Transient State Performance Research Articles

A new modeling method for both transient and steady-state analyses of inhomogeneous assembly systems

Production system modeling (PSM) focuses on revealing the component-level principles of production procedures. Despite the extensive studies for PSM of serial production systems, assembly systems have received much less investigation. Among existing PSM researches on assembly lines, most are focused on the steady-state system performance, while the transient behavior of the inhomogeneous assembly systems is largely unexplored. This paper presents a new analytical PSM method for inhomogeneous assembly systems considering Bernoulli machines and finite buffers. By using the proposed ‘Split-View’ method, both transient and steady-state analyses of such systems can be performed. This model can be solved without using the traditional decomposition technique. The solvability of the established model has been proven theoretically. The sensitivity studies of system performance in both transient and steady states are numerically investigated. Numerical studies demonstrate the high accuracy of the method comparing with the simulation results.

Dynamic model development of heat and mass transfer for a novel desiccant regeneration system in liquid desiccant dehumidification system

In this paper, from the control point of view, a simplified dynamic model of the Desiccant Regenerations System (DRS) is proposed. The DRS is a serial system of the heat pipe heat exchanger and regenerator whose models are developed by writing the thermal and moisture balance equations, and the heat and mass transfer rates of each subsystem are derived by using the effectiveness-NTU and hybrid modeling approach. The unknown Model parameters are identified through the nonlinear least squares method and unscented Kalman filter algorithm with commissioning information. The dynamic model of the whole system is obtained by integrating the subsystem models to predicts the system performance. Compared with the existing DRS models, the presented model not requires iterative computations and also can be easily transformed into a state-space model. The proposed model accurately reflects the transient and steady state performance of the DRS over the wide operating condition in the experimental validation and is expected to work well for intelligent dynamic control and optimization applications.

Nonlinear Uncertainties Canceling in Multi-Agent Systems Enabled by Cooperative Adaptation

This paper deals with uncertainties problem in multi-agent systems with novel cooperative adaptation approach. Since uncertainties in multi-agent systems are interconnected, local agent often faces uncertainties not only from itself but also from neighbors. The proposed approach is that a local agent estimates uncertainties from itself and neighboring agents and then changes control strategy. The uncertainties or the equivalences of neighbors can be estimated based on their available outputs; thus, the local agent can adapt to them to cancel out these effects. Stability analysis is also derived that characterizes the transient and steady state performance of multi-agent system. The simulation presents the details of the proposed cooperative adaptation mechanism by compared typical cooperative control.

Studying the Steady State Performance Characteristics of Induction Motor with Field Oriented Control Comparing to Scalar Control

Field oriented control is from the best methods to control the AC drives this is because this method of control transfers the advantages of DC drives into AC drives. With using this method of control, the torque per ampere for AC machines increases, the dynamic performance becomes higher, transient and steady state performance become improvement. This paper is comparing between the steady state characteristics of induction motor with using the field oriented control and scalar control to show the advantages of the field oriented control comparing to scalar control. this studying not only concerned with constant flux region but also focused in the field weakening region. The MATLAB program is used to studying the steady state performance characteristics of induction motor with field oriented control and scalar control.

Modified acceleration feedback for practical disturbance rejection in motor drives

Acceleration feedback techniques have been used in control systems for a long time in order to improve the stiffness. Basically, the acceleration of the motor is calculated using speed or position measurements and the current command is adjusted using the acceleration data for avoiding deviations from the commanded speed. This method has to deal with two challenges. The first challenge is calculating the acceleration correctly. If it is calculated by double differentiation of position feedback of a servo motor, it may lead to a high amount of noise. On the other hand, if observer techniques are used, the error and variation in system parameters and quantization noise in the measured current may lead to incorrect calculation of the motor acceleration. The second challenge is avoiding performance degradation in the transient response of the system and preventing oscillations. Since acceleration feedback will try to avoid any acceleration in the system, it may severely affect the transient-state performance. This paper presents a disturbance rejection method that does not depend on system parameters and that does not affect the transient-state response of the system. The method provides very significant improvement in disturbance rejection over a wide frequency range. The magnitude of disturbance response was --29.6 dB in the original scheme at its peak frequency of 5.17 Hz; using the proposed method, it improved to --44.7 dB at the same frequency.

