Frequency Identification of Nonparametric Hammerstein-Wiener Systems with Output Backlash Operator

Model identification is addressed for nonparametric Hammerstein-Wiener systems with static input nonlinearity and backlash output nonlinearity. Interestingly, both input and output nonlinearities are allowed to be nonparametric and nonsmooth. A frequency identification method is developed that involves the application of conveniently designed pulse width modulated (PWM) input signals. PWM inputs feature frequency-decoupling of the underlying Wiener subsystem, making possible its accurate frequency identification whatever the input nonlinearity. Then, a set of points on the input nonlinearity are in turn estimated applying PWM input signals repeatedly with fixed frequency but different amplitudes.