despite providing robustness, high-gain observers impose a peaking phenomenon, which may cause instability, on the system states. in this paper, an adaptive saturation is proposed to attenuate the undesirable mentioned phenomenon in high-gain observers. a real-valued and differentiable sigmoid function is considered as the saturating element whose parameters (height and slope) are adaptively tu...

in this paper, a new robust controller based on geometric homogeneity and adaptive integral sliding mode is proposed for a class of second order systems. the upper bound of the system disturbances is not required. fully unknown parameters have been considered in the described model and its finite–time convergence to zero equilibrium point is proved. moreover, the controller is developed in the ...

This paper introduces a neural network based model reference adaptive control architecture that allows adaptation in the presence of saturation. The given plant is approximately feedback linearized, with adaptation used to cancel any matched uncertainty. A nested saturation based reference model is used. This law allows the incorporation of magnitude actuator saturation and has useful small gai...

Despite providing robustness, high-gain observers impose a peaking phenomenon, which may cause instability, on the system states. In this paper, an adaptive saturation is proposed to attenuate the undesirable mentioned phenomenon in high-gain observers. A real-valued and differentiable sigmoid function is considered as the saturating element whose parameters (height and slope) are adaptively tu...

A direct adaptive nonlinear tracking control framework for multivariable nonlinear uncertain systems with actuator amplitude and rate saturation constraints is developed. To guarantee asymptotic stability of the closed-loop tracking error dynamics in the face of amplitude and rate saturation constraints, the adaptive control signal to a given reference (governor or supervisor) system is modifie...

In the application of adaptive flight control, significant issues arise due to limitations on the plant inputs, such as actuator displacement limits. The concept of utilizing a modified reference model to prevent an adaptation law from "seeing" this system-input characteristic is described. The method allows correct adaptation while the plant input is saturated. To apply the method, estimates o...

Abstract: In this paper, a dead zone based model of saturation phenomenon is proposed, which enables to model diverse kinds of saturation, such as hard limitted and soft limitted ones. Due to the use of a linear in parameter approach, the proposed model is consistent with the available adaptive control techniques in the literature. Besides, based on the proposed model, an adaptive controller is...