Control Design Techniques Research Articles

A Simple Closed-Loop Test Based Control of Boost Converter Using Internal Model Control and Direct Synthesis Approach

In this article, a simple controller design method for output voltage control of dc–dc boost converter (BC) has been proposed. A simple closed-loop step test with proportional gain <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k_{0}$ </tex-math></inline-formula> is performed. BC open-loop transfer function is obtained from the closed-loop step response test data, which does not require information of BC circuit parameters. Furthermore, the controller is designed from the open-loop model of the BC through the internal model control (IMC) scheme and direct synthesis (DS) approach. The robust stability analysis of both the control schemes has been carried out. The proposed modeling technique and controller design methods have been validated in the experimental setup. Both the controller design techniques work satisfactorily. Superior transient performance of the IMC scheme in comparison to the DS scheme has been observed.

Design of Active Disturbance Rejection Controller Variants for Solar Tracker System

In this paper, two controller design techniques such as linear active disturbance rejection control (LADRC) and generalized active disturbance rejection control (GADRC) are proposed for solar tracker system. The merit of the proposed method is that there is no need of tuning of proportional-integral-derivative (PID) parameters which is normally done in existing PID controller design techniques. As, the soft computing PID-based techniques involve very large iterations, so they consume much time. Also, these techniques are computationally inefficient. Therefore, to get rid of the conventional PID controller design topology, the LADRC scheme is proposed, which requires very few information of the system and even then the performance of the controller is impressive. The performance of the controller is further improved via GADRC scheme by including complete information of the system. Next, the robustness of proposed methods is investigated by the presence of system parametric uncertainty. Further, the performance of the proposed controllers is checked under time delays. Simulation results reveal that the proposed methods exhibit superb capability of disturbance rejection, high robustness and excellent transient performance in the presence of time delay in comparison to numerous existing PID-based control techniques.

Design of Approximate Explicit Model Predictive Controller Using Parametric Optimization

AbstractThis paper introduces a new technique, called state-parameterized nonlinear programming control (sp-NLPC), for designing a feedback controller that can stabilize intrinsically unstable nonlinear dynamical systems using parametric optimization. Stability-preserving constraints are included in the optimization problem solved offline by the predictive parameterized Pareto genetic algorithm (P3GA), a constrained nonlinear parametric optimization algorithm. The optimal control policy is approximated from P3GA output using radial basis function (RBF) metamodeling. The sp-NLPC technique requires fewer assumptions and is more data-efficient than alternative methods. Two nonlinear systems (single and double inverted pendulums on a cart) are used as benchmarking problems. Performance and computational efficiency are compared to several competing control design techniques. Results show that sp-NLPC outperforms and is more efficient than competing methods. A qualitative investigation on phase plane analysis for the controlled systems is presented to ensure stability. The approximating state-dependent solution for the control input lends itself to applications of control design for control co-design (CCD). Such extensions are discussed as part of future work.

Adaptive robust finite-time tracking control for quadrotor subject to disturbances

Quadrotors are extremely agile UAVs with many unknowns regarding their moment of inertia, drag coefficients, and mass. Aside from aerodynamic turbulence, the quadrotor has a high level of nonlinearity due to its underactuated mechanical system. These last two factors cause issues that necessitate adaptive and robust control. A hybrid robust nonlinear control approach for a quadrotor is described in this research paper. To address the quadrotor trajectory tracking problem, a combination of backstepping and sliding-mode approaches based on proportional integral derivative (PID) surfaces is developed, with the Lyapunov method used to evaluate the control system’s stability. The adaptive technique, in conjunction with sliding-mode and super-twisting algorithm, is then investigated in order to reduce the chattering impact of sliding mode control and estimate the various controller parameters. Super-twisting adaptive backstepping PID sliding mode approach for the quadrotor rotational and translational subsystems is presented to reduce error convergence time and improve speed tracking performance. The simulation results under various scenarios (parameters uncertainties under Gaussian random disturbances, constant and time-varying external disturbance) are given to demonstrate the efficacy and practicability of the proposed control. A comparative analysis is performed with different developed controllers using the performance of the integral of absolute error and the integral of the absolute value of the derivative of the control inputs to demonstrate the superiority and effectiveness of the designed control technique.

