Journal of Control Science and Engineering The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Application of Combinatorial Interaction Design for DC Servomotor PID Controller Tuning Wed, 16 Apr 2014 08:59:20 +0000 Combinatorial optimization has been used in different research areas. It has been employed successfully in software testing fields to construct minimum set of combinations (i.e., in terms of size) which in turn represents the minimum number of test cases. It was also found to be a successful approach that can be applied to solve other similar problems in different fields of research. In line with this approach, this paper presents a new application of the combinational optimization in the design of PID controller for DC servomotor. The design of PID controller involves the determination of three parameters. To find optimal initial PID parameters, different tuning methods have been proposed and designed in the literature. The combinatorial design is concerned with the arrangement of finite set of elements into combinatorial set that satisfies some given constraints. Consequently, the proposed method takes the interaction of the input parameters as a constraint for constructing this combinatorial set. The generated sets are then used in the proposed tuning method. The method proved its effectiveness within a set of experiments in a simulated environment. Mouayad A. Sahib, Bestoun S. Ahmed, and Moayad Y. Potrus Copyright © 2014 Mouayad A. Sahib et al. All rights reserved. Pinning Stabilization of Complex Networks Coupled with Time Delay and Disturbed with Stochastic Noise Sun, 06 Apr 2014 12:14:35 +0000 A pinning stabilization problem of complex networks with time-delay coupling is studied under stochastic noisy circumstances in this paper. Only one controller is used to stabilize the network to the equilibrium point when the network is connected and the minimal number of controllers is used when the network is unconnected, where the structure of complex network is fully used. Some criteria are achieved to control the complex network under stochastic noise in the form of linear matrix inequalities. Several examples are given to show the validity of the proposed control criteria. Chun-Xia Fan, Yu Gu, and Qingyang Wei Copyright © 2014 Chun-Xia Fan et al. All rights reserved. Adaptive Robust Quadratic Stabilization Tracking Control for Robotic System with Uncertainties and External Disturbances Wed, 26 Mar 2014 00:00:00 +0000 An adaptive robust quadratic stabilization tracking controller with hybrid scheme is proposed for robotic system with uncertainties and external disturbances. The hybrid scheme combines computed torque controller (CTC) with an adaptive robust compensator, in which variable structure control (VSC) and optimal control approaches are adopted. The uncertain robot manipulator is mainly controlled by CTC, the VSC is used to eliminate the effect of the uncertainties and ensure global stability, and approach is designed to achieve a certain tracking performance of closed-loop system. A quadratic stability approach, which allows separate treatment of parametric uncertainties, is used to reduce the conservatism of the conventional robust control approach. It can be also guaranteed that all signals in closed-loop system are bounded. The validity of the proposed control scheme is shown by computer simulation of a two-link robotic manipulator. Jinzhu Peng and Yan Liu Copyright © 2014 Jinzhu Peng and Yan Liu. All rights reserved. Adaptive Backstepping Controller Design for Leveling Control of an Underwater Platform Based on Joint Space Mon, 24 Mar 2014 09:36:23 +0000 This paper focuses on high precision leveling control of an underwater heavy load platform, which is viewed as an underwater parallel robot on the basis of its work pattern. The kinematic of platform with deformation is analyzed and the dynamics model of joint space is established. An adaptive backstepping controller according to Lyapunov's function is proposed for leveling control of platform based on joint space. Furthermore, the “lowest point fixed angle error” leveling scheme called “chase” is chosen for leveling control of platform. The digital simulation and practical experiment of single joint space actuator are carried out, and the results show high precision servo control of joint space. On the basis of this, the platform leveling control simulation relies on the hardware-in-loop system. The results indicate that the proposed controller can effectively restrain the influence from system parameter uncertainties and external disturbance to realize high precision leveling control of the underwater platform. Zhi-Lin Zeng, Guo-Hua Xu, Yin Zhao, and Fei Xie Copyright © 2014 Zhi-Lin Zeng et al. All rights reserved. An Improved Reinforcement Learning Algorithm for Cooperative