12 research outputs found
Nonlinear disturbance observer-based control for multi-input multi-output nonlinear systems subject to mismatching condition
For a multi-input multi-output (MIMO) nonlinear system, the existing disturbance observer-based control (DOBC) only provides solutions to those whose disturbance relative degree (DRD) is higher than or equal to its input relative degree. By designing a novel disturbance compensation gain matrix, a generalised nonlinear DOBC method is proposed in this article to solve the disturbance attenuation problem of the MIMO nonlinear system with arbitrary DRD. It is shown that the disturbances are able to be removed from the output channels by the proposed method with appropriately chosen control parameters. The property of nominal performance recovery, which is the major merit of the DOBCs, is retained with the proposed method. The feasibility and effectiveness of the proposed method are demonstrated by simulation studies of both the numerical and application examples
Nonlinear disturbance observer-based control for multi-input multi-output nonlinear systems subject to mismatching condition
This article was published in the serial International Journal of Control [© Taylor and Francis] and the definitive version is available at: http://www.tandfonline.com/doi/abs/10.1080/00207179.2012.675520For a multi-input multi-output (MIMO) nonlinear system, the existing disturbance observer-based control (DOBC) only provides solutions to those whose disturbance relative degree (DRD) is higher than or equal to its input relative degree. By designing a novel disturbance compensation gain matrix, a generalised nonlinear DOBC method is proposed in this article to solve the disturbance attenuation problem of the MIMO nonlinear system with arbitrary DRD. It is shown that the disturbances are able to be removed from the output channels by the proposed method with appropriately chosen control parameters. The property of nominal performance recovery, which is the major merit of the DOBCs, is retained with the proposed method. The feasibility and effectiveness of the proposed method are demonstrated by simulation studies of both the numerical and application examples
An Approach to Mismatched Disturbance Rejection Control for Continuous-Time Uncontrollable Systems
This paper focuses on optimal mismatched disturbance rejection control for
linear continuoustime uncontrollable systems. Different from previous studies,
by introducing a new quadratic performance index to transform the mismatched
disturbance rejection control into a linear quadratic tracking problem, the
regulated state can track a reference trajectory and minimize the influence of
disturbance. The necessary and sufficient conditions for the solvability and
the disturbance rejection controller are obtained by solving a forward-backward
differential equation over a finite horizon. A sufficient condition for system
stability is obtained over an infinite horizon under detectable condition. This
paper details our novel approach for transforming disturbance rejection into a
linear quadratic tracking problem. The effectiveness of the proposed method is
provided with two examples to demonstrate.Comment: arXiv admin note: substantial text overlap with arXiv:2209.0701
Disturbance rejection flight control for small fixed-wing unmanned aerial vehicles
Disturbance rejection flight control for small fixed-wing unmanned aerial vehicle
Dynamic output feedback sliding mode control for uncertain linear systems
In this paper, a class of uncertain linear systems with unmatched disturbances is considered, where the nominal system representation is allowed to be non-minimum phase. A sliding surface is designed which is dependent on the system output, observed state, and estimated uncertain parameters. A linear coordinate transformation is introduced so that the stability analysis of the reduced-order sliding mode dynamics can be conveniently performed. A robust output feedback sliding mode control (OFSMC) is then designed to drive the considered system state to reach the sliding surface in finite time and maintain a sliding motion thereafter. A simulation example for a high incidence research model (HIRM) aircraft is used to demonstrate the effectiveness of the proposed method
Robust nonlinear generalised predictive control for a class of uncertain nonlinear systems via an integral sliding mode approach
In this paper, a robust nonlinear generalised predictive control (GPC) method is proposed by combining an integral sliding mode approach. The composite controller can guarantee zero steady-state error for a class of uncertain nonlinear systems in the presence of both matched and unmatched disturbances. Indeed, it is well known that the traditional GPC based on Taylor series expansion cannot completely reject unknown disturbance and achieve offset-free tracking performance. To deal with this problem, the existing approaches are enhanced by avoiding the use of the disturbance observer and modifying the gain function of the nonlinear integral sliding surface. This modified strategy appears to be more capable of achieving both the disturbance rejection and the nominal prescribed specifications for matched disturbance. Simulation results demonstrate the effectiveness of the proposed approach
