Set-point Input Research Articles

Self-optimized efficient operation of trans-critical CO2 ejector-expansion heat pump water heater system with two-stage evaporation

In application scenarios with lower ambient temperatures and higher sink temperatures, the trans-critical CO2 heat pump water heater system using an ejector instead of a conventional expansion device offers better performance, and the higher pressure differential allows for partial pressure loss recovery through the ejector. However, the complexity of discharge pressure and ejector matching affects the further application of the system. Therefore an optimization method called Extremum seeking control method is proposed to achieve the lowest power consumption implementation under off-design conditions. The ESC controller applied to the system uses the compressor power consumption as the feedback signal and the discharge pressure is used as operating input set-point. The dynamical model of a trans-critical CO2 heat pump water heater built on Modelica/Dymola is used as the study object and optimized for three scenarios: fixed, sloped step profile, and actual ambient temperature. The simulation results show that the ESC applicable to the proposed system can optimize the matching of discharge pressure and ejector driving nozzle throat area to obtain the best performance. Compared with the benchmark system, the extremum seeking control for actual ambient temperature conditions results in a 5.7% increase in system efficiency.

MODELLING AND SIMULATION OF ELECTROPNEUMATIC POSITIONING SYSTEM INCLUDING THE LENGTH OF PNEUMATIC LINES

This paper presents a mathematical model of electropneumatic positioning system including the length of pneumatic lines for the determination of flow and pressure in unsteady operating modes. A simulation model is developed to study the dynamic processes in an electropneumatic positioning system. Simulation of the mathematical models of the screw compressor, proportional directional valve, pneumatic lines, pneumatic cylinder and PID controller were designed in “MatLab Simulink”. The simulation models of the transients in the electropneumatic positioning system at different line lengths from 1m and 10m with stepwise variation of the input setpoint are simulated developed. Graphical comparison is made of the obtained experimental results and simulation model influence of the pneumatic line length on the dynamics of the electropneumatic positioning system are made.

Robust Liquid Level Control of Quadruple Tank System: A Nonlinear Model-Free Approach

In this paper, two new versions of modified active disturbance rejection control (MADRC) are proposed to stabilize a nonlinear quadruple tank system and control the water levels of the lower two tanks in the presence of exogenous disturbances, parameter uncertainties, and parallel varying input set-points. The first proposed scheme is configured from the combination of a modified tracking differentiator (TD), modified super twisting sliding mode (STC-SM), and modified nonlinear extended state observer (NLESO), while the second proposed scheme is obtained by aggregating another modified TD, a modified nonlinear state error feedback (MNLSEF), and a fal-function-based ESO. The MADRC schemes with a nonlinear quadruple tank system are investigated by running simulations in the MATLAB/SIMULINK environment and several comparison experiments are conducted to validate the effectiveness of the proposed control schemes. Furthermore, the genetic algorithm (GA) is used as a tuning algorithm to parametrize the proposed MADRC schemes with the integral time absolute error (ITAE), integral square of the control signal (ISU), and integral absolute of the control signal (IAU) as an output performance index (OPI). Finally, the simulation results show the robustness of the proposed schemes with a noticeable reduction in the OPI.

A Comparative Study of DC-DC Buck, Boost, and Buck-boost Converters with Proportional-integral, Sliding Mode, and Fuzzy Logic Controllers

Background: DC-DC converters are utilized in a wide range of industrial and commercial applications such as automobiles, renewable energy systems, DC motor control, portable chargers, uninterruptable power supply, etc. because of their efficiency, ease of use, simpler circuits, and cheaper solution. The most common ones are the buck, boost, and buck-boost converters. Methodology: In this paper, the implementation of these converters has been proposed using advanced controllers: Proportional plus Integral (PI), Sliding Mode Control (SMC), and Fuzzy Logic Control (FLC). The controllers have been implemented with practical circuit values in MATLAB Simulink. Results: The results show that all proposed controllers can track the input set-point voltage. The PI controller response was superior in eliminating the steady-state error in all converters. However, it showed greater overshoot and ripple factor in boost operation. The SMC controller response was superior in terms of the shortest settling time. However, it showed the greatest peak time in buck converter and boost mode of the buck-boost converter. The FLC controller showed the highest settling time and steady-state error in all operations. Novelty and Significance: The proposed work is novel as compared to others available in the literature such that no such comprehensive study was found with all types of DC-DC converters together up to our best knowledge. The proposed work is significant as it will give complete guidance regarding simulation implementation of DC-DC converters with advanced intelligent control algorithms.

DNA Strand Displacement Reactions to Accomplish a Two-Degree-of-Freedom PID Controller and Its Application in Subtraction Gate.

