Digital Proportional Integral Derivative Controller Research Articles

Low Cost PID Controller for Student Digital Control Laboratory Based on Arduino or STM32 Modules

In the teaching process, it is important that students do not carry out exercises only by computer simulations, but also that they carry out research in real time. In times of distance learning during the COVID-19 pandemic, it would be necessary to find a solution so that the students can perform such exercises individually at home. Therefore, it has become necessary to develop cheap and simple modules of digital controllers along with analog objects with adjustable order and time constants. This paper describes a low-cost proportional–integral–derivative (PID) controller for teaching students control techniques and analog control objects in real time. The PID controller is based on the cheap and widely available microcontroller modules Arduino or STM32. The advantage of this solution is that the algorithm of the digital PID controller is calculated every constant period of time. Both the solutions presented in the paper have been successfully tested by students in practice during remote learning during the COVID-19 pandemic.

Control of the temperature in the hot liquid tank by using a digital PID controller considering the random errors of the thermometer indications

A digital PID (Proportional-Integral-Derivative) controller to maintain a constant hot water temperature in the tank was proposed. The thermometer's indications are subject to random errors. The water temperature is determined by solving the inverse problem for a thermometer in the form of a solid cylinder inside which the temperature is measured. The water temperature is determined using a first or second-order thermometer model. The use of differential quotients to calculate the first or second derivative after time causes the controller to be unstable. To increase the stability of the PID system operation, digital filters were used to eliminate the influence of random disturbances of the temperature indicated by the thermometer. This ensures stable, much faster, and more accurate operation of the controller. The operation of the PID controller with the proposed technique for determining the medium temperature was illustrated by using the example of an electric storage heater in which the water temperature should be equal to the pre-set temperature. The novelty of the presented PID control system is the determination of the fluid temperature based on the solution of the inverse problem of heat conduction formulated for a thermometer. As a result, the speed and accuracy of the PID controller are significantly improved.

Digital Stabilization System

A model of a discrete system for stabilizing the ship's course has been developed and the results of research on the choice of an optimal digital controller for it are presented. The method of the describing function is used as a research method. In developing a mathematical model of a discrete system, a typical block diagram of a continuous stabilization system was used. The location of the quantizer and extrapolator in it was determined. The latter was selected as a zero-order extrapolator, as the simplest, easily implemented with standard equipment, although the use of a first-order extrapolator can give some advantage in the accuracy of information recovery. Modeling is carried out in state variables and in a classical way based on a discrete transfer function of stabilization system. For the research, the package of visual block simulation modeling of the MatLab matrix system was used. Modeling of the system of stabilization with different types of controllers allowed to carry out their comparative assessment. To improve the properties of the digital proportional integral derivative controller, it is proposed to introduce in it a correction system.

DIGITAL CONTROL OF A CLOSED LOOP BUCK CONVERTER

The primary focus for the R&D in this area so far has been to figure out the best approach for evaluating and designing the DC-DC converter and perhaps the most appropriate control technique is being applied in different DC-DC converter circuits. Depending on power handling capacity as well as high-frequency switching, certain switching devices are chosen. This paper discusses the deployment of the digital PID controllers in the DC-DC converters. In an attempt to get a quicker response, voltage mode control has been used. Digital controllers started replacing traditional analog controllers more and more. Better immunity to changes in the environment which includes temperature and degradation of components, improved versatility by modifying the software, increasing advanced control methods, and decreased number of the components are the key benefits of the digital control against the analog control. A structured and concise strategy for designing a digitally operated close-loop Dc / Dc buck converter is discussed in this paper beginning with the Buck converter and giving the set of certain performance specification, implementations of the digital Proportional-IntegralDerivative(PID) controller is made. It addresses in depth all the appropriate DSP hardware and/or software methods and approaches needed to implement a controller. In order to illustrate the efficacy of the model, the dynamic response as well as the steady-state performance of controller is provided. The experimental outcomes fit well with the model of simulation. During the implementations of Switch Mode Power Supply (SMPS), application of dsPIC provides new perspectives towards affordable and versatile approaches of digital control.