Leg Shaping and Event-Driven Control of a Small-Scale, Low-DoF, Two-Mode Robot

Among small-scale mobile robots, multi-modal locomotion can help compensate for limited actuator capabilities. However, supporting multiple locomotion modes or gaits in small terrestrial robots typically requires complex designs with low locomotion efficiency. In this work, legged and rolling gaits are achieved by a 10~cm robot having just two degrees of freedom (DoF). This is acheived by leg shaping that facilitates whole body rolling and event-driven control that maintains motion using simple inertial sensor measurements. Speeds of approximately 0.4 and 2.2 body lengths per second are achieved in legged and rolling modes, respectively, with low cost of transport. The proposed design approach and control techniques may aid in design of further miniaturized robots reliant on transducers with small range-of-motion.

Disconnection-Aware Attack Detection and Isolation With Separation-Based Detector Reconfiguration

This study addresses incident handling during an adverse event for dynamical networked control systems. Incident handling can be divided into five steps: detection, analysis, containment, eradication, and recovery. For networked control systems, the containment step can be conducted through physical disconnection of an attacked subsystem. In accordance with the disconnection, the equipped attack detection unit should be reconfigured to maintain its detection capability. In particular, separating the detection subunit associated with the disconnected subsystem is considered as a specific reconfiguration scheme in this study. This article poses the problem of disconnection-aware attack detection and isolation with the separation-based detector reconfiguration. The objective is to design an attack detection unit that preserves its detection and isolation capability even under any possible disconnection and separation. The difficulty arises from network topology variation caused by disconnection that can possibly lead to stability loss of the distributed observer inside the attack detection unit. A solution is proposed based on an existing controller design technique referred to as retrofit control. Furthermore, an application to low-voltage power distribution networks with distributed generation is exhibited. Numerical examples evidence the practical use of the proposed method through a benchmark distribution network.

Stabilization of discrete-time semi-Markov jump singularly perturbed systems subject to actuator saturation and partially known semi-Markov kernel information

In this paper, the stabilization issue is investigated for a family of discrete-time semi-Markov jump singularly perturbed systems (S-MJSPSs) subject to actuator saturation. The information of the semi-Markov kernel (SMK) is considered as partly known on account of that it is laborious to obtain the complete one in practice. With the consideration of the actuator saturation existing in virtually all practical applications, the convex hull approach is adopted to tackle this obstacle. Meanwhile, a unified controller design technique is presented to stabilize the underlying system irrespective of whether the fast state can be detected. Based on Lyapunov stability theory and SMK approach, some sufficient conditions guaranteeing the S-MJSPSs is mean-square (MS) stable are derived. Finally, the correctness and the validity of the presented control strategy are validated by a numerical example.

A composite controller design using an adaptive internal type-2 fuzzy logic system and the fixed-time disturbance observer for an air-breathing hypersonic vehicle with a variable geometry inlet

In this paper, a novel composite controller design technique is addressed for using an adaptive interval type-2 fuzzy logic system (FLS) with the fixed-time disturbance observer (FTDO) such that the enhanced tracking performance is achieved for an air-breathing hypersonic vehicle with a variable geometry inlet (AHV-VGI). First, introducing the variable geometry inlet to take proper mass flow into the engine without any flow spillage ensures enough thrust for acceleration and maneuvering flight. The interval type-2 FLS integrated with an adaptive control algorithm is derived to approximate the complicated nonlinear items in the control strategy online, which assures that the tracking error are semi-globally uniformly bounded. After that, the fixed-time disturbance observer that is constructed to provide the estimations of uncertainty including external disturbance leads to a more practical and robust flight control system for AHV-VGI. The uniform stability of the whole system is proved under the framework of Lyapunov theory. Finally, simulation results and analysis are presented to demonstrate the effectiveness of the proposed composite control scheme.

Adaptive NN Control of Electro-Hydraulic System with Full State Constraints

This paper presents an adaptive neural network (NN) control approach for an electro-hydraulic system. The friction and internal leakage are nonlinear uncertainties, and the states in the considered electro-hydraulic system are fully constrained. In the control design, the NNs are utilized to approximate the nonlinear uncertainties. Then, by constructing barrier Lyapunov functions and based on the adaptive backstepping control design technique, a novel adaptive NN control scheme is formulated. It has been proven that the developed adaptive NN control scheme can sustain the controlled electro-hydraulic system to be stable and make the system output track the desired reference signal. Furthermore, the system states do not surpass the given bounds. The computer simulation results verify the effectiveness of the proposed controller.

Stabilisation of non-diagonal infinite-dimensional systems with delay boundary control

Here we deal with the stabilisation problem of non-diagonal systems by boundary control. In the studied setting, the boundary control input is subject to a constant delay. We use the spectral decomposition method and split the system into two components: an unstable and a stable one. To stabilise the unstable part of the system, we connect, for the first time in the literature, the famous backstepping control design technique with the direct-proportional control design. More precisely, we construct a proportional open-loop stabiliser, then, by means of the Artstein transformation we close the loop. At the end of the paper, an example is provided in order to illustrate the acquired results.

