Observer-based Dynamic Control Research Articles

A Robust Simplified Dynamic Observer-Based Backstepping Control of Six-Phase Induction Motor for Marine Vessels Applications

This article presents a robust simplified dynamic observer-based backstepping control (RSDO-BSC) and direct torque control (DTC) synthesized with duty cycle control strategy of a six-phase induction motor (6PIM) for marine vessels applications. RSDO-BSC and DTC are employed to estimate the rotor speed, while the DTC is utilized to accomplish enhanced steady-state torque performance via accurate inputs applied to the switching table of the six-phase inverter. Furthermore, by using the duty cycle control approach, the loss components in the subspace are disregarded via the appropriate choice of virtual voltage vectors. Consequently, the 6PIM torque ripples and the current harmonics are significantly reduced. First, both the flux and the torque are decoupled using Lyapunov theory on a 6PIM two-axis mathematical model represented in the stationary reference frame. The 6PIM actual stator voltages are acquired from the dc-link voltage via the space vector pulsewidth modulated inverter. Subsequently, when the 6PIM is loaded under the rated speed, a rapid search approach is used to maximize the 6PIM efficiency. A 750-W 6PIM drive test setup employs a dSPACE 1104 for real-time implementation. The proposed RSDO-BSC performance is experimentally investigated at different speed commands, load disturbance, and low speed command with low load torque conditions.

Dynamic observer-based control for fractional-order uncertain linear systems

ABSTRACTThis paper addresses the problem of dynamic observer-based control for fractional-order linear uncertain systems. By constructing a new linearising change of variables, the conditions for designing the observer and controller gains are obtained in terms of solutions to a set of linear matrix inequalities (LMIs) even in the presence of uncertainties in system, input and output matrices simultaneously. Meanwhile, owing to having additional degrees of freedom in the designed observer structure, the proposed methods have no equality constraint, which is needed by using Luenberger-type observer. Numerical examples are given to illustrate the benefits and the effectiveness of the proposed method.

Robust Sliding Mode Control of a Vapor Compression Cycle

This paper deals with the development of a mathematical dynamic model and observer-based set point control of a vapor compression cycle (VCC) system. The mean void fraction and moving boundary control volumes in a heat exchanger (HEX) are used for a lumped parameter model of an air conditioning system. A multi-input multi-output (MIMO) dynamic model of the VCC is presented in a nonlinear state space representation and is reformulated into a linearized regular form for control design. A modified observer-based controller with sliding mode control (SMC) is introduced to attenuate the effects of observing approximation errors and external disturbances. In the design of the discontinuous controller, a new type of gain function is introduced to reduce the time to reach the sliding mode compared to a conventional discontinuous gain. The proposed control methodology ensures uniformly ultimately bounded tracking results of the desired low pressure and suction superheat. A simulation of controlling the VCC illustrates the effectiveness and performance in the presence of disturbances.

Vehicle-manipulator system dynamic modeling and control for underwater autonomous manipulation

Underwater autonomous manipulation is a challenging task, which not only includes a complicated multibody dynamic and hydrodynamic process, but also involves the limited observation environment. This study systematically investigates the dynamic modeling and control of the underwater vehicle-manipulator multibody system. The dynamic model of underwater vehicle-manipulator system has been established on the basis of the Newton–Euler recursive algorithm. On the basis of dynamic analysis, a motion planning optimization algorithm has been designed in order to realize the coordinate motions between AUV and manipulator through reducing the restoring forces and saving the electric power. On the other hand, a disturbance force observer including the coupling and restoring forces has been designed. An observer-based dynamic control scheme has been established in combination with kinematic and dynamic controller. Furthermore, from the simulations, although the disturbance forces such as restoring and coupling forces are time varying and great, the observer-based dynamic coordinate controller can maintain the AUV attitude stable during the manipulator swing and pitch motions. During the precise manipulation simulation, the stable AUV attitude and minimization of disturbance forces have been realized through combination of optimal motion planning and the observer-based dynamic coordinate controller.

Self-triggered output feedback control for consensus of multi-agent systems

This paper studies the self-triggered control consensus problem of general linear multi-agent systems(MASs). A novel self-triggered control strategy based on output feedback is proposed for centralized and distributed cases, respectively. In consideration of the states of agents that are not available, a state observer is adopted. A dynamic observer-based control law is employed to improve the transient response. Under this triggering strategy, both the estimated states of MASs and the states of controller are updated at triggering time. The next triggering time is predetermined at the last triggering instant. Moreover, the asymptotic consensus of MASs can be guaranteed. Finally, the effectiveness of the proposed control strategy is illustrated by a numerical example.

