Flatness-based active disturbance rejection control for linear systems with unknown time-varying coefficients

Abstract

A flatness-based active disturbance rejection control approach is proposed to deal with the linear systems with unknown time-varying coefficients and external disturbances. By selecting appropriate nominal values for the parameters of the system, all the deviation between the nominal and actual dynamics of the controlled process, as well as all the external disturbances can be viewed as a total disturbance. Based on the accurately estimated total disturbance with the aid of the proposed extended state observer, a linear proportional derivative feedback control law taking into account the derivatives of the desired output is designed to eliminate the effect of the total disturbance on the system performance. Finally, the load frequency control problem of a single-area power system with non-reheated unit is employed as an illustrative example to demonstrate the effectiveness of the proposed approach.

Active Disturbance Rejection Based Robust Trajectory Tracking Controller Design in State Space

“…If a system is flat, i.e., a linear system is controllable, then the state and control input references of its trajectory tracking controller can be systematically generated in terms of the fictitious differentially flat output variable and its successive time derivatives [9]. However, a conventional DF-based trajectory tracking controller requires the precise dynamic model of the system and is sensitive to external disturbances [11,15]. Therefore, it is impractical in many applications such as robotics.…”

“…If DF is applicable (i.e., system dynamics is flat), then state and control input trajectories can be systematically generated in engineering applications such as under-actuated robots, compliant robots and unmanned aerial vehicles [12] - [14]. However, a conventional DF-based controller is sensitive to plant uncertainties and external disturbances; therefore, its stability and performance may significantly change in real implementations [11,15]. To improve the robustness of a DFbased trajectory tracking controller, the state and control input references are systematically modified by using the estimations of disturbances and their successive time derivatives; i.e., not only the matched but also the mismatched disturbances are cancelled with their estimations in this paper.…”

Composite active disturbance rejection robust control for a prototype of an active damping artificial ankle prosthesis

“…To solve these problems, an Active Disturbance Rejection Control (ADRC) scheme is proposed (see ) since the complexity in the control design can be reduced by means of lumping all the nonlinearities as well as the external disturbances into a generalized disturbance input, to be estimated and, subsequently, canceled . The lumped disturbance input estimation is to be carried out by a Generalized Proportional Integral (GPI) observer , which is an extended Luenberger‐class observer which includes a, self‐updating, linear model approximation of the perturbation input; the disturbance estimation is delivered to the controller for an on‐line cancellation while simultaneously estimating the phase variables related to the measured output , performing the ADRC for the trajectory tracking (see ).…”

Linear active disturbance rejection control approach for load frequency control of two-area interconnected power system

“…To further facilitate its application in practical engineering, the scaling and parameterization of ADRC approach, also named linear ADRC (LADRC) approach by (Gao, 2003), largely simplified the parameter tuning. And thus, the LADRC approach has also found its applications in the LFC problem in Dong et al (2012), Huang and Ramirez (2015) and Tang et al (2015), which essentially is a disturbance rejection control issue. The related disturbance rejection problem refers to He and Ge (2016) and He et al (2016aHe et al ( , 2016b.…”