Selection Of Control Parameters Research Articles

Preliminary study of a control algorithm for radio-frequency-induced intestinal tissue fusion

Purpose: A control algorithm for radio-frequency-induced intestinal tissue fusion was developed to explore the effects of different control parameters on intestinal tissue fusion.Materials and methods: Radio-frequency-induced fusion was performed on ex vivo small intestine tissue. The effect on the fusion was observed by changing the control parameters (power, interval time, and terminal impedance) in the algorithm. The quality of fusion was evaluated using the burst pressure and thermal damage measurement. Histological evaluation was used to assess the fusion quality indirectly.Results: A maximum burst pressure of 8.460 ± 0.2674 KPa was acquired when the power was set to 100 W, the interval time was set to 2000 ms, and the terminal impedance was set to 50 Ω. Moreover, the thermal damage range increased with an increase in power but decreased with an increase in the interval time and terminal impedance. Furthermore, the thermal damage range and temperature were presumably related.Conclusions: For an ex vivo small intestine tissue, the appropriate control parameters could be set when the power was approximately 100 W, the interval time was approximately 2000 ms, and the terminal impedance was approximately 50 Ω. This study could provide a basis for the selection of control parameters for intestinal tissue fusion.

DC-Link Voltage Disturbance Rejection Strategy of PWM Rectifiers Based on Reduced-Order LESO

In applications of pulse-width modulation (PWM) rectifiers, the high quality of the DC power is required. The fluctuation of grid voltage and the switching of equipment connected to the DC supply are likely to cause a sudden change in the DC-link voltage, resulting in equipment instability or even damage. Considering the bandwidth of the closed-loop current dynamic, this paper presents a novel DC-link voltage control strategy of PWM rectifiers based on the reduced-order linear extended state observer (RLESO). Using a first-order RLESO to observe and even compensate the model variations caused by grid voltage and DC-link voltage fluctuations or load transients, the proposed method can effectively improve the dynamic performance against grid and load disturbances, as well as for sudden changes in DC-link reference voltage. Combined with frequency domain analysis, this paper theoretically analyzes the sensitivity, stability, and tracking performance of the proposed method, providing a basis for the selection of controller parameters. And finally, simulation and experimental results are presented to demonstrate its validity and the superiority over the traditional PI control strategy.

Software/Hardware-Based Hierarchical Finite-Time Sliding-Mode Control With Input Saturation for an Omnidirectional Autonomous Mobile Robot

To track the desired pose of the omnidirectional autonomous mobile robot (OAMR) in finite time, the finite-time virtual desired trajectory (FTVDT) is designed by the 1st sliding surface with the linear dynamics and fractional order of pose's tracking error. To track the FTVDT in finite time, the finite-time sliding-mode saturated control (FTSMSC) is designed by the second sliding surface with the linear dynamics and fractional order of the FTVDT's tracking error. In short, the proposed hierarchical finite-time sliding-mode control with input saturation (HFTSMCIS) contains the FTVDT and the FTSMSC. As compared with previous studies, the finite-time trajectory tracking with the reduced chattering control input is achieved by the suitable selection of control parameters. The HFTSMCIS algorithm is executed in the CPU, and then it is transformed to a PWM signal using FPGA hardware and the motor velocity is simultaneously decoded by the FPGA hardware for feedback control. In contrast, the other state signals are achieved from the mathematical model such that the feedback control system is simple and effective. It is so-called software/hardware-based HFTSMCIS (SHB-HFTSMCIS). Finally, three experiments, including two different process time and obstacle avoidance, are presented to validate the effectiveness and robustness of the proposed control system.

