Advanced Control Design Research Articles

Advanced Control Strategies Applied to Bioprocesses: An Overview

In the last decades, biology, agriculture, food science, and medicine technologies have been gathered in a new science field recognized as biotechnology. Of course, human beings have always been dependent on chemical and biochemical processes to meet their needs. But health care has taken such an important place in everyone's life that the economic potentialities of the biotechnology market have pushed the industry, e.g., food and biopharmaceuticals, to engage in a race at peak performance requiring more than the heuristics. Optimization of bioprocesses through monitoring and control is now the spearhead of many big industries for the next decades. Mechanistic models are widely used in bioprocess modeling mainly because of their lower degree of complexity (in comparison with microscopic models) allowing an easier control design which must be chosen, taking the plant particularities into account: – What is the plant optimum? – Which state variables should be controlled? – Are the controlled variables measurable? – If not, is there a way to correctly estimate or observe them? – Is a suboptimal solution more practical? – Should the controller have a certain complexity degree? Is the complexity degree a source of limitation? An overview of advanced control design techniques applied to different fields of biotechnology is presented.

From multi-parametric programming theory to MPC-on-a-chip multi-scale systems applications

An overview of multi-parametric programming and control is presented with emphasis on historical milestones, novel developments in the theory of multi-parametric programming and explicit MPC as well as their application to the design of advanced controller for complex multi-scale systems.

Model predictive control of a wind turbine using short‐term wind field predictions

ABSTRACTAs wind turbines become larger and hence more flexible, the design of advanced controllers to mitigate fatigue damage and optimise power capture is becoming increasingly important. The majority of the existing literature focuses on feedback controllers that use measurements from the turbine itself and possibly an estimate or measurement of the current local wind profile. This work investigates a predictive controller that can use short‐term predictions about the approaching wind field to improve performance by compensating for measurement and actuation delays.Simulations are carried out using the FAST aeroelastic design code modelling the NREL 5 MW reference turbine, and controllers are designed for both above rated and below rated wind conditions using model predictive control. Tests are conducted in various wind conditions and with different future wind information available. It is shown that in above rated wind conditions, significant fatigue load reductions are possible compared with a controller that knows only the current wind profile. However, this is very much dependent on the speed of the pitch actuator response and the wind conditions. In below rated wind conditions, the goals of power capture and fatigue load control were considered separately. It was found that power capture could only be improved using wind predictions if the wind speed changed rapidly during the simulation and that fatigue loads were not consistently reduced when wind predictions were available, indicating that wind predictions are of limited benefit in below rated wind conditions. Copyright © 2012 John Wiley & Sons, Ltd.

Modeling of current mode controlled boost converter supplied by fuel cell suitable for controller design purposes

This paper presents the derivation of a linear model with changeable parameters of constant frequency peak current mode controlled DC/DC boost converter supplied by a PEM fuel cell stack. The derived model has the same structure irrespective of the conduction mode and therefore, it is suitable for design of simple and advanced controllers of the output voltage. Experimental results on the system with 450 W boost converter supplied by PEM fuel cell emulator show that the derived model accurately describes the system in a given operating point, determined by the load resistance or output current.

Decoupling control for spatial six-degree-of-freedom electro-hydraulic parallel robot

This paper presents a decoupling controller equipped with cross-coupling pre-compensation for an electro-hydraulic parallel robot, in order to weaken system dynamic coupling effects usually ignored on the design of advanced controllers and improve system control performance. The mathematical model of the electro-hydraulic parallel robot is built using the Kane method and a hydromechanics approach, and the kinematical model is established with a closed-form solution and the Newton-Raphson method. The feedback linearization theory is applied to reduce coupling effects stemmed from system dynamics of the parallel robot via incorporating force-velocity control with cross-coupling pre-compensations. The control performance involving stability, accuracy, and robustness of the proposed controller for spatial 6-DOF parallel robot is analyzed in theory and experiment. The experimental results illustrate that the proposed controller can highly improve the control performance by weakening system dynamic coupling effects of the electro-hydraulic parallel robot, especially for trajectory tracking performance.

