Showing papers on "Open-loop controller published in 2021"

Conditions for stabilizability of time-delay systems with real-rooted plant

Abstract: In this paper we consider the-stabilization of th-order linear time-invariant (LTI) dynamical systems using Multiplicity-Induced-Dominancy (MID)-based controller design in the presence of delays in the input or the output channels. A sufficient condition is given for the dominancy of a real root with multiplicity at least n + 1 and at least using an integral factorization of the corresponding characteristic function. A necessary condition for-stabilizability is analyzed utilizing the property that the derivative of \alpha-stable quasipolynomial is also-stable under certain conditions. Sufficient and necessary conditions are given for systems with real-rooted open loop characteristic function: the delay intervals are determined where the conditions for dominancy and \alpha-stabilizability are satisfied. The efficiency of the proposed controller design is shown in the case of a multi-link inverted pendulum.

Controller synthesis for linear system with reach-avoid specifications

Abstract: We address the problem of synthesizing provably correct controllers for linear systems with reach-avoid specifications. Our solution decomposes the overall synthesis problem into two smaller, and more tractable problems: one synthesis problem for an open-loop controller which can produce a reference trajectory, and a second for synthesizing a tracking controller, which can enforce the other trajectories to follow the reference trajectory. As a key building-block result, we show that these two controllers can be synthesized independently. Moreover, we are able to reduce the problem of synthesizing open-loop controllers to satisfiability problems over quantifier-free linear real arithmetic, with the number of constraints linear to the number of hyperplanes as the surfaces of the polytopic obstacles and goal sets. The overall synthesis algorithm computes a tracking controller, and then iteratively covers the entire initial set to find open-loop controllers for initial neighborhoods. The algorithm is sound and, for a class of robust systems, is also complete. We implement this synthesis algorithm in a tool and show promising results on several benchmarks with up to 20

Optimal PI–PD Controller Design for Pure Integrating Processes with Time Delay

Abstract: Though Proportional-Integral-Derivative (PID) controllers are commonly being used for process control applications, it has been proven that they may give unacceptable closed loop responses for open loop unstable processes including integrating ones. Hence, this paper addresses to tuning of PI–PD controllers which is an extension of PID controllers and uses PD part in an inner feedback loop to convert the open loop unstable processes to a stable one so that PI controller in the forward path can be used to achieve a better closed loop response. PI–PD tuning parameters are determined from simple analytical rules which were obtained from minimization of the control system error based on IST3E criterion which is an integral performance index and has been proven to be resulting in very satisfactory closed loop responses. Derived tuning rules are in terms of the assumed process transfer function parameters, namely the gain and time delay. Effectiveness and superiority of obtained tuning rules have been shown by simulation examples.

Input–output decoupling for mix-valued logical control networks via the semi-tensor product method

Abstract: This paper investigates the input–output decoupling problem of mix-valued logical control networks by using the semi-tensor product method. First, an algorithm is proposed to construct an output-fr...

An improved real-time temperature control for pulsed laser cutting of non-oriented electrical steel

Abstract: An improved method based on fuzzy gain scheduling (FGS) control is developed in this study to tune the PID parameters and precisely control the working temperature in situ during laser cutting of non-oriented electrical steel sheets. Experiments on laser cutting of thin electrical steel sheets are performed to compare the cutting quality of kerf features using an open loop controller with a constant power, a conventional PID controller, and the proposed FGS controller. An unstable and inconsistent cutting quality of kerf with a larger heat affected zone (HAZ) and dross attachment is observed under open loop control due to a significant variation of working temperature and kerf width along the cutting path. The FGS controller shows better cutting performance and tracking response than the conventional PID controller by reducing the settling time as well as enhancing the control stability in the steady period. A better quality of finer and uniform kerf width with parallel kerf edges of a smaller HAZ and dross attachment are thus produced by the improved FGS control through real-time tuning of control parameters. Finally, the average kerf width is well correlated with the set-point temperature in FGS control by a linear equation.

