3D Control Research Articles

Design of a 2-DOF Control and Disturbance Estimator for a Magnetic Levitation System

Design of a 2-DOF Control and Disturbance Estimator for a Magnetic Levitation System

二次元重心位置制御によるローバーの不整地走行性の検討

二次元重心位置制御によるローバーの不整地走行性の検討

Fictitious Reference Iterative Tuning-Based Two-Degrees-of-Freedom Method for Permanent Magnet Synchronous Motor Speed Control Using FPGA for a High-Frequency SiC MOSFET InverterMOSFET Inverter

This paper proposes proportional-integral/proportional gain controller parameter tuning in a two-degrees-of-freedom (2DOF) control system using the fictitious reference iterative tuning (FRIT) method for permanent magnet synchronous motor (PMSM) speed control using a field-programmable gate array (FPGA) for a high-frequency SiC MOSFET (metal oxide semiconductor field-effect transistor) inverter. The PI-P (proportional-integral/proportional) controller parameters can be tuned using the FRIT method from one-shot experimental data without using a mathematical model of the plant. Particle swarm optimization is used for FRIT optimization. An inverter that uses a SiC MOSFET is presented to achieve high-frequency operation at up to100 kHz using a switching pulse-width modulation (PWM) technique. As a result, a high-responsivity and high-stability PMSM (permanent magnet synchronous motor) control system is achieved, where the speed response follows the ideal response characteristic for both the step response and the disturbance response. High-responsivity and optimal disturbance rejection can be achieved using the 2DOF control system. FPGA-based digital hardware control is used to maximize the switching frequency of the SiC MOSFET inverter. Finally, an experimental system is set up, and experimental results are presented to prove the viability of the proposed method.

A robustification of the two degree-of-freedom controller based upon multivariable generalized predictive control law and robust H∞ control for a doubly-fed induction generator

A robustification method of primary two degree-of-freedom (2-DOF) controllers is proposed in this paper to control the wind turbine system equipped with a doubly-fed induction generator DFIG. The proposed robustification method should follow the following three step-procedures. First, the primary 2-DOF controller is designed through the initial form of the multivariable generalized predictive control MGPC law to ensure a good tracking dynamic of reference trajectories. Second, the robust [Formula: see text] controller is independently designed for the previous system to ensure good robustness properties of the closed-loop system against model uncertainties, neglecting dynamics and sensor noises. Finally, both above mentioned controllers are combined to design the robustified 2-DOF-MGPC controller using Youla parameterization method. Therefore, the obtained controller conserves the same good tracking dynamic that is provided by the primary 2-DOF-MGPC controller. It ensures the same good robustness properties which are produced by the robust [Formula: see text] controller. A wind turbine system equipped with a DFIG is controlled by the robustified 2-DOF-MGPC controller. Its dynamic behaviour is modelled by an unstructured-output multiplicative uncertainty plant. The controller performances are valid by comparison with those given through both controllers, which are primary 2-DOF-MGPC and robust [Formula: see text] controllers in time and frequency domains.

Robust RST control design based on Multi-Objective Particle Swarm Optimization approach

In this paper, a novel method for the digital two-Degrees-Of-Freedom (2DOF) controller design, called canonical RST structure, is proposed and successfully implemented based on a Multi-Objective Particle Swarm Optimization (MOPSO) approach. This is a polynomial control structure allowing independently the regulation and the tracking of discrete-time systems. An application to the variable speed control of an electrical DC Drive is investigated. The RST design and tuning problem is formulated as a multi-objective optimization problem. The proposed MOPSO algorithm which is based on the Pareto dominance is used to identify the non-dominated solutions. This approach used the leader selection strategy that is called a geographically-based system. In addition, the adaptive grid method is used to produce well-distributed Pareto fronts in the multi-objective formalism. The well known NSGA-II and the proposed MOPSO algorithms are evaluated and compared with each other in terms of several performance metrics in order to show the superiority and the effectiveness of the proposed method. Simulation results demonstrate the advantages of the MOPSO-tuned RST control structure in terms of performance and robustness.

Synthesised H∞ / μ Control Design for Dynamically Substructured Systems

In the dynamically substructured system (DSS) testing technique, a controller that synchronises the responses of physical and numerical substructures is an essential part of the testing scheme to ensure synchronisation fidelity. This paper discusses a novel approach that generates a two-degree-of-freedom (2-DOF) output feedback controller for multi-input, multioutput (MIMO) DSS via control synthesis. This 2-DOF output feedback controller yields robust stability and robust performance of the physical/numerical substructure synchronisation and enables controller tuning in the frequency domain. Simulation and experimental results have been shown to validate the efficacy of the method.