Design of a tower and drive train damping controller for the three‐bladed controls advanced research turbine operating in design‐driving load cases

AbstractWind turbines experience both fatigue and extreme loading, and individual components of a wind turbine are affected differently by these loads. The current practice to achieve the typical 20 year design life is to build a turbine with robust components that can withstand fatigue and extreme loads for this duration. Unfortunately, overbuilding of components may lead to higher‐than‐necessary initial capital costs. In this research, we studied design‐driving load cases and designed advanced control algorithms aimed at enabling a decrease in initial capital cost. Our approach used a subset of a full International Electrotechnical Commission loads case analysis and selected major components experiencing design‐driving extreme loads that can be alleviated using advanced control. We first describe the results from the loads case analysis and then discuss the components on which we focused the advanced control design. We next describe the controller design and finally compare the results from the advanced controller simulations with those using a baseline controller. The baseline consists of a nonlinear torque controller below rated wind speed and a proportional‐integral‐derivative‐like controller above rated and the advanced controller uses proportional feedback and state‐space design to reduce tower bending and drive train torsional loads. Copyright © 2011 John Wiley & Sons, Ltd.

An Overview of Renewable Wind Energy Conversion System Modeling and Control

Wind energy is pollution-free and renewable. Advanced control design for wind power generation systems represents a pivotal yet challenging research topic. Some sophisticated control schemes have been provided to ensure reliable and high efficient operation of wind turbines during various modes such as start-up, power production and protection shut-down. An overview on the latest developments in modeling and control of wind power generation systems is given in this paper. The main focus is on the effective operation of wind turbine in three well known modes covering safety: maximum power capturing, system protection and load impact reduction. Meanwhile, several key trends are discussed to demonstrate the possible solutions and feasibility of future implementation.

Hierarchical hybrid fuzzy strategy for column flotation control

Column flotation is widely used in the concentration of low grade ores. Often column flotation concentrate is the final product of a very complex circuit, and therefore control of the metallurgical performance has direct impact in the plant performance. Several control schemes has been implemented for the stabilization of column flotation process, including decentralized control, model predictive control and fuzzy approaches, which attempt to control froth depth, water bias and air holdup. At the same time many efforts have been oriented to improve process instrumentation, with the aim of providing better measurements for control purposes. Instrumentation improvements have made feasible the design of strategies focused on recovery and concentrate grade control. In this work we present the design and implementation of a new advanced controller for column flotation process. The controller was implemented in a 10 columns cleaning stage following a hierarchical scheme with two control levels: an improving level with the aim of metallurgical performance control of the whole process, and a stabilizing level in charge of the distribution of control actions in each column. The controller design was made based on a hybrid scheme with three different operation scenarios, defined by a recovery–concentrate grade domain partition. Results show that the controller is able to keep the process in the normal operation scenario 80% of the analyzed time; on the other hand, when the process was operated only with local control it achieved the normal operation scenario 43% of the analyzed time. Results also show that the controller is capable of increasing concentrate grade and recovery mean values, despite variations on feed grade; while reducing recovery and concentrate grade standard deviations.

A control design strategy of a reconfigurable manufacturing system

A Reconfigurable Manufacturing System (RMS) is defined as one that can provide adaptability to quickly adjust the production capacity and functionality in response to fluctuations in customer demand. An advanced analytical modelling approach and control design strategy is introduced to improve the system responsiveness of multistage feedback control RMS. A System Dynamics (SD)-based multistage RMS model is mathematically translated into block diagram representations and transfer functions. A control design technique called Root-Locus is presented to propose a new operation management policy to better predict and control the dynamic responses of a RMS in reduction of inventory and Lead-Time (LT). By applying this graphic view approach, one can improve the RMS responsiveness and also determine its relative system stability without iterative trial-and-error simulation replications as found in discrete event simulation and SD approach.