Trajectory tracking of quadrotor flying manipulators using [formula omitted] adaptive control

This paper concerns with tracking control of an unmanned quadrotor vehicle equipped with a multi-link robotic manipulator. We present an analytic model of the system that formulates unknown interactions between the aerial platform and the manipulator in the form of nonlinear time-varying uncertainties. Based on the proposed model, a novel trajectory tracking scheme is synthesized by combining two inner feedback linearization loops to stabilize the nominal quadrotor and manipulator dynamics and a master L1 adaptive loop to systematically compensate for uncertainties and realize the desired closed-loop behavior. We show that this scheme leverages predictable transient and steady state performance in the presence of coupling effects and given a specified reference trajectory. Simulation studies have shown the effectiveness of the proposed aerial manipulator control method.

Improved prescribed performance control for air-breathing hypersonic vehicles with unknown deadzone input nonlinearity

An improved prescribed performance controller is proposed for the longitudinal model of an air-breathing hypersonic vehicle (AHV) subject to uncertain dynamics and input nonlinearity. Different from the traditional non-affine model requiring non-affine functions to be differentiable, this paper utilizes a semi-decomposed non-affine model with non-affine functions being locally semi-bounded and possibly in-differentiable. A new error transformation combined with novel prescribed performance functions is proposed to bypass complex deductions caused by conventional error constraint approaches and circumvent high frequency chattering in control inputs. On the basis of backstepping technique, the improved prescribed performance controller with low structural and computational complexity is designed. The methodology guarantees the altitude and velocity tracking error within transient and steady state performance envelopes and presents excellent robustness against uncertain dynamics and deadzone input nonlinearity. Simulation results demonstrate the efficacy of the proposed method.

Design of two degree of freedom-internal model control configuration for load frequency control using model approximation

In this paper, a modified two degree of freedom-internal model control structure is proposed with dual feedback loop configuration for load frequency control problem of the single area and two area non-reheated power systems to achieve better transient and steady state performance. Predictive model of the proposed configuration is derived through Routh, Padé and SOPDT approximations. Hence, for all three cases, the proposed configuration is simulated considering the single area and two area power systems with non-reheated turbine along with 50% parametric uncertainty. Finally, a comparison with existing techniques is included to validate the effectiveness and performance of the proposed control configuration through responses and error indices. It is observed that the proposed scheme generates better results under parameter variations.

Design and real time implementation of sliding mode supervised fractional controller for wind energy conversion system under sever working conditions

Wind energy conversion system (WECS) is increasingly taking the place to be the most promised renewable source of energy, which obliges researchers to look for effective control with low cost. Thus, this paper proposes to build a suitable controller for speed control loop to reach the maximum power point of the wind turbine under sever conditions and to ensure the stability of the outer voltage regulation loop to meet high range of load variations. In literature, a major defect of the well-used conventional PI controller is the slow response time and the high damping. Nowadays, intelligent controllers have been used to solve the drawbacks of the conventional ones but they demand high speed calculators and expensive cost. Moreover, many solutions proposed the fractional order PI controller (FO-PI) by extending the order of integration from integer to real order. The FO-PI controller presents also some weakness in steady state caused by the approximation methods. The idea of this paper is to propose a Sliding Mode Supervised Fractional order controller (SMSF) which consists of conventional PI controller, FO-PI controller and sliding mode supervisor (SMS) that employs one of the controllers to ensure good steady and transient states. WECS laboratory prototype is built around real-time dSPACE cards and evaluated to verify the validity of the developed SMSF. The results clearly fulfill the requirements, confirm its high performance in steady and transient states and demonstrate its feasibility and effectiveness.

