Derivative Of Disturbance Research Articles

Fixed-time sliding mode-based consensus of multi-agent systems with mismatched disturbances

This paper investigates the fixed-time consensus of second-order multi-agent systems subject to matched and mismatched disturbances. The derivatives of disturbances are assumed to be bounded. A novel integral sliding mode-based observer is presented by utilizing the super-twisting algorithm to estimate the agent states. The estimations can achieve the convergence to the leader in a fixed time. Furthermore, the corresponding fixed-time controller is developed to make the agents converge to the estimated states. As the estimated states converge to the leader, the agents will track the leader states with the help of estimated states. In addition, the overall convergence of multi-agent systems is non-monotonic due to the disturbances. It is theoretically shown that the proposed control approach can maintain a bounded convergence and get the consensus of multi-agent systems in a fixed time. Some simulations are presented to verify the effectiveness of the proposed control protocol.

Control of nonlinear systems with compensation of disturbances under measurement noises

ABSTRACTThe control algorithm for nonlinear time-invariant systems with compensation of unknown disturbances under measurement noises is proposed. The dimension of noises is equal to the state vector dimension of the plant. Disturbances can be presented in any equation of the plant model. The novel control law is based on the noise estimator and the disturbance compensator. The accuracy in the steady state depends on the first derivative of disturbance and the smallest component of noise vector. A sufficient condition in terms of linear matrix inequality provides feasibility of the proposed algorithm. The simulations show the efficiency of the proposed method compared with some existing ones.

Output feedback stabilization for an anti-stable Schrödinger equation with internal unknown dynamic and external disturbance

In this paper, we consider output feedback stabilization for an anti-stable Schrödinger equation with both the internal unknown dynamic and external disturbance. An unknown input type state observer is designed in terms of a new disturbance estimator. Different from the existing results, we never use high gain in the observer design. Hence, the boundedness assumption on the derivative of disturbance, that is usually required by finite-dimensional extended state observer, is no longer required. The anti-stable term is treated by the backstepping transformation which is given by ODE form to make the controller design easier. Although the close-loop system is nonlinear, both the well-posedness and the asymptotic stability are obtained by a linear method in terms of an invertible transformation. The numerical simulations are presented to illustrate that the proposed scheme is very effective.

Global output regulation for a class of lower triangular nonlinear systems: A feedback domination approach

An alternative but new nonlinear output regulation approach is proposed for a class of lower triangular nonlinear systems by using the tool of adding a power integrator. The invariant manifold is solved and represented in terms of various derivatives of disturbances and references. As such, it is unnecessary to suppose that the external disturbances being governed by certain exosystems anymore. The nonlinearities are not restricted to be sufficiently smooth due the utilization of feedback domination approach. It is shown that the time taken to reach the desired invariant manifold from any initial states under external disturbances is guaranteed to be finite time. The control law is concise in structure for implementation since the feedback domination is implemented in each of the recursive design step.

Sliding mode control with disturbance observer for a class of nonlinear systems

This paper is concerned with the stabilization problem for a class of nonlinear systems with disturbance. The disturbance model is unknown and the first derivative of disturbance is bounded. Firstly, a general disturbance observer is proposed to estimate disturbance approximatively. Secondly, since the bound of the disturbance observer error is unknown, an adaptive sliding mode controller is designed to guarantee that the state of system asymptotically converges to zero and the unknown bound can be adjusted by an adaptive law. Finally, an example is given to illustrate the effectiveness of the proposed method.