PID-based Control Research Articles

CFD analysis of a TG–DSC apparatus

A ThermoGravimetric analyser with differential scanning calorimetry (TG–DSC) has been studied during the fusion of an indium sample using both an experimental procedure and a CFD simulation. To do so, a CAD model of the real device was built and meshed in detail, in order to take into account the small scale processes which occur inside the crucibles. Several theoretical models, some previously existing in the CFD software used and others developed ad hoc, were applied to simulate the whole facility. Therefore, realistic boundary conditions and a PID-based control system already developed for previous studies had to be used. The validation of the CFD model was done by comparing the outcome of the resulting simulation to the results obtained by experimental procedure in a case where natural convection is the main heat and mass transfer mechanism. This comparison was made for two different heating rates inside the furnace. Typical characteristics of phase change process inside a TG-DSC as thermal lag, onset temperature or heat flow exchange during the fusion could be analysed. As well, a more detailed approach to physical phenomena taking place inside the furnace could be done, since CFD simulations allow to obtain data which is not achievable experimentally. Besides, a valid CFD model for a TG-DSC could be later used in further CFD simulations.

Implementations of PID Controller and its Transient Behaviour in Active Suspension System

Advancement in computational technologies has accelerated the research effort in exploring the possibility of semi-active and active suspension. Computational simulations were used widely in the studies of the controller strategies. Among them are PID controllers. Studies from previous work suggested that PID controllers are capable of improving ride comfort and road holding capability. However, very little emphasis is given to examine the whole state of the vehicle suspension system resulted from this implementation. Therefore this study will examine the application of a basic PID controller to an active suspension system (ASS) to determine the requirement of active force that should be delivered in stabilizing the whole system. Two different configurations of electromagnetic suspension system (EMS) will be considered. One variable in the vehicle system will be selected to be the controlled output of PID controller and its effect to overall vehicle state will be observed. In the cases that the PID was able to stabilize the body responses, deterioration was noticed in the wheel responses. While it stabilizes the controlled output, the active force from controller was channelled into deteriorating other vehicle parameters.

A Pneumatic Miniature Robotic Control System Based on Improved Single Neural Network PID Control

At present pneumatic miniature robotic control system usually adopts PID control strategy. The basic PID control strategy has its limitations. To cope with this problem, a lot of methods to optimize this strategy have been researched. In the paper an improved single neural network PID control strategy is put forward. The control strategy is a single neuron adaptive controller with adjusting weighting coefficient. Both simulation and experimental results indicate that this scheme is a feasible control method for the 3-dof pneumatic miniature robotic control system.

Crystal shape 2D modeling for transient CZ silicon crystal growth

A non-stationary axisymmetric model of Czochralski silicon single crystal growth is presented. The model describes transient behavior of crystal–melt, melt–gas and crystal–gas interfaces in connection with PID-based control of crystal diameter by changing crystal pulling velocity and heater power. To calculate significant crystal shape changes, unstructured finite element mesh is used in crystal and melt together with automatic element size control. Heater temperature changes are modeled with a simplified integral model. A numerical simulation example of start cone growth is given.

Composite controller design for a 6DOF Stewart nanoscale platform

Abstract A composite controller combines of feedforward and feedback control for a 6DOF Stewart nanoscale platform driven by piezoelectric actuators is proposed. A hysteresis model derived by using a dynamic Preisach method is used for the feedforward control. A measurement method can directly measure the pose of the end-effector is developed to support the task-space on-line control in practice. An example of peg-in-hole insertion task is investigated. Lyapunov theory is used to search a stable PID-based controller whose optimal gain is found by using relay feedback test method and genetic algorithm. In experiment, conditions with/without external load are employed for performance evaluation. The composite controller is verified to be capable of improving position accuracy significantly.

Design of an Adaptive Predictive Control Strategy for a MIMO Process

An adaptive predictive (AP) control strategy for a multi-input multi-output (MIMO) industrial process is designed. The Relative Gain Array pairing technique is used to define the adaptive predictive control strategy, i.e. the AP models structure. The control strategy is simulated using the ADEX. The controllers' performance is evaluated on a simulator of a crude oil atmospheric distillation process which is currently operating in a Petroleos Mexicanos refinery. The simulation results are also compared with a PID-based control strategy, showing an improvement of operation stability.

