Discussion
Cluster analysis also avoids the problems that occur when the mtf is used as a
representative response, since the clustering explains the variations in a specific
set of driving cycles rather than the mtf.
6.1
Future work
Some of the improvements and extensions to the software that could be of interest
are listed below.
1. First principal component - The selection of a cluster representative can be
performed in many ways. A pca method is used here, which selects one
variable from each cluster. Another, perhaps better way, would be to use
the fpc to define a statistic (linear combination of all the variables in the
cluster) in each cluster that captures the most of the within cluster variations.
2. User defined car parameters - When developing cars, there is a desire to
calculate or simulate how much emissions the vehicle will emit. Make it
possible for the user to enter car specific parameters such as
• Vehicle mass.
• Frontal area.
• Aerodynamic coefficients.
When car parameters are set and a model for emissions has been implemented into the software, it will be possible to calculate the emissions over
several driving cycles of the same type. Since the cycles are stochastically
generated they will differ enough to avoid cycle beating when optimizing
parameters.
3. Connection to Simulink model - A common way to simulate vehicles is by
using a Simulink model. By connecting the cycle generation software to a
vehicle model, it will be possible to analyze the performance of the modeled
vehicle.
4. Generating cycles based on speed limits - Another way to categorize data
is based on speed limits. For Sweden, the driving will be categorized into
bins of 30 km/h, 40 km/h, 50 km/h, ... , and 120 km/h. When generating a
driving cycle, it should be possible to either
• Set a complete route: 50 km/h for 8.3 km followed by 70 km/h for 1.2
km and so on.
• Set a route ratio: 25% of the route is in 50 km/h, 30% is in 70 km/h,
and drive for a total of 40 km.
This includes collecting new data where the driving location is known, extracting data about speed limits from a database and categorize all mea-