Flatness-Based Torque Control of Saturated Surface-Mounted Permanent Magnet Synchronous Machines

Modern permanent magnet synchronous machines (PMSMs) may also be operated in regimes where significant magnetic saturation occurs. Classical fundamental wave models do not incorporate magnetic saturation in a systematic way. Mostly, only heuristic extensions can be found in the literature. Control schemes based on such $dq0$ -models are thus often unable to achieve the given control demands. This paper proposes a flatness-based torque control strategy for a saturated surface-mounted PMSM. Different to existing works, magnetic saturation is considered in a thorough and physically consistent way. Based on a calibrated magnetic equivalent circuit model of the PMSM, a simplified model suitable for the flatness-based controller design is derived. The proposed 2-DOF control scheme inherently accounts for the mutual coupling of the phase windings. Furthermore, the time-varying controller gains are obtained by pole placement technique. In contrast to the majority of controllers used for PMSM control, the proposed control scheme is formulated in the stator-fixed reference frame, and hence, no coordinate transformation is necessary. The flatness-based torque controller is implemented on an experimental test bench. An accelerated run-up of the PMSM with about four times the rated torque is performed to highlight the feasibility of the proposed approach. Finally, the flatness-based torque controller is compared with a common vector control implementation based on a $dq0$ -model of the motor.

2-DOF Block Pole Placement Control Application To: Have-DASH-IIBITT Missile

In a multivariable servomechanism design, it is required that the output vector tracks a certain reference vector while satisfying some desired transient specifications, for this purpose a 2DOF control law consisting of state feedback gain and feedforward scaling gain is proposed. The control law is designed using block pole placement technique by assigning a set of desired Block poles in different canonical forms. The resulting control is simulated for linearized model of the HAVE DASH II BTT missile; numerical results are analyzed and compared in terms of transient response, gain magnitude, performance robustness, stability robustness and tracking. The suitable structure for this case study is then selected.

Discrete-time domain two-degree-of-freedom control design for integrating and unstable processes with time delay

A discrete-time domain two-degree-of-freedom (2DOF) design method is proposed for integrating and unstable processes with time delay. Based on a 2DOF control structure recently developed, a controller is analytically designed in terms of the H2 optimal control performance specification for the set-point tracking, and another controller is derived by proposing the desired closed-loop transfer function for load disturbance rejection. Both controllers can be tuned relatively independent to realize control optimization. Analytical expression of the set-point response is given for quantitatively tuning the single adjustable parameter in the set-point tracking controller. At the meantime, sufficient and necessary conditions for holding robust stability of the closed-loop control system are established for tuning another adjustable parameter in the disturbance rejection controller, along with numerical tuning guidelines. Illustrative examples from the literature are used to demonstrate the effectiveness of the proposed method.

Simultaneous stabilisation for distributed networked multimode control systems with multiple packet dropouts

This study is concerned with the simultaneous H ∞ stabilisation problem for a physically interconnected large-scale system working in multiple operation modes. A distributed networked control framework is developed. The network-based distributed DOF controllers are designed, which use not only the local measurements but also the neighbouring controllers' broadcasts. The designed controllers guarantee the mean-square stability of the large-scale system in multiple operation modes, and achieve the prescribed H ∞ disturbance attenuation level. Furthermore, the consecutive packet dropouts that occur in multiple communication channels (from the local sensor to the local controller, from the neighbouring controllers to the local controller, and from the local controller to the local actuator) are considered. Based on a stochastic control approach and an orthogonal complement space technique, a sufficient condition for the existence of the simultaneous H ∞ stabilisation controllers is provided, and a parameterisation of the controller gains is derived. An iterative LMI algorithm is established to seek a feasible solution. Finally, a numerical simulation example is exploited to illustrate the validity of the proposed scheme.

H∞Optimal Inversion Feedforward and Robust Feedback Based 2DOF Control Approach for High Speed-Precision Positioning Systems

This paper proposed a novelH∞optimal inversion feedforward and robust feedback based two-freedom-of-freedom (2DOF) control approach to address the positioning error caused by system uncertainties in high speed-precision positioning system. To minimize theH∞norm of the positioning error in the presence of model uncertainty, a linear matrix inequality (LMI) synthesis approach for optimal inversion feedforward controller design is presented. The specification of position resolution, control width, robustness, and output signal magnitude imposed on the entire 2DOF control system are taken as optimization objectives of feedback controller design. The robust feedback controller design approach integrates with feedforward controller systematically and is obtained via LMI optimization. The proposed approach was illustrated through a simulation example of nanopositioning control in atomic force microscope (AFM); the experiment results demonstrated that the proposed 2DOF control approach not only achieves the performance specification but also could improve the positioning control performance compared withH∞mixed sensitivity feedback control and inversion-based 2DOF control.

