Method for estimating the pinking intensity of an internal combustion engine by inverting a wave equation

The method involves constructing a wave equation model of a cylinder-head based on a physical model describing propagation of waves in a solid medium. Coefficients of a Fourier decomposition of a vibration signal from a cylinder pressure sensor/an accelerometric sensor is determined in real time by inverting dynamics of the equation model by using an adaptive non-linear estimator. Energy contained in the signal is calculated by summing squares of the coefficients. A parameter correlated with knocking intensity equal to a square root of a maximum of the energy is determined (CAL) in real time.