Real-time feedback control system for ADITYA-U horizontal plasma position stabilisation

The ADITYA-U tokamak (R0 = 0.75 m, a = 0.25 m) is designed to shape plasma column in both single and double null diverter configurations. It is quite well known that sustaining a shaped plasma in tokamak requires very good plasma column position control, both horizontal and vertical. An FPGA-based proportional–integral–derivative (PID) control system has been designed and operated to achieve horizontal plasma position control in ADITYA-U tokamak. The complete system has been rigorously tested with sample signals before implementing to the ADITYA-U plasma discharges. The control system is integrated and time-synchronized with the plasma discharge operation of ADITYA –U. Furthermore, the system has been trained to take appropriate actions during the disruption or plasma failure in the tokamak operation. Detailed experimental results have been obtained by the operation of the digital PID controller. The complete design, installation, operation, tuning of the system along with all the relevant testing and operating experience of the digital PID controller for real-time horizontal plasma position control is presented in the paper.

Design of digital pulse width modulator architecture with digital PID controller for DC-DC converter using FPGA

A digital pulse width modulation architecture (DPWM) along with digital proportional integral derivative (PID) controller to control the DC-DC converter is presented in this paper. Difference between the actual output voltage and the reference voltage is calculated as error value. The look up table is created for PID controller to store the duty cycle ratio and the error value of power converters. Multipliers used in conventional algorithms are replaced by look up tables in the proposed work that enable the compact and low power implementation of digital controllers. DPWM architecture is developed with gray logic against the binary logic used in traditional DPWM architectures. Usage of gray counter also leads to low power consumption in the DPWM architecture. The proposed architecture is designed using Verilog hardware language and realized using field programmable gate array. PWM signals with varying duty cycle percentage can be derived from the proposed architecture. The generated PWM signal can control the switching condition of power converter to regulate the output voltage. Duty cycle percentage ranging from 16 to 96% can be developed with the proposed architecture. Simulation and experimental results of the architecture validate the proposed architecture. PWM signal with maximum operating frequency of 59.49 MHz and 60.22 MHz for SPARTAN 3A and SPARTAN 3E respectively can be generated with the proposed architecture.

Digital PID Control Law Design for Fuel Cell Model Based on FPGA Emulator System

This paper proposes an off-line adaptive digital Proportional Integral Derivative (PID) control algorithm based on Field Programmable Gate Array (FPGA) for Proton Exchange Membrane Fuel Cell (PEMFC) Model. The aim of this research is to obtain the best hydrogen partial pressure (PH2) value using FPGA emulator to design and implement a digital PID controller that track the fuel cell output voltage during a variable load current applied. The off-line Particle Swarm Optimization (PSO) algorithm is used for finding and tuning the optimal value of the digital PID controller parameters that improve the dynamic behavior of the closed loop digital control fuel cell system and to achieve the stability of the desired output voltage of fuel cell. The numerical simulation results (MATLAB) package and FPGA emulator experimental work show the performance of the proposed FPGA-PID controller in terms of voltage error reduction and generating optimal value of the (PH2) control action without oscillation in the output and no saturation state when these results are compared with other control methodology.

Tuning of Digital PID Controllers Using Particle Swarm Optimization Algorithm for a CAN-Based DC Motor Subject to Stochastic Delays

In this article, we investigate the tuning problem of digital proportional-integral-derivative (PID) parameters for a dc motor controlled via the controller area network (CAN). First, the model of the dc motor is presented with its parameters being identified with experimental data. By studying the CAN network characteristics, we obtain the CAN-induced delays related to the load rate and the priorities. Then, considering the system model, the network properties, and the digital PID controller, the tuning problem of PID parameters for the CAN-based dc motor is transformed into a design problem of a static-output-feedback controller for a time-delayed system. To solve this problem, particle swarm optimization algorithm and linear-quadratic-regulator method are adopted by incorporating the sufficient condition of time-varying delay system. Finally, the effectiveness of the proposed PID tuning strategy is validated by experimental results.

