IEEE Transactions on Industrial Informatics

1. Soft Synchronization: Synchronization for Network-Connected Machine Vision Systems
B. Armstrong and S. P. Veettil

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 ±1/2 inter-frame interval can be achieved with 99% confidence. Experiments confirm this result.

2. Experimental Evaluation of an Industrial Application Layer Protocol over Wireless Systems
S. Vitturi, I. Carreras, D. Miorandi, L. Schenato, A. Sona

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 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.

3. T-S Fuzzy-model-based Robust H_\infty Design for Networked Control Systems with Uncertainties
H. Zhang, J. Yang, and C-Y. Su

Abstract: This paper concerns a problem of robust H_\infty control of 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 H_\infty 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.

4. Adaptive Fuzzy Sliding Mode Control Algorithm for a Non-affine Nonlinear System
Z. Chen, C. Shan, H. Zhu

Abstract: This paper concerns the design of robust controller for a non-linear 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. And 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. And 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.

5. Development of a New Robot Controller Architecture with FPGA Based IC Design for Improved High-Speed Performance
X. Shao and D. Sun

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 DSP (Digital Signal Processor) and implement the high-speed servo loop in an FPGA (Field Programmable Gate Array). 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 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.

6. Failure Detection and Adaptive Compensation for Fault Tolerable Flight Control Systems
C-L. Lin and C-T. Liu

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 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.

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IEEE Industrial Electronics Society

IEEE Transactions on Industrial Informatics

Volume 3, Number 4, November 2007

Editorial

Regular Papers