Date of this Version
Marx, S.E. (2015). Controller Area Network (CAN) Bus J1939 Data Acquisition Methods and Parameter Accuracy Assessment Using Nebraska Tractor Test Laboratory Data (Master’s thesis). University of Nebraska-Lincoln, Lincoln, NE.
Electronics have become a standard in agricultural equipment and the trend of “smarter” equipment is on the rise. To have “smarter” equipment, a working knowledge of the accuracy of the data being transmitted throughout that equipment is needed. The controller area network (CAN) bus is the current interface to machine operation data transmitted between electronic control units (ECUs).
Because CAN bus has been around for nearly thirty years, numerous devices have been created for interfacing with the bus. Choosing a device can be a challenge, especially without knowing if there are differences between the logging methods for true data representation. By logging simultaneously with three different methods, data was analyzed to determine if excessive error existed between logged datasets.
Additionally because many messages are calculated (e.g., not measured directly), determining the accuracy of those messages can be important for management decisions or research studies. One calculated CAN bus message that holds a great deal of value is the engine fuel rate, and because it is calculated rather than measured, excessive error may exist in the CAN bus value. A comparison between the calculated CAN bus fuel rate message and a physically measured fuel rate provided information on the message accuracy. The Nebraska Tractor Test Laboratory (NTTL) has a certified fuel rate measuring system capable of ±0.5% accuracy.
Results showed that error between logging methods was quite low, however file size was an issue with some of the logging methods. Waveform file logging required only 6% memory space compared to the frame logging methods. Fuel rate as recorded from the CAN bus resulted in a ±5% error from physically measured fuel rates. Error for higher fuel rates within the torque curve were closer to ±1%. These results indicated that the fuel rate given by the CAN bus can indeed be used for management or research purposes.
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