Behaviors of Mobile Robots Wed, 05 Mar 2014 00:00:00 +0000 Reinforcement learning algorithm for multirobot will become very slow when the number of robots is increasing resulting in an exponential increase of state space. A sequential Q-learning based on knowledge sharing is presented. The rule repository of robots behaviors is firstly initialized in the process of reinforcement learning. Mobile robots obtain present environmental state by sensors. Then the state will be matched to determine if the relevant behavior rule has been stored in the database. If the rule is present, an action will be chosen in accordance with the knowledge and the rules, and the matching weight will be refined. Otherwise the new rule will be appended to the database. The robots learn according to a given sequence and share the behavior database. We examine the algorithm by multirobot following-surrounding behavior, and find that the improved algorithm can effectively accelerate the convergence speed. Yong Song, Yibin Li, Xiaoli Wang, Xin Ma, and Jiuhong Ruan Copyright © 2014 Yong Song et al. All rights reserved. Improved Robust Stability Criterion of Networked Control Systems with Transmission Delays and Packet Loss Wed, 12 Feb 2014 15:14:44 +0000 The problem of stability analysis for a class of networked control systems (NCSs) with network-induced delay and packet dropout is investigated in this paper. Based on the working mechanism of zero-order holder, the closed-loop NCS is modeled as a continuous-time linear system with input delay. By introducing a novel Lyapunov-Krasovskii functional which splits both the lower and upper bounds of the delay into two subintervals, respectively, and utilizes reciprocally convex combination technique, a new stability criterion is derived in terms of linear matrix inequalities. Compared with previous results in the literature, the obtained stability criterion is less conservative. Numerical examples demonstrate the validity and feasibility of the proposed method. Shenping Xiao, Liyan Wang, Hongbing Zeng, and Wubin Cheng Copyright © 2014 Shenping Xiao et al. All rights reserved. Research on Feature Extraction of Indicator Card Data for Sucker-Rod Pump Working Condition Diagnosis Sun, 22 Dec 2013 14:56:08 +0000 Three feature extraction methods of sucker-rod pump indicator card data have been studied, simulated, and compared in this paper, which are based on Fourier Descriptors (FD), Geometric Moment Vector (GMV), and Gray Level Matrix Statistics (GLMX), respectively. Numerical experiments show that the Fourier Descriptors algorithm requires less running time and less memory space with possible loss of information due to nonoptimal numbers of Fourier Descriptors, the Geometric Moment Vector algorithm is more time-consuming and requires more memory space, while the Gray Level Matrix Statistics algorithm provides low-dimension feature vectors with more time consumption and more memory space. Furthermore, the characteristic of rotational invariance, both in the Fourier Descriptors algorithm and the Geometric Moment Vector algorithm, may result in improper pattern recognition of indicator card data when used for sucker-rod pump working condition diagnosis. Yunhua Yu, Haitao Shi, and Lifei Mi Copyright © 2013 Yunhua Yu et al. All rights reserved. Workspace Tracking Control of Two-Flexible-Link Manipulator Using Distributed Control Strategy Tue, 03 Dec 2013 09:34:43 +0000 A distributed nonlinear control strategy for two-flexible-link manipulators is presented to track a desired trajectory in the robot’s workspace. The inverse dynamics problem is solved by transforming the desired trajectory from the workspace to the joint space using an intermediate space, called virtual space, and then using the quasi-static approach. To solve the nonminimum phase problem, an output redefinition technique is used. This output consists of the motor’s angle augmented with a weighted value of the link’s extremity. The distributed control strategy consists in controlling the last link by assuming that the first link is stable and follows its desired trajectories. The control law is developed to stabilize the error dynamics and to guarantee bounded internal dynamics such that the new output is as close as possible to the tip. The weighted parameter defining the noncollocated output is then selected. The same procedure is applied to control and stabilize the first link. The asymptotical stability is proved using Lyapunov theory. This algorithm is applied to a two-flexible-link manipulator in the horizontal plane, and simulations showed a good tracking of the desired trajectory in the workspace. Fareh Raouf, Saad Mohamad, and Saad Maarouf Copyright © 2013 Fareh Raouf et al. All rights reserved. Integrity Design for Networked Control Systems with Actuator Failures and Data