Class-8 Heavy Truck Duty Cycle Project Final Report - Center for ...

4. DUTY CYCLE GENERATION TOOL
The DCGenT is a software tool for generating a driving duty cycle that meets specific user-specified
criteria. The criteria, in addition to cycle duration, include the number of stops, and the statistical
distribution of speeds and accelerations obtained from measured driving data. Presently the tool is
focused on features of interest recorded in the HTDC database, such as traffic conditions, weather,
road slope, etc. The tool uses a menu-driven interface to allow the selection of pertinent features, and
finds the multiplicity of time-location data segments that meet the selected criteria. Subsequently, for
statistical processing purposes, it links the segments into a single continuous driving record. The
linked record includes not only speed versus time, but also the remaining available parameters of
interest, such as road conditions, engine data, etc. Finally, the tool creates a speed versus time record
that fits the time length desired, while attempting to preserve the statistical distributions of speed and
acceleration in the linked record. In future versions, the speed versus time duty cycle obtained will be
interfaced to a vehicle model that will facilitate a search of the HTDC database for real-world truck
performance data that can be added to the synthetic duty cycle that was generated. This will allow
users to generate benchmarking duty cycles based on real-world driving experience data that meet
user-specified characteristics.
4.1 PURPOSE/FUNCTION
Unlike the internet data access tool discussed in Section 3, which allows the mining of relevant data
from the large set of data collected in the FOT and produces a data set of segments that meet the
user’s search criteria within a Boolean “OR” logic, the DCGenT allows for the selection of data set
segments based on Boolean “AND” logic and facilitates the construction of a synthetic duty cycle
from this data. This tool allows the user to select parameters of interest from signals collected in the
FOT (e.g., temperature, time-of-day, tire type, weather conditions, and road grade) and to generate a
single duty cycle of any duration based on multiple segments of real-world data containing
parameters of interest. Statistical processing of the data facilitates the creation of a duty cycle which
is reflective of the speed and acceleration distributions of the original data.
4.2 HOW IT WORKS
The first step for all DCGenT functions is the selection of the duty cycle criteria of interest. As
shown in Fig. 31, selectable parameters include the following: 1) external factors such as time-of-day,
weather conditions, and topography; 2) vehicle parameters such as transmission and tire type; and 3)
traffic congestion data such as vehicle speed. In Fig. 31, the circles highlight the selected criteria.
All data is for segments lasting longer than ten minutes, for Truck Number 1, fitted with single tires
and having a manual transmission. The search is initiated by clicking on the box highlighted with the
orange colored number “1” in the Figure. The dotted box surrounds the list of names and durations of
the segments found. Other factors such as vehicle weight will be added in the future. In addition, a
User’s Guide for DCGenT will be developed in FY2009.
The user has the option of specifying each parameter individually or only some of them, leaving the
remaining fields with default values of “any” or “either.” Additionally, the database search can also
be limited to identifying segments that exceed a user-selected time duration. When the “Search
Database” button is clicked-on, the database is searched for segments fulfilling all desired parameters.
The resulting segments are temporarily stored in data files in a comma-separated format. As shown
in Fig. 31, the search results for the selected criteria appear in the right column with the white
background, and in addition to the file name assigned, include the time length of each segment.
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