Jafferi Jamaludin

Brief paper: Development of a self-tuning fuzzy logic controller for intelligent control of elevator systems

The search for an intelligent group controller that can satisfy multi-criteria requirements of an elevator group control system has become a great challenge for researchers. This paper presents the development of an elevator group controller based on fuzzy logic framework with a self-tuning scheme. Instead of basing on predicted traffic patterns to initiate modifications in the control outputs produced, the proposed group controller utilizes average waiting time (AWT) as the measured performance criterion used to adjust the membership functions and to select appropriate fuzzy rule sets, for the generation of suitable control actions. By comparing the measured performance results with the ones desired, better adjustment of the controller can be achieved to further improve the controllers performance. Computer simulation was carried out for three different cases in three traffic peaks. The results showed considerable overall improvements in the performance criteria evaluated as compared to the performance of conventional group controllers.

An Elevator Group Control System With a Self-Tuning Fuzzy Logic Group Controller

This paper presents a new group controllers adaptation mechanism with fuzzy logic for elevator group control system (EGCS) applications. Instead of depending heavily on the predicted passenger traffic pattern for adaptation, the fuzzy logic group controller (FLGC) adjusts itself to suit the systems environment through a self-tuning scheme. The average-waiting-time data that reflect the measured performance results of the EGCS are exploited to tune the membership functions of the input parameters and to modify the fuzzy rule sets employed by the FLGC, thus leading to better controllers performance and improved EGCS service quality. Computer simulation shows satisfactory improvements made in passenger waiting time and passenger riding time as compared to the performance of the conventional group controllers in three traffic peaks. The hardware implementation of the self-tuning FLGC on a TMS320C6416T digital signal processor further demonstrates its practicality.

New Three-Phase Multilevel Inverter with Shared Power Switches

Despite the advantages offered by multilevel inverters, one of the main drawbacks that prevents their widespread use is their circuit complexity as the number of power switches employed is usually high. This paper presents a new multilevel inverter topology with a considerable reduction in the number of power switches used through the switch-sharing approach. The fact that the proposed inverter applies two bidirectional power switches for sharing among the three phases does not prevent it from producing seven levels in the line-to-line output voltage waveforms. A modified scheme of space vector modulation via the application of virtual voltage vectors is developed to generate the PWM signals of the power switches. The performance of the proposed inverter is investigated through MATLAB/SIMULINK simulations and is practically tested using a laboratory prototype with a DSP-based modulator. The results demonstrate the satisfactory performance of the inverter and verify the effectiveness of the modulation method.

Self-tuning fuzzy-based dispatching strategy for elevator group control systems

Fuzzy logic is recognized as an intelligent approach to complex problems demanding fulfillment of several criteria. A smart solution for an elevator group control system is one complex problem. This paper discusses a fuzzy logic dispatching strategy for elevator group control that uses a self-tuning fuzzy logic controller to tune membership functions and adjust fuzzy rule sets. Computer simulation evaluates, in three traffic peaks, the strategypsilas effectiveness. The results, when compared with other strategies that use conventional controllers, show considerable overall improvements in both waiting time and riding time.

A novel self-tuning scheme for fuzzy logic elevator group controller

In this paper, an intelligent controller based on a novel self-tuning fuzzy logic framework for elevator control applications is presented. The proposed controller utilizes the measured performance data of the elevator control system i.e. average waiting time (AWT), to initiate self-tuning through the adjustment of the membership functions, and the modification of the rule set. The controllers adaptation to the systems environment that is based on the systems measured performance eliminates the heavy dependence on the predicted traffic patterns for adaptation. From computer simulation, the controllers effectiveness is satisfactorily verified.

New three-phase multilevel voltage source inverter with low switching frequency

This paper proposes a new multilevel circuit topology for a three-phase voltage source inverter. The inverter is built from the conventional three-phase full bridge configuration with the addition of five bidirectional switches. With this inverter, seven levels in the output line-to-line voltage waveforms are obtained. The operational principles of the inverter with low switching frequency are analyzed in detail. For verification, computer simulation has been carried out and hardware testing on a prototype inverter with the control algorithm implemented on a TMS320F2812 digital signal processor has been conducted.

Towards a Better Approach for Link Breaks Detection and Route Repairs Strategy in AODV Protocol

This paper describes a parameterized approach to the Ad Hoc On-Demand Distance Vector (AODV) routing protocol using a network-simulator 2 (ns2). By utilizing two AODV’s protocol functions, which are HELLO messages and local route repair, we explore the more flexible approach on these two important functions, rather than a fixed setting within the default AODV protocol. HELLO message is used to detect the broken link, while the local route repair in AODV is used to fix and discover alternative routes in the event of route failure. In this paper, two functions to optimize AODV performance have been utilized. The first is link break detection time ( ), using the HELLO message to detect link failure, and the second is link break position parameter ( ) for AODV’s local route repair. The results show that the default AODV setting does not yield the best results for most defined network scenarios. In some cases, improvement compared to the default setting can be as high as 38%, for local route repair strategies. This paper presents a potential flexible and parameterized approach for dealing with link breaks and route repairing strategies for AODV protocol.

Control of switch-sharing-based multilevel inverter suitable for photovoltaic applications

Abstract Owing to the higher amount and the better quality of power transferred, three-phase multilevel inverters have strengthened their presence in low-power photovoltaic (PV) applications. However, the existing topologies investigated for low-power PV systems are basically meant for medium- and high-power applications, thus making them underutilized for low-power range. In order to address this shortcoming, this paper proposes a three-phase multilevel inverter with a switch-sharing capability and its control solution. It combines the characteristics of the two-level full-bridge topology and the diode-clamped multilevel structure. As a result, the inverter can be used with full capacity and without being underutilized, and significantly improves the output quality. A control strategy that is able to maximize the full potential of the inverter is developed. A digital proportional-integral (PI) controller with a new tuning algorithm is designed to effectively deal with the load changes. The result reveals that the load current is always retained at the intended quality level despite the variations in load. The performance of the inverter is validated from the experimental work conducted on a laboratory prototype under closed-loop conditions.