Control Design Methodology Research Articles

Design methodology for digital active disturbance rejection control of the DC motor drive

Digital active disturbance rejection controllers (DADRC) have a wide scope as they have inherent advantages such as: easy hardware implementation, the entire system's mathematical model it is not necessary, is a linear controller dealing with uncertainty and is intended to ensure that energy savings are achieved. This document provides a procedure for designing a DADRC for a dc motor drive from the perspective of a Generalized Proportional Integral observer and differential flatness. The angular speed of a dc motor drive is the main purpose of the controller. The proposed DADRC was implemented using floating point operations on a field programmable gate array Artix-7™ using a Nexys 4 board. The system is subject to current demands, parameter variations, dc power supply changes and external load torque variations. The coupling of buck converter and dc motor resulting in external and internal disturbances that are actively counteracts the linear controller, as shown in the results.

Towards Secure Consensus of Multi-Agent Systems via a Virtual Network and Heterogeneous Controller Gains

This paper addresses the problem of resilient consensus in a multi-agent system under cyber-attacks that may affect the shared state information among the neighboring agents. We solve this problem by considering that there exists a virtual network which is not exposed to the attacker and only the physical layer of the agents can be influenced by the attacker. In this direction, our control design methodology relies on integrating physical and virtual layers appropriately. The proposed controller uses the state information of both physical and virtual networks and operates with heterogeneous control gains, which provides a greater flexibility in achieving the consensus as close as possible to the desired value. Furthermore, the conditions on these controller gains are obtained explicitly and the stability of the attacked system is analyzed. Simulations are given to support our theoretical findings.

Vibration control of a class of mechatronic systems using Negative Imaginary theory

This paper proposes a new controller design methodology for a class of mechatronics systems that satisfy stable and minimum-phase Negative Imaginary (NI) property. The proposed methodology relies on the classical Internal Model Control (IMC) principle. The closed-loop stability of the proposed scheme depends only on the DC loop gain, which is theoretically established by the internal stability result of NI theory. In this scheme, the design problem of the IMC parameter (known as the Youla parameter) has been cast as a Negative Imaginary (NI) controller synthesis problem. We propose an LMI-based IMC design approach, which can be readily solved using the commercially available SDP solver packages. A frequency-domain design approach is also presented, which depends on the solution of a simple constrained least-square problem. An in-depth simulation case study on the vibration attenuation problem of a lightweight cantilever beam is executed to demonstrate the usefulness and potential application of the proposed NI-based IMC scheme.

Robust fractional-order [proportional integral derivative] controller design with specification constraints: more flat phase idea

This paper presents a new design methodology for robust fractional-order controllers with more than three parameters for first-order plus dead time systems using the synthesis scheme of the ‘more flat phase’ idea for a fractional-order controller with [proportional integral derivative] (FO[PID]) structure. The stability region of the FO[PID] controller and the synthesis scheme with the ‘more flat phase’ idea are illustrated through a simulation example. The corresponding pseudo-codes of the synthesis scheme are also summarised. The implementation and approximation error of the FO[PID] controller are also discussed. Likewise, the superiority of the FO[PID] controller designed with the ‘more flat phase’ idea is verified by additional simulations and experimental results where the closed-loop system with FO[PID] controller is not sensitive to the variations of the loop gain, ensuring satisfactory control performance. Obtained results show high potential in practical industrial applications.

Dissipativity-based synthesis for semi-Markovian systems with simultaneous probabilistic sensors and actuators faults: A modified event-triggered strategy

Aided by a modified event-triggered communication policy (ETCP), this article addresses the dissipativity-based control synthesis problem for semi-Markovian switching systems (SMSSs) with simultaneous multiplicative probabilistic faults on sensors and actuators modules. The resulting model under consideration is more extensive, which covers semi-Markovian switching coefficients, transmission delays, and randomly occurring sensors and actuators faults in a unified systematic analytical framework instead of investigating separately in some existing works. More specifically, the probabilistic faults are assumed to happen on both the sensors and actuators modules simultaneously, and the distortion probability for each sensor and actuator is irrelevant, which can be characterized by multiplicate mutually independent stochastic variables that obeys certain statistical features and probabilistic distribution delineate on the interval [0,✠](✠≥1). To reduce the bandwidth usage, a novel event-triggered strategy is designed. Additionally, in the light of this newly developed ETCP, and considering the effects of the signal transmission delays and multitudinous probabilistic failures, a generalized and more realistic faulty pattern for SMSSs is presented, which is more fit for real applications. Hereby, the principal superiority of the established new type faulty pattern lies in its practicality and generality, which contains some previous faulty models as special scenarios. By constructing an appropriate semi-Markovian Lyapunov functional (SMLF) together with mathematical analysis technique and matrix inequality decoupling operation, sojourn-time-dependent sufficient conditions for determining both the control gain matrices and triggered configuration coefficients are developed and formulated in terms of a group of feasible linear matrix inequalities (LMIs). Eventually, several practical examples are exploited to substantiate the validity and practicability of the developed control design methodology.

