Showing papers in "IEEE Transactions on Industrial Informatics in 2007"

T-S Fuzzy-Model-Based Robust $H_{\infty}$ Design for Networked Control Systems With Uncertainties

Abstract: This paper concerns a problem of robust Hinfin control for a class of uncertain nonlinear networked control systems (NCSs), which can be represented by a T-S fuzzy model with uncertainties. Both network-induced delay and packet dropout are addressed. The controller design method is presented based on a delay-dependent approach, and the robust Hinfin controller gain matrices are obtain by solving a set of linear matrix inequalities (LMIs). Moreover, a general Lyapunov-Krasovskii functional is used, and some slack matrices, which bring much flexibility in solving LMIs, are introduced during the proof. Simulation results show the validity of the proposed method.

Channel Characterization and Link Quality Assessment of IEEE 802.15.4-Compliant Radio for Factory Environments

Abstract: Wireless sensors have started being utilized for process monitoring in factory environments, which are typically harsh for low-power wireless communication due to their complicated layout and plentiful stationary/moving obstacles. Sensor radios available so far have been engineered for consumer-grade applications, featuring low cost, low power, and minimal radio complexity. In order to utilize such radios for factory applications, their channel characteristics and link quality must be investigated for optimal design and reliability assessment. In this paper, a series of measurements were made with IEEE 802.15.4-compliant sensor radios to study both their spatial and temporal characteristics with respect to the factory surroundings found in a university machine shop. Critical communication properties were investigated in terms of received signal strength, link quality indication, and packet error rate. It is found that received signal strength shows dependency on surrounding structures, radio link qualities with respect to received signal strength and link quality indication are stable before a grey zone is reached, and average link quality indicator serves as a better packet success rate indication than average received signal strength indication. The findings in this paper provide a useful guidance to the ongoing explorations for a methodology to predict radio performance at any location within a given factory floor plan and to online assess the time-variant link qualities.

Adaptive Fuzzy Controller of the Overhead Cranes With Nonlinear Disturbance

Abstract: Overhead cranes are common industrial structures that are used in many factories and harbors. They are usually operated manually or by some conventional control methods, such as the optimal and PLC-based methods. The theme of this paper is to provide an effective all-purpose adaptive fuzzy controller for the crane. This proposed method does not need the complex dynamic model of the crane system, but it uses trolley position and swing angle information instead to design the fuzzy controller. An adaptive algorithm is provided to tune the free parameters in the crane control system. The ways to speed the transportation and reduce the computational efforts are also given. Therefore, the designing procedure of the proposed controller will be very easy. External disturbance, such as the wind and the hit, which always deteriorates the control performance, is also discussed in this paper to verify the robustness of the proposed adaptive fuzzy algorithm. At last, several experimental results with different wire length and payload weight compare the feasibility and effectiveness of the proposed scheme with conventional methods

Modular Wireless Real-Time Sensor/Actuator Network for Factory Automation Applications

Abstract: Modern factory facilities are characterized by highly flexible manufacturing cells and highly dynamic processes, where clusters of fixed or moving sensors and actuators have to be controlled in a limited space under stringent real-time and reliability constraints. In such demanding industrial environments, wireless systems can also be beneficial by improving flexibility, cutting cables, and enabling solutions, which are cumbersome or even not possible to realize with wireline systems, especially in controlling moving or rotating parts. In this paper, we present a conceptual study of a wireless real-time system dedicated for remote sensor/actuator control in production automation. System development is based on user requirements, which were extracted from customer interviews and a market research. Low level measurements of frequency- and space-selective wireless channels in a factory-like environment were carried out. System design aspects, i.e., network topology, multiple access schemes, and radio technologies, will be thoroughly reviewed. The performance of a first prototype implementation will be discussed with emphasis on timing behavior and power consumption, as sensors and actuators of the wireless system are intended to operate without power lines or batteries