Comparative Study on Small-Signal Stability of LCC-HVDC System With Different Control Strategies at the Inverter Station

The constant extinction angle control and constant DC voltage control are widely used for the inverter station of Line Commutated Converter based High Voltage Direct Current (LCC-HVDC) system in practical engineering. Under different control strategies, the control system parameters would have totally different effects on the stability of the LCC-HVDC system. In this paper, the small-signal models of the LCC-HVDC system with constant extinction angle control and LCC-HVDC system with constant DC voltage control are developed, respectively. Based on the eigenvalue analysis, this paper conducts a comprehensive comparison of the effects of a phase-locked loop (PLL) and LCC controller on the small-signal stability of LCC-HVDC system with different control strategies at the inverter station under weak AC grid condition. Then, the coupling effect between the PLL and LCC controller parameters is investigated when LCC-HVDC system adopts different control strategies. This paper can provide useful guidance for the systematic design and control parameter selection of LCC-HVDC projects.

Variable Structure Control Design for a Magnetic Levitation System

In this paper the variable structure control theory is utilized to derive a discontinuous controller to the magnetic levitation system. The magnetic levitation system model is considered uncertain, which subjected to the uncertainty in system parameters, also it is open-loop unstable and strongly nonlinear. The proposed variable structure control to magnetic levitation system is proved, and the area of attraction is determined. Additionally, the chattering, which induced due to the discontinuity in control law, is attenuated by using a non-smooth approximate. With this approximation the resulted controller is a continuous variable structure controller with a determined steady state error according to the selected control parameters. Finally the ability and the effectiveness of the proposed continuous variable structure controller to the magnetic levitation system are verified via numerical simulations. When state initiated inside the area of attraction, the results show that the ball position can be directed to follow various desired positions, with steady state error not exceeding . 

A novel method for determining the spatial responses of a cable-stayed bridge with four cable-planes

In this paper, a novel method for determining the spatial responses of a cable-stayed bridge with four cable-planes at the design and construction stages is proposed. Herein, the entire construction stage includes many intermediate steps and one completion step. In this method, the spatial responses of the bridge at the design stage (SRBDS) are firstly determined by minimizing the bending and torsion strain energy of the cable-stayed bridge. Simultaneously, the optimal cable forces and the ratios of the inside to outside plane cables are also determined at this stage. Note that the SRBDS are considered as the target responses of the construction stage at the completion step. Then, the Forward process method is used to calculate the spatial responses of the bridge at the construction stage (SRBCS). The least square method is employed to minimize the difference values of the selected control parameters, e.g., cable forces and displacement, between the completion step at the construction stage and the design stage. Finally, the revised results, which satisfy the designated error requirements, are preserved as the SRBCS. To verify the proposed method, an example cable-stayed bridge with four cable-planes and double-girders, the Jiashao bridge, is analyzed. The structural responses, e.g., the stress and displacement of the girder and tower, of the bridge at the design and construction stages are analyzed and compared to demonstrate the superiority of the proposed method and investigate the spatial responses, e.g., the torsion in the main girder, of this cable-stayed bridge with four cable-planes.

Affine formation control for heterogeneous multi-agent systems with directed interaction networks

In this paper, affine formation control problems of heterogeneous multi-agent systems with linear dynamics are studied. As a novel method, the affine formation control has the ability to handle various movement constraints based on the affine transformation. A proportional-integral (PI)-type control scheme is proposed to ensure the effective affine formation control of the leader-following group with directed interaction graphs and successfully eliminate the steady-state errors. Sufficient conditions for the selection of control parameters are given and proved. Considering that the followers are subjected to the external bounded time-varying disturbances, the designed protocol shows good robustness and can guarantee uniformly ultimate boundedness of affine formation errors. Numerical simulations are carried out to verify the theoretical results.

The choice of control parameters for regulating modes of operation of a switched reluctance motor

The article discusses the choice of control parameters for regulating various modes of operation of a switched reluctance motor. The analysis of articles published during the 2005-2018 year a switched reluctance motors for various drives in Ukraine and abroad. The analysis showed that there is a great diversity in the choice of control parameters from different authors, and most authors do not have an analysis of transients when using selected control parameters. The author of the article in previous works used phase control for a switched reluctance motor of a mine electric locomotive with a capacity of 27 kW and a rotational speed of 1146 min-1. In order to select the optimal control parameters in this work for the specified engine, the PWM voltage was chosen as the control parameter. Transients are considered when changing the load torque in the engine mode, as well as from the engine mode to the recuperative braking mode at a constant rotation speed using the developed engine model for transients in the Simulink program of the Matlab software package. When switching from engine mode to recuperative braking, the on and off angles changed. The pulse duty rates in PWM were determined using mechanical characteristics calculated on the engine models for steady-state conditions. The results of the analysis can be used in the development of a program for the microprocessor controller.

