Showing papers on "PID controller published in 2006"

Proportional-resonant controllers and filters for grid-connected voltage-source converters

Abstract: The recently introduced proportional-resonant (PR) controllers and filters, and their suitability for current/voltage control of grid-connected converters, are described. Using the PR controllers, the converter reference tracking performance can be enhanced and previously known shortcomings associated with conventional PI controllers can be alleviated. These shortcomings include steady-state errors in single-phase systems and the need for synchronous d-q transformation in three-phase systems. Based on similar control theory, PR filters can also be used for generating the harmonic command reference precisely in an active power filter, especially for single-phase systems, where d-q transformation theory is not directly applicable. Another advantage associated with the PR controllers and filters is the possibility of implementing selective harmonic compensation without requiring excessive computational resources. Given these advantages and the belief that PR control will find wide-ranging applications in grid-interfaced converters, PR control theory is revised in detail with a number of practical cases that have been implemented previously, described clearly to give a comprehensive reference on PR control and filtering.

Attitude stabilization of a VTOL quadrotor aircraft

Abstract: In this paper, we propose a new quaternion-based feedback control scheme for exponential attitude stabilization of a four-rotor vertical takeoff and landing aerial robot known as a quadrotor aircraft. The proposed controller is based upon the compensation of the Coriolis and gyroscopic torques and the use of a PD/sup 2/ feedback structure, where the proportional action is in terms of the vector quaternion and the two derivative actions are in terms of the airframe angular velocity and the vector quaternion velocity. We also show that the model-independent PD controller, where the proportional action is in terms of the vector-quaternion and the derivative action is in terms of the airframe angular velocity, without compensation of the Coriolis and gyroscopic torques, provides asymptotic stability for our problem. The proposed controller as well as some other controllers have been tested experimentally on a small-scale quadrotor aircraft.

Multiple harmonics control for three-phase grid converter systems with the use of PI-RES current controller in a rotating frame

Abstract: Voltage source inverters connected to the grid in applications such as active rectifiers, active filters, uninterruptible power supplies, and distributed generation systems need an optimal ac current control. To obtain zero steady-state error at the fundamental frequency (i.e., unity power factor), the use of a standard integrator in a rotating frame is as effective as the use of a resonant controller in a stationary frame. However, the grid voltage harmonics influence the current controller and generate current harmonics unless several integrators in multiple rotating frames or resonant compensators in a stationary frame are adopted. In this letter, a hybrid system consisting of a proportional integral (PI) controller plus a generic hth harmonic resonant controller implemented in a frame rotating at the n th harmonic frequency is discussed in detail. The hth harmonic controller is able to decrease both the (h - n)th and (h + n)th harmonics, while the PI controller is able to decrease other harmonics if the synchronization phase signal adopted for the frame transformation is unfiltered. It is demonstrated that the use of a PI and sixth harmonic resonant compensator is effective for both positive and negative sequence fifth and seventh harmonics; hence, four harmonics are compensated with the proportional integral-resonant (PI-RES) controller implemented in a synchronous frame. Simulation and experimental tests validate the proposed analysis

Practical PID Control

Abstract: Basics of PID Control.- Derivative Filter Design.- Anti-windup Strategies.- Set-point Weighting.- Use of a Feedforward Action.- Plug&Control.- Identification and Model Reduction Techniques.- Performance Assessment.- Control Structures.

PID control system analysis and design

Abstract: With its three-term functionality offering treatment of both transient and steady-state responses, proportional-integral-derivative (PID) control provides a generic and efficient solution to real-world control problems. The wide application of PID control has stimulated and sustained research and development to "get the best out of PID", and "the search is on to find the next key technology or methodology for PID tuning". This article presents remedies for problems involving the integral and derivative terms. PID design objectives, methods, and future directions are discussed. Subsequently, a computerized simulation-based approach is presented, together with illustrative design results for first-order, higher order, and nonlinear plants. Finally, we discuss differences between academic research and industrial practice, so as to motivate new research directions in PID control.