WiDom: A Dominance Protocol for Wireless Medium Access

Abstract: Wireless networks play an increasingly important role in application areas such as factory-floor automation, process control, and automotive electronics. In this paper, we address the problem of sharing a wireless channel among a set of sporadic message streams where a message stream issues transmission requests with real-time deadlines. For this problem, we propose a collision-free wireless medium access control (MAC) protocol, which implements static-priority scheduling and supports a large number of priority levels. The MAC protocol allows multiple masters and is fully distributed; it is an adaptation to a wireless channel of the dominance protocol used in the CAN bus, a proven communication technology for various industrial applications. However, unlike that protocol, our protocol does not require a node having the ability to receive an incoming bit from the channel while transmitting to the channel. The evaluation of the protocol with real embedded computing platforms is presented to show that the proposed protocol is in fact collision-free and prioritized. We measure the response times of our implementation and find that the response-time analysis developed for the protocol indeed offers an upper bound on the response times

Evaluation of Response Times in Industrial WLANs

Abstract: The adoption of wireless communication technologies in industrial environments for supporting (soft) real-time applications heavily depends on the ability to grant bounded response times for messages, at least from a probabilistic point of view. This aspect is particularly important in factory automation systems, where response times are considered much more significant than other performance indices, such as throughput, that are usually considered in different application areas. The ever-increasing availability on the market of products and solutions based on the IEEE 802.11 standard and the introduction of the 802.11e amendment for enhancing the quality of service (QoS) and prioritizing traffic make this kind of communication technology interesting also for adoption in (loosely coupled) distributed control systems. This paper reports on some experimental measures and the related analysis that have been carried out on real 802.11g/e networks for better understanding the statistical distribution of response times and can be of help in characterizing these solutions when used to support noncritical real-time traffic.

Development of a New Robot Controller Architecture with FPGA-Based IC Design for Improved High-Speed Performance

Abstract: In this paper, a new robot controller architecture is proposed to implement various complex control algorithms for improved high-speed performance. The main thrust of the research is to remove the servo control loop from the digital signal processor (DSP) and implement the high-speed servo loop in a field programmable gate array (FPGA). The main objective of this architecture is to utilize the ultra-high-speed hardwired logic of the FPGA to enhance the overall computational capability and relieve the computational load of the DSP for other tasks. The control algorithm is partitioned into a linear portion and a nonlinear portion. The linear portion with position/velocity feedback represents the major control loop and is implemented in the FPGA. The nonlinear portion acts as dynamic compensation to the linear portion to calculate model-related control gains/parameters, and it is implemented in the DSP. In tandem, with the newly developed control hardware architecture, an FPGA-based motion control integrated circuit (IC) is designed. Experiments are conducted on an industrial robot manipulator to compare the closed-loop performance with this new control architecture and the traditional one, when the same control algorithm is used. The experimental results demonstrate that the proposed new control architecture exhibits much improved motion performance indeed, especially in high-speed motions.

Fault-Tolerant Time-Triggered Communication Using CAN

Abstract: The controller area network (CAN) protocol was originally introduced for automotive applications but is now also widely used in process control and many other industrial areas. In this paper, we present a low-cost redundancy-management scheme for replicated CAN channels that helps to ensure that clocks (and, hence, tasks) on the distributed nodes remain synchronized in the event of failures in the underlying communication channels, without the need for expensive or proprietary interface electronics. We argue that, when using this framework with duplicated channels, the probability of inconsistent message delivery drops to acceptable levels for a wide range of systems. Through an analysis of the protocol and a case study, we conclude that the creation of reliable, low-cost, distributed embedded systems using CAN is a practical possibility.

System Level Design for Clustered Wireless Sensor Networks

Abstract: We present a system level design methodology for clustered wireless sensor networks based on a semi-random communication protocol called SERAN, a mathematical model that allows to optimize the protocol parameters, and a network initialization and maintenance procedure. SERAN is a two-layer (routing and MAC) protocol. At both layers, SERAN combines a randomized and a deterministic approach. While the randomized component provides robustness over unreliable channels, the deterministic component avoids an explosion of packet collisions and allows our protocol to scale with network size. The combined result is a high reliability and major energy savings when dense clusters are used. Our solution is based on a mathematical model that characterizes performance accurately without resorting to extensive simulations. Thanks to this model, the user needs only to specify the application requirements in terms of end-to-end packet delay and packet loss probability, select the intended hardware platform, and the protocol parameters are set automatically to satisfy latency requirements and optimize for energy consumption.