Two Degree of Freedom Controller Design by AGTM\\AGMP Matching Method for Time Delay Systems

This paper proposes the design of a general Two Degree Of Freedom (2-DOF) controller for time delay systems using a novel method which combines model order reduction, approximate model matching concepts as well as optimization techniques. The desired spectrum is embodied in the form of a transfer function which can be constructed from a set of time domain specifications. The problem of finding the parameters of the 2-DOF controller is formulated as that of obtaining the solution of a set of non-homogeneous linear equations. These set of non-homogeneous linear equations is obtained by using Approximate Generalized Time Moments (AGTM) matching concept, where closed loop response at certain frequency points in s-plane is matched with that of the desired model response. Using genetic algorithm optimum selection of frequency points (expansion points) in s-plane are obtained, which results in an optimum solution of controller parameters. This leads to a high degree of matching of the closed loop response with that of the desired model. The proposed method not only ensures the stability of the closed loop system with a 2-DOF controller but also satisfies the required performance criteria. The developed method does not pose any restriction on either the order of the model or on the structure/order of the controller transfer function. Moreover, this method is computationally simple and easy to implement. Simulation results demonstrate the effectiveness of the proposed method.

Two-degree-of-freedom fractional order-PID controllers design for fractional order processes with dead-time

Recently, fractional order (FO) processes with dead-time have attracted more and more attention of many researchers in control field, but FO-PID controllers design techniques available for the FO processes with dead-time suffer from lack of direct systematic approaches. In this paper, a simple design and parameters tuning approach of two-degree-of-freedom (2-DOF) FO-PID controller based on internal model control (IMC) is proposed for FO processes with dead-time, conventional one-degree-of-freedom control exhibited the shortcoming of coupling of robustness and dynamic response performance. 2-DOF control can overcome the above weakness which means it realizes decoupling of robustness and dynamic performance from each other. The adjustable parameter η2 of FO-PID controller is directly related to the robustness of closed-loop system, and the analytical expression is given between the maximum sensitivity specification Ms and parameters η2. In addition, according to the dynamic performance requirement of the practical system, the parameters η1 can also be selected easily. By approximating the dead-time term of the process model with the first-order Padé or Taylor series, the expressions for 2-DOF FO-PID controller parameters are derived for three classes of FO processes with dead-time. Moreover, compared with other methods, the proposed method is simple and easy to implement. Finally, the simulation results are given to illustrate the effectiveness of this method.

Design of a Nonlinear, Dynamic Feedforward Part for the Evaporator Control of an Organic Rankine Cycle in Heavy Duty Vehicles

A model-based two degree of freedom (2DOF) controller for the evaporator outlet condition in an organic Rankine cycle (ORC) system is presented. The ORC is used in a heavy duty vehicle to convert exhaust gas heat into mechanical power which increases the fuel efficiency The evaporator outlet condition of the working fluid is a crucial variable for the ORC efficiency which thus has to be controlled very accurately However, the exhaust gas thermal energy which serves as heat source to the evaporator, is highly transient depending on the actual engine load. Therefore, excellent disturbance rejection is required with help of an efficient feedforward part. Its novel derivation is based on an exact inversion of a nonlinear, dynamic evaporator model, obtained by the finite volume method that is reduced subsequently. The resulting feedforward controller is therefore very close to the exact inverse dynamic model. Furthermore, online parameter adaption enhances the steady state accuracy of the feedforward part and compensates for model uncertainties. The improvements by the feedforward controller are shown in simulations and its applicability on the vehicle control unit is demonstrated by measurements on a Daimler prototype truck under real traffic conditions.

Internal Model Control–Proportional Integral Derivative–Fractional-Order Filter Controllers Design for Unstable Delay Systems

An analytical design for proportional integral derivative (PID) controller cascaded with a fractional-order filter is proposed for first-order unstable processes with time delay. The design algorithm is based on the internal model control (IMC) paradigm. A two degrees-of-freedom (2DOF) control structure is used to improve the performance of the closed-loop system. In the 2DOF control structure, an integer order controller is used to stabilize the inner-loop, and a fractional-order controller for the stabilized system is employed to improve the performance of the closed-loop system. The Walton–Marshall's method, which is applicable to quasi-polynomials, is then used to establish the internal stability condition of the closed-loop system (the fractional part of the controller in particular) and to seek the set of stabilizing proportional (P) or proportional-derivative (PD) controller parameters.