Nonlinear Model-Based Multivariable Control for Air & Charging System of Diesel Engine with Short and Long Route EGR Valves

The objective of this study is to investigate a nonlinear model-based multivariable (MIMO, Multi Input Multi Output) technique to decouple actuators interaction and to reduce the calibration effort, while increasing control performances, above all in transient conditions, and robustness with respect to model uncertainties and system parameter variations. The presented control technique is based on the development of a nonlinear dynamical physical model of the diesel air and charging system. Feedback Linearization control is then applied to decouple actuators’ interactions and compensate for nonlinearities. A new set of virtual inputs are defined inverting the system differential equations. Relation among the new virtual inputs and the outputs is purely linear and decoupled, meaning that each virtual input affects linearly only one output. Moreover, a linear control block is added to guarantee transient and steady state performances and closed loop robustness. The proposed control approach has been validated through small diesel engine dyno and vehicle activities. Transient test bench maneuvers show that the control is able to coordinate the actuators in order to fulfill the targets and to guarantee similar performances in different operating points. In addition the robustness to environmental changes has been demonstrated by vehicle tests at different ambient conditions.

Investigating the ability of shunt hybrid power filter based on SRF method under non-ideal supply voltage

This study presents the capacity of a self-tuning filter based on the synchronous reference frame method with a fuzzy logic controller for the improvement of the efficiency of harmonic suppression of a shunt hybrid active power filter in an unbalanced distorted and un-distorted voltage supply conditions. The simulation results indicated that the filter with a fuzzy logic controller had a good filtering performance in steady and transient states, irrespective of whether the voltage supply is distorted or unbalanced.

TRANSIENT AND STEADY STATE PERFORMANCE CHARACTERISTICS OF A THERMOELECTRIC GENERATOR

The global energy and environmental issues are promoting the development of innovative energy solutions. Thermoelectric generators (TEGs) are regarded as a promising alternative to conventional energy technologies. TEG is a device that converts thermal energy directly into electric power by exploiting Seebeck effect. It is essential to understand the behavior of thermoelectric devices during both thermal transient and steady state to accurately simulate and design complex and dynamic thermoelectric systems. So a comprehensive model for simulating the dynamic TEG performance is developed, taking into consideration all the thermoelectric effects (Seebeck, Peltier and Thomson), in addition to Joule heating and Fourier heat conduction. Additionally, the effects of temperature-dependence of thermoelectric materials are accounted. Computational results are retrieved using “MATLAB” software. To verify the integrity of the modeling processes, the predicted results are compared with data obtained from the experimental evaluation. It is found that the outcomes of the experimental analysis validated the accuracy of the developed model and the possibility to be used as a simulation tool. The dynamic performance characteristics of a TEG is experimentally studied under different operating conditions. The effect of input heat rate and the influence of utilizing extended surfaces (fins) on both transient and steady state performance of a TEG are experimentally investigated. The variation in the temperature of the TEG hot and cold sides in addition to the output voltage is taken as a denotation of the performance characteristics. Input heat rate of 15.0 W, 17.5 W, 20.0 W, 22.0W and 25.0 W are applied to the TEG hot side. Free air convection is the utilized for heat dissipation from the TEG module through the cold side. From the experimentation, it can be deduced that increasing the input heat rate provides higher temperature difference across the module sides leading to higher power output. Additionally, using fins to aid heat dissipations enhanced the TEG performance by lowering the temperature of cold side and increasing the temperature difference across the module. The experimental data obtained are compared with the data available by the TEG module manufacturer and excellent agreement is obtained.