Improvement of Linear Algebra Controllers using Sliding Surface Concepts: Applications to Chemical Processes

This work presents a novel control technique that combines concepts of Sliding Surface with a Linear Algebra methodology for controller design. The result is a controller with an improved robustness, while the chattering effect attributed to great uncertainties is avoided. A First Order Plus Dead Time (FOPDT) model of the process is used to develop a controller based on Linear Algebra and the concept of sliding surface is used to improve its performance under uncertainties. An interesting feature of this new controller is its ability to follow variable references without overshoot, a highly desirable characteristic for most process systems, and avoids the chattering problem. Results of the control of a CSTR and a laboratory batch reactor using this novel technique are presented. Simulated and experimental results demonstrate the outstanding performance of this new control algorithm.

𝓗∞ calibratable LPV control strategies for torque control in automotive turbocharged engines

This paper presents some outcomes of a recently completed research project aimed at developing torque control strategies for automotive turbocharged combustion engines with modern control design methodologies. Traditional torque control consists of maintaining some relevant signals close to certain set-points generated by a map representing the static inverse model of the engine, without any consideration for the optimality of the responses. The proposed model-based control strategy does not make use of any static map and all signals of interests are regulated at the same time by a unique centralised multivariable controller. A Linear Parameter Varying (LPV) optimal control design problem, formulated via Linear Matrix Inequality (LMI) feasibility conditions, is solved to generate the controller, whose main objectives are the reduction of fuel consumption while maintaining good torque tracking. The resulting regulator presents is gain-scheduled and is designed to be calibratable in real-time. Some numerical simulations demonstrate the effectiveness of the presented approach.

Design methodology and experimental verification of intelligent speed controllers for sensorless permanent magnet Brushless DC motor

Design methodology and experimental verification of intelligent speed controllers for sensorless permanent magnet <scp>Brushless DC</scp> motor

Robust structured controller synthesis for interleaved boost converters using an H∞ control method

The regulation of output voltage and equivalent distribution of phase currents of multi-phase converters which have non-minimum phase characteristic are still challenges, especially in the presence of uncertainties in real parameters, duty cycle, input voltage, and load disturbances. However, in classical third-order integral-lead (Type-III) controller design methodologies, the controller is synthesized considering only the nominal performance conditions. This paper proposes a structured [Formula: see text] synthesis framework based on an optimization methodology to the design of a robust Type-III controller for interleaved boost converters. The structured [Formula: see text] control approach is adapted for optimization of Type-III feedback and feedforward controllers in two-degree-of-freedom (2-DOF) control system configuration. The robust stability of the closed-loop interleaved boost converter system against model uncertainties is ensured via the classical [Formula: see text]-analysis technique. Numerical comparisons are made among the classical, i.e. unstructured or full order, [Formula: see text]-based controller design method, a dual-loop PI controller, and proposed 1-DOF and 2-DOF structured controller synthesis approaches on an interleaved boost converter model. Simulation results verify the effectiveness and advantages of the proposed approach from the viewpoint of the output voltage regulation under different disturbance points.

Network-based quantized [formula omitted] control for T–S fuzzy singularly perturbed systems with persistent dwell-time switching mechanism and packet dropouts

This paper focuses on the H∞ control problem for a class of discrete-time persistent dwell-time (PDT) switched nonlinear singularly perturbed systems (SPSs) under T–S fuzzy model. In order to make the system more consistent with the actual situation, the signal quantization associated with a logarithmic quantizer and the packet dropouts governed by a Bernoulli variable are considered simultaneously. And, the persistent dwell-time switching mechanism is employed to describe the fast and slow switching among several subsystems in the investigated systems alternatively. Based on the Lyapunov function approach and Takagi–Sugeno (T–S) fuzzy technique, some sufficient conditions are obtained, which can ensure the exponentially mean-square stable (EMSS) and H∞ performance of the closed-loop system. In addition, a unified fuzzy controller design methodology is established for the nonlinear SPSs, so that the fuzzy controller can be designed depending on whether the fast states of the systems are available or not. Finally, a numerical example and a series DC motor model are provided to demonstrate the superiority and practicability of the obtained theoretical results.