VTP-CSMA: A Virtual Token Passing Approach for Real-Time Communication in IEEE 802.11 Wireless Networks

Abstract: Currently, there is a trend towards the implementation of industrial communication systems using wireless networks. However, keeping up with the timing constraints of real-time traffic in wireless environments is a hard task. The main reason is that real-time devices must share the same communication medium with timing unconstrained devices. The VTP-CSMA architecture has been proposed to deal with this problem. It considers an unified wireless system in one frequency band, where the communication bandwidth is shared by real-time and non-real-time communicating devices. The proposed architecture is based on a virtual token passing (VTP) procedure that circulates a virtual token among real-time devices. This virtual token is complemented by an underlying traffic separation mechanism that prioritizes the real-time traffic over the non-real-time traffic. This is one of the most innovative aspects of the proposed architecture, as most part of real-time communication approaches are not able to handle timing unconstrained traffic sharing the same communication medium. A ring management procedure for the VTP-CSMA architecture is also proposed, allowing real-time stations to adequately join/leave the virtual ring.

A New Model for Autonomous, Networked Control Systems

Abstract: Existing communication utilities, such as the ISO/OSI model and the associated automation pyramid, have limitations regarding the increased complexity of modern automation systems. The introduction of profiles for fieldbus systems, or field-area networks (FANs), was an important innovation. However, in the foreseeable future the number of FAN nodes in building automation systems is expected to increase drastically. And here the authors see an opportunity to revolutionize the operation of intelligent, autonomous systems based on FANs. The paper introduces a system based on bionic principles to process the information obtained from a large number of diverse sensors. By means of multilevel symbolization, the amount of information to be processed is substantially reduced. A symbolic processing model is introduced that enables the processing of real world information, creates a world representation, and evaluates scenarios that occur in this representation. Two applications involving human actions in a building automation environment are briefly discussed. It is argued that the use of internal symbolization leads to greater flexibility in the case of a large number of sensors, providing the ability to adapt to changing sensor inputs in an intelligent way

Constraint-Based Control of Boiler Efficiency: A Data-Mining Approach

Abstract: In this paper, a data-mining approach is used to develop a model for optimizing the efficiency of an electric-utility boiler subject to operating constraints. Selection of process variables to optimize combustion efficiency is discussed. The selected variables are critical for control of combustion efficiency of a coal-fired boiler in the presence of operating constraints. Two schemes of generating control settings and updating control variables are evaluated. One scheme is based on the controllable and noncontrollable variables. The second one incorporates response variables into the clustering process. The process control scheme based on the response variables produces the smallest variance of the target variable due to reduced coupling among the process variables. An industrial case study and its implementation illustrate the control approach developed in this paper

Elastic DVS Management in Processors With Discrete Voltage/Frequency Modes

Abstract: Applying classical dynamic voltage scaling (DVS) techniques to real-time systems running on processors with discrete voltage/frequency modes causes a waste of computational resources. In fact, whenever the ideal speed level computed by the DVS algorithm is not available in the system, to guarantee the feasibility of the task set, the processor speed must be set to the nearest level greater than the optimal one, thus underutilizing the system. Whenever the task set allows a certain degree of flexibility in specifying timing constraints, rate adaptation techniques can be adopted to balance performance (which is a function of task rates) versus energy consumption (which is a function of the processor speed). In this paper, we propose a new method that combines discrete DVS management with elastic scheduling to fully exploit the available computational resources. Depending on the application requirements, the algorithm can be set to improve performance or reduce energy consumption, so enhancing the flexibility of the system. A reclaiming mechanism is also used to take advantage of early completions. To make the proposed approach usable in real-world applications, the task model is enhanced to consider some of the real CPU characteristics, such as discrete voltage/frequency levels, switching overhead, task execution times nonlinear with the frequency, and tasks with different power consumption. Implementation issues and experimental results for the proposed algorithm are also discussed

