Acoustic Engine Speed Measurement

Project Type: Master/Diploma Thesis
Student: Neffe Michael

 

 The measurement of exhaust gas in combustion engines is usually performed in dependency on the engine speed. The purpose of this work is the acoustic estimation of the engine speed not only for stationary but also for transient engine speeds. The existing system should be further developed to achieve a reliable measurement of motorbike engine speeds. The analysis of the engine speed is carried out with the recorded signals of an airborne and a structure-borne signal of the combustion engine. Basically, the estimation of the engine speed can be reduced to a fundamental frequency (F0) determination problem. Similar to the existing system for the engine speed measurement of gas and diesel engines, the determination of the engine speed is divided into two parts. The first part uses linear prediction for the engine speed measurement and the second part applies a fine tuning to get a more accurate estimation based on the first estimate. The goal of a better detection rate of the engine speed has been achieved. Furthermore the possibility to implement the system on the existing hardware was verified. The number of multiplications and additions per second is approximately 60000 each and hence is only a fraction of the provided resource by the used hardware. In the measurement mode the maximal system's delay is 100ms.