Iterative Method for Tuning Multiloop PID Controllers Based on Single Loop Robustness Specifications in the Frequency Domain

Abstract: Multiloop proportional-integral-derivative (PID) controllers are widely used for controlling multivariable processes due to their understandability, simplicity and other practical advantages. The main difficulty of the methodologies using this approach is the fact that the controllers of different loops interact each other. Thus, the knowledge of the controllers in the other loops is necessary for the evaluation of one loop. This work proposes an iterative design methodology of multiloop PID controllers for stable multivariable systems. The controllers in each step are tuned using single-input single-output (SISO) methods for the corresponding effective open loop process (EOP), which considers the interaction of the other loops closed with the controllers of the previous step. The methodology uses a frequency response matrix representation of the system to avoid process approximations in the case of elements with time delays or complicated EOPs. Consequently, different robustness margins on the frequency domain are proposed as specifications: phase margin, gain margin, phase and gain margin combination, sensitivity margin and linear margin. For each case, a PID tuning method is described and detailed for the iterative methodology. The proposals are exemplified with two simulations systems where the obtained performance is similar or better than that achieved by other authors.

Energy-Efficient Optimal Guaranteed Cost Intermittent-Switch Control of a Direct Expansion Air Conditioning System

Abstract: To improve the energy efficiency of a direct expansion air conditioning (DX A/C) system while guaranteeing occupancy comfort, a hierarchical controller for a DX A/C system with uncertain parameters is proposed The control strategy consists of an open loop optimization controller and a closed-loop guaranteed cost periodically intermittent-switch controller (GCPISC) The error dynamics system of the closed-loop control is modelled based on the GCPISC principle The difference, compared to the previous DX A/C system control methods, is that the controller designed in this paper performs control at discrete times For the ease of designing the controller, a series of matrix inequalities are derived to be the sufficient conditions of the lower-layer closed-loop GCPISC controller In this way, the DX A/C system output is derived to follow the optimal references obtained through the upper-layer open loop controller in exponential time, and the energy efficiency of the system is improved Moreover, a static optimization problem is addressed for obtaining an optimal GCPISC law to ensure a minimum upper bound on the DX A/C system performance considering energy efficiency and output tracking error The advantages of the designed hierarchical controller for a DXA/C system with uncertain parameters are demonstrated through some simulation results

Design and Implementation of a Fuzzy Control System Applied to a 6 × 4 SRG

Abstract: This article presents an experimental methodology to control the voltage generated from a switched reluctance generator (SRG) using fuzzy logic control. The generated voltage is controlled by varying the demagnetization angle ( θ off), maintaining the magnetization angle ( θ on) fixed. The developed strategy operates on the upper switches of the asymmetric half-bridge converter. The converter topology is used in conjunction with an intermediate freewheeling stage between the steps of magnetization and demagnetization of the phases. The control algorithm was developed in a DSP/FPGA with high processing capacity using LabVIEW graphical platform. Results in open loop and closed loop are presented, subjecting the SRG to variable speeds and load application. For the purpose of performance comparison, a PI compensator has been implemented and tuned for this specific application and the results for both controllers are presented and discussed. For the open-loop tests, the SRG was subjected to variations in the rotor speed, namely, shaft speed varying sinusoidally and triangularly. In these tests, it was observed that the bus voltage suffered great variations. Load variations were also implemented in open loop and, once again, the bus voltage varied significantly. In laboratory tests in closed loop, the SRG was again subjected to variations in sinusoidal and triangular speed and still under load step. In all these experiments, comparisons of results were made between PI controllers and using fuzzy logic control. At the end, it was observed that the imposition of a control loop allowed the bus voltage to be maintained at the preestablished value.

Adaptive Parameter Modulation of Deep Brain Stimulation Based on Improved Supervisory Algorithm

Abstract: Clinically deployed deep brain stimulation (DBS) for the treatment of Parkinson's disease operates in an open loop with fixed stimulation parameters, and this may result in high energy consumption and suboptimal therapy. The objective of this manuscript is to establish, through simulation in a computational model, a closed-loop control system that can automatically adjust the stimulation parameters to recover normal activity in model neurons. Exaggerated beta band activity is recognized as a hallmark of Parkinson's disease and beta band activity in model neurons of the globus pallidus internus (GPi) was used as the feedback signal to control DBS of the GPi. Traditional proportional controller and proportional-integral controller were not effective in eliminating the error between the target level of beta power and the beta power under Parkinsonian conditions. To overcome the difficulties in tuning the controller parameters and improve tracking performance in the case of changes in the plant, a supervisory control algorithm was implemented by introducing a Radial Basis Function (RBF) network to build the inverse model of the plant. Simulation results show the successful tracking of target beta power in the presence of changes in Parkinsonian state as well as during dynamic changes in the target level of beta power. Our computational study suggests the feasibility of the RBF network-driven supervisory control algorithm for real-time modulation of DBS parameters for the treatment of Parkinson's disease.