Synthesis control circuits can be used to effectively control biochemical molecule processes. In the controller design based on chemical reaction networks (CRNs), generally only the tracking set-point is considered. However, the influence of disturbances, which are frequently encountered in biochemical systems, is often neglected, thus weakening the control effect of the system. In this article, tracking set-point input and suppressing disturbance input are considered in the control effect. Firstly, CRNs are adopted to construct a two-degree-of-freedom PID controller by combining a one-degree-of-freedom PID controller with a feedforward controller for the first time. Then, CRN expressions of the two input functions (step function and ramp function) used as input signals are defined. Furthermore, the two-degree-of-freedom PID controller is founded by DNA strand displacement (DSD) reaction networks, because DNA is an ideal engineering material to constitute molecular devices based on CRNs. The overshoot of the two-degree-of-freedom PID control system is significantly reduced compared to the one-degree-of-freedom PID control system. Finally, a leak reaction is treated as an extraneous disturbance input to a subtraction gate. The influence of external disturbance is solved by the two-degree-of-freedom PID controller. It is worth noting that the two-degree-of-freedom subtraction gate control system better restrains the impact of a disturbance input (leak reaction).

Fuzzy-PID in BLDC Motor Speed Control Using MATLAB/Simulink

Brushless DC motors (BLDC) are one of the most widely used types of DC motors, both in the industrial and automotive fields. BLDC motor was chosen because it has many advantages over other types of electric motors. However, in its application in the market, most of the control systems used in BLDC motors still use conventional controls. This conventional method is easy and simple to apply but has many weaknesses, one example is that if the system state changes, then the parameters of the PID must also be changed so that static and dynamic performance will decrease, causing slow response and frequent oscillations. In this study, the design and simulation of a speed control system for BLDC motors using the Fuzzy-PID method were carried out. The research method is performed through simulation with Matlab / Simulink. The simulation is carried out by providing a speed setpoint input of 650 rpm and used 2 methods, namely Fuzzy-PID Logic and Pi conventional method which was carried out for 1 second. The test results show that the Fuzzy-PID control can provide better and more stable performance than the conventional PI control. The use of Fuzzy-PID control can reduce speed fluctuation and torque stability so that the BLDC motor can operate more efficiently and reliably.

Perancangan Sistem Kontrol Kelistrikan Otomatis Kompor Listrik Halogen Berbasis Mikrokontroler

Abstract- The stove is one of the main tools used in households. Used to heat an object in the form of food. In its development, the stove used for cooking has experienced many advances, one of which is an electric stove. Currently electric stoves on the market, especially the electric stove, halogen heater, single ceramic stove, are available in the form of a rotary switch on / off. The purpose of writing this scientific research is to design an automatic control system on this single ceramic stove type halogen electric stove. Where previously stove control using only a rotary switch was changed to automatic control via a keypad in the form of a timer and temperature input with a digital display via LCD. The electrical components used are the Arduino Mega 2560 microcontroller as the control center, MAX6675 as a temperature sensor, ACS712 sensor to read current values, ZMPT101B sensor to read voltage values, relay as electric switch, buzzer as alarm, keypad as input and LCD as display output on electric stove. The results of this design were obtained in accordance with what was the goal of this scientific research where previously the electric stove was manually controlled to be converted into automatic control by inputting the required temperature value and working based on the temperature setpoint input and displaying the amount of energy released on the electric stove. 
 Keywords— Arduino Mega 2560 Microcontroller, MAX6675, LCD, Keypad, Halogen Electric Stove.

Real-time efficiency optimization of a cascade heat pump system via multivariable extremum seeking

In this paper, the Extremum Seeking Control (ESC) is proposed as a model-free real-time optimizing control strategy for efficient operation of a cascade air source heat pump (CASHP). ESC is a model-free real-time optimization framework, which can search for the unknown and slowly varying input setpoint for optimizing specific performance index. The ESC strategy is realized for the scenarios of power minimization and COP maximization, respectively. For the power minimization, the ESC optimizes the setpoints of intermediate temperature and the superheat setpoints for the high-temperature and low temperature cycles; while for the COP maximization, the manipulated inputs are the compressor speeds of the high-temperature and low-temperature cycles and the evaporator fan speed. To validate the effectiveness of the proposed ESC strategy, a Modelica based dynamic simulation model of a CASHP water heater is built with Dymola and TIL Library. The CASHP is designed to provide the discharge water temperature of 85 °C, with R404A and R245fa as the refrigerants for the low temperature cycle and high temperature cycle, respectively. Under both fixed and realistic ambient temperature profiles, the simulation results show satisfactory convergence performance for both steady-state and transient characteristics. Thus, the feasibility of the proposed CASHP control strategy is validated.

