Journal of Control Science and Engineering The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Boundary Control for a Kind of Coupled PDE-ODE System Sun, 14 Sep 2014 00:00:00 +0000 A coupled system of an ordinary differential equation (ODE) and a heat partial differential equation (PDE) with spatially varying coefficients is discussed. By using the PDE backstepping method, the state-feedback stabilizing controller is explicitly constructed with the assumptions and , respectively. The closed-loop system is proved to be exponentially stable by this controller. A simulation example is presented to illustrate the effectiveness of the proposed method. Yuanting Wang, Fucheng Liao, Yonglong Liao, and Zhengwei Shen Copyright © 2014 Yuanting Wang et al. All rights reserved. Multiobjective Optimization of PID Controller of PMSM Sun, 31 Aug 2014 06:22:56 +0000 PID controller is used in most of the current-speed closed-loop control of permanent magnet synchronous motors (PMSM) servo system. However, , , and of PID are difficult to tune due to the multiple objectives. In order to obtain the optimal PID parameters, we adopt a NSGA-II to optimize the PID parameters in this paper. According to the practical requirement, several objective functions are defined. NSGA-II can search the optimal parameters according to the objective functions with better robustness. This approach provides a more theoretical basis for the optimization of PID parameters than the aggregation function method. The simulation results indicate that the system is valid, and the NSGA-II can obtain the Pareto front of PID parameters. Qingyang Xu, Chengjin Zhang, Li Zhang, and Chaoyang Wang Copyright © 2014 Qingyang Xu et al. All rights reserved. ESO-Based Fuzzy Sliding-Mode Control for a 3-DOF Serial-Parallel Hybrid Humanoid Arm Sun, 03 Aug 2014 12:48:09 +0000 This paper presents a unique ESO-based fuzzy sliding-mode controller (FSMC-ESO) for a 3-DOF serial-parallel hybrid humanoid arm (HHA) for the trajectory tracking control problem. The dynamic model of the HHA is obtained by Lagrange method and is nonlinear in dynamics with inertia uncertainty and external disturbance. The FSMC-ESO is based on the combination of the sliding-mode control (SMC), extended state observer (ESO) theory, and fuzzy control (FC). The SMC is insensitive to both internal parameter uncertainties and external disturbances. The motivation for using ESO is to estimate the disturbance in real-time. The fuzzy parameter self-tuning strategy is proposed to adjust the switching gain on line according to the running state of the system. The stability of the system is guaranteed in the sense of the Lyapunov stability theorem. The effectiveness and robustness of the designed FSMC-ESO are illustrated by simulations. Yueling Wang, Runjie Shi, and Hongbin Wang Copyright © 2014 Yueling Wang et al. All rights reserved. An Approach to Evaluating Computer Network Security with Intuitionistic Trapezoidal Fuzzy Information Thu, 17 Jul 2014 12:15:30 +0000 We investigate the multiple attribute decision-making problems for evaluating the computer network security with intuitionistic trapezoidal fuzzy information. We utilize the intuitionistic trapezoidal fuzzy weighted average (ITFWA) operator to aggregate the intuitionistic trapezoidal fuzzy information corresponding to each alternative and get the overall value of the alternatives and then rank the alternatives and select the most desirable one(s) according to the distance between the overall value of the alternatives and ideal solution. Finally, an illustrative example for evaluating the computer network security is given. Ming Xue Copyright © 2014 Ming Xue. All rights reserved. Cost Control Method and Software in Bidding Process Based on Gray System Forecast Thu, 17 Jul 2014 10:49:28 +0000 With the fast development of social economy, the competition between enterprises in construction projects becomes more and more serious. The cost control method is proposed to the bidding process of enterprises based on the gray system forecast. At the same time, the cost control software is also constructed to the bidding process of enterprises. Experimental results suggest that the proposed approach is feasible and correct. Xi-Liu Zhou Copyright © 2014 Xi-Liu Zhou. All rights reserved. Research on the Evaluation Model of Urban Tourism Management Efficiency with Uncertain Linguistic Information Thu, 17 Jul 2014 08:09:19 +0000 We investigate the multiple attribute decision making problems for evaluating the urban tourism management efficiency with uncertain linguistic information. We utilize the uncertain linguistic weighted averaging (ULWA) operator to aggregate the uncertain linguistic information corresponding to each alternative and get the overall value of the alternatives and, then rank the alternatives and select the most desirable one(s). Finally, a numerical example for evaluating the urban tourism management efficiency with uncertain linguistic information is used to illustrate the proposed model. Song-Mao Wang, Liang-Yan