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The presence of strong disturbances usually causes great performance degradation of industrial process control systems. A disturbance observer (DOB) enhanced composite cascade control consisting of model predictive control (MPC), proportional-integral-derivative (PID) control, and DOB is proposed in this paper. DOB is employed here to estimate the...
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... The block diagram of the proposed disturbance observer enhanced model predictive control scheme is shown in Fig. 1 According to Fig. 1, the output can be expressed ...
Context 2
... The block diagram of the proposed disturbance observer enhanced model predictive control scheme is shown in Fig. 1 According to Fig. 1, the output can be expressed ...
Context 3
... static disturbance rejection ability of the DOB is analyzed as follows. According to Fig. 1, the output Y (s) can be represented ...
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Citations
... Based on this mechanism, in recent trends, the significant results on the observer-based technique have been reported in various industrial models such as cyber-physical system [7] , multi-agent systems [8] , miniature aerial vehicle [9] , and chemical reactors [10] where the states of a system can be completely obtained with the available external measurement. ...
This paper is concerned with the problem of exponentially extended dissipative criteria for a class of delayed discrete-time neural networks (DNNs) subject to resilient observer-based controller design. For this objective, a memoryless full-order Luenberger state observer is designed, and further, its observer error system is calculated with resilient control. Initially, some new improved weighted summation inequalities are proposed by combining weighted summation inequality and an extended reciprocal convex matrix inequality. By constructing the suitable Lyapunov-Krasovskii functional (LKF) and utilizing the developed summation inequalities, the exponentially extended dissipative criterion is obtained for the considered delayed DNNs. The designed observer and resilient control gain matrices can be determined by solving a set of linear matrix inequalities (LMIs) subject to the prescribed exponential decay rate. Finally, two numerical examples are carried out to illustrate the feasibility and effectiveness of the established theoretical results obtained through the newly developed summation inequalities.
... However, notice that the robustness and disturbance rejection performance of aforementioned control schemes were all achieved at the price of sacrificing the nominal control performance, and most of them failed to consider active disturbance rejection ability in the control design [15,16]. An effective approach to tackle the above-mentioned problem is disturbance observer-based control (DOBC), which employs a disturbance observer to estimate the lumped disturbances rapidly and adds the estimated item to the baseline feedback controllers for improving disturbance attenuation ability [7,15,[17][18][19][20][21][22][23][24][25][26][27][28][29]. Actually, disturbance estimation techniques have been well developed to tackle the system disturbances in various industrial applications [21,30,31], such as hypersonic vehicles [7,[32][33][34][35][36][37], small unmanned helicopters/quadrotors [5,38,39] and fixed-wing UAVs [1]. ...
... with M e ,M e as illustrated in (18). A typical transformation function of Γ e (·) can be selected as ...
An integrated control scheme composed of modified nonlinear disturbance observer and predefined-time prescribed performance control is proposed to address the high-accuracy tracking problem of the unmanned aerial vehicles (UAVs) subjected to external mismatched disturbances. By utilizing the transformation technique that incorporates the desired performance characteristic and the newly predefined-time performance function, the original controlled system can be transformed into a new unconstrained one to achieve the fixed-time convergence of the tracking error. Then, by virtual of the transformed unconstrained system, a modified nonlinear disturbance observer (NDO) which possesses fast convergence speed is established to estimate the external disturbance. With the application of the precise estimation value to compensate the normal control design in each back-stepping step, a novel composite control scheme is constructed. The light spot of the proposed scheme is that it not only has the superior capability to attenuate unknown mismatched disturbances, but also can guarantee that the output tracking errors converge to their prescribed regions within predefined time. Finally, simulation studies verify the effectiveness of the proposed control scheme.
... Then, the composite disturbance observer for system (24) is designed as follows: ...
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... While the vertical velocity (dx/dt) of a moving object can be easily estimated using the available information of x and i using the reduced-order dynamics [22], or trackingdifferentiator [23]. In the past decade, the Disturbance Observer-Based Control (DOBC) methodologies have gained wide acceptance for estimating and rejecting the disturbances, uncertainties, unmodeled dynamics as a single lumped disturbance [24,25]. However, the design constraints, robustness issues, and unavailability of estimating the individual component may reduce the applicability of DOBC for the MLS. ...
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... Therefore, disturbance-observer-based control (DOBC) is applied, which is another prominent approach for tackling the problem of disturbance rejection. DOBC-strategies at first emerged in the 1980s and since then have been implemented in various areas, such as flight control, mechanical engineering and chemical processes (see Chen, Li, Yang, & Li, 2013;de Jesús Rubio, Meléndez, & Figueroa, 2014;Yang, Li, Sun, & Guo, 2013). There are numerous different variations of DOBC. ...
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... Under this assumption, it is possible to estimate the i-th time derivative of the output using an observer. This issue has motivated the development of several control techniques based on output feedback, for instance active disturbance rejection [14][15][16], neural networks control [17][18][19], sliding mode observers [3,9,13,20,21], and high-gain observers, [22][23][24][25]. ...
