in this paper, a nonlinear model of the underactuated six degrees of freedom (6 dof) quadrotor helicopter was derived based on the newton-euler formalism. a new nonlinear robust control strategy was proposed to solve the stabilizing and path following problems in presence of external disturbances and parametric uncertainties. the proposed control structure consist of a sliding mode control base...

this paper employs nonlinear disturbance observer (ndo) for robust trajectory-free nonlinear model predictive control (nmpc) of biped robots. the ndo is used to reject the additive disturbances caused by parameter uncertainties, unmodeled dynamics, joints friction, and external slow-varying forces acting on the biped robots. in contrary to the slow-varying disturbances, handling sudden pushing ...

non-fragile observer design is the main problem of this paper. using continuous frequency distribution, the stability conditions based on integer order lyapunov theorem are derived for lipschitz class of nonlinear fractional order systems. the proposed observer is stable beside the existence of both gain perturbation and input disturbance. for the first time, in this paper a systematic method i...

A robust control scheme is proposed for a class of systems with uncertainty and time delay based on disturbance observer technique. A disturbance observer is developed to estimate the disturbance generated by an exogenous system, and the design parameter of the disturbance observer is determined by solving linear matrix inequalities (LMIs). Based on the output of the disturbance observer, a rob...

In disturbance-observer-based control, the closed loop system consists of a main feedback control loop and an inner disturbance observer loop. This paper presents a design method for a disturbance observer to satisfy closed loop performance specifications, provided that the main feedback controller is known. Taking advantage of certain fixedstructure disturbance observers, the disturbance obser...

In the paper, algorithms for disturbance observers are newly presented in the time-domain. Attention is paid to observing a ramp disturbance by introducing an integral term to the output equation of a constant disturbance observer. In order to reduce the sensitivity to the measurement noise, the disturbance observer is combined with the state observer. It will be shown that the estimation dynam...

In this paper, a disturbance observer based controller is proposed for the compensation of nonlinear friction in a servodrive system. The designed nonlinear controller uses the estimated system states (position, velocity) and disturbance to enhance tracking performance of the servodrive using high stiff gains for the compensation of the effects of nonlinear friction. The effectiveness of this d...

This paper presents a new observer based fuzzy terminal sliding mode controller design for a class of fractional order nonlinear systems. Robustness against uncertainty and disturbance, the stability of the close loop system and the convergence of both the tracking and observer errors to zero are the merits of the proposed the observer and the controller. The high gain observer is applied to es...

Using Tracking Differentiators in Designing Nonlinear Disturbance Observers for Uncertain SystemsNaser Kazemzadeh, Saeed BarghandanAbstractIn the present paper, a practical designing method has been proposed for a novel class of NDOs based on TD. Such NDOs can nearly estimate all uncertain disturbances (specifically disturbances without prediction information). Regarding the outstanding perform...