Robust identification of nonlinear frictional dynamics for advanced controller design

The robust identification of nonlinear frictional dynamics constitutes a significant challenge for the model based friction compensation in advanced control of electro-mechanical drives. This paper discusses the frictional phenomena in pre-sliding and gross sliding regime described by the advanced General-Maxwell-Slip friction model and proposes a robust identification approach to determine their distributed parameters. The nonlinear dynamics of a drive chain with multiple frictional surfaces is described. The appropriate control signals are designed to excite the friction dynamics in both pre-sliding and sliding regimes. The estimation of friction parameters relies on the recursive least square (RLS) technique with a suitable set of regressors. The identified model is compared with experimental data and applied in a tunable framework for the model based friction compensation.

Modeling and Verification of a Diamond-Shape Narrow-Tilting Vehicle

The authors use planar multibody system dynamics to model an intelligent personal mobility (IPM) narrow-tilting vehicle (NTV) with four wheels arranged in a diamond configuration. A planar multibody system tire model is used to represent ground-vehicle interaction. In addition to analyzing the roll plane dynamics, the proposed model supports the measuring of joint reaction forces (a difficult task with actual vehicles) to assist in advanced controller and mechanical system design. We also propose a separate calculation method using two acceleration sensors and one angular position sensor for the purpose of obtaining ground forces. Results from model verification tests (i.e., comparisons with actual data from a slalom test) indicate that the proposed IPM model performed with a high degree of accuracy.

A Generic Model-Based Advanced Control of Electric Power-Assisted Steering Systems

Electric power-assisted steering (EPS) systems have been used to replace traditional hydraulic power steering systems in vehicles. In an EPS system, the assisting steering torque is from an electric motor. In principle, the control of an EPS system involves two aspects: 1) motor torque control to satisfy the torque requirement and 2) steering motion control to yield a satisfied feeling of the driver during the steering process in a disturbed environment. In this paper, a column-mounted steering system is taken as a generic target system to illustrate a model-based approach for advanced steering control design. In particular, we present a two-controller structure proposal for the generic EPS system, addressing motor torque and steering motion, by applying <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">infin</sub> design methods, respectively. Controller model reduction is also discussed and compared to show that, actually, a reduced-order controller could be applied. This is important for industrial applications because a reduced-order control law costs less in computing resources. Finally, simulation for the EPS control system is discussed and a software-in-loop approach is presented using off-the-shelf software. It is interesting to see that, based on the simulation results, the advanced two-controller design yields superior performance to the one-controller structure for the steering control.

Minimizing transient energy growth in plane Poiseuille flow

The feedback control of laminar plane Poiseuille flow is considered. In common with many flows, the dynamics of plane Poiseuille flow is very non-normal. Consequently, small perturbations grow rapidly with a large transient that may trigger non-linearities and lead to turbulence, even though such perturbations would, in a linear flow, eventually decay. This sensitivity can be measured using the maximum transient energy growth. The linearized flow equations are discretized using spectral methods and then considered at one wave-number pair in order to obtain a model of the flow dynamics in a form suitable for advanced control design. State feedback controllers that minimize an upper bound on the maximum transient energy growth are obtained by the repeated solution of a set of linear matrix inequalities. The controllers are tested using a full Navier—Stokes solver, and the transient energy response magnitudes are significantly reduced compared with the uncontrolled case.

Development and Validation of a Civil Aircraft Engine Simulation Model for Advanced Controller Design

This paper presents details of the design and validation of a complex nonlinear real-time simulation model for a civil turbofan aircraft engine. The model was developed in a modular fashion using wherever possible the underlying physics and avoiding empirical approximations

Wind turbines: New challenges and advanced control solutions

Wind turbines: New challenges and advanced control solutions

Design of advanced PID controller for enhanced disturbance rejection of second‐order processes with time delay