This work presents a solution to the output feedback trajectory tracking problem for an uncertain DC motor pendulum system under the effect of an unknown bounded disturbance. The proposed algorithm uses a Proportional Derivative (PD) controller plus a novel on-line estimator of the unknown disturbance. The disturbance estimator is obtained by coupling a standard second-order Luenberger observer with a third-order sliding modes differentiator. The Luenberger observer provides estimates of the motor angular position and velocity. Moreover, an ideal disturbance estimator in terms of the Luenberger observer error and its first and second time derivatives is obtained from the observer error formulae; these time derivatives are not available from measurements. Subsequently, the sliding modes third-order differentiator allows obtaining estimates of these time derivatives in finite time. The estimates replace the real values of the first and second time derivatives in the ideal disturbance estimator thus producing a practical disturbance estimator, and also permit obtaining an estimate of the motor angular velocity. A depart from previous approaches is the fact that the disturbance is not directly estimated by the Luenberger observer or the third-order differentiator. Numerical simulations and real-time experiments validate the effectiveness of the proposed approach. © 2017 Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag Berlin Heidelberg
... These factors and their combinations usually result in significant degradation of the production quality of these processes. DOBC and related methods have been applied to deal with these problems, e.g., chemical reactors [69], [70], heat exchanger [71], extrusion process [72], and, in particular, ball mill grinding circuits [73], [74]. ...
Disturbance-observer-based control (DOBC) and related methods have been researched and applied in various industrial sectors in the last four decades. This survey, at first time, gives a systematic and comprehensive tutorial and summary on the existing disturbance/uncertainty estimation and attenuation techniques, most notably, DOBC, active disturbance rejection control, disturbance accommodation control, and composite hierarchical antidisturbance control. In all of these methods, disturbance and uncertainty are, in general, lumped together, and an observation mechanism is employed to estimate the total disturbance. This paper first reviews a number of widely used linear and nonlinear disturbance/uncertainty estimation techniques and then discusses and compares various compensation techniques and the procedures of integrating disturbance/uncertainty compensation with a (predesigned) linear/nonlinear controller. It also provides concise tutorials of the main methods in this area with clear descriptions of their features. The application of this group of methods in various industrial sections is reviewed, with emphasis on the commercialization of some algorithms. The survey is ended with the discussion of future directions.
... The DOB method is known as an effective technique to estimate the unknown disturbances and has been extensively applied for feedforward compensation design. And different kinds of DOBs have been developed, including linear DOBs [33][34][35][36][37], neural network DOBs [38,39], fuzzy DOBs [40,41] and other nonlinear DOBs [42,43]. Disturbance observer based control schemes for linear and nonlinear systems have been proposed and applied successively in many control fields [44][45][46]. ...
... Considering this situation and combining with the advantages of disturbance observer mentioned in Fig. 2 and Refs. [33][34][35][36][37][38][39][40][41][42][43], a new type of compound neural network predictive model is proposed, as shown in Fig. 3(b). ...
... There are various kinds of disturbance observers in recent researches [33][34][35][36][37][38][39][40][41][42][43], such as linear DOBs, nonlinear DOBs, neural network DOBs and fuzzy DOBs. In the compound NN predictive model, the type of disturbance observer can be selected according to the needs or the characteristics of the real systems. ...
Graphical abstract
For traditional MPC, the deviations between the predicted output and the real output of system may become large when meeting strong disturbances. Therefore, the MPC control law obtained by the objective function with a receding horizon optimization will not be optimal, which makes the dynamic performance of the closed-loop system become sluggish and the closed-loop system may even become unstable. The “feedforward compensation + feedback controller” compound method is only a simple superposition of two control effects, in which the feedforward compensation does not participate in the receding horizon optimization process, and how to coordinate the effects of the feedback and feedforward controllers is an important problem to address. In this paper, an optimal disturbance rejection control approach based on a compound neural network prediction method is proposed by considering the disturbances and model mismatches. The novelty of this paper lies in that the estimate of disturbances by a disturbance observer is introduced into the neural network predictive model, which makes the predictive model output more accurate in the presence of disturbances and model mismatches. Thus, the feedback control law obtained by the objective function with a receding horizon optimization is optimal with strong disturbance rejection ability. The proposed scheme is applied to control the temperature of a simplified jacketed stirred tank heater (JSTH). Simulation results demonstrate the effectiveness of the proposed control method.
... Alternatively, the DOB-based controller is robust to external disturbances and model mismatches without the use of high control gain or extensive computational power [15]. The DOB provides a feasible approach to estimate disturbances while relying only on knowledge of the nominal model and limits of the disturbances [15,16].With the introduction of DOB, the controller can then be developed based on traditional methods. Comparing to the adaptive control, the DOB makes the controller design more flexible and reduces the complexities [17]. ...
