Fuzzy logic arbiters for multiple-bus multiprocessor systems

This paper describes and evaluates the use of fuzzy logic arbiters for multiple-bus shared memory multiprocessor system. Multiple-bus systems allow multiple and simultaneous bus transfer in addition to a high degree of fault tolerance. In such systems, arbiters are used to resolve conflicts to system resources, which are the shared memory modules and the buses. Typically, these conflicts are resolved by using two-stage arbitration schemes that employ policies such as random choice, daisy chaining, round-robin, etc. A new way of implementing these arbiters is the use of fuzzy logic to resolve resource request conflicts based on the system state and performance variables. This paper describes a new technique for implementation of fuzzy logic in the system arbiters and presents a simulation program that evaluates the system performance. The program is coded in such a way as to accommodate any arbitration scheme, from which the fixed priority and fuzzy priority have been implemented. Parameters affecting multiple-bus system performance are considered and used as inputs to the fuzzy arbiters. The inputs are fuzzified by using appropriate membership functions, and rules have been defined in such a way as to increase and distribute evenly the acceptance probability of each processor in the system. Results from the simulation program using a prioritized arbitration scheme are compared against other published results and show very close agreement. Furthermore, results show an increase in the acceptance probability of the processors using fuzzy arbiters.     

Cooperative congestion control schemes in ATM networks

One of the basic problems faced in the design of efficient traffic and congestion control schemes is related to the wide variety of services with different traffic characteristics and quality of service (QoS) requirements supported by ATM networks. The authors propose a new way of organizing the control system so that complexity is easier to manage. The multi-agent system approach, which provides the use of adaptative and intelligent agents, is investigated. The authors show, through the two congestion control schemes proposed, how to take advantage of using intelligent agents to increase the efficiency of the control scheme. First, TRAC (threshold based algorithm for control) is proposed, which is based on the use of fixed thresholds which enables the anticipation of congestion. This mechanism is compared with the push-out algorithm and it is shown that the authors' proposal improves the network performance. Also discussed is the necessity of taking into account the network dynamics. In TRAC, adaptative agents with learning capabilities are used to tune the values of the thresholds according to the status of the system. However, in this scheme, when congestion occurs, the actions we perform are independent of the nature of the traffic. Subsequently, we propose PATRAC (predictive agents in a threshold based algorithm for control) in which different actions are achieved according to the QoS requirements and to the prediction of traffic made by the agents. Specifically, re-routing is performed when congestion is heavy or is expected to be heavy and the traffic is cell loss sensitive. This re-routing has to deflect the traffic away from the congestion point. In this scheme, we propose a cooperative and predictive control scheme provided by a multi-agent system that is built in to each node     

能量回收电容耦合逻辑及其综合方法

提出了一种新型能量回收电路ERCCL（能量回收电容耦合逻辑）,该电路的能耗低于传统CMOS电路及其他能量回收电路．ERCCL利用电容耦合进行逻辑求值,因此可以在一个门中低能耗地实现高扇入、高复杂度的逻辑．同时ERCCL是一种阈值逻辑．所以一个基于ERCCL的系统可以大大减少逻辑门数,从而降低系统能耗．针对ERCCL提出了一种阈值逻辑综合方法．用基准电路集MCNC做了相应的实验．与SIS的综合结果相比,该方法大约减少80％的逻辑门．     

能量回收电容耦合逻辑及其综合方法

提出了一种新型能量回收电路ERCCL(能量回收电容耦合逻辑),该电路的能耗低于传统CMOS电路及其他能量回收电路.ERCCL利用电容耦合进行逻辑求值,因此可以在一个门中低能耗地实现高扇入、高复杂度的逻辑.同时ERCCL是一种阈值逻辑.所以一个基于ERCCL的系统可以大大减少逻辑门数,从而降低系统能耗.针对ERCCL提出了一种阈值逻辑综合方法.用基准电路集MCNC做了相应的实验.与SIS的综合结果相比,该方法大约减少80%的逻辑门.     

A fuzzy logic based buffer management scheme with traffic differentiation support for delay tolerant networks

Delay tolerant networks (DTNs) are an emerging class of wireless networks which enable data delivery even in the absence of end-to-end connectivity. Under these circumstances, message replication may be applied to increase the delivery ratio. The requirement of long term storage and message replication puts a burden on network resources such as buffer and bandwidth. Buffer management is an important issue which greatly affects the performance of routing protocols in DTNs. Two main issues in buffer management are drop decision when buffer overflow occurs and scheduling decision when a transmission opportunity arises. The objective of this paper is to propose an enhancement to the Custom Service Time Scheduling traffic differentiation scheme by integrating it with a fuzzy based buffer ranking mechanism based on three message properties, namely, number of replicas, message size and remaining time-to-live. It uses fuzzy logic to determine outgoing message order and to decide which messages should be discarded within each traffic class queue. Results of simulation study show that the proposed fuzzy logic-based traffic differentiation scheme achieves improved delivery performance over existing traffic differentiation scheme for DTNs.     

