Napsiah Ismail

Development of a new minimum avoidance system for a behavior-based mobile robot

A new fuzzy logic algorithm is developed for mobile robot navigation in local environments. A Pioneer robot perceives its environment through an array of eight sonar sensors and self positioning-localization sensors. While the fuzzy logic body of the algorithm performs the main tasks of obstacle avoidance and target seeking, an actual-virtual target switching strategy resolves the problem of limit cycles in any type of dead-ends encountered on the way to the target. This is an advantage beyond pure fuzzy logic approach and common virtual target techniques. In this work, multiple traps may have any shape or arrangement from barriers forming simple corners and U-shape dead-ends to loops, maze, snail shape, and other complicated shapes. Robot trajectories are demonstrated by simulation work and compared with results from other related methods to prove the robustness of this method.

Artificial neural network-based kinematics Jacobian solution for serial manipulator passing through singular configurations

Singularities and uncertainties in arm configurations are the main problems in kinematics robot control resulting from applying robot model, a solution based on using Artificial Neural Network (ANN) is proposed here. The main idea of this approach is the use of an ANN to learn the robot system characteristics rather than having to specify an explicit robot system model. Despite the fact that this is very difficult in practice, training data were recorded experimentally from sensors fixed on each joint for a six Degrees of Freedom (DOF) industrial robot. The network was designed to have one hidden layer, where the input were the Cartesian positions along the X, Y and Z coordinates, the orientation according to the RPY representation and the linear velocity of the end-effector while the output were the angular position and velocities for each joint, In a free-of-obstacles workspace, off-line smooth geometric paths in the joint space of the manipulator are obtained. The resulting network was tested for a new set of data that has never been introduced to the network before these data were recorded in the singular configurations, in order to show the generality and efficiency of the proposed approach, and then testing results were verified experimentally.

An expert fuzzy cognitive map for reactive navigation of mobile robots

A control technique is described for reactive navigation of mobile robots. The problems of large number of rules, and inefficient definition of contributing factors, e.g., robot wheel slippage, are resolved. Causal inference mechanism of the fuzzy cognitive map (FCM) is hired for deriving the required control values from the FCMs motion concepts and their causal interactions. The FCM-based control is proven to be advantageous over rule-based techniques. The developed system is utilized to control a Pioneer platform. The results and comparisons with the related works are given using ActivMedia simulation and a developed FCM simulation tool. An error estimation technique is used to measure the error between the actual and the simulation results.

A prototype knowledge-based system for material selection of ceramic matrix composites of automotive engine components

A prototype knowledge based system (KBS) for material selection of ceramic matrix composites (CMC) for engine components such as piston, connecting rod and piston ring is proposed in this paper. The main aim of this research work is to select the most suitable material for the automotive engine components. The selection criteria are based upon the pre-defined constraint value. The constraint values are mechanical, physical properties and manufacturing techniques. The constraint values are the safety values for the product design. The constraint values are selected from the product design specification. The product design specification values are selected from the past design calculation and some values are calculated by the help of past design data. The knowledge-based system consists of several modules such as knowledge acquisition module, inference module and user interface module. The domains of the knowledge-based system are defined as objects and linked together by hierarchical graph. The system is capable of selecting the most suitable materials and ranks the materials with respect to their properties. The design engineers can choose the required materials related to the materials property.

Application of value stream mapping using simulation to decrease production lead time: a Malaysian manufacturing case

Lean concept has been applied across many companies which offer value and eliminate wastes. Value stream map (VSM) as one of the fundamental tools in lean concept outlines the material and information flows for a product family to reduce wastes at discrete event production routine. In this paper, the improvement of the production lead time using VSM as a technique in a Malaysian supplier, with a job shop production system, is investigated. The main contribution of this paper is reducing production lead time when the Takt Time is much higher than the highest stations cycle time, and reducing unplanned released orders. This paper evaluates the present routing events using current state map and the future state is created answering the eight standard questions. Then, a detailed simulation model was developed to verify the result from future state map and answering the questions that are unable to be addressed by VSM.