Nested Robust Controller Design for Interconnected Linear Parameter Varying Aerial Vehicles

A framework for a systematic design of robust controllers to guarantee desired output performance for an interconnected group of multi-input–multi-output dynamic systems is presented. The framework enables design of a robust linear parameter varying (LPV) controller for all individual vehicles as well as the interconnected group to account for uncertainties associated with the individual vehicles as well as the interconnections. In this paper, the robust controller design methodology for the individual systems and the cooperative system is implemented in a nested manner to enhance the performance. The application of the nested robust controller is distributed wherein well-known robust performance analysis is adopted and modified, and the controller synthesis methodology is developed on top of the same performance condition. Nested robust LPV controllers are synthesized for the short-period dynamics of F-16 VISTA over a flight envelope defined by Mach number and altitude of the aircraft. Then a group of homogeneous F-16 VISTA with individually designed LPV controllers is interconnected using a connection topology that suffers time delays, and a cooperative controller is designed using two methods described in this work. Numerical simulation results presented in the paper show that the group performance is enhanced with the robust LPV controller design methodology.

Model Decoupled Synchronization Control Design with Fractional Order Filter for H-Type Air Floating Motion Platform.

H-type motion platform with linear motors is widely used in two-degrees-of-freedom motion systems, and one-direction dual motors need to be precisely controlled with strict synchronization for high precision performance. In this paper, a synchronous control method based on model decoupling is proposed. The dynamic model of an H-type air floating motion platform is established and one direction control using two motors with position dependency coupling is decoupled and converted into independent position and rotation controls, separately. For the low damping second-order oscillation system of the rotation control loop, a new fractional order biquad filtering method is proposed to generate an antiresonance peak to improve the phase and control gain of the open loop system, which can ensure system stability and quick attenuation for external disturbances. In the multiple-degree-of-freedom decoupled control loops, a systematic feedback controller design methodology is proposed to satisfy the given frequency domain design specifications; a feed-forward control strategy is also applied to compensate the disturbance torque caused by the platform motion. The simulation and experimental results demonstrate that the proposed synchronization control method is effective, and achieves better disturbance rejection performance than the existing optimal cancellation filtering method and biquad filtering method.

Robust control design for the FLEXOP demonstrator aircraft via tensor product models

AbstractThe paper proposes a control design methodology for active flutter suppression for the aeroservoelastic (ASE) aircraft of the European project FLEXOP. The aim of the controller is to robustly stabilize the aeroelastic modes. The control design is based on a control‐oriented linear parameter‐varying (LPV) model, which is derived via “bottom–up” modeling approach and includes the parametric uncertainties of the flutter modes. The tensor product (TP) type LPV model is generated via TP model transformation. The symmetric and asymmetric flutter modes are decoupled, which allows independent control design for each. LPV observer‐based state feedback control structure is applied with constraints on the maximal control value to avoid input saturation. The scheduling parameters of the TP‐type LPV models are split into measured and uncertain parameters for robust control design. Convex hull manipulation‐based optimization and model complexity effects are investigated. The resulting controller is validated via the high‐fidelity ASE model of the FLEXOP aircraft.

A novel approach for robust control design of hidden synthetic inertia for variable speed wind turbines

This work presents a novel design methodology for hidden synthetic inertia control of variable speed wind turbines that considers the compromise between grid frequency response and operating limits of the wind turbine states. Two state space design strategies are proposed: one based on H∞ robust control with dynamic output feedback; and other based on H∞ static state feedback control; both strategies operate as supplementary controllers. The study was carried out on simulation with dynamic mathematical modeling of a variable speed wind turbine and an isolated system with conventional power plants, aiming to evaluate the grid frequency response to load-generation disturbances and wind speed variations. The proposed control strategies are compared with two topologies: without wind turbine frequency control and another with synthetic inertia contribution by Proportional-Derivative control. The proposed strategies allow to optimize performance of synthetic inertia control in accordance with wind turbine operating limits. H∞-based topologies presented greater attenuation of the impacts of load-generation disturbances on the frequency response, and also minimizes a cost function based on H2 norm of the frequency signal in comparison with other controllers, thus providing better performance against reference variations and changes of operation point.

Iterative learning control of dispatchable grid-connected distributed energy resources for compensation of grid current harmonic distortions

This paper proposes a power regulation scheme for dispatchable grid-connected distributed energy resource (DER) units based on the iterative learning control (ILC) strategy. The proposed control provides fast and stable control of the real and reactive powers that the DER unit delivers to the grid. In addition, it compensates the harmonic distortion of the grid current caused by the local nonlinear loads and delivers a high quality power to the grid. To this end, the paper presents the mathematical model on which the proposed control is based, as well as the control design methodology. A new MIMO iterative learning control with perfect power tracking and harmonic rejection performance as well as minor measurement requirements is proposed. The performance of the proposed ILC strategy is demonstrated through time-domain simulation of a grid-connected DER unit under various operating scenarios, and it is compared with the performance of the conventional control based on the instantaneous power theory (IPT).

