Crankshaft position measurement for engine testing, control, and diagnosis

The authors present several applications of a precise, moderate sampling rate measurement of the crankshaft angular position of a reciprocating internal combustion engine. It is shown that the measurement can be made with a relatively inexpensive noncontacting sensor. Given sufficient precision and sampling rate, the various applications include crankshaft reference position measurements for ignition timing (gasoline fueled engines) or injector timing (for electronically controlled diesel engines); and crankshaft angular speed and acceleration measurements for estimating instantaneous indicated torque and for diagnosing engine malfunctions. The torque estimate is potentially useful for engine control, to improve engine performance with respect to reducing cycle-to-cycle and cylinder-to-cylinder nonuniformity and with respect to fuel economy. The crankshaft angular speed measurement also provides an input to a computationally efficient diagnosis method for detecting failures in any sensor or actuator on the vehicle. The theory and experimental verification of the applications are discussed