Design of Digital PID Controller Based on FPGA

PID controller has been widely used in many different areas such as power systems, drives control, automotive mechatronics, aerospace, process control, and robotics. Recently, FPGA (field programmable gate array) has become an alternative solution for the realization of digital control algorithm systems. In this paper FPGA-based incremental PID (Proportional, Integral, Derivative) controller is designed and simulated. After the analysis of PID control algorithm, VerilogHDL language is used to design the software programs. Simulation results show the effectiveness and feasibility of the proposed method.

Self-Tuning Robust Fuzzy Controller Design Based on Multi-Objective Particle Swarm Optimization Adaptation Mechanism

In this paper, an adaptive fuzzy controller design methodology via multi-objective particle swarm optimization (MOPSO) based on robust stability criterion is proposed. The plant to be controlled is modeled from its input–output experimental data considering a Takagi–Sugeno (TS) fuzzy nonlinear autoregressive with exogenous input model, by using the fuzzy C-means clustering algorithm (antecedent parameters estimation) and the weighted recursive least squares (WRLS) algorithm (consequent parameters estimation). An adaptation mechanism as MOPSO problem for online tuning of a fuzzy model based digital proportional-integral-derivative (PID) controller parameters, based on the gain and phase margins specifications, is formulated. Experimental results for adaptive fuzzy digital PID control of a thermal plant with time-varying delay are presented to illustrate the efficiency and applicability of the proposed methodology.

Wavelength-stabilization-based photoacoustic spectroscopy for methane detection

A compact and portable photoacoustic gas sensor was developed for sensitive methane (CH4) detection at 1.6 µm using a software-based wavelength stabilization scheme. A transmission-type photoacoustic cell was connected in series with a reference gas cell to measure the photoacoustic signal and the reference gas absorption for wavelength stabilization simultaneously. The central wavelength of the diode laser was locked to the target CH4 line with a fluctuation of less than 10.6 MHz using a digital proportional–integral–derivative controller. The CH4 sensor was designed to be insensitive to the incoherent external acoustic noise by the cumulative average of the demodulated photoacoustic signal by a digital lock-in amplifier. With an incident laser power of 6 mW, our CH4 sensor achieved a minimum detection limit of 11.5 ppm at 10 s response time and an excellent linearity (R2 = 0.9999) in the concentration range of 400–6300 ppm.

Design of a decoupled AP1000 reactor core control system using digital proportional–integral–derivative (PID) control based on a quasi-diagonal recurrent neural network (QDRNN)

The control system of the AP1000 reactor core uses the mechanical shim (MSHIM) strategy, which includes a power control subsystem and an axial power distribution control subsystem. To address the strong coupling between the two subsystems, an interlock between the two subsystems is used, which can only alleviate but not eliminate the coupling. Therefore, sometimes the axial offset (AO) cannot be controlled tightly, and the flexibility of load-following operation is limited. Thus, the decoupling of the original AP1000 reactor core control system is the focus of this paper. First, a two-node disperse dynamic model is established for the AP1000 reactor core to use PID control. Then, a digital PID control system based on a quasi-diagonal recurrent neural network (QDRNN) is designed to decouple the original system. Finally, the decoupling of the control system is verified by the step signal and load-following condition. The results show that the designed control system can decouple the original system as expected and the AO can be controlled much more tightly. Moreover, the flexibility of the load following is increased.