A Rule-Based Energy Management Strategy Based on Dynamic Programming for Hydraulic Hybrid Vehicles

Energy management strategy is very important for hydraulic hybrid vehicles to improve fuel economy. The rule-based energy management strategies are widely used in engineering practice due to their simplicity and practicality. However, their performances differ a lot from different parameters and control actions. A rule-based energy management strategy is designed in this paper to realize real-time control of a novel hydraulic hybrid vehicle, and a control parameter selection method based on dynamic programming is proposed to optimize its performance. Firstly, the simulation model of the hydraulic hybrid vehicle is built and validated by the data tested from prototype experimental platform. Based on the simulation model, the optimization method of dynamic programming is used to find the global optimal solution of the engine control for the UDDS drive cycle. Then, the engine control parameters of the rule-based energy management strategy are selected according to the engine control trajectory of the global optimal solution. The simulation results show that the 100 km fuel consumption of the proposed rule-based energy management strategy is 12.7L, which is very close to the global optimal value of 12.4L and is suboptimal.

Pitch Controller Design of Wind Turbine Based on Nonlinear PI/PD Control

This paper analyzed and discussed the nonlinear PI/PD control for wind energy conversion system (WECS) pitch controller design. The nonlinear PI/PD controller consists of a classical PI/PD controller and a nonlinear gain table. In this paper, the detailed design procedures of the controller including not only the selection of control parameters but also the formulation of nonlinear gain table were given. In order to verify the effectiveness and correctness of the algorithm, a detailed 2 MW simulation test platform based on MATLAB/SIMULINK environment was established. Meanwhile, some valuable conclusions were also obtained. The presented contents of this article have the reference value and guiding significance for practical engineering application.

Fractional-order PID control of a MIMO distillation column process using improved bat algorithm

In this paper, a new bat algorithm (BA) based on dynamic control parameters selection is presented. The dynamic BA (DBA) uses a new mechanism to dynamically select the best performing combination of the pulse rate coefficient, the pulse frequency coefficient, and the population size. A fractional-order PID (FOPID) controller based on the DBA is implemented to improve the performance of a distillation column process. The proposed FOPID controller is used to control the distillate and bottom mole fractions. The influence of the feed rate disturbance is considered for this model. The efficacy of the DBA-based FOPID is compared with the performance of the controllers based on the conventional BA, directional BA, enhanced BA, genetic algorithm, and particle swarm optimization algorithm. The analyses and simulation results show the superiority of the proposed method.

On finite‐time robust stabilization via nonlinear state feedback

SummaryA nonlinear control law is designed for finite‐time stabilization of a chain of integrators. The method is based on the implicit Lyapunov function technique and homogeneity properties. The scheme of control parameter selection is presented by a linear matrix inequality. The method is simple in implementation and does not assume an online procedure for the computation of the implicit Lyapunov function value at the current state that is an improvement with respect to the works of Polyakov et al. The control law is presented in an explicit form and allows finding the values of all control parameters that make the solution one of the most constructive. The theoretical results are supported by numerical examples.

Accuracy optimization of combined multiparameter measuring systems with application to polarized light microscopy.