Line-Interactive Transformerless Uninterruptible Power Supply (UPS) with a Fuel Cell as the Primary Source

This paper presents line-interactive transformerless Uninterruptible Power Supply (UPS) with a fuel cell as the prime energy source. The proposed UPS consists of three major parts (i.e., an output inverter, a unidirectional DC–DC converter, and a battery charger/discharger). Non-isolated topologies of both the unidirectional converter and battery charger/discharger ensure transformerless operation of the UPS system. A new topology of high gain converter is employed for boosting the low voltage of the fuel cell to a higher DC link voltage, with minimum semiconductor count, and high efficiency. A high-gain battery charger/discharger realizes the bidirectional operation between the DC link and the battery bank. Besides, it regulates the DC link voltage during the cold start of fuel cells and keeps the battery bank voltage to only 24 V. A new inverter control scheme is introduced that regulates the output voltage and minimizes the total harmonic distortion for non-linear loading condition. The proposed control scheme integrates proportional-resonant control with slide mode control, which improves the controller’s performance in transient conditions. The proposed UPS system is validated by developing a 1-kVA experimental prototype.

Torque-Ripple Reduction and Fast Torque Response Strategy for Predictive Torque Control of Induction Motors

This paper proposes a simple control method of induction motors (IMs) with improved dynamic response and steady-state performance by using a model-based predictive control algorithm. The predictive torque control (PTC) method analyzes the relationship between the electrical torque and stator voltage of IMs by using the stator voltage vector magnitude to obtain the reference voltage vector angle and accurately control the electrical torque. However, the conventional PTC method has a fixed reference voltage vector magnitude and thus has a large torque ripple in the steady state and slow dynamics in the transient state. The proposed PTC method is based on mathematical equations, which allow minimization of torque error and calculation of a relevant reference voltage to establish a better dynamic response in the transient state and accurate control performance in the steady state. Excellent steady-state performance and a quick dynamic response of the proposed method are proved by the simulation and experimental results.

A distributed control and parameter estimation protocol with prescribed performance for homogeneous lagrangian multi-agent systems

In this paper, we consider the formation control problem for uncertain homogeneous Lagrangian nonlinear multi-agent systems in a leader-follower scheme under a directed communication protocol. A distributed adaptive control protocol of minimal complexity is proposed that achieves prescribed, arbitrarily fast and accurate formation establishment as well as synchronization of the parameter estimates of all followers. The estimation and control laws are distributed in the sense that the control signal and the update laws are calculated based solely on local relative state information. Moreover, provided that the communication graph is strongly connected and contrary to the related works on multi-agent systems, the controller-imposed transient and steady state performance bounds are fully decoupled from: (i) the underlying graph topology, (ii) the control gains selection and (iii) the agents’ model uncertainties. Finally, extensive simulation studies on the attitude control of flying spacecrafts clarify and verify the approach.

TRANSIENT AND STEADY STATE PERFORMANCE CHARACTERISTICS OF A THERMOELECTRIC GENERATOR

The global energy and environmental issues are promoting the development of innovative energy solutions. Thermoelectric generators (TEGs) are regarded as a promising alternative to conventional energy technologies. TEG is a device that converts thermal energy directly into electric power by exploiting Seebeck effect. It is essential to understand the behavior of thermoelectric devices during both thermal transient and steady state to accurately simulate and design complex and dynamic thermoelectric systems. So a comprehensive model for simulating the dynamic TEG performance is developed, taking into consideration all the thermoelectric effects (Seebeck, Peltier and Thomson), in addition to Joule heating and Fourier heat conduction. Additionally, the effects of temperature-dependence of thermoelectric materials are accounted. Computational results are retrieved using “MATLAB” software. To verify the integrity of the modeling processes, the predicted results are compared with data obtained from the experimental evaluation. It is found that the outcomes of the experimental analysis validated the accuracy of the developed model and the possibility to be used as a simulation tool. The dynamic performance characteristics of a TEG is experimentally studied under different operating conditions. The effect of input heat rate and the influence of utilizing extended surfaces (fins) on both transient and steady state performance of a TEG are experimentally investigated. The variation in the temperature of the TEG hot and cold sides in addition to the output voltage is taken as a denotation of the performance characteristics. Input heat rate of 15.0 W, 17.5 W, 20.0 W, 22.0W and 25.0 W are applied to the TEG hot side. Free air convection is the utilized for heat dissipation from the TEG module through the cold side. From the experimentation, it can be deduced that increasing the input heat rate provides higher temperature difference across the module sides leading to higher power output. Additionally, using fins to aid heat dissipations enhanced the TEG performance by lowering the temperature of cold side and increasing the temperature difference across the module. The experimental data obtained are compared with the data available by the TEG module manufacturer and excellent agreement is obtained.