Hysteresis Controlled Single-Switch High Step-Up Coupled-Inductor Boost Converter

Abstract: In the frameworks of fuel cell or PV grid-connected generation, high step-up boost converters with coupled inductor have gotten a lot of attention. This work deals with the design, analysis and simulation of Open loop and closed loop coupledinductor basedhigh stepupconverter with Proportional Resoanant(PR) controller and Hysteresis controller (HC). The outcomes are compared in terms of time domain parameters and evaluated. The objective is to enahnce the output power and to condense the steadystate error. -The outcomes represents the superior performance of Hysteresis controlled closed loop coupledinductorbasedhigh-stepupconverter.

Model Decoupled Synchronization Control Design with Fractional Order Filter for H-Type Air Floating Motion Platform.

Abstract: H-type motion platform with linear motors is widely used in two-degrees-of-freedom motion systems, and one-direction dual motors need to be precisely controlled with strict synchronization for high precision performance. In this paper, a synchronous control method based on model decoupling is proposed. The dynamic model of an H-type air floating motion platform is established and one direction control using two motors with position dependency coupling is decoupled and converted into independent position and rotation controls, separately. For the low damping second-order oscillation system of the rotation control loop, a new fractional order biquad filtering method is proposed to generate an antiresonance peak to improve the phase and control gain of the open loop system, which can ensure system stability and quick attenuation for external disturbances. In the multiple-degree-of-freedom decoupled control loops, a systematic feedback controller design methodology is proposed to satisfy the given frequency domain design specifications; a feed-forward control strategy is also applied to compensate the disturbance torque caused by the platform motion. The simulation and experimental results demonstrate that the proposed synchronization control method is effective, and achieves better disturbance rejection performance than the existing optimal cancellation filtering method and biquad filtering method.

Brushless DC Motor Based E-Rickshaw Controller Design

Abstract: This paper discusses and elaborates designing of Brushless DC (BLDC) motor based e-rickshaw controller. The controller design is based on STM32F072 microcontroller with dedicated features for commercial motor control applications. The controller system is used for controlling BLDC motor operation, detection of throttle, hall signals, speed, current and, to control the parameters in open loop and closed loop operation. Hall sensor failure is a common fault in such type of applications which is addressed in the design with its detection and mitigation technique which leads to timely save the drive system from unwanted operation and damage. Further, modification in the heat sink design is proposed considering the issue of overheating of controllers in e-rickshaws. Over current protection method independent of software calculations to reduce delay in corresponding corrective action is also incorporated in the design.

Impact of Airgap on the Performance of 3-Phase Permanent Magnet Hybrid Stepper Motor

Abstract: Hybrid 3-phase stepper motors remain the preferred solution for many applications in robotics and aerospace industries as they can provide accurate position and speed control in open loop systems. On the other hand, they are rarely used in oil and gas industry. In this paper, potential use of this motor technology to oil and gas industry specifically downhole applications is investigated. For this purpose, design and analyses of a 3-phase hybrid stepper motor are carried out with the detailed investigation on the impact of airgap on the motor performance. The difficulty of the design comes from extremely large L/D ratio of the stepper motor due to the application requirements. Fundamental design-based equations are used for the initial design of the motor and detailed 3D finite element analysis (FEA) models are carried out to check the motor performance. Finally, modelling and design of two 3-phase hybrid stepper motors with different airgaps are presented to illustrate the effect of the airgap length on motor performance.

A new control design and robustness analysis of a variable speed hydrostatic transmission used to control the velocity of a hydraulic cylinder

Abstract: Controlling the velocity of a hydraulic cylinder is a common objective in fluid power industry. This objective is achieved by controlling the hydraulic fluid quantity that enters the cylinder. In this work, a control system that is used to control the velocity of a hydraulic cylinder was designed considering uncertainty in some of the design parameters. A fixed displacement pump was used to reduce the cost and complexity of the system. Furthermore, using variable speed drive eliminates the energy losses associated with valve controlled systems since no throttling or flow recirculation is needed. First, the system dynamics was modelled. Then, the stability and performance of the open loop system was studied using MATLAB/SIMULINK®. Next, controllers (PID and H-infinity) were designed and the stability and the performance of the closed loop system were studied and compared with those of the open loop system. Finally, the robustness of the system was studied considering multiplicative parametric uncertainty. Three parameters were considered as uncertain parameters which are the fluid bulk modulus, the viscous friction coefficient, and the leakage coefficient with a variation of ± 5% of their nominal values. The results showed that the open loop system is stable with a poor response in terms of input tracking and disturbance rejection. Using PID controller improved the system response. The system with the PID controller does not meet the robustness requirements. The system with H-infinity controller has better performance and satisfies the robustness requirements.