Packet Dropouts Thu, 21 Nov 2013 15:02:00 +0000 The integrity design problem of fault tolerant control for networked control system (NCS) with actuator failures and data packet dropouts is investigated. The data packet dropouts in both sensor-controller (S-C) and controller-actuator (C-A) links are described by two switches, which can be modeled as a discrete event system with known rate. After introducing the matrix of actuator failure, the closed-loop NCS is developed, which can be viewed as asynchronous dynamical systems (ADSs). Then, the sufficiency of exponential stability for the NCS is obtained based on the theory of ADSs. The output feedback controllers that can guarantee system stability are also proposed. Finally, two numerical examples are given to demonstrate the validity of our proposed approach. Xiaomei Qi and Jason Gu Copyright © 2013 Xiaomei Qi and Jason Gu. All rights reserved. External Periodic Force Control of a Single-Degree-of-Freedom Vibroimpact System Thu, 21 Nov 2013 14:40:53 +0000 A single-degree-of-freedom mechanical model of vibro-impact system is established. Bifurcation and chaos in the system are revealed with the time history diagram, phase trajectory map, and Poincaré map. According to the bifurcation and chaos of the actual vibro-impact system, the paper puts forward external periodic force control strategy. The method of controlling chaos by external periodic force feedback controller is developed to guide chaotic motions towards regular motions. The stability of the control system is also analyzed especially by theory. By selecting appropriate feedback coefficients, the unstable periodic orbits of the original chaotic orbit can be stabilized to the stable periodic orbits. The effectiveness of this control method is verified by numerical simulation. Jingyue Wang, Haotian Wang, and Tie Wang Copyright © 2013 Jingyue Wang et al. All rights reserved. FPGA Control Implementation of a Grid-Connected Current-Controlled Voltage-Source Inverter Sun, 10 Nov 2013 09:12:22 +0000 The full control system of a grid-connected current-controlled voltage-source inverter (CC-VSI) has been designed and implemented on a field-programmable gate array (FPGA). Various control functions and implementation methods are described and discussed. The practical viability of the system is evaluated in an experimental setup, where a VSI supplies 30 kW into the local grid at 400 V. A phase-locked loop (PLL) is used for grid phase tracking and evaluated for simulated abnormal grid conditions. Power factor is kept at unity, and the implemented control system is stressed with step responses in the supplied active power. A moving-average filter is implemented to reduce the effects of noise and harmonics on the current control loops. A coupling between active and reactive power flow is observed for the step responses but may be ignored in this context. The proposed system is fully comparable with more conventional microprocessor-based control systems. Rickard Ekström and Mats Leijon Copyright © 2013 Rickard Ekström and Mats Leijon. All rights reserved. Improved Weighted Shapley Value Model for the Fourth Party Logistics Supply Chain Coalition Wed, 09 Oct 2013 15:21:00 +0000 How to make the individual get the reasonable and practical profit among the fourth party logistics supply chain coalition system is still a question for further study. Considering the characteristics of the fourth party logistics supply chain coalition, this paper combines Shapley Value with Distribution according to Contribution, two methods in the application, and then adjusts the profit allocated to each member reasonably based on the actual coalition situation named improved weighted Shapley Value model. In this paper, we first analyze the fourth party logistics supply chain coalition profit allocation models, the classical Shapley value method. Then, we analyze the weight of individual enterprise in the coalition by the analytic hierarchy process. To each enterprise, the weight is determined by the investment risks, information divulging risks, and failure risks. Finally, the numerical study shows that the profit allocation method improved weighted Shapley value model is relatively rational and practical. Thus, the proposed combined model is a useful profit allocation mechanism for the fourth party logistics supply chain coalition that the contribution and risks are fully considered. Na Xu Copyright © 2013 Na Xu. All rights reserved. Design of Telerobotic Drilling Control System with Haptic Feedback Sat, 05 Oct 2013 11:11:54 +0000 The paper deals with the design of control algorithms for virtual reality based telerobotic system with haptic feedback that allows for the remote control of the vertical drilling operation. The human operator controls the vertical penetration velocity using