Fang, and Feng Deng Copyright © 2014 Song-Mao Wang et al. All rights reserved. An Approach to Evaluating Enterprise Financial Performance Based on the Control Inheritance of Family Businesses with Intuitionistic Fuzzy Information Thu, 17 Jul 2014 08:04:19 +0000 We investigate the multiple attribute decision making problems for evaluating the enterprise financial performance based on the control inheritance of family businesses with intuitionistic fuzzy information. We utilize the intuitionistic fuzzy Bonferroni mean (IFBM) operator to aggregate the intuitionistic fuzzy information corresponding to each alternative and get the overall value of enterprise financial performance and then rank the enterprises and select the most desirable one(s) by using the overall value of enterprise financial performance. Finally, an illustrative example for evaluating the enterprise financial performance based on the control inheritance of family businesses is given to verify the developed approach and to demonstrate its practicality and effectiveness. Hui Liu Copyright © 2014 Hui Liu. All rights reserved. An Approach to Evaluate the Clothing Creative Design with Dual Hesitant Fuzzy Information Sun, 13 Jul 2014 00:00:00 +0000 The problem of evaluating the clothing creative design with dual hesitant fuzzy information is the multiple attribute decision making problem. In this paper, we have utilized dual hesitant fuzzy hybrid average (DHFHA) operator to develop the model to solve the multiple attribute decision making problems for evaluating the clothing creative design. Finally, a practical example for evaluating the clothing creative design is given to verify the developed approach. Ya-Mei Li Copyright © 2014 Ya-Mei Li. All rights reserved. Inflight Parameter Identification and Icing Location Detection of the Aircraft: The Time-Varying Case Thu, 10 Jul 2014 07:02:42 +0000 This paper considers inflight parameter identification and icing location detection of the aircraft in a more common time-varying nature. In particular, ice accumulation is modeled as a continuous process, and the effect of the ice upon aircraft dynamics is to be accreted with time. Time-varying case of the Hinf algorithm is implemented to provide inflight estimate of aircraft dynamic parameters, and the estimated results are delivered to a probabilistic neural network to decide icing location of the aircraft; an excitation measure of the aircraft is also adopted in the network input layer. A database corresponding to different icing cases and severities was generated for the training and test of the detection network. Based on the test results, the icing detection framework presented in this paper is believed to be with promising applicableness for our further studies. Yiqun Dong and Jianliang Ai Copyright © 2014 Yiqun Dong and Jianliang Ai. All rights reserved. Synthesis of Decentralized Variable Gain Robust Controllers for Large-Scale Interconnected Systems with Structured Uncertainties Wed, 09 Jul 2014 10:39:52 +0000 In this paper, we propose a decentralized variable gain robust controller which achieves not only robust stability but also satisfactory transient behavior for a class of uncertain large-scale interconnected systems. For the uncertain large-scale interconnected system, the uncertainties and the interactions satisfy the matching condition. The proposed decentralized robust controller consists of a fixed feedback gain controller and a variable gain one determined by a parameter adjustment law. In this paper, we show that sufficient conditions for the existence of the proposed decentralized variable gain robust controller are given in terms of LMIs. Finally, a simple numerical example is included. Shunya Nagai and Hidetoshi Oya Copyright © 2014 Shunya Nagai and Hidetoshi Oya. All rights reserved. FxLMS Method for Suppressing In-Wheel Switched Reluctance Motor Vertical Force Based on Vehicle Active Suspension System Wed, 04 Jun 2014 12:06:54 +0000 The vibration of SRM obtains less attention for in-wheel motor applications according to the present research works. In this paper, the vertical component of SRM unbalanced radial force, which is named as SRM vertical force, is taken into account in suspension performance for in-wheel motor driven electric vehicles (IWM-EV). The analysis results suggest that SRM vertical force has a great effect on suspension performance. The direct cause for this phenomenon is that SRM vertical force is directly exerted on the wheel, which will result in great variation in tyre dynamic load and the tyre will easily jump off the ground. Furthermore, the frequency of SRM vertical force is broad which covers the suspension resonance frequencies. So it is easy to arouse suspension resonance and greatly damage suspension performance. Aiming at the new problem, FxLMS (filtered-X least mean square) controller is proposed to improve suspension performance. The FxLMS controller is based on active suspension system which can generate the controllable force to suppress the vibration caused by SRM vertical