Extensive Tracking Performance Analysis of Classical Feedback Control for XY Stage Ballscrew Drive System

Performance analysis in term of identifying the system's transient response, stability and system's dynamical behavior in control system design is undeniably a must process. There are several ways in which a system can be analyzed. An example of well known techniques are using time domain and frequency domain approach. This paper is focused on the fundamental aspect of analysis of classical feedback controller in frequency domain of XY milling table ballscrew drive system. The controller used for the system is the basic PID controller using Matlab SISOTOOL graphical user interface. For this case, the frequency response function (FRF) of the system is used instead of using estimated model of transfer function to represent the real system. Result in simulation shows that after proper tuning of the controller, the system has been successfully being controlled accordingly. In addition, the result also fulfill the set requirement of frequency domain analysis in terms of the required gain and phase margin, the required maximum peak sensitivity and complimentary sensitivity function and the required stability.

Development of ANN model for geothermal district heating system and a novel PID-based control strategy

This article refers to development of ANN modeling for geothermal district heating systems, and the novel and optimal control strategy for exergy efficiency maximization by using these systems. As a real case study, the geothermal district heating system in Afyonkarahisar (AGDHS), Turkey is considered. Its actual thermal data as of average weekly data are collected in heating seasons during the period 2006–2010 for ANN model and control strategy. In this study, a novel control strategy-based PID controller is proposed to ensure the maximum exergy efficiency via the flow rate control of the AGDHS. ANN model of the AGDHS is used as a test system to demonstrate the effectiveness of the proposed control strategy under various operating conditions. The results of this study show that the network yields a good statistical performance with respect to maximum correlation coefficient (0.9986) with minimum RMSE and MAPE values. Moreover, the proposed PID controller has better control performance compared to the manual control even in the presence of the AGDHS. Energy efficiency and cost saving of the system are increased by 13% by the proposed control strategy. Thus, the proposed control strategy has the potential for creating more comfortable thermal environments for district heating systems.

Simultaneous gains tuning in boiler/turbine PID-based controller clusters using iterative feedback tuning methodology

Tuning a complex multi-loop PID based control system requires considerable experience. In today's power industry the number of available qualified tuners is dwindling and there is a great need for better tuning tools to maintain and improve the performance of complex multivariable processes. Multi-loop PID tuning is the procedure for the online tuning of a cluster of PID controllers operating in a closed loop with a multivariable process. This paper presents the first application of the simultaneous tuning technique to the multi-input-multi-output (MIMO) PID based nonlinear controller in the power plant control context, with the closed-loop system consisting of a MIMO nonlinear boiler/turbine model and a nonlinear cluster of six PID-type controllers. Although simplified, the dynamics and cross-coupling of the process and the PID cluster are similar to those used in a real power plant. The particular technique selected, iterative feedback tuning (IFT), utilizes the linearized version of the PID cluster for signal conditioning, but the data collection and tuning is carried out on the full nonlinear closed-loop system. Based on the figure of merit for the control system performance, the IFT is shown to deliver performance favorably comparable to that attained through the empirical tuning carried out by an experienced control engineer.

Robust Real-Time Model Predictive Control for Torsional Vibration System

In this paper, explicit, robust Model Predictive Control (MPC) is proposed for the control of a two-mass system in order to achieve not only good tracking performance and load-change effect rejection, but also low torsional vibration, when the measurement noise contains outliers. The control structure presented in this paper is based fundamentally on the combination of explicit MPC and region detection via a self-optimizing variable. In addition, the well-known Kalman filter is replaced by the robust Kalman filter to deal with the outlier signals. The effectiveness of the proposed method is compared with a PID-based control.