a haptic device while simultaneously receiving the haptic feedback from the locally implemented virtual environment. The virtual environment is rendered as a virtual spring with stiffness updated based on the estimate of the stiffness of the rock currently being cut. Based on the existing mathematical models of drill string/drive systems and rock cutting/penetration process, a robust servo controller is designed which guarantees the tracking of the reference vertical penetration velocity of the drill bit. A scheme for on-line estimation of the rock intrinsic specific energy is implemented. Simulations of the proposed control and parameter estimation algorithms have been conducted; consequently, the overall telerobotic drilling system with a human operator controlling the process using PHANTOM Omni haptic device is tested experimentally, where the drilling process is simulated in real time in virtual environment. Faraz Shah and Ilia G. Polushin Copyright © 2013 Faraz Shah and Ilia G. Polushin. All rights reserved. Mobile Robot Path Planning Using Polyclonal-Based Artificial Immune Network Sun, 29 Sep 2013 09:37:57 +0000 Polyclonal based artificial immune network (PC-AIN) is utilized for mobile robot path planning. Artificial immune network (AIN) has been widely used in optimizing the navigation path with the strong searching ability and learning ability. However, artificial immune network exists as a problem of immature convergence which some or all individuals tend to the same extreme value in the solution space. Thus, polyclonal-based artificial immune network algorithm is proposed to solve the problem of immature convergence in complex unknown static environment. Immunity polyclonal algorithm (IPCA) increases the diversity of antibodies which tend to the same extreme value and finally selects the antibody with highest concentration. Meanwhile, immunity polyclonal algorithm effectively solves the problem of local minima caused by artificial potential field during the structure of parameter in artificial immune network. Extensive experiments show that the proposed method not only solves immature convergence problem of artificial immune network but also overcomes local minima problem of artificial potential field. So, mobile robot can avoid obstacles, escape traps, and reach the goal with optimum path and faster convergence speed. Lixia Deng, Xin Ma, Jason Gu, and Yibin Li Copyright © 2013 Lixia Deng et al. All rights reserved. Real-Time Detection of Application-Layer DDoS Attack Using Time Series Analysis Thu, 26 Sep 2013 16:58:15 +0000 Distributed denial of service (DDoS) attacks are one of the major threats to the current Internet, and application-layer DDoS attacks utilizing legitimate HTTP requests to overwhelm victim resources are more undetectable. Consequently, neither intrusion detection systems (IDS) nor victim server can detect malicious packets. In this paper, a novel approach to detect application-layer DDoS attack is proposed based on entropy of HTTP GET requests per source IP address (HRPI). By approximating the adaptive autoregressive (AAR) model, the HRPI time series is transformed into a multidimensional vector series. Then, a trained support vector machine (SVM) classifier is applied to identify the attacks. The experiments with several databases are performed and results show that this approach can detect application-layer DDoS attacks effectively. Tongguang Ni, Xiaoqing Gu, Hongyuan Wang, and Yu Li Copyright © 2013 Tongguang Ni et al. All rights reserved. An Improved Differential Evolution Algorithm Based on Adaptive Parameter Thu, 19 Sep 2013 15:04:27 +0000 The differential evolution (DE) algorithm is a heuristic global optimization technique based on population which is easy to understand, simple to implement, reliable, and fast. The evolutionary parameters directly influence the performance of differential evolution algorithm. The adjustment of control parameters is a global behavior and has no general research theory to control the parameters in the evolution process at present. In this paper, we propose an adaptive parameter adjustment method which can dynamically adjust control parameters according to the evolution stage. The experiments on high dimensional function optimization showed that the improved algorithm has more powerful global exploration ability and faster convergence speed. Zhehuang Huang and Yidong Chen Copyright © 2013 Zhehuang Huang and Yidong Chen. All rights reserved. Achieving Relative Time Synchronization in Wireless Sensor Networks Wed, 11 Sep 2013 08:53:25 +0000 Time synchronization is required for a variety of distributed control applications in wireless sensor networks (WSNs). In this paper, a novel distributed time synchronization technique for WSNs is presented. The proposed technique does not require