9. Conclusion

Clearly, we have only scratched the surface of the problem of designing an observer to estimate certain variables of a dynamic system described by differential equations in an unnoisy setting. Apart from the fact that for non-linear models, this question is still largely open, many methods of designing observers such as sliding-mode observers, differential observers, finite-time observers where the estimation error is zero after a certain time, or other types of estimators have not been addressed. Nor have we discussed the algebraic techniques for estimating the derivatives of signals which, starting from the expression of the variable to...