AbstractA design method for a proportional‐integral‐derivative (PID) cascaded with a lead‐lag compensator is proposed for enhanced disturbance rejection of the second‐order stable and unstable processes with time delay. A two‐degree‐of‐freedom control scheme is used to cope with both regulatory and servo problems. An ideal feedback controller equivalent to internal model control (IMC) is obtained through the IMC design principle, and is further simplified to the PID cascaded with a first‐order lead‐lag compensator. The simulation is conducted for a broad class of stable and unstable processes and the results are compared with those of recently published PID type controllers to illustrate the superiority of the proposed controller. For a reasonable comparison, the controllers in the simulation study are tuned to have the same degree of robustness by measuring the maximum sensitivity, Ms. The robustness of the controller is also investigated by simultaneously inserting a perturbation uncertainty in all parameters in order to obtain the worst‐case model mismatch. The proposed method illustrates greater robustness against process parameter uncertainty. © 2008 American Institute of Chemical Engineers AIChE J, 2008

Reaching Criterion of a Three-Phase Voltage-Source Inverter Operating With Passive and Nonlinear Loads and Its Impact on Global Stability

We develop and demonstrate a technique based on composite Lyapunov functions (CLFs) to analyze the impacts of passive (RL and RC) and nonlinear (diode rectifier) loads on the reaching dynamics of a three-phase voltage-source inverter (VSI). The reaching criterion (which ensures convergences of state trajectories to an orbit) is synthesized using piecewise linear models of the VSI and the loads and conditions for switching among the various models (corresponding to the different switching states). Once orbital existence is ensured using the reaching criterion , we extend the CLF-based approach to predict the stability of the nominal (period-1) orbit of the system (comprising the three-phase VSI and the load) and compare these predictions with those obtained using a conventional impedance-criterion technique that is developed based on a linearized averaged model. Overall, we demonstrate the significance of analyzing the reaching condition from the standpoint of orbital existence and why such a criterion is necessary for analyzing global stability. On a broader note, the methodology outlined in this paper is useful for analyzing the global stability of multiphase inverters, potentially leading to advanced control design of VSI for applications including uninterrupted power supplies, telecommunication power supplies, grid-connected inverters, motor drives, and active filters.

Nonlinear position controller design with input–output linearisation technique for an interior permanent magnet synchronous motor control system

A novel, advanced position controller design for an interior permanent magnet synchronous motor control system is proposed. The input–output linearisation technique is used to transfer the system model into a linearised system model. Then, based on the linearised system model, an H∞ controller is designed to achieve robust performance of the position control system. To improve the system performance, a load estimator is used to compensate the external load and the influence of the parameter variations as well. In addition, a maximum torque/ampere control is applied to increase the output torque of the motor. A digital signal processor, TMS 320LF2407, is used to execute the speed-loop and position-loop control algorithms. As a result, the hardware circuit is quite simple. Several experimental results show that the proposed system has fast transient responses, good load disturbance rejection responses and good tracking responses.

Design and implementation of an H ∞ controller for a micropermanent-magnet synchronous motor position control system

Design and implementation of an H∞ controller for a micropermanent- magnet synchronous motor position control system is proposed. The diameter of the micromotor is only 6 mm. In addition, the weighting functions of the H∞ controller are selected using the genetic algorithms. A state-space H∞ controller, obtained using a systematic design procedure, is incorporated in a closed-loop position control micromotor system. The system has good performance, including fast transient responses and good load disturbance rejection responses, although its encoder is only 100 pulses/revolution. A digital signal processor, TMS320F2407, is used to execute the position control algorithms. Experimental results validate the theoretical analysis and show the correctness and feasibility of the proposed method. An advanced controller design is proposed for a micromotor.

Adaptive controller design for a synchronous reluctance motor drive system with direct torque control

The design and implementation of adaptive controllers for a sensorless synchronous reluctance drive system with direct torque control is proposed. Two adaptive control algorithms, which include adaptive backstepping control and model-reference adaptive control, are proposed to improve the performance of a sensorless direct torque control synchronous reluctance motor drive system. A digital signal processor, TMS320-C30, is used to execute the rotor position estimating technique and the adaptive control algorithms. The system shows good transient responses, good load disturbance responses and good tracking responses. Several experimental results validate the theoretical analysis. The advanced controller design for a sensorless synchronous reluctance motor drive with direct torque control is proposed.