A multi-channel varvec{H}_infty preview control approach to load alleviation design for flexible aircraft

Gust load alleviation functions are mainly designed for two objectives: first, alleviating the structural loads resulting from turbulence or gust encounter, and hence reducing the structural fatigue and/or weight; and second, enhancing the ride qualities, and hence the passengers’ comfort. Whilst load alleviation functions can improve both aspects, the designer will still need to make design trade-offs between these two objectives and also between various types and locations of the structural loads. The possible emergence of affordable and reliable remote wind sensor techniques (e.g., Doppler LIDAR) in the future leads to considering new types of load alleviation functions as these sensors would permit anticipating the near future gusts and other types of turbulence. In this paper, we propose a preview control design methodology for the design of a load alleviation function with such anticipation capabilities, based on recent advancements on discrete-time reduced-order multi-channel H_infty techniques. The methodology is illustrated on the DLR Discus-2c flexible sailplane model.

Disturbance rejection sliding mode control for robots and learning design

The control of a robot to achieve both good dynamic and static performance against external disturbances is a challenging task, especially when high speed and a wide range of motion is required. In this paper, a disturbance rejection sliding mode control (SMC) methodology is designed for a robot manipulator. This methodology synthesizes the SMC design with the active disturbance rejection control (ADRC) technique. An extended state observer is employed to estimate unknown disturbances, which is difficult to deal with in a conventional SMC design, and to simplify the SMC law design. A learning-based parameter tuning methodology is presented to autonomously obtain the control parameters offline. To develop a robust and transferring controller, a neural network is used to learn the joint actuation ability for the controller optimizing process. Compared with other state-of-the-art controllers, both numerical simulations and experiments of a 6-DOF robot are provided to demonstrate the proposed control method and design methodology. These results reveal that the proposed control method has a satisfying tracking performance and strong disturbance rejection ability.

Inverse Optimal Control Via Diagonal Stabilization Applied to Attitude Tracking of a Reusable Launch Vehicle

In this work, a novel strategy for the inverse optimal control of a class of affine nonlinear systems is proposed. The proposed strategy involves translation of the infinite horizon nonlinear optimal control problem into a Diagonal stability problem, followed by the formulation of a set of criteria for the synthesis of a stabilizing feedback control law. Hence, the proposed controller design methodology is refered to as inverse optimal control via diagonal stabilization. Besides providing a closed-form solution, the methodology also possesses the added advantage of inherent robustness, on account of adequate stability margins. Most importantly, the methodology ensures an estimate of the associated domain of attraction, which is a highly desirable feature especially in the case of crucial and stringent aerospace applications. The proposed methodology is applied for the re-entry control of a reusable launch vehicle which provides a full envelope optimality-based design philosophy. For this, the control-oriented attitude model based on the three-degree-of-freedom dynamic model is utilized. The resulting control law possess desirable features of guaranteed estimate of stability domain, assured design flexibility, and inherent robustness. Simulation results verify the validity of these theoretically proven facets in terms of the efficacy and robustness of the proposed controller.

Model-matching methods and distributed control of networks consisting of a class of heterogeneous dynamic agents

Many recent results on distributed control of multi-agent networks rely on a number of simplifying assumptions that facilitate the solution of regulation problems associated with large-scale networked systems. Identical subsystem models are a typical assumption made in networked control systems which often fail in practice. In this paper, we propose a systematic method for removing this assumption, leading to a general approach to distributed-control design for stabilising networks of multiple non-identical dynamic agents. Local subsystems represented as autonomous dynamic agents are assumed to share a set of structural properties, (controllability) indices. Our approach relies on the solution of certain model-matching type problems using local state-feedback and state/input-matrix transformations that map local dynamics to a target system, selected to minimise joint control effort. By adapting well-established distributed LQR control design methodologies to our framework, the stabilisation problem of networks of non-identical dynamic agents is solved. The applicability of our approach is illustrated via a synchronisation example of eleven harmonic oscillators with non-identical dynamics communicating over a connected graph.

Robust and resilient stabilization and tracking control for chaotic dynamical systems with uncertainties

In this article, a robust resilient design methodology for stabilization and tracking control for a class of chaotic dynamical systems is proposed. In particular, a resilient quasi-sliding mode control law is formulated to suppress the chaotic behaviour of these dynamical systems, while considering uncertainties in control input. By using Lyapunov stability theory, sufficient conditions are derived in terms of Linear Matrix Inequalities (LMIs) for a more general class of chaotic nonlinear dynamical systems satisfying the Lipschitz continuity condition. The control gains are obtained via LMI technique in the presence of bounded additive uncertainties in control input. Numerical simulations are provided for Chua’s circuit, Lorenz system, and 4D Lu hyper-chaotic system to show the supremacy and effectiveness of the proposed design methodologies.