A Jumping-Genes Paradigm for Optimizing Factory WLAN Network

Abstract: In this paper, a jumping-genes paradigm is proposed for optimizing the wireless local area network for an integrated-circuit factory. Through the base station placement, not only the best quality of service of the network is guaranteed, but also the performance of the network can be a tradeoff with the number of allowable base stations. This provides a greater flexibility for the designer when the factory environment such as physical space, building structure, equipment, and cost are the significant parts of the overall design criteria. The main feature of this optimization scheme is its capacity to yield the extreme minmax solutions under a specific allowable design, power-loss threshold. It provides a much wider range of solutions for selection, which includes the ultimate low-cost design without sacrificing the performance or vice versa. The obtained results revealed from this study indicated that the jumping-genes paradigm is an effective and reliable methodology for this type of design problem

Architecture Design and Implementation of an Ad-Hoc Network for Disaster Relief Operations

Abstract: This paper presents an ad-hoc sensor network especially developed for a disaster relief application that provides the rescue teams with a quickly deployable, cost-effective, and reliable tool to collect information about the presence of people in a collapsed building space and the state of the ruins. The hardware/software architecture of the wireless sensor nodes is developed for a low-cost design implementation. Energy efficiency is another objective of this paper, achieved by the combination of a low-power-mode algorithm and a power-aware routing strategy. A selected set of simulation studies indicate a reduction in energy consumption and a significant increase in node lifetime whereas network performance is not affected significantly. Finally, a lightweight management architecture is presented to facilitate autonomous management of ad-hoc sensor networks

Guest Editorial Special Section on Wireless Technologies in Factory and Industrial Automation—Part II

Abstract: The three papers in this special section focus on wireless technologies in factory and industrial automation. The papers which appear in this second part cover everything from protocol design and evaluation to the design and assessment of system-level solutions for wireless sensor networks in industrial automation.

Data Architectures for RFID Transactions

Abstract: We focus on the data models for storing the data generated by radio frequency identification (RFID) transactions and architectures for processing such data. We consider the supply chain comprised of the manufacturer, distributor, retailer, and the consumer. We discuss details of the data generated by RFID transactions and data models to store such data. Different organizations in the supply chain may use this data for different applications such as automatic product ordering, shelf replenishment, and product recall. We present models to anticipate the data requirements generated by RFID transactions and indicate how existing enterprise applications can be adapted to handle RFID data. The results presented in this paper will help a practitioner to 1) design and develop databases and applications for handling RFID data and 2) significantly reduce the storage requirements of RFID data. Using the data architectures, we discuss two supply chain applications-product recall and shelf replenishment-in detail. We present analytical models for the cost and time required for shelf replenishment in a retail store.

A Framework for CAD- and Sensor-Based Robotic Coating Automation

Abstract: Coating automation of a complex product family with changes and uncertainties is investigated. A CAD- and scanner-based robotic coating system is proposed. Its software system consists of a data-processing system and automatic programming and simulation system. The data processing system is capable of generating accurate surface model from points-cloud and/or as-designed CAD model. The automatic programming and simulation system is capable of creating robot programs based on the surface models. In this paper, the system framework and the methodology for generating robot programs are focused

Adaptive Fuzzy Sliding Mode Control Algorithm for a Non-Affine Nonlinear System

Abstract: This paper concerns the design of robust controller for a nonlinear system that can be represented or approximated in a non-affine form. The control algorithm is based on sliding mode control that incorporates a fuzzy tuning technique, and it superposes equivalent control, switching control, and fuzzy control. An equivalent control law is firstly designed based on a nominal system model that was obtained by using curve fitting techniques under MATLAB. Switching control is then added to guarantee that the state reaches the sliding surface in the presence of parameter and disturbance uncertainties. Also, fuzzy tuning schemes, which can be supported by learning techniques derived from neural networks, are employed to improve control performance and to reduce chattering in the sliding mode. To verify the performance of this controller, an experimental platform of a pneumatically actuated top-guided single-seated control valve, which belongs to a classical complex nonlinear system, was constructed. Also, the experimental results show that high performance and attenuated chatter are achieved and thus verify the validity of the proposed control approach to dynamic systems characterized by severe uncertainties.