A robust interaction control approach for underwater vehicle manipulator systems

In underwater robotic interaction tasks (e.g., sampling of sea organisms, underwater welding, panel handling, etc) various issues regarding the uncertainties and complexity of the robot dynamic model, the external disturbances (e.g., sea currents), the steady state performance as well as the overshooting/undershooting of the interaction force error, should be addressed during the control design. Motivated by the aforementioned considerations, this paper presents a force/position tracking control protocol for an Underwater Vehicle Manipulator System (UVMS) in compliant contact with a planar surface, without incorporating any knowledge of the UVMS dynamic model, the exogenous disturbances or the contact stiffness model. Moreover, the proposed control framework guarantees: (i) certain predefined minimum speed of response, maximum steady state error as well as overshoot/undershoot concerning the force/position tracking errors, (ii) contact maintenance and (iii) bounded closed loop signals. Additionally, the achieved transient and steady state performance is solely determined by certain designer-specified performance functions/parameters and is fully decoupled from the control gain selection and the initial conditions. Finally, both simulation and experimental studies clarify the proposed method and verify its efficiency.

Field Current Estimation for Wound-Rotor Synchronous Starter–Generator With Asynchronous Brushless Exciters

Accurate information about the field current of the wound-rotor synchronous starter generator (WRSSG) is prerequisite for optimal start control research for WRSSG in the starting mode. However, as the field winding of WRSSG is in the rotating parts and there is no slip ring and brush mounted in the shaft, the measurement of the field current is not possible. A field current estimation method for the WRSSG from the brushless exciter side was proposed in this paper. In this estimation method, the rotor currents and voltages of the asynchronous brushless exciter were first estimated and then used to calculate the field current of WRSSG through the parametric average-value model of the rotating rectifier. Experimental results verified that the proposed estimation method showed sufficiently accurate estimation performance both in steady and transient states.

A Full Mean Square Analysis of CLMS for Second-Order Noncircular Inputs

A full mean square transient and steady-state analysis of the complex least mean square (CLMS) algorithm is provided for strictly linear estimation of general second-order noncircular (improper) Gaussian inputs. To this end, we also consider the performance assessment in terms of the evolution of the complementary mean square error (CMSE) and the complementary covariance (pseudocovariance) matrix of the weight error vector of CLMS. This makes it possible to measure the degrees of noncircularity of the output error and the weight error vector, which arise due to second-order noncircularity (improperness) of the system input and system noise. The recently introduced approximate uncorrelating transform, which allows for joint direct diagonalization of both the input covariance and complementary covariance matrices with a single singular value decomposition, is then employed in order to derive a unified bound on the step-size, which guarantees the convergence of both the standard MSE and the proposed CMSE. A joint consideration of the standard mean square performance analysis and the proposed complementary performance analysis is shown to provide full second order, closed form, statistical descriptions of both the transient and steady state performances of CLMS for second-order noncircular (improper) Gaussian input data. Simulations in the system identification setting support the analysis.

Adaptive backstepping H∞ tracking control with prescribed performance for internet congestion

This paper extends the well-known control method, prescribed performance control (PPC), to network congestion control problems. An adaptive H∞ tracking problem for Transmission Control Protocol/Active Queue Management (TCP/AQM) system with external disturbance is studied. Firstly, a modified network model is given. And then, the model is changed to an equivalent error model by using error transformation. Next, to solve the network congestion problem, prescribed performance, backstepping technique, adaptive control and H∞ control are combined to design a congestion controller. Due to the use of prescribed performance, the controller can guarantee both the transient and steady state performance of the system. Meanwhile, the output of the system can track the desired queue, and unknown link capacity can be estimated. Finally, a simulation result is shown to clarify the feasibility and effectiveness of proposed approach.