Using the Fractional Differential Equation for the Control of Objects with Delay

This paper proposes a new structure and substantiates the choice of a technique for controller design using fractional integration and fractional differentiation. The method of fractional integration is based on extrapolation using a series of integrating and differentiating links, the time constant of which changes symmetrically from one step to another. The new controller structure does not contain the three traditional links (proportional, integrating, and differentiating) but contains six links, three of which are incomplete integration, incomplete differentiation, and redundant (for example, one and a half) integration. The proposed technique consists of modeling a controller with the indicated six paths and using the numerical optimization method to calculate the coefficients of each such path. Alternative controllers are known PID controllers and PIλDµ controllers. Both of these species contain only three tracts. The proposed structure has never been used before, and publications with examples of calculation of such structures were not found in the literature. The effectiveness of the proposed method is confirmed by modeling and examples.

A Robust Backstepping Sliding Mode Controller with Chattering-Free Strategy for a Swarm of Drones

This paper presents a robust controller for a swarm of drones that are subjected to external disturbances. Integrating a fuzzy-based system in the sliding mode control technique, a chattering-free controller is proposed for the trajectory tracking of a drone. Furthermore, the formation controller for a group of drones is developed using the Backstepping control design technique. The integration of a fuzzy rule-based system in the sliding mode tracking controller enables overcoming the inherent chattering problem due to discontinuous switching function in the sliding mode control technique and provides smooth and chattering-free control signals. The asymptotic stability of the overall system is shown using the Lyapunov stability theory. Finally, the control design performance is evaluated using numerical simulations.

1차 시간지연 프로세스를 위한 IMC 기법에 기초한 PID 제어기 설계

In the design of the PID controller, if the gain is increased to speed up the response speed, the overshoot may become large and become unstable. Conversely, if the gain is reduced to mitigate the overshoot, the response speed is slowed down and the response performance is degraded. Because of these opposed relationships, an appropriate compromise between excellent response performance and stability is necessary. In addition, a conventional PID controller with fixed parameters cannot expect excellent performance when used in a control environment different from the design conditions, and in some cases may become unstable, so a stability margin must be ensured. This paper proposes IMC-PID controller design and tuning techniques based on IMC principles. In an IMC based PID controller, the only adjustment parameter to obtain the controller

DC 모터 속도 제어시스템을 위한 내부모델 원리 기반 제어기와 외란 관측기 기반 제어기의 등가 조건

Asymptotic tracking of a reference model and nonlinear disturbance rejection are two of the most important attributes of an effective control system. A DOB-based controller, which is designed based on an augmented system model including the disturbance dynamics, relies mainly on the disturbance estimation to provide robust reference tracking performance. While IMP-based controller design technique achieves the same result by including a dynamic model of the reference and disturbance in the control system model. However, the similarity of these two control techniques extends beyond basic design consideration. This paper presents an analytical study that reaches an equivalent condition between the two classes of controllers for a DC motor speed control problem. Based on the obtained condition, it is proposed that the DOB-based controller can be designed such that it shows the same performance as the IMP-based controller. This has been further verified through a simulation which shows the same robust performance in both cases.

Finite-Dimensional Controllers for Consensus in a Leader-Follower Network of Marginally Unstable Infinite-Dimensional Agents

We consider the output-feedback state consensus problem for a homogeneous multi-agent system consisting of one leader agent and N follower agents. The dynamics of each of these agents is governed by a single-input single-output regular linear system (RLS), with the input to the leader agent being zero at all times. The transfer function of this RLS has all its poles in the closed left-half of the complex-plane, with only a finite number of them lying on the imaginary axis. Each follower agent can access the relative output of all its neighboring agents and some of the follower agents can access the relative output of the leader. The communication graph associated with the exchange of relative outputs is directed. Under this setting, we first establish that a controller solves the above leader-follower consensus problem if and only if it can simultaneously stabilize N regular linear systems. We then adapt a recently developed frequency-domain technique to construct a stable finite-dimensional output-feedback controller which solves the simultaneous stabilization problem, and hence the consensus problem. We demonstrate the efficacy of our controller design technique using a numerical example.