Comparison of various controller design for the speed control of DC motors used in two wheeled mobile robots

Abstract: This work describes the study of modeling and controller on wheeled mobile robots designed the motors which is driving the wheels. According to the structure and design of wheeled mobile robot, DC motors are the best suited for the motion control. The kinematical model is required for the designing process of the wheels in the WMR. The analysis of the mathematical model is divided into angle and velocity of the dc motor build in wheeled mobile robot because of the importance of motor parameters for stability. The main focus of the work is to develop an efficient controller to control the speed of the dc motor applied in the wheels of the robot. PID tuning has been implemented in designing of the controller for the speed control of dc motor. The open loop and closed loop performance of a two wheeled mobile robot with PID and LQR controllers are obtained and compared by using MATLAB programs and simulations.

Development and Experimental Validation of an Adaptive, Piston-Damage-Based Combustion Control System for SI Engines: Part 1—Evaluating Open-Loop Chain Performance

Abstract: This work is focused on the development and validation of a spark advance controller, based on a piston “damage” model and a predictive knock model. The algorithm represents an integrated and innovative way to manage both the knock intensity and combustion phase. It is characterized by a model-based open-loop algorithm with the capability of calculating with high accuracy the spark timing that achieves the desired piston damage in a certain period, for knock-limited engine operating conditions. Otherwise, it targets the maximum efficiency combustion phase. Such controller is primarily thought to be utilized under conditions in which feedback is not needed. In this paper, the main models and the structure of the open-loop controller are described and validated. The controller is implemented in a rapid control prototyping device and validated reproducing real driving maneuvers at the engine test bench. Results of the online validation process are presented at the end of the paper.

An Enhanced Controller for Four Leg Inverter-fed Loads in an Aircraft Power System

Abstract: This paper proposes a novel controller for improving the output voltage regulation of a three phase four-leg inverter feeding balanced and unbalanced ac loads in an aircraft power system. Conventional autonomous three phase inverter control uses open loop reference phase angle to perform transformation from stationary to synchronously rotating reference frame and vice versa. However, this method can cause inaccuracy in output voltage tracking under heavy loads, due to phase delay caused by significant voltage drop in the output filter and long cable impedances from inverter to load end. To obtain accurate tracking and dynamic response of output voltage with respect to the commanded reference, control improvement based on forward transformation of the sensed feedback output voltage and current using PLL angle is proposed. The proposed strategy is verified through simulation, and also the Controller Hardware-in-Loop(C-HIL) results are provided to show the effectiveness of the proposed control improvement.

Feedback Control for the Precise Shape Morphing of 4D-Printed Shape Memory Polymer

Abstract: Four-dimensional printing (4DP) is a newly emerged technology that uses smart materials for additive manufacturing and thus enables shape and/or property change upon stimulus after the printing process. Present study on 4DP has been focused on open-loop stimulus, which can hardly ensure high shape precision and predictable final states. In this article, a new closed-loop 4DP (CL4DP) process supplementing 4D printed actuation with closed loop control methods is proposed. Image feedback is used for enhancing the conventional open loop 4DP morphing process and a controller is implemented to regulate the intensity of the stimulus accordingly in real-time. To achieve precise control, a nonlinear affine system model is built by model identification with measurement data to describe the dynamic shape recovery process of the 4D-printed shape memory polymer (SMP). Precise shape control is achieved and the effects of controller parameters on the precision of CL4DP are studied. Traditionally, SMP has a discrete number of selected steady states. With CL4DP, such steady states can be continuous and arbitrary.