Capability-based virtual cellular manufacturing systems formation in dual-resource constrained settings using Tabu Search

Formation of Virtual Cellular Manufacturing Systems (VCMSs), as one of the main applications of Group Technology (GT), by presentation of unique and shared capability boundaries of machine tools through defining Resource Elements (REs) creates a good solution for Capability-Based VCMSs (CBVCMSs), which increases opportunities to create systems with more efficient utilizations. Considering workers as the second important resources in Dual-Resource Constraint (DRC) settings makes this problem more serious and critical to research because, in reality, jobs cannot be processed if workers, machines, or both are not available. This paper attempts to form CBVCMSs with DRC settings using a multi-objective mathematical model with a Goal Programming (GP) approach. Using the developed model, parts, machines, and workers are grouped and assigned to the generated virtual cells at the same time. The proposed model is solved through a multi-objective Tabu Search (TS) algorithm to find optimum or near-to-optimum solutions. The validity of the developed model is illustrated by two numerical examples taken from the literature and evaluated through comparing the performance of the CBVCMSs and the original classical CMSs in the System Capacity Utilization (SCU) point of view.

Concurrent Decisions on Design Concept and Material Using Analytical Hierarchy Process at the Conceptual Design Stage

There is an increased study for considering the precise decisions on the design concept (DC) and material concurrently at the early stage of development of product. Inappropriate decisions on DC and material always lead to huge cost involvement and ultimately drive toward premature component or product failure. To overcome this problem, concurrent engineering (CE) is an approach which allows designers to consider early decision making (EDM) need to be implemented. To illustrate the use of CE principle at the early stage of design process, a concept selection framework called concurrent DC selection and materials selection (CDCSMS) was proposed. In order to demonstrate the proposed CDCSMS framework, eight DC s and six different types of composite materials of automotive bumper beam have been considered. Both of these decisions were then verified by performing various scenarios of sensitivity analysis by using analytical hierarchy process through utilizing Expert Choice software.

Distribution Network Design for Fixed Lifetime Perishable Products: A Model and Solution Approach

Nowadays, many distribution networks deal with the distribution and storage of perishable products. However, distribution network design models are largely based on assumptions that do not consider time limitations for the storage of products within the network. This study develops a model for the design of a distribution network that considers the short lifetime of perishable products. The model simultaneously determines the network configuration and inventory control decisions of the network. Moreover, as the lifetime is strictly dependent on the storage conditions, the model develops a trade-off between enhancing storage conditions (higher inventory cost) to obtain a longer lifetime and selecting those storage conditions that lead to shorter lifetimes (less inventory cost). To solve the model, an efficient Lagrangian relaxation heuristic algorithm is developed. The model and algorithm are validated by sensitivity analysis on some key parameters. Results show that the algorithm finds optimal or near optimal solutions even for large-size cases.

A computer‐based intelligent system for fault diagnosis of an aircraft engine

In this paper, an intelligent knowledge‐based system (KBS) capable of assisting aircraft mechanics and engineers to deal with fault diagnosis of the turbo‐prop aircraft engine is presented. The KBS intelligent jet engine trouble‐shooting system (IJETSS) employs expert knowledge to act in a way similar to that of a human expert in an aircraft maintenance field by using if‐then rule‐based system. The major aim of the KBS of IJETSS is to generate rapid and precise engine fault diagnosis that can simulate the work of experienced aircraft maintenance mechanics and engineers. The developed system can also be useful for the inexperienced aircraft mechanics and engineers and can be used for training module for them.

Reviewing the Literature of Inventory Models under Trade Credit Contact

In the classical inventory models, it was assumed that the buyer pays for the purchased items as they are received from the seller. In practice, however, the seller allows the buyer to settle the account with a delay period. Such a contract has attracted the attention of many researchers and practitioners in recent years. Thus, this paper addresses the researches with delay in payment and presents pertinent information about developments and extensions of such models to provide an up-to-date review of the studies conducted since 1973 and assist in developing the future researches.