Predictive State Observer Research Articles

A Real-Time Capable Simulation of Open Volumetric Receiver Surface Temperatures With Spatially High Resolution

The performance of open volumetric receivers can profit from advanced control of the heliostat aim points and the air mass flow. Advanced control techniques like model predictive control and state observer are based on dynamic system models. A suitable model for this purpose is introduced and validated with data recorded at the solar tower Jülich. The model shows good performance with respect to the dynamics of individual absorber cups. The simulation of the whole receiver requires an advanced optimization of the model parameters.

Predictive State Observer-Based Set-Point Learning Control for Batch Manufacturing Processes With Delay Response

A predictive state observer (PSO) based iterative learning control (ILC) scheme is proposed for industrial batch manufacturing processes with delay response suffering from nonrepetitive uncertainties and disturbances. Combining with a delay-free output predictor, a PSO based feedback control structure is firstly presented to improve set-point tracking and disturbance rejection performance against nonrepetitive process uncertainties and disturbances for the initial batch run. Then an ILC law is introduced to update the closed-loop system set-point in order to improve the tracking performance from batch to batch. A delay-independent sufficient condition is established to ensure the convergence of output tracking error along the batch-direction, based on double-dynamic analysis. Moreover, another delay-dependent sufficient condition is constructed by linear matrix inequality to assess robust stability of the proposed two-dimensional control system along both the time- and batch-directions. Finally, an illustrative example and a real application to the batch temperature regulation of a 4-litre crystallizer are shown to validate the effect and advantage of the proposed ILC scheme.

Distributed Consensus Tracking of Multi-Agent Systems with Time-varying Input/Output Delays and Mismatched Disturbances

This paper investigates the distributed consensus tracking control problem for general linear multi-agent systems (MASs) with bounded time-varying input/output delays and mismatched disturbances under a directed communication graph containing a spanning tree. First, a part of the mismatched disturbances is transformed into the input channel as the matched disturbance, that allows the deployment of a predictive extended state observer (ESO) in order to estimate the consensus tracking error and transformed matched disturbance simultaneously. Subsequently, the ESO is used for designing a controller. The stability of the closed-loop system is guaranteed via a Lyapunov-Krasovskii functional with sufficient conditions in terms of delay-dependent linear matrix inequalities (LMIs). An additional LMI is proposed which, in conjunction with the rest of LMIs, results in a solution with a larger upper bound on delays than what would be feasible without it. The efficacy of the proposed scheme is demonstrated via simple numerical examples.

Predictive ESO-based control with guaranteed stability for uncertain MIMO constrained systems

In this paper, a novel predictive Extended State Observer (ESO)-based discrete controller with guaranteed input-to-state stability is developed. Predictive controllers based on ESOs are gaining acceptance for regulating MIMO systems with disturbances, uncertainties or actuator constrains. However, there is an important concern about this control structure regarding its closed-loop stability; a key property that is not strictly guaranteed with the most part of the previous formulations. This paper shows that –under the same assumptions that are normally taken in the ESO literature– a predictive ESO-based controller that is proved to be input-to-state stable can be easily constructed by adding two fixed terms in the cost-index definition. A simulation case study of the glucose control in patients with type-1 diabetes is additionally given in order to illustrate the main advantages of this control structure.

Observer-based robust model predictive control of switched nonlinear systems with time delay and parametric uncertainties

In this study, an observer-based robust model predictive control scheme is proposed to control a class of switched nonlinear systems in the presence of time delay and parametric uncertainties under arbitrary switching. Constructing an appropriate Lyapunov–Krasovskii functional in conjunction with an infinite horizon cost function, sufficient conditions are obtained to guarantee the asymptotic stability of the closed-loop switched system in terms of linear matrix inequalities depending on the time delay, the upper bounds of uncertain parameters, and the Lipschitz constant of subsystems. To model the uncertainty of the system, the parametric uncertainty is used to reduce the computational burden and the conservatism of the method. In the proposed method, a predictive state observer and an observer-based controller are synthesized via an online optimization problem to minimize the upper bound of the cost function, while handling the constraints. Finally, the obtained results are validated using practical and numerical simulations.