Dynamic output feedback sliding mode control for uncertain linear systems
In this paper, a class of uncertain linear systems with unmatched disturbances is considered, where the nominal system representation is allowed to be non-minimum phase. A sliding surface is designed which is dependent on the system output, observed state, and estimated uncertain parameters. A linear coordinate transformation is introduced so that the stability analysis of the reduced-order sliding mode dynamics can be conveniently performed. A robust output feedback sliding mode control (OFSMC) is then designed to drive the considered system state to reach the sliding surface in finite time and maintain a sliding motion thereafter. A simulation example for a high incidence research model (HIRM) aircraft is used to demonstrate the effectiveness of the proposed method
Robust nonlinear generalised predictive control for a class of uncertain nonlinear systems via an integral sliding mode approach
This is an Accepted Manuscript of an article published by Taylor & Francis in International Journal of Control on 15/02/2016, available online: http://dx.doi.org/10.1080/00207179.2016.1145356.In this paper, a robust nonlinear generalised predictive control (GPC) method is proposed by combining an integral sliding mode approach. The composite controller can guarantee zero steady-state error for a class of uncertain nonlinear systems in the presence of both matched and unmatched disturbances. Indeed, it is well known that the traditional GPC based on Taylor series expansion cannot completely reject unknown disturbance and achieve offset-free tracking performance. To deal with this problem, the existing approaches are enhanced by avoiding the use of the disturbance observer and modifying the gain function of the nonlinear integral sliding surface. This modified strategy appears to be more capable of achieving both the disturbance rejection and the nominal prescribed specifications for matched disturbance. Simulation results demonstrate the effectiveness of the proposed approach
Continuous Recursive Sliding Mode Control for Hypersonic Flight Vehicle with Extended Disturbance Observer
A continuous recursive sliding mode controller (CRSMC) with extended disturbance observer (EDO) is proposed for the longitudinal dynamics of a generic hypersonic flight vehicle (HFV) in the presence of multiple uncertainties under control constraints. Firstly, sliding mode tracking controller based on a set of novel recursive sliding mode manifolds is presented, in which the chattering problem is reduced. The CRSMC possesses the merits of both nonsingular terminal sliding mode controller (NTSMC) and high-order sliding mode controller (HOSMC). Then antiwindup controller is designed according to the input constraints, which adds a dynamic compensation factor in the CRSMC. For the external disturbance of system, an improved disturbance observer based on extended disturbance observer (EDO) is designed. The external disturbance is estimated by the disturbance observer and the estimated value is regarded as compensation in CRSMC for disturbance. The stability of the proposed scheme is analyzed by Lyapunov function theory. Finally, numerical simulation is conducted for cruise flight dynamics of HFV, where altitude is 110000 ft, velocity is 15060 ft/s, and Mach is 15. Simulation results show the validity of the proposed approach
Robust Adaptive Control of Linear Parameter-Varying Systems with Unmatched Uncertainties
This paper presents a robust adaptive control solution for linear
parameter-varying (LPV) systems with unknown input gain and unmatched nonlinear
(state- and time-dependent) uncertainties based on the adaptive
control architecture and peak-to-peak gain (PPG) analysis/minimization from
robust control. Specifically, we introduce new tools for stability and
performance analysis leveraging the PPG bound of an LPV system that is
computable using linear matrix inequality (LMI) techniques. A
piecewise-constant estimation law is introduced to estimate the lumped
uncertainty with quantifiable error bounds, which can be systematically
improved by reducing the estimation sampling time. We also present a new
approach to attenuate the unmatched uncertainty based on the PPG minimization
that is applicable to a broad class of systems with linear nominal dynamics. In
addition, we derive transient and steady-state performance bounds in terms of
the input and output signals of the actual closed-loop system as compared to
the same signals of a virtual reference system that represents the possibly
best achievable performance. Under mild assumptions, we prove that the
transient performance bounds can be uniformly reduced by decreasing the
estimation sampling time, which is subject only to hardware limitations. The
theoretical development is validated by extensive simulations on the
short-period dynamics of an F-16 aircraft