Teaching learning based optimization algorithm for automatic generation control of power system using 2-DOF PID controller

Abstract In this paper, a novel Teaching Learning Based Optimization (TLBO) algorithm with 2-Degree Freedom of Proportional–Integral–Derivative (2-DOF PID) controller is proposed for Automatic Generation Control (AGC). Initially a widely used two area thermal system is considered and the gains of the PI/PID/2-DOF PID controller are optimized employing a TLBO algorithm. The supremacy of the proposed 2-DOF PID controller has been shown by comparing the results with recently published technique such as conventional ZN, GA, BFOA, DE and hBFOA-PSO based PI controllers for the same system. Additionally, the proposed approach is further extended to multi source power system such as thermal, hydro and gas power plant. The advantage of the proposed approach is demonstrated by comparing the results with some recently published approaches. Sensitivity analysis is performed which demonstrates the ability of the proposed approach to wide changes in system parameters. Finally the proposed approach is investigated under random load variation.

Two-Degree-of-Freedom PID Controller, Its Equivalent Forms and Special cases

<p>The design of control systems is a multi-objective problem so, a two-degree-of-freedom (abbreviated as 2DOF) control system naturally has advantages over a one degree- of-freedom (abbreviated as 1DOF) control system. The main objective of 2DOF control is to control both set point tracking and disturbance rejections.Various 2DOF PID controllers and its equivalent transformations were proposed for industrial use by different researchers. Most of the above researches were published in Japanese language and have not been translated into English language yet. An objective here is to provide detail analysis regarding structure of 2DOF controller, its equivalent forms and its special cases. A system transfer function having transport delay and load disturbance is considered as a test bench to verify various 2DOF control strategies. MATLAB is used as software tool to verify the various 2DOF control strategies. The analysis will be helpful to the engineers and researchers to understand the topic in detail for further exploration.</p>

Radiometric compensation for cooperative distributed multi-projection system through 2-DOF distributed control.

This paper proposes a novel radiometric compensation technique for cooperative projection system based-on distributed optimization. To achieve high scalability and robustness, we assume cooperative projection environments such that 1. each projector does not have information about other projectors as well as target images, 2. the camera does not have information about the projectors either, while having the target images, and 3. only a broadcast communication from the camera to the projectors is allowed to suppress the data transfer bandwidth. To this end, we first investigate a distributed optimization based feedback mechanism that is suitable for the required decentralized information processing environment. Next, we show that this mechanism works well for still image projection, however not necessary for moving images due to the lack of dynamic responsiveness. To overcome this issue, we propose to implement an additional feedforward mechanism. Such a 2 Degree Of Freedom (2-DOF) control structure is well-known in control engineering community as a typical method to enhance not only disturbance rejection but also reference tracking capability, simultaneously. We theoretically guarantee and experimentally demonstrate that this 2-DOF structure yields the moving image projection accuracy that is overwhelming the best achievable performance only by the distributed optimization mechanisms.

Rate-Dependent Modeling and <inline-formula> <tex-math notation="LaTeX">$\text{H}_{\mathrm {\infty }}$ </tex-math></inline-formula> Robust Control of GMA Based on Hammerstein Model With Preisach Operator

In this brief, a new Hammerstein model is proposed for a rate-dependent hysteresis in giant magnetostrictive actuators (GMAs). A Preisach operator and an autoregressive model with exogenous input are used to represent, respectively, the static nonlinear function and the linear dynamic subsystem of this model. It is shown that the proposed model can satisfactorily describe the hysteresis of a GMA within a frequency range of 0–100 Hz. Based on this model, a 2 DOF control scheme with an $\text{H}_{\infty }$ robust controller combined with an inverse compensator is proposed for real-time trajectory tracking. The proposed control scheme can maintain system stability and tracking performance in the presence of system uncertainties and external disturbances. The simulation and experimental results show that the proposed model and the corresponding control scheme can significantly improve the performance of the rate-dependent hysteresis system.

2DOF Controller Tuning

At present the two degrees of freedom (2DOF) controllers are more often available. These controllers enable to tune both from point of view of the desired variable and the disturbance variable as well. It allows increase the overall quality of control. For the tuning of the 2DOF controllers to date there are only a few suitable methods. This paper is devoted to the tuning of the 2DOF PI and PID controllers by the multiple dominant pole method (MDPM) for first order plants and integrating plants with time delay. It is an analytical method and it is shown that by the corresponding tuning of the 2DOF controllers it is possible to obtain the non-oscillatory servo and regulatory step responses without overshoots. The use is demonstrated in the example.