Robust stability check for fractional PID-based control systems

This paper considers a closed-loop system consisting of a fractional/integer order system and a fractional PID controller. Assuming that the uncertain coefficients of the fractional PID controller lie in some known intervals independently (i.e. that controller is a member of an interval family), the paper presents some easy to use theorems to investigate the robust bounded-input bounded-output stability of the resultant closed-loop system. Moreover, a finite frequency bound required in drawing the related graphs has also been provided. Finally, some numerical examples are presented to illustrate the results.

Research Trends for PID Controllers

This paper analyses the most significant issues that have been recently been addressed by researchers in the field of Proportional-Integral-Derivative (PID) controllers. In particular, the most recent techniques proposed for tuning and designing PID-based control structures are briefly reviewed, together with methods for assessing their performance. Finally, fractional-order and event-based PID controllers are presented among the most significant developments in the field.

Discrete Time Variable Structure Control for the Dynamic Positioning of an Offshore Supply Vessel

This paper presents a Discrete-Time Variable-Structure Control (DTVSC) for the dynamic positioning system of a marine supply vessel. The DTVSC guarantees robustness with respect to disturbances and parametric variations. Two wave-filtering approaches are employed: the Extended Kalman filter (EKF) and the multi-rate Kalman filter (MREKF). The proposed solution is compared with a PID-based control and a passive non-linear wave filter. The reported simulations show that the proposed solution produces better performances and it is robust in the presence of input disturbances and model uncertainties.

Model-Based Split-Range Algorithm for the Temperature Control of a Batch Reactor

In the manufacturing processes of high value-added products in the pharmaceutical, fine chemical polymer and food industry, insufficient control might produce off-grade products. This can cause significant financial losses, or in the pharmaceutical industry, it can result in an unusable batch. In these industries, batch reactors are commonly used, the control of which is essentially a problem of temperature control. In the industry, an increasing number of heating-cooling systems utilising three different temperature levels can be found, which are advantageous from an economic point of view. However, it makes the control more complicated. This paper presents a split-range designing technique using the model of the controlled system with the aim to design a split-range algorithm more specific to the actual sys- tem. The algorithm described provides high control performance when using it with classical PID-based cascade temperature control of jacketed batch reactors; however, it can be used with or as part of other types of controllers, for ex- ample, model-based temperature controllers. The algorithm can be used in the case of systems where only two as well as where three temperature levels are used for temperature control. Besides the switching between the modes of opera- tion and calculating the value of the manipulated variable, one of the most important functions of the split-range algo- rithm is to keep the sign of the gain of the controlled system unchanged. However, with a more system-specific split-range solution, not only can the sign of the gain be kept unchanged, but the gain can also be constant or less de- pendent on the state of the system. Using this solution, the design of the PID controller becomes simpler and can be implemented in existing systems without serious changes.

Minimum-time rest-to-rest feedforward action for PID feedback MIMO systems

In this paper we present a methodology for the design of a feedforward control law to be applied to a closed-loop PID-based control system for a multi-input multi-output process in order to achieve a minimum-time rest-to-rest transition of the system from an equilibrium point to another subject to constraints on both the control and process variables. In particular, the proposed approach uses decentralized PID controllers which can be designed by any of the conventional methods, such as, for example, those aiming at rejection of load disturbances. Then, the closed-loop generalized bang-bang command input vector is determined by applying a linear programming approach in order to minimize the rest-to-rest output transitions. Conditions for the constraints for which the problem admits a solution are given. Simulations for a two-inputs two-outputs plant highlight the effectiveness of the approach.

PI and PID Regulation Approaches for Performance-Constrained Adaptive Multiprocessor System-on-Chip

Adaptive multiprocessor systems are appearing as a promising solution for dealing with complex and unpredictable scenarios. Given the large variety of possible use cases that these platforms must support and the resulting workload variability, offline approaches are no longer sufficient because they do not allow coping with time changing workloads. This letter presents a novel approach based on the utilization of PI and PID controllers, widely used in control automation, for optimizing resources utilization in Multiprocessor System-on-Chip (MPSoC). Several architecture characteristics such as response time during frequency changing, noise and perturbations are modeled and validated in a high-level model and results are compared to information obtained on a homogeneous MPSoC platform prototype. Power and energy consumption figures are discussed and two controllers are proposed: 1) PI-; and 2) PID-based controllers. Results show the system capability of adapting under disturbing conditions while ensuring application performance constraints and reducing energy consumption.