Real-Time Gait Planning for Pushing Motion of Humanoid Robot

Abstract: This paper describes real-time gait planning for pushing motion of humanoid robots. This method deals with an object whose mass is not known. In order that a humanoid robot pushes an unknown object in both single support phase and double support phase, real-time gait planning for pushing the unknown object is proposed. Real-time gait planning consists of zero moment point (ZMP) modification and cycle time modification. ZMP modification is the method that modifies the influence of reaction force to ZMP. By cycle time modification, the period in double support phase is modified to avoid a robot tipping over. These modifications are calculated from reaction force on arms in every cycle. With these methods, trajectory planning for pushing an unknown object in both single support phase and double support phase is calculated. Even if parameters of an object and friction coefficient on the floor vary, the robot keeps on walking while pushing an object. The effectiveness of the proposed method is confirmed by a simulation and an experiment.

Adaptive Internet Integration of Field Bus Systems

Abstract: Field buses are used to network sensors, actuators, and control devices inside automation systems. The Internet integration of field bus systems enables information from these devices to be exchanged across enterprises and businesses. An essential prerequisite to this aim is the interoperability of field bus systems with external systems and applications. Therefore, many efforts are made to establish a common information exchange standard which all field bus systems are supposed to support. However, the longer these efforts are ongoing the less it seems that they will ever yield the expected breakthrough. The present paper introduces an substantially different approach to interoperability. Field bus systems may keep their individual application interfaces and data exchange formats. All the same, external infrastructures do not have to be redesigned to match the specific needs of certain field bus systems. Rather, field bus systems become capable of adapting the information exchange flexibly according to the needs of the outside environment

Intelligent Control and Integration Software for Flexible Manufacturing Cells

Abstract: Flexible manufacturing cells (FMC) are capable of producing a broad variety of products and changing their characteristics quickly and frequently. This flexibility provides for more efficient use of resources but makes the control of these systems more difficult. This paper presents several software applications developed for industrial robots and computer numerical control (CNC) machines. The objective of this software is to allow these equipments to be integrated, in an easy and efficient way, in modern FMC. For the industrial robots, we developed the "winRS232ROBOTcontrol" and "winEthernetROBOTcontrol" software. For the CNC machines, the software that was developed was "winMILLcontrol" for the mill and "winTURNcontrol" for the lathe. With this software, industrial robots and CNC machines can be integrated in modern FMC, in an easy and efficient way. An FMC was developed, with industrial characteristics, with the objective of showing the potentialities of the developed software. Thus, the proposed software in this paper was tested and validated in the developed FMC, and the experimental results show the viability and success of this software in the coordination of the different sectors in the FMC and in the improvement of their performance

Failure Detection and Adaptive Compensation for Fault Tolerable Flight Control Systems

Abstract: This paper presents an advanced aircraft flight control system which is capable of providing failure detection, identification, and adaptive compensation in the event of the damage of control surfaces. The new approach is based on the detection of immediate changes of correlation between pitching, yawing, and rolling rates. The failure compensation mechanism is realized by an adaptive wavelet neural net-based proportional-integral-derivative (PID) controller. The fault-tolerant mechanism is activated to regain effective control of the damaged aircraft whenever a control surface failure is detected. Design of a real-time executive kernel based on the RT-Linux operating system is experimentally conducted to realize and verify functions of our proposed design.