all the sensor nodes to have the same time periods or starting times. Furthermore, the communication topology of the WSN is not assumed to be static; it can change with time. The WSN is modeled by a time-varying discrete-time system. The objective is to design local control inputs to achieve relative time synchronization by using the neighbor sensor nodes information. By employing tools from nonnegative matrix and graph theories, the convergence analysis is presented. Numerical examples are presented to demonstrate the effectiveness of the proposed protocol. Salman Ahmed, Feng Xiao, and Tongwen Chen Copyright © 2013 Salman Ahmed et al. All rights reserved. Realization of a Biped Robot Lower Limb Walking without Double Support Phase on Uneven Terrain Sun, 01 Sep 2013 11:30:47 +0000 Zero moment point (ZMP) is widely used in dynamical walking control of the biped robot, but it is hard to obtain the ZMP exactly. The paper describes a simple walking control method without using ZMP information directly. Firstly, the paper introduced a biped robot lower-limb prototype which is driven by linear hydraulic servocylinder. Then the paper simplifies the walking control in the lateral plane with a simple walking pattern generation method named “dynamic equilibrium method,” which is fit for active and underactuated biped robots. In the following section the paper provides the balance control methods without using ZMP information directly. Finally, simulation experiments with MD.DAMS and experiments in physical prototype are given. The experimental results confirm the effectiveness of the proposed control methods. Hai-yan Wang and Yi-bin Li Copyright © 2013 Hai-yan Wang and Yi-bin Li. All rights reserved. Model Based Control System Design Using SysML, Simulink, and Computer Algebra System Tue, 20 Aug 2013 10:51:30 +0000 The Systems Modeling Language (SysML) is a standard, general-purpose, modeling language for model-based systems engineering (MBSE). SysML supports the specification, analysis, and design of a broad range of complex systems such as control systems. The authors demonstrate how they can integrate a SysML modeling tool (IBM Rational Rhapsody) with a proprietary simulation tool (MathWorks Simulink) and a Computer Algebra System (CAS) to validate system specification. The integration with Simulink enables users to perform systems engineering process in a SysML model, while designing continuous control algorithms and plant behavior in Simulink, and to validate the behavior by simulating the overall composition in Simulink. The integration with a CAS enables the evaluation of mathematical constraints defined in SysML parametric diagrams. The authors also show the overall approach using a Dual Clutch Transmission (DCT) and a Cruise Control System as examples. Takashi Sakairi, Eldad Palachi, Chaim Cohen, Yoichi Hatsutori, Junya Shimizu, and Hisashi Miyashita Copyright © 2013 Takashi Sakairi et al. All rights reserved. Modeling of Random Delays in Networked Control Systems Tue, 30 Jul 2013 11:31:00 +0000 In networked control systems (NCSs), the presence of communication networks in control loops causes many imperfections such as random delays, packet losses, multipacket transmission, and packet disordering. In fact, random delays are usually the most important problems and challenges in NCSs because, to some extent, other problems are often caused by random delays. In order to compensate for random delays which may lead to performance degradation and instability of NCSs, it is necessary to establish the mathematical model of random delays before compensation. In this paper, four major delay models are surveyed including constant delay model, mutually independent stochastic delay model, Markov chain model, and hidden Markov model. In each delay model, some promising compensation methods of delays are also addressed. Yuan Ge, Qigong Chen, Ming Jiang, and Yiqing Huang Copyright © 2013 Yuan Ge et al. All rights reserved. Embedded-Model-Based Control Sun, 21 Jul 2013 14:13:23 +0000 Sabri Cetinkunt, Shin-ichi Nakajima, Brad Nelson, and Salem Haggag Copyright © 2013 Sabri Cetinkunt et al. All rights reserved. Real Time Monitoring of Diesel Engine Injector Waveforms for Accurate Fuel Metering and Control Tue, 18 Jun 2013 12:05:01 +0000 This paper presents the development, experimentation, and validation of a reliable and robust system to monitor the injector pulse generated by an engine control module (ECM) which can easily be calibrated for different engine platforms and then feedback the corresponding fueling quantity to the real-time computer in a closed-loop controller in the loop (CIL) bench in order to achieve optimal fueling. This research utilizes field programmable gate arrays (FPGA) and direct memory access (DMA) transfer capability to achieve high speed data