A MODEL-FREE APPROACH FOR ACCURATE JOINT MOTION CONTROL IN HUMANOID LOCOMOTION

A new model-free approach to precisely control humanoid robot joints is presented in this article. An input–output online identification procedure will permit to compensate neglected or uncertain dynamics, such as, on the one hand, transmission and compliance nonlinear effects, and, on the other hand, network transmission delays. Robustness to parameter variations will be analyzed and compared to other advanced PID-based controllers. Simulations will show that not only good tracking quality can be obtained with this novel technique, but also that it provides a very robust behavior to the closed-loop system. Furthermore, a locomotion task will be tested in a complete humanoid simulator to highlight the suitability of this control approach for such complex systems.

ASTRA-Matlab Integration for the Control of Tokamaks

The current increment in energy consumption has renewed the interest in the development of alternatives to fossil fuels. In this regard, the interest in solving the different control problems existing in nuclear fusion reactors like Tokamaks has been intensified. The aim of this manuscript is to show how the ASTRA code, which is used to simulate the performance of Tokamaks, can be integrated into the Matlab-Simulink tool in order to make easier the development of suitable controllers for Tokamaks. As a demonstrative case study to show the feasibility and the goodness of the proposed integration, a modified anti-windup PID-based controller coupled with an optimization algorithm for the loop voltage has been implemented. This integration represents an original and innovative work in the Tokamak control area and it provides new possibilities for the development and application of advanced control schemes to the standardized ASTRA code.

SVC-06 A Significant Improvement to Tape Drive PES by Canceling LTM with a Robust, High Performance Controller(Servo Control II,Technical Program of Oral Presentations)

Achieving higher tape densities requires a significant reduction in the position-error-signal (PES). The current state-of-the-art for controlling lateral tape motion is a well-tuned proportional-integral-derivative (PID) controller with notches and a large integrator for tracking. This controller is robust to changes in servo dynamics between drives and has desirable tracking properties. Even with these qualities, this controller does not meet the requirements for the next generation of devices. For the next generation of drives to function, the servo system and controller must reduce the 3-sigma value of the PES significantly while preserving the tracking and robustness characteristics of the current controllers. In this paper, we seek to improve upon the current PID-based control design by designing a high performance add-on controller to target lateral tape motion (LTM).

Full Operating Range Robust Hybrid Control of a Coal-Fired Boiler/Turbine Unit

Multi-input-multi-output robust controllers recently designed for the megawatt output/throttle pressure control in a coal-fired power plant boiler/turbine unit have demonstrated performance robustness noticeably superior to that of the currently employed nonlinear PID-based controller. These controllers, however, have been designed only for the range of 150–185MW around the 185MW nominal operating point, exhibiting a significant loss of performance in the lower range of 120–150MW. Through system identification, the reason for this performance loss is demonstrated in the current work to be a pronounced dependence of the boiler/turbine unit steady state gains on the operating point. This problem is addressed via a hybrid control law consisting of two robust controllers and a robust switch between them activated by the set point change. The controllers are designed to cover the corresponding half-ranges of the full operating range. This permits attainment of the desired overall performance as well as reduction of modeling uncertainty induced by the operating point change to approximately 25% of that associated with the previous designs. Robust switching is accomplished through a novel hybrid mode of behavior—robustly controlled discrete transition. The latter mode is produced through realizing that the off-line transfer speedup suggested by Zaccarian and Teel (2005, “The L2(l2) bumpless Transfer Problem for Linear Parts: Its Definition and Solution,” Automatica, 41, pp. 1273–1280) can be taken to the limit and incorporating the result into a robust bumpless transfer technique recently developed by the authors. As demonstrated by simulation results, the proposed strategy provides an adequate solution to the problem of robust boiler/turbine unit performance over the full operating range. This fact combined with numerical algorithm tractability, relative ease of its design, its insensitivity to implementation nonidealities, and accompanying identification methodology for nominal model generation makes it a viable candidate for industrial acceptance.