force. The conclusion shows that it is effective to take advantage of active suspensions to reduce the effect of SRM vertical force on suspension performance. Yan-yang Wang, Yi-nong Li, Wei Sun, Chao Yang, and Guang-hui Xu Copyright © 2014 Yan-yang Wang et al. All rights reserved. Advances in Methods for Networked and Cyber-Physical System Thu, 29 May 2014 08:31:49 +0000 Jason Gu, Xiaomei Qi, Ying Wang, Fei Liu, and Chengjin Zhang Copyright © 2014 Jason Gu et al. All rights reserved. Distributed Event-Triggered Control of Multiagent Systems with General Linear Dynamics Mon, 26 May 2014 00:00:00 +0000 This paper discusses the event-triggered consensus problem of multiagent systems. To investigate distributed event-triggering strategies applied to general linear dynamics, we employ a dynamic controller to convert the general linear dynamic to the single-integrator model by a change of variable. The consensus value of these new states is a constant so that the distributed event-triggering scheme is obtained under periodic event detections, in which agents with general linear dynamics require knowledge only of the relative states with their neighbors. Further, an event-triggered observer is proposed to address the case that only relative output information is available. Hence, the consensus of both the state-based and observer-based cases is achieved by the distributed event-triggered dynamic controller. Finally, numerical simulations are provided to demonstrate the effectiveness of theoretical results. Xieyan Zhang and Jing Zhang Copyright © 2014 Xieyan Zhang and Jing Zhang. All rights reserved. JAUS to EtherCAT Bridge: Toward Real-Time and Deterministic Joint Architecture for Unmanned Systems Sun, 27 Apr 2014 00:00:00 +0000 The Joint Architecture for Unmanned Systems (JAUS) is a communication standard that allows for interoperability between Unmanned Vehicles (UVs). Current research indicates that JAUS-compliant systems do not meet real-time performance guidelines necessary for internal systems in UVs. However, there is a lack of quantitative data illustrating the performance shortcomings of JAUS or clear explanations on what causes these performance issues or comparisons with existing internal communication systems. In this research, we first develop a basic C++ implementation of JAUS and evaluate its performance with quantitative data and compare the results with published performance data of Controller Area Network (CAN) to determine the feasibility of the JAUS standard. Our results indicate that the main reason of JAUS’s poor performance lies in the latency inherent in the hierarchical structure of JAUS and the overhead of User Datagram Protocol (UDP) messages, which has been used with JAUS and is slower than the high-speed CAN. Additionally, UDP has no scheduling mechanism, which makes it virtually impossible to guarantee messages meeting their deadlines. Considering the slow and nondeterministic JAUS communication from subsystems to components, which is JAUS Level 3 compliance, we then propose a solution by bringing Ethernet for Control Automation Technology (EtherCAT) to add speed, deterministic feature, and security. The JAUS-EtherCAT mapping, which we called a JEBridge, is implemented into nodes and components. Both quantitative and qualitative results are provided to show that JEBridge and JAUS Level 3 compliance can bring not only interoperability but also reasonable performance to UVs. Jie Sheng, Sam Chung, Leo Hansel, Don McLane, Joel Morrah, Seung-Ho Baeg, and Sangdeok Park Copyright © 2014 Jie Sheng et al. All rights reserved. State Estimation and Model-Based Control of a Pilot Anaerobic Digestion Reactor Tue, 22 Apr 2014 00:00:00 +0000 A state estimator and various model-based control systems have been designed for a real anaerobic digestion (AD) pilot reactor fed with dairy manure. The model used is a modified Hill model which is a relatively simple dynamical AD process model. The state estimator is an Unscented Kalman Filter (UKF) which uses only methane gas flow measurement to update its states. The model and the state estimates are used in different control systems. One of the control systems aims at controlling the methane gas flow to a setpoint. Simulations indicate that the setpoint tracking performance of a predictive control system is considerably better comparing with PI control, while disturbance compensation is not much better. Consequently, assuming the setpoint is constant, the PI controller competes well with the predictive controller. A successful application of predictive control of the real reactor is presented. Also, three different control systems aiming at retaining the reactor at an operating point where the volatile fatty acids (VFA) concentration has a maximum, safe value are designed. A simulation study indicates that the best control solution among the three alternatives is PI control based on feedback from estimated VFA. Finn Haugen, Rune Bakke, and Bernt Lie Copyright © 2014 Finn Haugen et al. 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.