PID tuning using extremum seeking: online, model-free performance optimization

Abstract: Extremum seeking (ES) tunes PID controllers by minimizing a cost function that characterizes the desired behavior of the closed-loop system. This tuning method is demonstrated on four typical plants and found to give parameters that yield performance better than or comparable to that of other popular tuning methods. Additionally, ES produces favorable results in the presence of actuator saturation. The ES method thus has an advantage over model-based PID tuning schemes in applications that exhibit actuator saturation. However, since ES requires initial values of the PID parameters, the method can be viewed as a complement to another PID parameter design method. Furthermore, the ES cost function can be chosen to reflect the desired performance attributes.

Fractional order PID control of a DC-motor with elastic shaft: a case study

Abstract: In this paper, a fractional order PID controller is investigated for a position servomechanism control system considering actuator saturation and the shaft torsional flexibility. For actually implementation, we introduced a modified approximation method to realize the designed fractional order PID controller. Numerous simulation comparisons presented in this paper indicate that, the fractional order PID controller, if properly designed and implemented, will outperform the conventional integer order PID controller.

Sliding mode control with PID sliding surface and experimental application to an electromechanical plant.

Abstract: In this study, a sliding mode control system with a proportional+integral+derivative (PID) sliding surface is adopted to control the speed of an electromechanical plant. A robust sliding mode controller is derived so that the actual trajectory tracks the desired trajectory despite uncertainty, nonlinear dynamics, and external disturbances. The proposed sliding mode controller is chosen to ensure the stability of overall dynamics during the reaching phase and sliding phase. The stability of the system is guaranteed in the sense of the Lyapunov stability theorem. The chattering problem is overcome using a hyperbolic function for the sliding surface. Experimental results that are compared with the results of conventional PID verify that the proposed sliding mode controller can achieve favorable tracking performance, and it is robust with regard to uncertainties and disturbances.

Patents, software, and hardware for PID control: an overview and analysis of the current art

Abstract: The wide application of proportional-integral-derivative (PID) control has stimulated and sustained the development and patenting of various tuning and associated system identification techniques. However, to achieve optimal transient performance, tuning methods vary, and at present there exists no standardization of PID structures. This article provides an overview and analysis of PID patents, commercial software packages, and hardware modules. It also highlights the differences between academic research and industrial practice so as to motivate new research directions in PID technology.

TS-fuzzy-controlled active power filter for load compensation

Abstract: This paper describes the application of Takagi-Sugeno (TS)-type fuzzy logic controller to a three-phase shunt active power filter for the power-quality improvement and reactive power compensation required by a nonlinear load. The advantage of fuzzy logic control is that it does not require a mathematical model of the system. The application of the Mamdani-type fuzzy logic controller to a three-phase shunt active power filter was investigated earlier but it has the limitation of a larger number of fuzzy sets and rules. Therefore, it needs to optimize a large number of coefficients, which increases the complexity of the controller. On the other hand, TS fuzzy controllers are quite general in that they use arbitrary input fuzzy sets, any type of fuzzy logic, and the general defuzzifier. Moreover, the TS fuzzy controller could be designed by using a lower number of rules and classes. Further, in this paper, the hysteresis current control mode of operation is implemented for pulsewidth-modulation switching signal generation. Computer simulation results show that the dynamic behavior of the TS fuzzy controller is better than the conventional proportional-integral (PI) controller and is found to be more robust to changes in load and other system parameters compared to the conventional PI controller.

An Improved ILMI Method for Static Output Feedback Control With Application to Multivariable PID Control

Abstract: An improved iterative linear matrix inequality (ILMI) algorithm for static output feedback (SOF) stabilization problem without introducing any additional variables is proposed in this note. The proposed ILMI algorithm is also extended to solve the SOF Hinfin controller design problem. They are applied to the multivariable PID controllers. Numerical examples show that the proposed algorithms yield better results and faster convergence than the existing ones

Comparison between PSO and GA for Parameters Optimization of PID Controller

Abstract: Based on the conception of evolution, the Particle Swarm Optimization (PSO) algorithm and Genetic Algorithm (GA) are applied to parameters optimization of PID controller. Simulations are carried out in the typical industrial models. Comparing PSO with GA, it is shown that the performance of PSO is better than that of GA, it is provided that a preferable method to optimization parameters of PID controller.

