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1.18.2017

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technical director

For more information, please contact Oscar Franzese, Technical Director, at franzeseo@ornl.gov or (865) 946-1304.

Real-time dynamic brake assessment proof of concept (POC)

PBBTThe real-time dynamic brake assement proof-of-concept research was performed to explore the feasibility of using real-world braking data from commercial motor vehicles to make a diagnosis of brake condition similar to that of the performance-based brake tester (PBBT).  This was done by determining the relationship between pressure and brake force (P-BF), compensating for the gross vehicle weight (GVW). The nature of this P-BF relationship (e.g., low braking force for a given brake application pressure) may indicate brake system problems.

In order to determine the relationship between brake force and brake application pressure, a few key parameters of duty cycle information were collected.  Because braking events are often brief, spanning only a few seconds, a sample rate of 10 Hertz (Hz) was needed.  The algorithm under development required brake application pressure and speed (from which deceleration was calculated).  Accurate weight estimation was also needed to properly derive the braking force from the deceleration.  In order to ensure that braking force was the predominant factor in deceleration for the segments of data used in analysis, the data was screened for grade as well. Also, the analysis needed to be based on pressures above the crack pressure; the individual brakes were not applied below the pressure of approximately 10 pounds per square inch (psi).  Therefore, only pressures 15 psi and above were used in the analysis. The Department of Energy’s Medium Truck Duty Cycle research indicated that under the real-world circumstances of the test vehicle brake pressures of up to approximately 30 psi can be expected.

Initial analysis of the data revealed that the data collected in the field (i.e., day-to-day operations) provided the same information as that obtained from the controlled tests.  Analysis of the data collected revealed a strong linear relationship between brake application pressure and deceleration for given GVWs.  As anticipated, initial speed was not found to be a significant factor in the deceleration-pressure relationship, unlike GVW.

See Poster (PDF, .6MB) and Final Report (PDF 1.5MB)