Robust predictive extended state observer for a class of nonlinear systems with time-varying input delay

ABSTRACTThis paper deals with asymptotic stabilisation of a class of nonlinear input-delayed systems via dynamic output feedback in the presence of disturbances. The proposed strategy has the structure of an observer-based control law, in which the observer estimates and predicts both the plant state and the external disturbance. A nominal delay value is assumed to be known and stability conditions in terms of linear matrix inequalities are derived for fast-varying delay uncertainties. Asymptotic stability is achieved if the disturbance or the time delay is constant. The controller design problem is also addressed and a numerical example with an unstable system is provided to illustrate the usefulness of the proposed strategy.

Gain-scheduled predictive extended state observer for time-varying delays systems with mismatched disturbances

In this paper, a novel control scheme for systems with input and output time-varying delays is provided in discrete-time domain. The control strategy combines predictor-like techniques with a delay-dependent gain-scheduled extended state observer. The main goal is twofold: (i) to minimize the negative effect of time-varying delays in the closed-loop performance and, (ii) to actively compensate the effect of mismatched disturbances in the controlled output. Moreover, a sufficient condition based on Linear Matrix Inequalities (LMI) is provided to obtain the maximum delay interval that ensures the stability of the closed-loop system. Finally, the achieved benefits of the proposal are shown by simulation in open-loop unstable plants, and experimentally validated in a test-bed quadrotor platform.

Distributed consensus of linear MASs with an unknown leader via a predictive extended state observer considering input delay and disturbances

Abstract The problem of disturbance rejection/attenuation for constant-input delayed linear multi-agent systems (MASs) with the directed communication topology is tackled in this paper, where a classic model reduction technique is introduced to transform the delayed MAS into the delay-free one. First, when the leader has no control input, a novel adaptive predictive extended state observer (ESO) using only relative state information of neighboring agents is designed to achieve disturbance-rejected consensus tracking. The stabilization analysis is presented via the Lyapunov function and sufficient conditions are derived in terms of linear matrix inequalities. Then the result is extended to disturbance-attenuated case where the leader has bounded control input which is only known by a portion of followers. Finally, two numerical examples are presented to illustrate the effectiveness of proposed strategies. The main contribution focuses on the design of adaptive predictive ESO protocols with the fully distributed property.

Rejection of mismatched disturbances for systems with input delay via a predictive extended state observer

SummaryThe problem of output stabilization and disturbance rejection for input‐delayed systems is tackled in this work. First, a suitable transformation is introduced to translate mismatched disturbances into an equivalent input disturbance. Then, an extended state observer is combined with a predictive observer structure to obtain a future estimation of both the state and the disturbance. A disturbance model is assumed to be known but attenuation of unmodeled components is also considered. The stabilization is proved via Lyapunov‐Krasovskii functionals, leading to sufficient conditions in terms of linear matrix inequalities for the closed‐loop analysis and parameter tuning. The proposed strategy is illustrated through a numerical example.

Speed sensorless induction motor drive with motor choke and predictive control

PurposeThe purpose of this paper is to present a complete solution for speed sensorless AC drive with voltage source inverter, induction machine, and motor choke. Major problems with adjustable speed drives are underlined and the use of motor choke is justified. An AC drive with motor choke can work only if specific modifications in the control algorithms are done.Design/methodology/approachThe goal of the paper is to present new nonlinear vector control method for induction motor drive. In the control system, the presence of motor choke is taken into account. The choke changes the structure of the predictive controller and state observer. The new concept of integrating the predictive controller with electromagnetic forces observer is presented. The paper presents theoretical description of the system as well the simulation and experimental verification.FindingsThe paper shows that the suggested decoupled AC drive control system is operating better than a system without decoupling. The system with motor choke requires modifications in the current controller and observer system. With omitting the motor choke a speed sensorless drive cannot work properly.Practical implicationsThe solution is oriented for industrial applications because in numerous industrial dives the motor choke is utilized. However, with motor choke many sophisticated control algorithms cannot work properly. The concept presented in the paper solves such practical problems.Originality/valueThe paper presents a completely new decoupled field‐oriented control system with load angle controller, predictive current controller and state observer for AC drive with motor choke.