Adaptive resonant controller for grid-connected converters in distributed power generation systems

Abstract: Due to its superior performance when regulating sinusoidal waveforms and the possibility to compensate for low order harmonics by means of harmonic compensator (HC), proportional resonant (PR) controller is a real alternative to the conventional proportional integral (PI) controller, when implemented in a grid connected system like distributed power generation systems (DPGS). Anyway, both PR and HC necessitate the resonant frequency value inside their internal model. Normally, the nominal value of the grid frequency and its multiples are used, but in the case when the grid frequency experiences fluctuations, the performance of both PR and HC is diminished. This paper discuss the possibility of improving the behavior of resonant controller and harmonic compensator in the case of grid frequency variations. The proposed solution makes use of the frequency information provided by the phase-locked loop (PLL) system already used in most of DPGS today. Experimental results are presented in order to validate the proposed solution and it shows to work very well.

Position Control of Shape Memory Alloy Actuators by Using Self Tuning Fuzzy PID Controller

Abstract: Shape Memory Alloy (SMA) actuators, which have ability to return to a predetermined shape when heated, have many potential applications in aeronautics, surgical tools, robotics and so on. Although the number of applications is increasing, there has been limited success in precise motion control since the systems are disturbed by unknown factors beside their inherent nonlinear hysteresis or the surrounding environment of the systems is changed. This paper presents a new development of SMA position control system by using self-tuning fuzzy PID controller. The use of this control algorithm is to tune the parameters of the PID controller by integrating fuzzy inference and producing a fuzzy adaptive PID controller that can be used to improve the control performance of nonlinear systems. The experimental results of position control of SMA actuators using conventional and self tuning fuzzy PID controller are both included in this paper.

Combined Feedback Linearization and Constrained Model Predictive Control for Entry Flight

Abstract: The advantages of constrained model predictive control over proportional integral derivative (PID) control applied to a feedback-linearized entry flight-control problem are discussed. The feedback linearization is based on the full rotational equations of motion rather than on a conventional model derived from time-scale separation. Input and state constraints are applied to avoid input saturations, to guarantee a minimum level of tracking performance, and to avoid physical vehicle state constraints violation. A constraint mapping algorithm is developed to map the input and state constraints on the new inputs after feedback linearization. The performance of the constrained model predictive control design is compared with that of two PID control designs. Simulation of a complete entry flight demonstrates the advantages of the constrained model predictive control design, because control surfaces do not saturate, control actions are more smooth and efficient, no gain scheduling is required, and all performance requirements are satisfied.

Controllers, observers, and applications thereof

Abstract: Controller scaling and parameterization (2900) are described. Techniques that can be improved by employing the scaling and parameterization include, but are not limited to, controller design, tuning and optimization. The scaling and parameterization methods described here apply to transfer function based controllers, including PID controllers. The parameterization methods also apply to state feedback and state observer based controllers, as well as linear active disturbance rejection (ADRC) controllers. Parameterization simplifies the use of ADRC. A discrete extended state observer (DESO) and a generalized extended state observer (GESO) are described. They improve the performance of the ESO and therefore ADRC. A tracking control algorithm is also described that improves the performance of the ADRC controller. A general algorithm is described for applying ADRC to multi-input multi-output systems. Several specific applications of the control systems and processes are disclosed.

Design of Fractional Order Controller Based on Particle Swarm Optimization

Abstract: An intelligent optimization method for designing Fractional Order PID (FOPID) controllers based on Particle Swarm Optimization (PSO) is presented in this paper. Fractional calculus can provide novel and higher performance extension for FOPID controllers. However, the difficulties of designing FOPlD controllers increase, because FOPID controllers append derivative order and integral order in comparison with traditional PID controllers. To design the parameters of FOPID controllers, the enhanced PSO algorithms is adopted, which guarantee the particle position inside the defined search spaces with momentum factor. The optimization performance target is the weighted combination of ITAE and control input. The numerical realization of FOPlD controllers uses the methods of Tustin operator and continued fraction expansion. Experimental results show the proposed design method can design effectively the parameters of FOPID controllers.