RobustH∞Observer-Based Control of Uncertain Neutral Systems with Mixed Delays

In this paper, the robust In this paper, the robust H ∞ control problem of output dynamic observer-based control for a class of uncertain neutral systems with discrete and distributed time delays is considered. Linear matrix inequality (LMI) optimization approach is used to design the new H ∞ output dynamic controls. The minimal H ∞ -norm bound and the maximal perturbed bound are given. Based on the result of this paper, the constraint of matrix equality is not necessary for designing the H ∞ observer-based controls. Finally, a numerical example is given to illustrate the efficiency of the proposed approach.

Robust Output Observer-Based Control of Neutral Uncertain Systems with Discrete and Distributed Time Delays

In this paper, the robust control problem of output dynamic observer-based control for a class of uncertain neutral systems with discrete and distributed time delays is considered. Linear matrix inequality (LMI) optimization approach is used to design the new output dynamic observer-based controls. Three classes of observer-based controls are proposed and the maximal perturbed bound is given. Based on the results of this paper, the constraint of matrix equality is not necessary for designing the observer-based controls.

Dynamic observer-based controllers for linear uncertain systems

This paper addresses robust controller design for uncertain linear systems via a dynamic observer-based controller. A dynamic observer is an alternative structure for a classical observer which can be regarded as a general form of a usual observer and has additional degrees of freedom in the observer structure. Using this new observer structure, a new observer-based controller for linear systems is proposed. Some strict linear matrix inequalities (LMIs) have been given to find the dynamic observer parameters and controller gain. It is shown that dynamic observer can be used effectively for tackling the drawbacks of the classical observer-based robust controller design methods. As an advantage, LMIs are derived even in the presence of uncertainties in system, input and output matrices simultaneously, whereas by using the traditional observer, bilinear matrix inequalities (BMIs) are given in the presence of such uncertainties. Moreover, the proposed LMIs do not imply the equality constraint. Simulation results are used to illustrate the effectiveness of the proposed design technique.

Dynamic observer-based robust control and fault detection for linear systems

This study is concerned with the design of dynamic observer-based robust controller that also facilitates the acquisition of information used for fault detection (FD) purpose in feedback control systems. Through introducing a weighting matrix, the combination of observer states is utilised to generate a residual signal to detect faults. The first technical contribution is to construct a new linearising change-of-variables that is able to convert the dynamic observer-based controller design problem into linear matrix inequality-based optimisation problem. The second one is to show that the proposed dynamic observer-based controller can achieve a better H∞ performance compared with the existing static (Luenberger) observer-based controller design approaches. Finally, via the simple residual structure, a convex fault detector design condition with some parameter matrices fixed is developed for guaranteeing the H− performance used to measure the fault sensitivity. An F-18 aircraft model is given to show the satisfactory FD performance and control performance.

H∞ robust fuzzy dynamic observer-based controller for uncertain Takagi–Sugeno fuzzy systems

This study considers the problem of robust controller design for uncertain Takagi–Sugeno (T–S) fuzzy systems with H∞ performance through fuzzy dynamic observer (FDO). Dynamic observer is an alternative structure for classical observer which can be regarded as a general form of a usual observer and has additional degrees of freedom in the observer structure. In this study first the idea of dynamic observer in linear systems is extended to T–S fuzzy systems and it is shown that FDO can be used effectively for tackling the drawbacks of the existing methods of classical observer-based robust controller design. Strict linear matrix inequality (LMI) conditions are presented for designing robust H∞ observer-based controller even in the presence of uncertainties in system matrix, input and output matrices simultaneously by employing FDO. Finally, efficiency of the proposed design method is shown in simulation results.

Robust Passivity Control for Uncertain Time-Delayed Systems

This paper focuses on the robust passivity synthesis problem for a class of linear time-delayed systems subject to parameter uncertainties. The time delay is assumed to be unknown, and the parameter uncertainties are allowed to appear in all matrices of the model. The aim lies in designing observer-based dynamic controller that render the closed-loop system be strongly robustly stable and strict passive for all admissible uncertainties, independently of time delay. Using a scaling parameterization approach, the problem being considered is transformed into a class of strongly stable and strictly passive control problem for a parameterized system without uncertainties. And then, the controller gain and the observer gain are obtained in terms of a linear matrix inequality. Finally, a numerical example is provided to demonstrate the validity of the proposed approach.

