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

determined that the particular CANopen protocol used by the Posital device was incompatible with
the standard CAN protocol used by the eDAQ.
After additional efforts, it was determined that no suitable CAN-based tilt sensor was available on the
market. As a result, an analog tilt sensor was ordered in addition to an analog layer for the eDAQ.
The AccuStar IP-66 tilt sensor was connected to the eDAQ and communication was successfully
established. The unit functioned as expected during benchtop testing, and further testing in a
passenger vehicle was conducted. During this testing, it was noted that in periods of acceleration and
deceleration, the vehicle’s tilt did not give a consistent indication of road grade. This occurred
because during those events, the vehicle did not remain parallel to the ground. It was assumed that
this phenomenon may be less noticeable on a Class-8 trailer. The research team subsequently focused
on examining vibration issues. Since the vehicle vibrated at a frequency of approximately 2-3 Hz,
and the sample rate for all signals for the FOT was to be 5 Hz, the effect of this vibration was such
that at this sampling rate, it could not be filtered out in post-processing. As a result, it was
determined that the vibration of the vehicle could be an insurmountable problem with the use of a tilt
sensor, and as a result, a discrete tilt sensor was not selected for use in the FOT.
Once it was realized that the use of a tilt sensor would not provide the needed tilt data, height data (Zdata)
from the VBOX was reconsidered to determine if this data could be used to provide the needed
grade data. It was discovered that although the VBOX height data was inaccurate, reasonable grade
data could be obtained from the information collected over short intervals of time. Given the
repeatability of routes over the course of the year-long data collection, it was surmised that sufficient
data could be obtained from the VBOX for each point along the route to build a complete set of grade
information from these “short intervals” for well-traveled roads.
2.4.2 Obtaining Identifier from Instrumented Trailers
The majority of long-haul fleets in the U.S. use a “drop-and-hook” operation, in which freight is
delivered to a terminal, drop lot, or customer; and the tractor returns to its point of origin with a
totally different trailer. Thus, a given trailer is rarely connected to the same tractor again, or at best,
very infrequently. Because a 100% mating rate was impossible to achieve, vehicle identifiers were
needed in order to link the identity of the tractor and trailer(s) that were providing data, to the actual
tire type utilized by the trailer. One initial setback was the inability to get vehicle identification
information from the tractor or the trailer. This problem was solved by getting a portion of the Air-
Weigh serial number from the J1708 bus for the situations in which the test truck was connected to
one of the instrumented trailers. Each Air-Weigh unit (one on the tractor and another on the trailer)
has a unique serial number which can be requested through the appropriate request code on the J1708
databus used by the Air-Weigh for communication. The value read from the databus in response to
this request is then looked-up in a file created on the eDAQ, and this data is saved with the
appropriate code to indicate the specific trailer, and hence, the types of tires used on the trailer. For
all of the other trailers (i.e., un-instrumented trailers), Schrader provided ORNL with a weekly
schedule of which trailers were connected to the test tractors. A separate lookup table was also
provided in which the tire type of each Schrader trailer was listed. Although the weight information
for these un-instrumented trailers was not available, this did allow the addition of trailer tire type
information to the collected data through post-processing.
2.5 PARTNERSHIP BUILDING
Field tests tend to be relatively expensive when compared to laboratory-based research. Because of
this, significant effort was directed toward leveraging the needs of this project with industry
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