A Modified Method of an Inverse Neural and Adaptive Correction Factor for Speed Control of DC Motor

This Article Proposes a modified method of adaptive controlling for the DC motor and it is deriver circuit based on Inverse Neural Controller. The proposed controller composed of two parts: the first is the inverse neural control that will control the speed of the direct current motor and, the second is adaptive correction factor that will act as an adaptive compensator to overcome the error (offset) in the steady state response of the motor (eliminate the steady state error). The obtained results prove that the new method successfully controlled the DC motor speed by eliminating the error in the steady state response, and letting the output correctly tracking the input set-point with minimum rising time and minimum peak overshoot. Simulation done using MATLAB SIMULINK. Results compared with the conventional Inverse Neural controller to demonstrate the impact of the proposed method also a load test had been done.

Space Heating Control by Estimating Acceptable Set-Point Temperature Based on Survival Analysis

This study proposes space heating control that considers both the operating time and change status of set-point temperature. To estimate acceptable set-points from such data, survival analysis is used to model acceptable rates of set-points. The proposed method determines whether a given set-point is acceptable based on the shape parameters of the acceptable rate. According to the determination, the proposed method inputs a new set-point. The proposed method is evaluated using data obtained from an experiment where the proposed method was applied to apartments in a newly constructed building in France. Set-points for the apartments were input according to the proposed method in an experiment performed for 3 weeks from the end of November 2016. This study shows transition of input set-points that were estimated to be acceptable during the experiment. The present paper evaluates the use rates of input set-points by groups according to the estimated acceptability of input set-points. This study also shows rough computations of energy-saving effects by the proposed method. A benefit from considering the operating times of set-points is also presented. The results demonstrate that the proposed method likely uses a set-point suitable to each apartment for energy-saving, with avoiding incorrect estimation of acceptable set-points.

Trajectory Planning for Reconfigurable Industrial Robots Designed to Operate in a High Precision Manufacturing Industry

This paper presents an algorithm for an automated planning of time-jerk optimal trajectories on a reconfigurable robot with an anthropomorphic structure. The trajectory planning algorithm is designed to provide reachable input set-points for the reconfigurable control system to accommodate not only changes in task objectives but also various reconfigurations of the robot kinematic structure and motion behavior adaptation in response to operational constraints. Firstly, appropriate reference frames are defined on the robotic modules and the position and orientation of the end effector in the Cartesian space is dynamically generated through a reconfigurable forward kinematics module. Secondly, through an iterative inverse kinematic method, the robot configuration space for the start and goal destinations and the geometric path for every motion tasks are generated. Finally, the joint space trajectories with coordinated motion profiles are generated by incorporating the motion laws and joint kinematic parameter values. The general outcome of the algorithm is a trajectory plan of the robot joints expressed as a time history of the robot motion. The trajectories are dynamically generated to satisfy widely varying tasks, constraints and objectives aiming towards a fully reconfigurable control without any hardware or software adjustment.

An innovative approach to self-optimizing batch evaporating crystallizer control

Various approaches to batch evaporating crystallizer control have been utilized in the sugar industry for many years with varying degrees of success and ability to produce a consistent massecuite quality. The development of improved and more reliable devices for the measurement of mother syrup dry substance (DS) concentration (refractometric measurement) and overall massecuite DS concentration (microwave density measurement) during the sugar crystallization process have enabled a more or less complete control of the crystallization process to manage both syrup concentration (supersaturation) and crystal content (massecuite; concentration relative to syrup concentration) during the crystallization cycle. This paper discusses the theory, development and application of refractometric and microwave measurement for the automatic and self-optimizing computerized control of the batch crystallization process developed and installed at the Mini-Cassia Factory of the Amalgamated Sugar Company, LLC, USA. Operator interaction and selection of various input set points allow adjustment for seeding optimization and final grain size while the control system offers feed-back for seeding set point adjustment relative to standard liquor purity (sucrose solubility) and processing conditions to maintain consistent massecuite quality and uniform crystal size distribution. Multiple operating modes allow for continued operation in the event of necessary refractometer or microwave measurement maintenance and calibration.

Higher-Order Derivative Compensators for Controlling the Systems With Higher Dynamics

The PID controller is a popular choice for the control of industrial processes. The PDN controller introduced in this paper is a better alternative to PIDN. The paper presents the design and computer simulation of the PDN controller. The PDN controller is a simpler and more effective choice when dealing with higher-order dynamic systems. The gain components of the controller are introduced to improve transient characteristics of the higher-order industrial systems or processes by directly modifying the components of their characteristic equations. As a result the system under control becomes stable and able to respond faster to the inputs as compared to PID-based systems. The tunable command feed-forward steady-state gain (K S ) of the PDN controller helps to track the constant or time-varying input commands much faster and more precisely than the integral component of the PID controller. The paper discusses the steady-state performance, stability problems and the gain tuning strategies to improve the transient responses of the feedback system. The quality of the PDN performance is demonstrated by solving the set point input (step) and tracking a time-varying input (ramp) problems. The paper also presents the detailed higher-order derivative compensators tuning procedures for the general case of unknown order, stable/unstable plant and particular case of unknown order but stable plant.