We study the accuracy of combined multiparameter measuring systems (CMPMSs) that determine several unknown quantities from measurements of a single variable at different preprogrammed conditions determined by control parameters. To reduce inaccuracies of determined quantities, we propose a mathematical method for selection of control parameters that are optimal for all possible values of determined quantities. Using the submultiplicativity of the spectral and Frobenius matrix norms, we construct the upper bound of the error function and determine the set of control parameters by minimizing this bound. To demonstrate the capability of our method for CMPMSs, we apply it to the polarized light microscopy technique called LC-PolScope, which is used for determining inhomogeneous two-dimensional fields of optical retardation and orientation of the slow optic axis in thin organic and inorganic samples. We compare the computed set of control parameters with other sets, including the one used in the PolScope, and demonstrate that our choice of control parameters works very well even though it does not take into account any specific features of the PolScope. We expect that our method will be successful in various CMPMSs, as it is applicable to any error distribution of the control parameters and measured values.

Robust attitude predictive control design for hypersonic vehicles with state constraints

In this paper, a novel robust predictive controller based on the tangent barrier Lyapunov function (BLF-Tan) is proposed for the attitude tracking problem of the hypersonic vehicles with full state constraints. The finite-time nonlinear disturbance observer is involved to improve the predictive controller’s property of disturbance rejection. It is strictly proved that with the proposed approach, all state constraints are not violated, all signals in the closed-loop systems are bounded and asymptotical tracking is achieved. Furthermore, the relationship among state constraints, initial state conditions, tracking performance and controller parameters is analyzed, which provides a guideline for the selection of controller parameters. And the solvability analysis of the constrained tracking problem provides a guideline for the selection of desired states trajectories. Finally, the numerical simulation shows that the proposed method for hypersonic vehicles can guarantee all state constraints are not violated compared with the classical predictive controller, and also has fast convergence rate and enough robustness.

Model-free chaos control based on AHGSA for a vibro-impact system

For a vibro-impact system with clearance, the model-free chaos control method based on adaptive hybrid gravitational search algorithm (or AHGSA algorithm for short) is proposed. Nonparametric time-varying dynamic linear model based on pseudo-partial-derivative is established using input/output data of the controlled system, and on this basis, the optimal controller is designed according to the quadratic performance index, and the controller parameters is optimized using AHGSA algorithm. By combining the artificial bee colony search operator and chaos optimization strategy, gravitational search algorithm (or GSA algorithm for short) is improved from three aspects (i.e., population initialization, velocity and position update, gravity coefficient adjustment) to achieve a balance between the global detection ability and the local development ability. AHGSA algorithm has good optimization accuracy and efficiency: The arbitrariness is avoided in controller parameters selection, and the quality of the chaos control is ensured as well. In simulation experiment, the model-free controller optimized is used to control the chaotic motion of a single-degree-of-freedom vibro-impact system with clearance to verify the validity and feasibility of the proposed chaos control method. The simulation results show that the control effect is good, and the proposed chaos control method has the following advantages: the proposed chaos control method does not depend on the precise model of the controlled system, and the controller is easy to be designed and implemented.

Optimal homotopy analysis and control of error for implicitly defined fully nonlinear differential equations

Implicitly defined fully nonlinear differential equations can admit solutions which have only finitely many derivatives, making their solution via analytical or numerical techniques challenging. We apply the optimal homotopy analysis method (OHAM) to the solution of implicitly defined ordinary differential equations, obtaining solutions with low error after few iterations or even one iteration of the method. This is particularly true in cases where an auxiliary nonlinear operator was employed (in contrast to the commonly used choice of an auxiliary linear operator), highlighting the need for further study on using auxiliary nonlinear operators in the HAM. Through various examples, we demonstrate that the approach is efficient for an appropriate selection of auxiliary operator and convergence control parameter.

Chattering reduced sliding mode control for a class of chaotic systems

This paper presents a sliding mode control scheme for chaotic systems. Finite time stability of the system states is realized by implementing the proposed controller, which is designed on the basis of a nonlinear sliding surface and a new sliding mode reaching law. The new reaching law contributes good control performance in terms of system reaching time and input chattering reduction. Principles for controller parameter selection are given in detail. Simulation results of two controlled chaotic systems are provided to demonstrate effectiveness of the proposed method.