acquisition and delivery. This work is conducted in two stages: the first stage is to study the variability involved in the injected fueling quantity from pulse to pulse, from injector to injector, between real injector stators and inductor load cells, and over different operating conditions. Different thresholds have been used to find out the best start of injection (SOI) threshold and the end of injection (EOI) threshold that capture the injector “on-time” with best reliability and accuracy. Second stage involves development of a system that interprets the injector pulse into fueling quantity. The system can easily be calibrated for various platforms. Finally, the use of resulting correction table has been observed to capture the fueling quantity with highest accuracy. Q. R. Farooqi, B. Snyder, and S. Anwar Copyright © 2013 Q. R. Farooqi et al. All rights reserved. Design of Attitude Control Systems for CubeSat-Class Nanosatellite Tue, 28 May 2013 08:36:04 +0000 We present a satellite attitude control system design using low-cost hardware and software for a 1U CubeSat. The attitude control system architecture is a crucial subsystem for any satellite mission since precise pointing is often required to meet mission objectives. The accuracy and precision requirements are even more challenging for small satellites where limited volume, mass, and power are available for the attitude control system hardware. In this proposed embedded attitude control system design for a 1U CubeSat, pointing is obtained through a two-stage approach involving coarse and fine control modes. Fine control is achieved through the use of three reaction wheels or three magnetorquers and one reaction wheel along the pitch axis. Significant design work has been conducted to realize the proposed architecture. In this paper, we present an overview of the embedded attitude control system design; the verification results from numerical simulation studies to demonstrate the performance of a CubeSat-class nanosatellite; and a series of air-bearing verification tests on nanosatellite attitude control system hardware that compares the performance of the proposed nonlinear controller with a proportional-integral-derivative controller. Junquan Li, Mark Post, Thomas Wright, and Regina Lee Copyright © 2013 Junquan Li et al. All rights reserved. Gain Performance for a Class of Lipschitz Uncertain Nonlinear Systems via Variable Gain Robust Output Feedback Controllers Tue, 14 May 2013 15:24:21 +0000 We consider a design problem of a variable gain robust output feedback controller with guaranteed gain performance for a class of Lipschitz uncertain nonlinear systems. The proposed variable gain robust output feedback controller achieves not only robust stability but also a specified gain performance. In this paper, we show that sufficient conditions for the existence of the proposed variable gain robust output feedback controller with guaranteed gain performance are given in terms of linear matrix inequalities (LMIs). Finally, a simple numerical example is included. Hidetoshi Oya and Kojiro Hagino Copyright © 2013 Hidetoshi Oya and Kojiro Hagino. All rights reserved. Full Static Output Feedback Equivalence Mon, 13 May 2013 10:14:14 +0000 We present a constructive solution to the problem of full output feedback equivalence, of linear, minimal, time-invariant systems. The equivalence relation on the set of systems is transformed to another on the set of invertible block Bezout/Hankel matrices using the isotropy subgroups of the full state feedback group and the full output injection group. The transformation achieving equivalence is calculated solving linear systems of equations. We give a polynomial version of the results proving that two systems are full output feedback equivalent, if and only if they have the same family of generalized Bezoutians. We present a new set of output feedback invariant polynomials that generalize the breakaway polynomial of scalar systems. Aristotle G. Yannakoudakis Copyright © 2013 Aristotle G. Yannakoudakis. All rights reserved. Implementation of Control System for Hydrokinetic Energy Converter Thu, 02 May 2013 09:07:06 +0000 At Uppsala University, a research group is investigating a system for converting the power in freely flowing water using a vertical-axis turbine directly connected to a permanent magnet generator. An experimental setup comprising a turbine, a generator, and a control system has been constructed and will be deployed in the Dalälven river in the town of Söderfors in Sweden. The design, construction, simulations, and laboratory tests of the control system are presented in this paper. The control system includes a startup sequence for the turbine and load control. These functions have performed satisfactorily in laboratory tests. Simulations of the system show