Dynamic buffer management using per‐queue thresholds

Shared buffer switches consist of a memory pool completely shared among output ports of a switch. Shared buffer switches achieve low packet loss performance as buffer space is allocated in a flexible manner. However, this type of buffered switches suffers from high packet losses when the input traffic is imbalanced and bursty. Heavily loaded output ports dominate the usage of shared memory and lightly loaded ports cannot have access to these buffers. To regulate the lengths of very active queues and avoid performance degradations, threshold‐based dynamic buffer management policy, decay function threshold, is proposed in this paper. Decay function threshold is a per‐queue threshold scheme that uses a tailored threshold for each output port queue. This scheme suggests that buffer space occupied by an output port decays as the queue size of this port increases and/or empty buffer space decreases. Results have shown that decay function threshold policy is as good as well‐known dynamic thresholds scheme, and more robust when multicast traffic is used. The main advantage of using this policy is that besides best‐effort traffic it provides support to quality of service (QoS) traffic by using an integrated buffer management and scheduling framework. Copyright © 2006 John Wiley & Sons, Ltd.     

A fuzzy logic sliding mode controlled electronic differential for a direct wheel drive EV

In this study, a direct wheel drive electric vehicle based on an electronic differential system with a fuzzy logic sliding mode controller (FLSMC) is studied. The conventional sliding surface is modified using a fuzzy rule base to obtain fuzzy dynamic sliding surfaces by changing its slopes using the global error and its derivative in a fuzzy logic inference system. The controller is compared with proportional–integral–derivative (PID) and sliding mode controllers (SMCs), which are usually preferred to be used in industry. The proposed controller provides robustness and flexibility to direct wheel drive electric vehicles. The fuzzy logic sliding mode controller, electronic differential system and the overall electrical vehicle mechanism are modelled and digitally simulated by using the Matlab software. Simulation results show that the system with FLSMC has better efficiency and performance compared to those of PID and SMCs.     

A Combined Hard and Soft Variable-Structure Control Scheme for a Class of Nonlinear Systems

This paper presents a novel variable-structure-based control scheme for nonlinear systems. First, a hard variable-structure control is constructed for achieving a uniform ultimate boundedness control. Then, a soft variable-structure control using fuzzy logic is incorporated to help improve dynamic responses when trajectories enter into the ultimate bound. For practical consideration, we added a genetic-algorithm-based alpha–beta filter in front of the fuzzy controller to suppress noise and obtain smooth input signals. For comparison purposes, an inverted pendulum system was first used as a simulated example to demonstrate the effectiveness of the design. Then, the performance of the control scheme was practically tested with an experimental PC-based magnetic levitation system. The simulation and experimental results strongly suggest that the newly proposed control scheme is encouraging for practical applications.      

A deadzone compensator of a DC motor system using fuzzy logiccontrol

A deadzone compensator is designed for a DC motor system using a fuzzy logic controller. The classification property of fuzzy logic systems makes them a natural candidate for the rejection of errors induced by the deadzone, which has regions in which it behaves differently. A tuning algorithm is given for the fuzzy logic parameters, so that the deadzone compensation scheme becomes adaptive, guaranteeing small tracking errors and bounded parameter estimates. Formal nonlinear stability proofs are given to show that the tracking error is small. The fuzzy logic deadzone compensator is implemented on a DC motor system to show its efficacy     

A New Method to Find a High Reliable Route in IoT by Using Reinforcement Learning and Fuzzy Logic

Recently, Internet is moving quickly toward the interaction of objects, computing devices, sensors, and which are usually indicated as the Internet of things (IoT). The main monitoring infrastructure of IoT systems main monitoring infrastructure of IoT systems is wireless sensor networks. A wireless sensor network is composed of a large number of sensor nodes. Each sensor node has sensing, computing, and wireless communication capability. The sensor nodes send the data to a sink or a base station by using wireless transmission techniques However, sensor network systems require suitable routing structure to optimizing the lifetime. For providing reasonable energy consumption and optimizing the lifetime of WSNs, novel, efficient and economical schemes should be developed. In this paper, for enhancing network lifetime, a novel energy-efficient mechanism is proposed based on fuzzy logic and reinforcement learning. The fuzzy logic system and reinforcement learning is based on the remained energies of the nodes on the routes, the available bandwidth and the distance to the sink. This study also compares the performance of the proposed method with the fuzzy logic method and IEEE 802.15.4 protocol. The simulations of the proposed method which were carried out by OPNET (Optimum Network performance) indicated that the proposed method performed better than other protocols such as fuzzy logic and IEEE802.15.4 in terms of power consumption and network lifetime.