Multivariable System Regulation

The regulation of multivariable systems which are subjected to input set point changes and disturbances is considered. A regulation strategy, for analysis purposes, employing both an inner- and an outer-loop feedback structure is proposed. Prescribed, closed-loop, dynamic behaviour using minimum control effort while confining steady-state output coupling is achieved. Output recovery, following disturbance perturbations, via proportional, outer-loop control is advocated. Elementary procedures enabling the computation of conventional pre and feedback compensators are provided, facilitating thereby cost-effective implementation. Stability assessment via established frequency domain techniques is acknowledged. Application studies, enabling comparisons with existing controller design methods, are outlined.

Optimum Multivariable Wind Tunnel System Control

The control of multivariable system models following input set point and load disturbance changes is considered. An inner and outer loop control strategy is proposed, for analysis purposes, enabling targeted recovery rates, off-set attenuation and constrained steady state interaction to be achieved. Proportional control and passive network compensation alone are employed. Gain ratio selection, ensuring energy efficient confinement of output perturbations, following low frequency load disturbances and reference input changes, is exercised. Disturbance suppression and transient recovery rate adjustment, via outer loop feedback advancement, is advocated. An application study is presented for purposes of illustration, confirming the theoretical predictions thereby.

Closed-loop system disturbance recovery

The regulation of linearized multivariable system models, following input set point and load disturbance changes, is considered. An inner and outer closed-loop control strategy is outlined, enabling targeted recovery rates, offset attenuation and low steady state interaction to be achieved. Proportional control and passive network compensation alone are employed. Gain ratio selection and outer loop tuning are exercised, ensuring thereby the confinement of output perturbations to low-frequency load disturbances and reference input changes. Application studies are presented for purposes of comparison.

Design of a Hybrid External Structure for a Multi-Fingered Hand

A previous paper described a decentralized hybrid control structure for a multi-fingered hand (Perdereau and Drouin, 1998). Input set-points were given by a supervisory level to the individual position/force units in an open loop manner. In such a solution, force is explicitly controlled during the object motion, contrary to impedance strategy usually found in the literature, by an external hybrid position/force controller (Perdereau and Drouin, 1996). This paper proposes a hierarchical solution where the actual object position and orientation are measured and used in a closed loop to cancel disturbances. In fact, two decoupled control loops are implemented: one for the position and the other for the orientation. For the last one, an original method is suggested.

5455763 Process control method and device wherein models of the process and the control system are used to correct an input set point signal

This work proposes a nonlinear control strategy for steam power plants that efficiently controls the superheated steam temperature while accommodating large and frequent variations in power demand. The variables to be controlled are the pressure in the boiler, power generation, and superheater/reheater temperatures. The proposed strategy decomposes the overall plant into three separate subsystems and applies decoupling with deadtime compensation for each one of them. The derived strategy is implemented within a MATLAB/Simulink environment for different setpoint tracking and disturbance rejection cases, showing excellent performance and robustness.

Control of photoresist properties: a Kalman filter based approach

The photolithography step in the semiconductor manufacturing process becomes increasingly critical as linewidths decrease for the next generation of integrated electronics. It therefore becomes necessary to reduce variations in photoresist parameters such as resist film thickness and photoactive compound concentration during manufacture. In this paper, we present a simple feedback scheme for accurately regulating these parameters. Our approach involves obtaining a simple, static process model the coefficients of which are recursively adjusted based on previous wafer measurements. We use this adaptive model to determine appropriate input setpoints for the next wafer. The effectiveness of this scheme in reducing process drift is exhibited by experimental data. Our results supports the widespread contention that modern feedback control offers the promise of improving the semiconductor manufacturing processes, often with relative ease and minimal capital cost.

Reliable control via an additive redundant controller

A multiple controller structure consisting of a typical feedback controller and an additive redundant controller is proposed for enhancing the reliability of the control system. This scheme ensures the performance of tracking a given set-point input under failure in one of controllers or parameter perturbations of the plant. Dynamic reliability for the double control system is formulated in terms of the mean time to failure (MTTF) and asymptotic convergence of the tracking error to zero is shown. For the case in which the main controller is chosen as the optimal set-point tracking controller and the redundant controller as the model-reference adaptive controller (MRAC) whose reference model is the closed-loop combination of the plant and the main controller, it is proven that the control system is more reliable than the system with only the single main controller in the sense of extended dynamic reliability, and further reliable operation of the control system is illustrated by numerical examples when the...