Comparison of single-sensor current control in the DC link for three-phase voltage-source PWM converters

This paper presents a technique for reconstructing converter line currents using the information from a single current sensor in the DC link of a converter and comparative evaluation of the performance of single sensor control techniques in the DC link for voltage-source pulsewidth modulation (V-S PWM) converters. When 3/spl phi/ input currents cannot be reconstructed, three methods to acquire the DC-link current are compared. Two of them are methods of modifying the switching state (I, II), and another is a method of using the predictive state observer. Also, compensation of sampling delay, and a simultaneous sample value of input currents in the center of a switching period are included. Suitable criteria for the comparison are identified, and the differences in the performance of these methods are investigated through experimental results for a typical V-S PWM converter rated at 10 kVA.

A novel control method for three-phase PWM rectifiers using a single current sensor

This paper proposes a control method for three-phase voltage-source PWM rectifiers using only a single current sensor in the DC-link. A PWM modulation strategy for reconstructing three phase currents from the DC-link current is given. When 3/spl phi/ input currents cannot be reconstructed, a method for modifying the switching state of the PWM rectifier and a method for the predictive state observer is proposed. Compensation of the 2 sampling delays is also included, and this method is combined with all of the experiments. Performance differences between the two methods in a typical voltage source PWM rectifier are investigated experimentally.

Combined deadbeat control of a series-parallel converter combination used as a universal power filter

This paper presents the notion of combined control of a system of interconnected power electronic converters. The concept is demonstrated using a three-phase series-parallel active power filter as an example. The described active power filter consists of a series-parallel combination of two full bridge VSIs capable of arbitrarily controlling the input current and output voltage. The proposed control scheme treats the converter combination as a single unit and uses the inverse system model to generate deadbeat control response for both input current and output voltage. A full-order predictive state observer is used to reduce the number of sensors. Simulation results show better disturbance rejection characteristics of the proposed control when compared to the separately controlled converter scheme.

Digital control of induction motor current with deadbeat response using predictive state observer

For a high-power induction motor drive, the switching frequency of the inverter cannot become higher than one kilohertz, and such a switching frequency produces a large current ripple, which then produces torque ripple. To minimize the current ripple, a method based on deadbeat control theory for current regulation is proposed. The pulsewidth modulation (PWM) pattern is determined at every sampling instant based on stator current measurements, motor speed, current references, and rotor flux vector, which is predicted by a state observer with variable poles selection, so that the stator currents are controlled to be exactly equal to the reference currents at every sampling instant. The proposed method consists of two parts: (1) derivation of a deadbeat control and (2) construction of a state observer that predicts the rotor flux and the stator currents in the next sampling instant. This paper describes a theoretical analysis, computer simulations and experimental results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A fully digitized field-oriented controlled induction motor drive using only current sensors

A field-oriented control method based on a predictive observer with digital current regulation of an induction motor, without speed and voltage sensors, is proposed. Measuring only stator currents and estimating motor speed and rotor fluxes by a predictive state observer with variable pole selection the stator currents are controlled to be exactly equal to the reference currents at every sampling instant. The resulting speed and rotor fluxes are estimated with low sensitivity to parameter variation, and the torque ripples are reduced. The proposed method consists of four parts: identification of the rotor speed, derivation of a digital control law, construction of a state observer that predicts the rotor flux and the stator currents, and derivation of field-oriented control. A theoretical analysis of the method, computer simulations, and experimental results are described. >

Digital current regulation of field-oriented controlled induction motor based on predictive flux observer

A new technique based on deadbeat control theory is proposed to control induction motor stator currents under field-oriented control. Stator currents and motor speed were measured. Rotor fluxes are predicted using a state observer with variable poles selection. Then, the pulse-width-modulated (PWM) pattern of the inverter is controlled such that the stator currents are exactly equal to the reference currents at every sampling instant. From the theoretical analysis, digital simulations, and experimental results, the following conclusions were made. The deadbeat controller permitted low current ripple with lower switching frequency, which, in turn, resulted in low torque ripple. The predictive state observer made possible the estimation of rotor flux with very low sensitivity to parameter variation and then contributed to performance improvement of conventional vector control.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

New design method for discrete-time multi-variable predictive controllers

Abstract A new method for designing discrete-time multi-variable predictive controllers is presented. It is based on the ‘predictive state’ model developed directly from the step response of the plant. With the usual state space techniques, the control law with predictive state feedback is derived by using a discrete-time moving horizon optimization. A predictive state observer is then introduced to realize the control law. Some aspects about parameter selection are discussed. The performance of the new design method is demonstrated by some simulation results. Finally, a comparison between the new method and the usual discrete-time optimal control is made to illustrate the characteristic of the predictive control method.