     

Drift controlled scalable wavelet based video coding in the overcomplete discrete wavelet transform domain

Traditional video coders use the previous frame to perform motion estimation and compensation. Though they are less complex and have minimum coding delays, these coders lose their efficiency when subjected to scalability requirements. Recent 3D wavelet coders using lifting schemes offer high compression efficiency and scalability without significant loss in performance. The main drawback of 3D coders is that they process several frames at a time. This introduces additional delay, which makes them less suitable for real time applications.In this work, we propose a novel scheme to minimize drift in scalable wavelet based video coding, which gives a balanced performance between compression efficiency and reconstructed quality with less drift. Our drift control mechanism maintains two frame buffers in the encoder and decoder; one that is based on the base layer and one that is based on the base plus enhancement layers. Drift control is achieved by switching between these two buffers for motion estimation and compensation. Our prediction is initially based on the base plus enhancement layers buffer, which inherently introduces drift in the system if a part of the enhancement layer is not available at the receiver. A measure of drift is computed based on the channel information and a threshold is set. When the measure exceeds the threshold, i.e., when drift becomes significant, we switch the prediction to be based on the base layer buffer, which is always available to the receiver. We also developed an adaptive scheme with additional computation overhead at the encoder to decide the switching instance. The performance of the threshold case that needs fewer computations is comparable with the adaptive scheme. Our coder offers high compression efficiency and sustained video quality for variable bit rate wireless channels. This proves that we need not completely eliminate drift and decrease compression efficiency to get better received video quality.     

Hierarchical fuzzy force control for industrial robots

In this paper, we present a hierarchical force control framework consisting of a high-level control system based on fuzzy logic and the existing motion control system of a manipulator in the low level. In order to adapt various contact conditions, an adaptable fuzzy force control scheme has been proposed to improve the performance. The ability of the adaptable force control system is achieved by tuning the scaling factor of the fuzzy logic controller (FLC). A Mitsubishi MELFA RV-M1 industrial robot equipped with a BL Force/Torque sensor is utilized for implementing the hierarchical fuzzy force control system. Successful experiments for various contact motions are carried out. Additionally, discussion of a peg-in-hole insertion is presented, and the experimental results are given     

Fuzzy control of multi‐rate traffic in multimedia cell‐based networks

In this paper, an intelligent scheme for controlling the QoS in multimedia, multi‐rate networks is presented. The scheme implements a dynamic control mechanism, based on buffers with vaguely defined thresholds represented with fuzzy sets. This approach guarantees the QoS of real‐time traffic and delivers non‐realtime traffic at acceptable performance levels. The fuzzy mechanism, based on the principles of fuzzy control, dynamically responds to the alternating traffic patterns at the access node using a set of fuzzy control rules. The fuzzy control rules are carefully formulated to reduce the starvation of non‐realtime traffic which is usually assigned a low priority. We also show in this paper how the proposed schemes offer an improved performance over other access control mechanisms such as moving boundaries and other static priority strategies. This revised version was published online in June 2006 with corrections to the Cover Date.     

Fuzzy tuning PI control for initial levitation of micromachined electrostatically levitated gyroscope

A novel microgyroscope based on UV-LIGA technology is described, in which the wheel-like rotor is levitated and rotated by the electrostatic forces. A simple fuzzy logic scheme for online tuning of PI (proportional integral) controller parameters to improve system robustness of initial levitation is outlined. Experimental results indicate that, with fuzzy tuning, the overshoot is reduced to 17% compared with 27% of the conventional PI controller. The rise time for the two channels of the four is 3.6 ms and the settle time is nearly 25.6 ms, which shows a quick response time and good steady-state performance. From the experiment of 0.5 g pulse acceleration input, sensitivity along axial direction is 1 V g when it acts as an accelerometer.     