An Efficient FPGA Based Scalar V/f Control Mechanism of Three Phase Induction Motor for Electric Vehicles

Abstract: Electric motors more specifically induction motors are the key ingredients of the modern industry for various control applications and are responsible for considerable power consumption. The cost incurred on the energy consumption of induction motors can be mitigated to a greater extent by optimizing motor control. Since the motors are not always required to run at their rated speed, so considerable saving can be made if the motor is allowed to run at a speed below the rated speed, depending upon the load requirements. This is usually achieved by the use of adjustable speed drives or variable frequency drives that offers smooth control of speed, torque and various other soft starting features. Efficient performance and control of induction motor can be achieved by the utilization of advance control strategies, fast performance controllers and PWM converters. In this study, open loop scalar v/f control of three phase induction motor is implemented using high performance FPGA integrated with LABVIEW. Comparative analysis of Sinusoidal Pulse Width Modulation (SPWM) and Space Vector Pulse Width Modulation (SVPWM) is presented using MATLAB/ SIMULINK. The results show the effectiveness of SVPWM over SPWM.

Design and implementation of a Model-Free Fractional Order Intelligent PI Fractional Order Sliding Mode Controller for water level tank system.

Abstract: This paper presents a combination of three nonlinear control methods, namely Model free Controller (MFC), Fractional-order Proportional Integral Controller (FO-PIC) and Fractional-order Sliding Mode Controller (FO-SMC), which gives rise to the new MFC algorithm with the term MF-FOiPI-FOSMC called Model Free-Fractional Order Intelligent Proportional Integral-Fractional Order Sliding Mode Controller. The stability analysis of the closed loop system (CLS) and the attractiveness of the proposed method are established by Lyapunov theorem analysis. The validation of the MF-FOiPI-FOSMC is first presented by simulation results and then performed by experimental results on the water level tank system. In addition, the effectiveness and performance of the new proposed FOiPI-FOSMC strategy is proved by comparing it to other strategies such as the classical PI controller and intelligent proportional–integral controller (i-PI).

Influence of Microstepping Signal Shape on Shaft Movement Precision and Torque Variation of the Stepper Motor

Abstract: Stepper motors are widely used in many applications where discrete, precise movement is required. There is a variety of dedicated stepper motor controllers (sometimes referred to as “step sticks”) available on the market. Those controllers provide a number of different motor control schemes that vary by aspects like current control method, reference current shape or maximum resolution increase (microstepping). The two most widely acknowledged signal shapes are sine-cosine microstepping and quadrature microstepping. The choice of the control scheme impacts torque output, torque variation, positioning error and maximum power supply requirements. This paper presents a family of generalised microstepping signal shapes, ranging from sine-cosine microstepping to quadrature microstepping. Derivation of signal shapes as well as their mathematical analyses are provided. Those signals are then implemented on the control board. A series of experiments is performed on a test bench to analyse the influence of different signal shapes on the performance of the motor in both load and no load conditions. The comparison of the new generalized shapes influence on the motor operation to the commonly used sine-cosine and quadrature control is provided.

Designing Of Controller for BLDC Driven Solar Water Pump

Abstract: This article offers an efficient and user friendly controller circuit for BLDC to operate the water pump from solar energy. This water pumping system will work under variable atmospheric conditions, hence ZETA converter is implemented. Zeta converter is operated through INC-MPPT (incremental conductance maximum power point tracking) algorithm by controlling duty ratio. Here minimum circuits are used for speed control. So this will reduce the costing of system. Speed control of BLDC is done by maintaining voltage of dc link voltage source inverter (VSI). Switching of VSI is performed through electronic commutation of BLDC motor. Here open loop system is used without making it complicated. The simulation of proposed controller circuit using MATLAB/Simulink is presented in this paper.

A Reinforcement Learning Approach for Transient Control of Liquid Rocket Engines

Abstract: Nowadays, liquid rocket engines use closed-loop control at most near-steady operating conditions. The control of the transient phases is traditionally performed in open loop due to highly nonlinear system dynamics. This situation is unsatisfactory, in particular for reusable engines. The open-loop control system cannot provide optimal engine performance due to external disturbances or the degeneration of engine components over time. In this article, we study a deep reinforcement learning approach for optimal control of a generic gas-generator engine's continuous startup phase. It is shown that the learned policy can reach different steady-state operating points and convincingly adapt to changing system parameters. Compared to carefully tuned open-loop sequences and proportional-integral-derivative (PID) controllers, the deep reinforcement learning controller achieves the highest performance. In addition, it requires only minimal computational effort to calculate the control action, which is a big advantage over approaches that require online optimization, such as model predictive control.