Overcoming Babbling-Idiot Failures in CAN Networks: A Simple and Effective Bus Guardian Solution for the FlexCAN Architecture

Abstract: This paper is concerned with the issue of protecting CAN networks against the consequences of babbling-idiot faults such as unscheduled traffic generated by a faulty node that denies any other communication. A full solution of the problem would greatly enhance the dependability of the CAN networks, making them applicable to safety-critical systems. After explaining the weakness of the native CAN protocol in tolerating the babbling-idiot faults, this paper shows how the FlexCAN architecture is suitable to tolerate them effectively. To this aim, a simple bus guardian is proposed and tested. The results of the test are given in this paper.

Ontology Development for Designing and Managing Dynamic Business Process Networks

Abstract: Recent advances in flexible process design and deployment technologies, such as web services and flexible workflow systems, promise the development of flexible intra- and inter-organizational business process networks with potential economic benefits. However, exploiting this potential requires the development of scalable process-management technologies that provide a consistent viewpoint and common language (for describing properties of the process network) to all stakeholders involved in its management. Current approaches to managing such networks requires one to use a babel of languages (in the formal sense) at different levels of abstraction. The development of explicit process ontologies is one of the potentially viable approaches to provide an unified view. In this paper, we discuss the need for process ontologies, propose a task-based ontological framework synthesizing recent research in the fields of AI planning and software engineering, and illustrate the need to link declarative and procedural process representations. We illustrate the use of this ontological framework for managing processes in developing applications for integrating information from disparate information sources in multiple domains. Further, based on this experience, we discuss potential benefits and areas for future research.

Experimental Evaluation of an Industrial Application Layer Protocol Over Wireless Systems

Abstract: Several recent studies have addressed the suitability of current wireless technologies for industrial communications which, frequently, are requested to cope with severe timing constraints. Most of the analysis that have lately appeared in the literature have focused on the performance offered by the lower layers of the communication stack. However, in order to obtain a complete picture, it is important to analyze how this gets coupled with the features of higher layer protocols typically employed by industrial communication applications. In this paper, we investigate the performance obtained by an application layer protocol, derived from those currently employed by wired fieldbuses, running over COTS devices based on two popular wireless communication standards, namely, IEEE 802.15.4 and IEEE 802.11. In particular, we present a mapping of the application service elements onto the services offered by the mentioned wireless systems and discuss some possible design choices. A prototype of the application layer protocol is then implemented for each considered wireless technology and the performance figures evaluated by means of experimental measurements.

Algorithms for Transitive Dependence-Based Coalition Formation

Abstract: Coalition formation methods allow autonomous agents to join together in order to act as a coherent group in which they increase their individual gains by collaborating with each other. Although there are some research efforts toward coalition formation in multiagent systems (MAS), such as game theory-based approaches, these methods cannot be easily applied in real-world scenarios. Based on a novel social reasoning theory, namely, transitive dependence theory, this work proposes two dynamic coalition formation algorithms for coalition formation: 1) without and-action dependence and 2) with and-action dependence, respectively. While most related work addresses the problem of searching for the optimal coalition structure (CS), the proposed algorithms aim to find out the optimal coalitions for specific goals. Theoretical analysis and experimental results suggest that 1) the algorithm for coalition formation without and-action dependence is of polynomial complexity and is efficient, and 2) when the incidence rate of and-action dependence is not high, the anytime algorithm for coalition formation with and-action dependence is also efficient although it has relatively high complexity (NP-complete).

Soft Synchronization: Synchronization for Network-Connected Machine Vision Systems

Abstract: Many computer vision applications require synchronization between image acquisition and external trigger events. Hardware and software triggering are widely used but have several limitations. Soft synchronization is investigated, which operates by time tagging both trigger events and images in a video stream and selecting the image corresponding to each trigger event. A stochastic model is developed for soft synchronization; and, based on the model, the uncertainty interval and confidence for correct image selection are determined, and an efficient calibration method is derived. Soft synchronization is experimentally demonstrated on a Linux image processing computer with a camera connected by the IEEE-1394 serial bus. To minimize timing variability, time tags are associated with images and events in the corresponding interrupt service routines within the operating system of the image processing computer. The model-based analysis applied to the experimental hardware shows that image/event synchronization within inter-frame interval can be achieved with 99% confidence. Experiments confirm this result.