Reliability and routability consideration for MCM placement

This paper presents a methodology based on the fuzzy logic approach for the placement of the power dissipating chips on the multichip module substrate. Our methodology considers both thermal distribution and routing length constraints during multichip module placement. In this paper, the main design issue is the coupled placement for reliability and routability. The objective of the coupled placement is to enhance the system performance and reliability by obtaining an optimal cost during multichip module placement. For reliability considerations, the design methodology is addressed on the placement of the power dissipating chips to achieve uniform thermal distribution. The thermal placement analysis is based on the modified fuzzy force-directed placement method. Placement for routability is based on minimizing the total wire length estimated by semi-perimeter method. The placement trade-off between routability and reliability is illustrated by varying a weighting factor. Case studies of the coupled placement are presented. In addition, the thermal distribution of the coupled placement results is simulated with the finite element method.     

A two-layered fuzzy logic controller for systems with deadzones

Existing fuzzy control methods do not perform well when applied to systems containing nonlinearities arising from unknown deadzones. In particular, we show that a usual "fuzzy PD" controller applied to a system with a deadzone suffers from poor transient performance and a large steady-state error. In this paper, we propose a novel two-layered fuzzy logic controller for controlling systems with deadzones. The two-layered control structure consists of a fuzzy logic-based precompensator followed by a usual fuzzy PD controller. Our proposed controller exhibits superior transient and steady-state performance compared to usual fuzzy PD controllers. In addition, the controller is robust to variations in deadzone nonlinearities. We illustrate the effectiveness of our scheme using computer simulation examples.<>     

异构无线网络中基于模糊逻辑的分级垂直切换算法

在异构无线网络中,针对综合考虑网络端和用户端参数的垂直切换算法,参数权重难以确定,同时基于模糊逻辑的垂直切换算法存在复杂度高的问题,该文提出一种基于模糊逻辑的分级垂直切换算法。首先,将接收信号强度(RSS)、带宽、时延输入到1级模糊逻辑系统,结合规则自适应匹配,推理出QoS模糊值,并通过QoS模糊值对网络进行初步筛选得到候选网络集;然后通过触发机制触发2级模糊逻辑系统,并将候选网络的QoS模糊值、网络负载率、用户接入费用输入2级模糊逻辑系统,同时结合规则自适应匹配,得到输出判决值,从而选择最佳接入网络。最后,实验结果表明,该算法能保证网络性能的同时,降低系统的时间开销。     

Sliding-mode motion controller with adaptive fuzzy disturbance estimation

This paper proposes a motion control scheme which belongs to the class of the control schemes known as sliding-mode control with disturbance estimation. A novel adaptive fuzzy disturbance estimator works as an estimator of a major part of robot dynamics. The adaptation algorithm is derived by using the Lyapunov stability theory and provides global asymptotic stability of the state errors, resulting in the sliding-mode regime. The structure of the disturbance estimator is optimized by the introduction of three fuzzy logic subsystems, based on the physical properties of the robot mechanism. This also significantly lowers the computational burden and enables real-time implementation. Performance of the proposed controller scheme, as well as some practical design aspects, are demonstrated by the control of a direct-drive robot.     

Fuzzy logic rotor position estimation based switched reluctance motor DSP drive with accuracy enhancement

This paper describes a novel angle estimation scheme for a real time digital signal processor (DSP) based switched reluctance motor drive using fuzzy logic where several unique techniques are implemented to improve the estimation accuracy. First, an optimized fuzzy model of the motor was created using an adaptive neuro-fuzzy inference system (ANFIS) based on accurately measured flux linkage data. Secondly, an improved fuzzy optimal sensing phase selector was developed based on the analysis of both modeling error and measurement error. Lastly, a delayless polynomial predictive filter and an online phase winding resistance estimator are also implemented to further improve the position estimation accuracy. Both simulation and experiment results on a DSP based real time drive are presented to show the effectiveness of this scheme.     

Threshold logic circuit design of parallel adders using resonanttunneling devices

Resonant tunneling devices and circuit architectures based on monostable-bistable transition logic elements (MOBILEs) are promising candidates for future nanoscale integration. In this paper, the design of clocked MOBILE-type threshold logic gates and their application to arithmetic circuit components is investigated. The gates are composed of monolithically integrated resonant tunneling diodes and heterostructure field-effect transistors. Experimental results are presented for a programmable NAND/NOR gate. Design related aspects such as the impact of lateral device scaling on the circuit performance and a bit-level pipelined operation using a four phase clocking scheme are discussed. The increased computational functionality of threshold logic gates is exploited in two full adder designs having a minimal logic depth of two circuit stages. Due to the self-latching behavior the adder designs are ideally suited for an application in a bit-level pipelined ripple carry adder. To improve the speed a novel pipelined carry lookahead addition scheme for this logic family is proposed