Active flow control analysis at the rear of an SUV

PurposeThis paper aims to present an experimental investigation of an active flow control solution mounted at rear of a sport utility vehicle (SUV) with the objective of drag reduction, thanks to a selection of flow control parameters leading to a pressure increase on the tailgate.Design/methodology/approachA flow control design of experiments was conducted with a pulsed jet system mounted on the top and sides of the rear window of the vehicle. The wall pressure, instantaneous velocity and drag were measured with this prototype in a wind tunnel. A dynamic modal decomposition (DMD) analysis of the pressure enables to describe the pressure fluctuations. Fluid dynamic computations show relation between pressure and velocity fields.FindingsMeasurements with this prototype in the wind tunnel revealed small improvements in drag for the best flow control configurations. This small benefit is because of the core of the upper span wise vortex further away from the rear window than the lower span wise vortex. These small improvements in drag were confirmed with pressure measurements on the rear window and tailgate. The DMD analysis of the surface pressure showed a low frequency pendulum oscillation on the lower area of the tailgate, linked with low velocity frequencies in the shear layers near the tailgate.Originality/valueExperimental and numerical results show interest to increase pressure at bottom of the rear end of this SUV prototype. The dynamic description of the wall pressure shows importance of flow control solutions reducing pressure fluctuations at low frequencies in the lower area of the tailgate.

Hybrid FGWO Based FLCs Modeling for Performance Enhancement in Wireless Body Area Networks

The progression over wireless technologies paves the way for the emergence of wireless body area networks (WBAN) towards several motivating applications. Specifically, in terms of health concern applications, both the performance and reliability is regarded as the essential elements of WBANs. Many of the soft computational methodologies employed the manual modeling of fuzzy logic controllers (FLCs) by evolutionary algorithms in WBAN. This existing model encodes the entire control parameters of “FLCs” membership functions. This leads to the degradation of network performance by maximizing the latency. In order to rectify this issue, here we propose a hybrid firefly grey wolf optimizer (hybrid FGWO) approach for the optimal modeling of “FLC”. The major goal behind our proposed work relays on the optimal selection of control parameters from the “FLCs” with hybrid FGWO. The modeling of “FLCs” is carried out with CLFB (cross-layer fuzzy logic dependent back-off controller) mechanism to control the frequent access of channels. The efficiency of the “FLCs” model is enhanced by utilizing the coding technique known as unrestricted coding scheme. The performance of our hybrid FGWO approach is contrasted with three conventional “EAs”. Two major modeling goals are established whereas, the initial goal aims for the modeling of “FLCs” on particular configuration of network and the second goal aims on the modeling of “FLCs” over multiple network configurations. The “FLCs” modeled by means of our proposed hybrid FGWO approach exhibits its performance in terms of throughput, latency and packet delivery ratio with some of the challenging algorithms.

Control rules extraction and parameters optimization of energy management for bus series-parallel AMT hybrid powertrain

A rule-based energy management strategy, that the control rules are extracted from acknowledged optimal algorithms and its control parameters are optimized offline and corrected online, for a series-parallel hybrid powertrain with an automatic mechanical transmission (AMT) is proposed in this paper to achieve near optimal fuel economy and battery state-of-charge (SOC) balance. Firstly, the dynamic programming (DP) global optimization method is applied to extract driving-mode transition rules and gear shifting rules. Furthermore, an instantaneous equivalent fuel consumption minimizing optimization method (ECMS) is utilized to determinate the engine torque distribution rules during its parallel driving mode. Then selected control parameters of driving-mode switching rules and torque split distribution are optimized based on genetic algorithm (GA) for further fuel consumption improvement. And the adaptive correction of optimized control parameters based on online driving cycle recognition method is discussed also. The simulation results show that this real-time rule-based energy management control strategy associated with the series of optimization approaches comprehensively can achieve a relatively close fuel consumption results to global optimal results and sustain the battery SOC balance after the end of driving cycle without much cycle-depending care.