Optimized Digital Proportional Integral Derivative Controller for Heating and Cooling Injection Molding System

Proportional integral derivative (PID) control is one of the conventional control strategies. Industrial PID control has many options, tools, and parameters for dealing with the wide spectrum of difficulties and opportunities in manufacturing plants. It has a simple control structure that is easy to understand and relatively easy to tune. Injection mold is warming up to the idea of cycling the tool surface temperature during the molding cycle rather than keeping it constant. This “heating and cooling” process has rapidly gained popularity abroad. However, it has discovered that raising the mold wall temperature above the resin’s glass-transition or crystalline melting temperature during the filling stage is followed by rapid cooling and improved product performance in applications from automotive to packaging to optics. In previous studies, optimization methods were mainly selected on the basis of the subjective experience. Appropriate techniques are necessary to optimize the cooling channels for the injection mold. In this study, a digital signal processor (DSP)-based PID control system is applied to injection molding machines. The main aim of this study is to optimize the control of the proposed structure, including a digital PID control method with a DSP chip in the injection molding machine.

Mathematical modeling and control of plate fin and tube heat exchangers

The aim of the study is to develop a new method for numerical modeling of tubular cross-flow heat exchangers. Using the method proposed in the paper, a numerical model of a car radiator was developed and implemented in a digital control system of the radiator. To evaluate the accuracy of the numerical method proposed in the paper, the numerical model of the car radiator was compared with an analytic model. The proposed method based on a finite volume method and integral averaging of gas temperature across a tube row is appropriate for modeling of plate fin and tube heat exchangers, especially for exchangers in which substantial gas temperature differences in one tube row occur. The target of control is to regulate the number of fan revolutions per minute so that the water temperature at the heat exchanger outlet is equal to a set value. Two control techniques were developed. The first is based on the numerical model of the heat exchanger developed in the paper while the second is a digital proportional–integral–derivative control. The first control method is very stable. The digital proportional–integral–derivative controller becomes unstable when the water volume flow rate varies considerably. The developed techniques were implemented in digital control system of the water exit temperature in a plate fin and tube heat exchanger. The measured exit temperature of the water was very close to the set value of the temperature if the first method was used. The experiments show that the proportional–integral–derivative controller works also well but becomes frequently unstable if the water flow rate varies.

Digital current control of a three‐phase four‐leg voltage source inverter by using p – q – r theory

In this study, balanced/unbalanced linear/non-linear current control in three-phase four-leg voltage source inverter (VSI) is carried out by using modified p - q - r method instead of the classical p - q - r method, digital proportional integral derivative (PID) control rule and three-dimensional (3D) space vector pulse width modulation (3D SVPWM). For this purpose, three-phase four-leg power inverter and PWM signal generation circuits are designed and modelled separately. Even if the power source voltage is unsymmetrical, the proposed modified p - q - r method leads to measurement and to generating the instantaneous harmonic and reactive components of load current accurately. The performance of the classical p - q - r theory under non-ideal mains voltages is improved and the accuracy of the proposed modified p - q - r theory is demonstrated both through simulation and real-time application. Each phase of the three-phase four-leg VSI modelled directly in abc reference frame is decoupled from each other This simplifies the digital PID controller design significantly. Modelling of the whole system, modified p - q - r measurement and digital PID design steps are given in detail. Real-time experimental results for the designed three-phase four-leg VSI in stand-alone mode are compared with the simulation results.

Application of SDGM to Digital PID and Performance Comparison with Analog PID Controller