Intelligent Dynamic Inversion Controller Design for Ball and Beam System

The Ball and beam system (BBS) is an attractive laboratory experimental tool because of its inherent nonlinear and open-loop unstable properties. Designing an effective ball and beam system controller is a real challenge for researchers and engineers. In this paper, the control design technique is investigated by using Intelligent Dynamic Inversion (IDI) method for this nonlinear and unstable system. The proposed control law is an enhanced version of conventional Dynamic Inversion control incorporating an intelligent control element in it. The Moore-Penrose Generalized Inverse (MPGI) is used to invert the prescribed constraint dynamics to realize the baseline control law. A sliding mode-based intelligent control element is further augmented with the baseline control to enhance the robustness against uncertainties, nonlinearities, and external disturbances. The semi-global asymptotic stability of IDI control is guaranteed in the sense of Lyapunov. Numerical simulations and laboratory experiments are carried out on this ball and beam physical system to analyze the effectiveness of the controller. In addition to that, comparative analysis of RGDI control with classical Linear Quadratic Regulator and Fractional Order Controller are also presented on the experimental test bench.

Fault-Tolerant Control for a High Altitude Long Endurance Aircraft

High Altitude Long Endurance (HALE) aircraft consist of extremely light-weight structures in combination with a high wingspan and high aspect ratio. The combination of these properties results in an unique dynamic behavior of the aircraft system featuring a strong interaction of structural and rigid body eigenmodes. These characteristics lead to specific demands on the robustness and fault tolerance of flight control algorithms of such aircraft. The control system must be able to navigate the aircraft safely along defined tracks even in case of fault scenarios. Due to the size of these aircraft they are usually over-actuated featuring multiple redundant control surfaces. This redundancy is used in this paper to design a fault tolerant control system ensuring optimal control performance during fault scenarios. The strategy is based on a fault detection and isolation (FDI) algorithm to detect malfunctioning control surfaces. This fault information is used to switch to alternate control laws in a multi-model control approach. The FDI filters are designed using the nullspace-based design paradigm, while the alternate controllers are synthesized applying structured H∞ control design techniques.

Adaptive Backstepping Integral Sliding Mode Control Combined with Super-Twisting Algorithm For Nonlinear UAV Quadrotor System

Quadrotors are extremely agile UAVs with many uncertainties related to their moment of inertia, drag coefficients, and mass. Besides aerodynamic turbulence, the quadrotor is rich in non-linearity due to its underactuated mechanical system. These last two factors lead to problems that require adaptive and robust control. This research paper describes a new hybrid robust nonlinear control technique for a quadrotor. First, a combination of backstepping and sliding-mode approaches based on proportional integral derivative modified surfaces is developed to address the quadrotor trajectory tracking problem, where the Lyapunov method is used to evaluate the control system's stability. Second, adaptive technique combined with sliding mode control to estimate the various parameters of the proposed controller. Super-Twisting algorithm is examined in order to minimize the chattering impact of sliding mode control. To reduce the error convergence time and to increase the performance of speed tracking, a novel super-twisting adaptive backstepping PID sliding mode approach is presented for the quadrotor rotational and translational subsystems. Simulation results are shown to demonstrate the efficacy and practicality of the proposed control. To illustrate the superiority and the designed control technique's effectiveness, a comparative analysis is performed with different newly developed controllers.

Adaptive fuzzy output-feedback event-triggered control for fractional-order nonlinear system.

This paper studies the issue of adaptive fuzzy output-feedback event-triggered control (ETC) for a fractional-order nonlinear system (FONS). The considered fractional-order system is subject to unmeasurable states. Fuzzy-logic systems (FLSs) are used to approximate unknown nonlinear functions, and a fuzzy state observer is founded to estimate the unmeasurable states. By constructing appropriate Lyapunov functions and utilizing the backstepping dynamic surface control (DSC) design technique, an adaptive fuzzy output-feedback ETC scheme is developed to reduce the usage of communication resources. It is proved that the controlled fractional-order system is stable, the tracking and observer errors are able to converge to a neighborhood of zero, and the Zeno phenomenon is excluded. A simulation example is given to verify the availability of the proposed ETC algorithm.

Preliminary Analysis of Control Design for Long-Endurance AUVs

Motivated by the needs of long-endurance autonomous underwater vehicles, we seek to better understand trade-offs associated with control systems that seek to reduce energy consumption. In this paper we demonstrate a technique for controller design for an autonomous underwater vehicle (AUV). We examine the well-known design requirements, such as reference tracking performance and agility (e.g, step-response characteristics) in the context of energy required by control surface servos. The results of our analysis are used to inform an H∞ controller synthesis problem with the objective of balancing these tradeoffs while reducing energy consumption.