Observer design for time fractional reaction–diffusion systems with spatially varying coefficients and weighted spatial averages measurement

In this paper, we consider an observer design problem of a time fractional reaction–diffusion system with space-dependent coefficients and measurement of weighted spatial averages. Different from the boundary measurement, here, the output is a weighted spatial average of the state over the entire spatial domain. In order to apply the backstepping approach to obtain the observer gains, we first use a conversion of weighting functions to transform the error system into an intermediate system. With a change of variable, this intermediate system is then converted into the final target system with boundary measurement where backstepping is easily applicable. The resultant observer realises Mittag-Leffler convergence of the error system. Finally, numerical simulations are provided to check the effectiveness of the proposed observer.