Observer-Based Dynamic Control of an Underactuated Hand

The purpose of this paper was to construct a velocity observer based on the dynamic model and realize accurate dynamic curve and force control. Curve fitting with the observer obtained precise velocity signals. Compared with PID and factored moment methods, it decreased the fitting errors a lot and achieved ideal results. Compensated with the inverse dynamic equation, the force-based impedance control with the observer could not only realize accurate force tracking, but achieve finger dynamic control by the combination of curve fitting and force tracking. Furthermore, a static grasp model was established for appropriate force distribution. The finger could grasp slippery, fragile, comparatively heavy and large objects like an egg with only base joint torque and position sensors, which illustrated that the hand could accomplish difficult tasks by using the static grasp model and dynamic control.

Robust H ∞ controller design for uncertain neutral systems via dynamic observer based output feedback

In this paper, the dynamic observer-based controller design for a class of neutral systems with H∞ control is considered. An observer-based output feedback is derived for systems with polytopic parameter uncertainties. This controller assures delay-dependent stabilization and H∞ norm bound attenuation from the disturbance input to the controlled output. Numerical examples are provided for illustration and comparison of the proposed conditions.

Robust H ∞ Output Dynamic Observer-Based Control Design of Uncertain Neutral Systems

In this paper, the robust H∞ control problem of output dynamic observer-based control for a class of uncertain neutral systems is considered. The linear matrix inequality optimization approach is used to design the new H∞ output dynamic controls. Three classes of H∞ observer-based controls are proposed. The minimal H∞-norm bound and the maximal perturbed bound are given. Based on the result of this paper, the constraint of matrix equality is not necessary for designing the H∞ observer-based controls. A numerical example is given to stress the usefulness of the proposed results.

Robust output observer-based control of neutral uncertain systems with discrete and distributed time delays: LMI optimization approach

In this paper, the robust control problem of output dynamic observer-based control for a class of uncertain neutral systems with discrete and distributed time delays is considered. Linear matrix inequality (LMI) optimization approach is used to design the new output dynamic observer-based controls. Three classes of observer-based controls are proposed and the maximal perturbed bound is given. Based on the results of this paper, the constraint of matrix equality is not necessary for designing the observer-based controls. Finally, a numerical example is given to illustrate the usefulness of the proposed method.

Robust H∞ output dynamic observer-based control of uncertain time-delay systems

In this paper, the robustness and H∞ control problems of output dynamic observer-based control for a class of uncertain linear systems with time delay are considered. Under no disturbance input, the asymptotic stabilization for uncertain time-delay systems will be guaranteed. Linear matrix inequality (LMI) optimization approach is used to design three classes of the H∞ output dynamic controls. Based on the results of this paper, the constraint of matrix equality is not necessary for designing the observer-based controls.

Robust H ∞ control of a class of nonlinear uncertain time-delay systems

The robust H∞ control problem of a class of uncertain nonlinear time-delay systems is considered in this paper. The parametric uncertainties are real time-varying and norm-bounded and the nonlinearities are state-dependent and cone-bounded. The delays are time-varying and bounded both in the state and at the input. We provide sufficient conditions for robust stability and robust state-feedback stabilization with disturbance attenuation. Then, we establish sufficient conditions for designing a linear dynamic observer-based controller which stabilizes the uncertain time-delay system and guarantees an H∞-norm bound constraint on the disturbance attenuation for all admissible uncertainties and unknown delays. Several examples are simulated to illustrate the developed theory.

Robust $ {\cal H}_{\infty}$ Control of a Class of Nonlinear Uncertain Time-Delay Systems

The robust $ {\cal H}_{\infty}$ control problem of a class of uncertain nonlinear time-delay systems is considered in this paper. The parametric uncertainties are real time-varying and normbounded and the nonlinearities are state-dependent and cone-bounded. The delays are time-varying and bounded both in the state and at the input. We provide sufficient conditions for robust stability and robust state-feedback stabilization with disturbance attenuation. Then, we establish sufficient conditions for designing a linear dynamic observer-based controller which stabilizes the uncertain time-delay system and guarantees an $ {\cal H}_{\infty}$ -norm bound constraint on the disturbance attenuation for all admissible uncertainties and unknown delays. Several examples are simulated to illustrate the developed theory.

Dynamic observer-based power system emergency control

This paper considers the problem of centralized structural control of power systems in emergency states, when large generation/load disturbances provoke power mismatch in the system, causing a viability crisis. The proposed control strategy with the action on demand and/or generation is initiated by the fast detection and estimation of disturbance magnitudes, using a decentralized low-order observer, based on locally available frequency and tie-line power exchange measurements in control centres of all the areas operating in a large interconnected power system. The paper proposes a suitable control strategy for this type of emergency and presents a systematic procedure for decentralized observer design. Finally, it gives an illustrative example of the application of such a power mismatch estimator in a two-area interconnected power system.