Now -a-days PID (proportional-integral-derivative) controller is used in every type of small or large industries. For this the digital PID controller is so popular. But it is necessary to design and tune the PID controller in a proper method for applying the plant. The paper represents a method of tuning a digital proportional-integral-derivative (PID) controller. The name of the method is Steepest Gradient Descent Method (SDGM). It is an iterative method. The SDGM method is very simple, easy to use and each iteration is very fast. It is also a guaranteed method to find the minima through numerous times of iterations as long as it exists. By applying this optimization method PID controller is tuned both of digital and analog process. In the paper by applying the method of some plant the comparison result of analog and digital are shown. From the comparison it is found that the digital scheme is preferable than analog scheme. Index Terms—PID controller, SDGM. I. INTRODUCTION The fi rst controllers with proportional, integral, and derivative (PID) feedback control action became commercially available during the 1930s. The 1940s saw widespread acceptance in industry of pneumatic PID controllers, and their electronic counterparts entered the market in the 1950s. Digital hardware has been routinely used since the 1980s with significant impact on process control. Even several decades after three-mode controllers were introduced; the vast majority of controllers used in the chemical process industry are based on PI/PID models (1). The popularity of these controllers has led to research on tuning methods, resulting in hundreds of publications on this topic. Ziegler-Nichols tuning relations and Cohen-Coon tuning rules are among the earliest published methods. Tuning relations based on error criteria are more recent model-based tuning rules, which offer improvements over earlier tuning methods. Tuning rules also exist for unstable processes as well as for tuning in the presence of plant model mismatch (2). Despite the numerous approaches available for controller tuning, surveys indicate that poorly tuned control loops are abundant in industry. In general, the gain scheduling of the PID controllers is an optimization problem. The method of steepest descent (SDGM) is also known as The Gradient Descent, which is basically an optimization algorithm to find the local minimum of a function. By applying the SDGM to the PID controller, the controller is tuned and applied to some conventional plant then the digital and analog results are compared to the paper.

Performance Analysis and FPGA Implementation of Digital PID Controller for Speed Control of DC Motor

This paper deals with the performance analysis and implementation of PID(Proportional-Integral-Derivative) Controller on FPGA platform.The hardware implementation has been done on Xilinx Spartan 3E FPGA board.The software implementation has been done using Xilinx ISE 8.1i as a tool and simulation is performed using ModelSim 5.4a as a simulator.The PWM signal is generated by FPGA board,which further given to dc motor for its speed control. A new technique has been introduced for the generation of the control input as a PWM signal for controlling the motor driver circuit and decoding the optical encoder data for using it for the speed feedback in the PID control loop. The VHDL algorithm for the proposed implementation has been presented in this paper. Performance analysis of PID controller using MATLAB software shows the effectiveness of the proposed method.

Adaptive digital PID control of pressure process

In this paper the adaptive digital control of the pressure process based on PID (proportional-integral-derivative) controllers is investigated. A method for optimization of closed-loop parameters and the continuous-time sampling period of the control system is proposed. The adaptive PID control with optimization significantly improves the control quality of the pressure process, which is demonstrated experimentally.

Self-tuning PID Controller using Genetic Algorithm

This work presents design, modeling, simulation and hardware implementation of a separately excited DC motor speed control using Field Programmable Analog Array (FPAA) Technology. The framework presents a low power self-tuning analog Proportional-Integral-Derivative (PID) controller using a model-free tuning method, this overcomes the problems associated with reconfigurable analog arrays. In comparison with a self-tuning digital PID controller, the analog self-tuning PID controller combines the advantages of low power, no quantization noise, high bandwidth and high speed. The prototype hardware uses a commercially available field programmable analog array and Genetic Algorithm as tuning method. The practical results show that a self-tuned controller can outperform a hand tuned solution and demonstrate adaptability to plant drift, also it shows enhancement in the reduction of overshoot, settling time and the steady-state transient response of the controlled plant.

Inverse heat transfer problem in digital temperature control in plate fin and tube heat exchangers

Inverse heat transfer problem in digital temperature control in plate fin and tube heat exchangersThe aim of the paper is a steady-state inverse heat transfer problem for plate-fin and tube heat exchangers. The objective of the process control is to adjust the number of fan revolutions per minute so that the water temperature at the heat exchanger outlet is equal to a preset value. Two control techniques were developed. The first is based on the presented mathematical model of the heat exchanger while the second is a digital proportional-integral-derivative (PID) control. The first procedure is very stable. The digital PID controller becomes unstable if the water volumetric flow rate changes significantly. The developed techniques were implemented in digital control system of the water exit temperature in a plate fin and tube heat exchanger. The measured exit temperature of the water was very close to the set value of the temperature if the first method was used. The experiments showed that the PID controller works also well but becomes frequently unstable.