that the power output is not maximized at the same tip-speed ratio as that which maximizes the turbine power capture. Katarina Yuen, Senad Apelfröjd, and Mats Leijon Copyright © 2013 Katarina Yuen et al. All rights reserved. Real-Time Energy Management Control for Hybrid Electric Powertrains Tue, 30 Apr 2013 09:53:35 +0000 This paper focuses on embedded control of a hybrid powertrain concepts for mobile vehicle applications. Optimal robust control approach is used to develop a real-time energy management strategy. The main idea is to store the normally wasted mechanical regenerative energy in energy storage devices for later usage. The regenerative energy recovery opportunity exists in any condition where the speed of motion is in the opposite direction to the applied force or torque. This is the case when the vehicle is braking, decelerating, the motion is driven by gravitational force, or load driven. There are three main concepts for energy storing devices in hybrid vehicles: electric, hydraulic, and mechanical (flywheel). The real-time control challenge is to balance the system power demands from the engine and the hybrid storage device, without depleting the energy storage device or stalling the engine in any work cycle. In the worst-case scenario, only the engine is used and the hybrid system is completely disabled. A rule-based control algorithm is developed and is tuned for different work cycles and could be linked to a gain scheduling algorithm. A gain scheduling algorithm identifies the cycle being performed by the work machine and its position via GPS and maps both of them to the gains. Mohamed Zaher and Sabri Cetinkunt Copyright © 2013 Mohamed Zaher and Sabri Cetinkunt. All rights reserved. Optimal Robust Adaptive Fuzzy Tracking Control without Reaching Phase for Nonlinear System Mon, 22 Apr 2013 09:02:58 +0000 An optimal tracking-based indirect adaptive fuzzy controller for a class of perturbed uncertain affine nonlinear systems without reaching phase is being developed in this paper. First a practical Interval Type-2 (IT2) fuzzy system is used in an adaptive scheme to approximate the system using a nonlinear model and to determine the optimal value of the gain control. Secondly, to eliminate the trade-off between tracking performance and high gain at the control input, a modified output tracking error has been used. The stability is ensured through Lyapunov synthesis and the effectiveness of the proposed method is proved and the simulation is also given to illustrate the superiority of the proposed approach. El Mehdi Mellouli, Siham Massou, and Ismail Boumhidi Copyright © 2013 El Mehdi Mellouli et al. All rights reserved. Model Reduction Using Proper Orthogonal Decomposition and Predictive Control of Distributed Reactor System Mon, 15 Apr 2013 17:35:36 +0000 This paper studies the application of proper orthogonal decomposition (POD) to reduce the order of distributed reactor models with axial and radial diffusion and the implementation of model predictive control (MPC) based on discrete-time linear time invariant (LTI) reduced-order models. In this paper, the control objective is to keep the operation of the reactor at a desired operating condition in spite of the disturbances in the feed flow. This operating condition is determined by means of an optimization algorithm that provides the optimal temperature and concentration profiles for the system. Around these optimal profiles, the nonlinear partial differential equations (PDEs), that model the reactor are linearized, and afterwards the linear PDEs are discretized in space giving as a result a high-order linear model. POD and Galerkin projection are used to derive the low-order linear model that captures the dominant dynamics of the PDEs, which are subsequently used for controller design. An MPC formulation is constructed on the basis of the low-order linear model. The proposed approach is tested through simulation, and it is shown that the results are good with regard to keep the operation of the reactor. Alejandro Marquez, Jairo José Espinosa Oviedo, and Darci Odloak Copyright © 2013 Alejandro Marquez et al. All rights reserved. Solution to Singular Optimal Control by Backward Differential Flow Tue, 09 Apr 2013 15:19:04 +0000 This paper presents a backward differential flow for solving singular optimal control problems. By using Krotov equivalent transformation, the cost functional is converted to a class of global optimization problems. Some properties of the flow are given to reveal the significant relationship between the dynamic of the flow and the geometry of the feasible set. The proposed method is also used in solving a class of variational problems. Some examples are illustrated. Jinghao Zhu, Shangrui Zhao, and Guohua Liu Copyright © 2013 Jinghao Zhu et al. All rights reserved.