Zamberi Jamaludin

An agile FCM for real-time modeling of dynamic and real-life systems

Fuzzy cognitive map (FCM) is a well-established model of control and decision making based on neural network and fuzzy logic methodologies. It also serves as a powerful systematic way for analyzing real-life problems where tens of known, partially known, and even unknown factors contribute to complexity of a system. FCM-based inference requires a neural activation function much like other neural network systems. In modeling, in addition to an activation function, FCM involves with weight training to learn about relationships as they exist among contributing factors. Therefore, numerous contributing factors could be analyzed to understand the behaviors of factors within a real-life system and to represent it in form of tangible matrices of weights. This article discusses a new incremental FCM activation function, named cumulative activation, and introduces a new weight training technique using simulated annealing (SA) known as agile FCM. Smooth variation of FCM nodes that is due to cumulative nature of inference results into faster convergence, while a unique minimum cost solution is guaranteed using the SA training module that is entirely expert-independent. A combination of these two techniques suits time-related applications where inclusion of temporal features is necessary. The resulted system is examined through numerical example datasets where the candidate FCM shows sensitivity to dynamic variables over time. A real-life example case is included as well to further support the effectiveness of the developed FCM in modeling of natural and complex systems.

Extensive Tracking Performance Analysis of Classical Feedback Control for XY Stage Ballscrew Drive System

Performance analysis in term of identifying the systems transient response, stability and systems dynamical behavior in control system design is undeniably a must process. There are several ways in which a system can be analyzed. An example of well known techniques are using time domain and frequency domain approach. This paper is focused on the fundamental aspect of analysis of classical feedback controller in frequency domain of XY milling table ballscrew drive system. The controller used for the system is the basic PID controller using Matlab SISOTOOL graphical user interface. For this case, the frequency response function (FRF) of the system is used instead of using estimated model of transfer function to represent the real system. Result in simulation shows that after proper tuning of the controller, the system has been successfully being controlled accordingly. In addition, the result also fulfill the set requirement of frequency domain analysis in terms of the required gain and phase margin, the required maximum peak sensitivity and complimentary sensitivity function and the required stability.

Theoretical Analysis of Friction Compensation Using Sliding Mode Control

Friction is an undesired nonlinear phenomenon that reduces position and tracking accuracy in machine tools application. This paper focuses on development of control technique to compensate friction force at motion reversal of a drive system that generates quadrant glitch phenomenon thus improving tracking accuracy. Sliding Mode Control (SMC) is designed to compensate friction. The Generalized Maxwell-Slip (GMS) friction model is applied for numerical analysis. The performance of the controller is analysed based on the reduction in the quadrant glitches magnitude. The performance of the SMC controller is compared with the classical PID controller. Results show that SMC controller yields the smallest quadrant glitch magnitudes.

Design and Analysis of Linear Quadratic Regulator for a Non-Linear Positioning System

The control of rotary inverted pendulum is a case of classical robust controller design of non-linear system applications. In the control system design, a precise system model is a pre-requisite for an enhanced and optimum control performance. This paper describes the dynamic system model of an inverted pendulum system. The mathematical model was derived, linearized at the upright equilibrium points and validated using non-linear least square frequency domain identification approach based on measured frequency response function of the physical system. Besides that, a linear quadratic regulator (LQR) controller was designed as the balancing controller for the pendulum. An extensive analysis was performed on the effect of the weighting parameter Q on the static time of arm, balance time of pendulum, oscillation, as well as, response of arm and pendulum, in order to determine the optimum state-feedback control vector, K. Furthermore, the optimum control vector was successfully applied and validated on the physical system to stabilize the pendulum in its upright position. In the experimental validation, the LQR controller was able to keep the pendulum in its upright position even in the presence of external disturbance forces.

Methodology On Investigating The Influences Of Automated Material Handling System In Automotive Assembly Process

A case study was selected as a method to collect data in actual industry situation. The study aimed to assess the influences of automated material handling system in automotive industry by proposing a new design of integration system through simulation, and analyze the significant effect and influence of the system. The method approach tool will be CAD Software (Delmia & Quest). The process of preliminary data gathering in phase 1 will collect all data related from actual industry situation. It is expected to produce a guideline and limitation in designing a new integration system later. In phase 2, an idea or concept of design will be done by using 10 principles of design consideration for manufacturing. A full factorial design will be used as design of experiment in order to analyze the performance measured of the integration system with the current system in case study. From the result of the experiment, an ANOVA analysis will be done to study the performance measured. Thus, it is expected that influences can be seen from the improvement made in the system.

Development of System Identification for Piezoelectric Patch Actuator

This paper presents the development of the system identification (SI) for the highly nonlinear piezoelectric patch actuator. The transfer function is determined by using the nonlinear least square (NLS) method after the direct measurements of input-output data are taken from the actuator that is installed on a well-equipped platform. The results were validated to ensure that the transfer function derived fits well with the experimental output.

Improvement of Corrosion Detection Using Vision System for Pipeline Inspection

Nowadays, the utilization of cameras as an inspection tool has been increasing. The flexibility functions of camera fits to get different kind of information. This research is focusing on developing a robust visual inspection system for corrosion detection that is able to detect corrosion in any environment, and the corrosion detection will be using visual data as primary tools. A review on current pipeline inspection would give a brief detail on the improvement of the proposed inspection system. Furthermore, the inadequacies of the proposed visual corrosion detection are identified and discussed from the reviewing process on existing researches and analysis on preliminary data obtained. It is expected that the output of the proposed system will be a new method of corrosion detection and pioneer for the inspection system on robust environment.

Theoretical Analysis of Velocity and Position Loop Behaviour of Nonlinear Cascade Feedforward Controller for Positioning of XY Table Ballscrew Drive System

The trend in machine tools and positioning systems nowadays are demanding for accuracy, precision and robustness attributes. In addition to those characteristics, a low-cost and adaptive control systems towards various disturbance forces also add a significant advantage to control engineers who can fulfill those needs. The objective of this paper is to introduce a newly improved control strategy named as Nonlinear Cascade Feedforward. It is basically, a cascade control structure with the additional of two add on modules called Nonlinear function plus independent feedforward function. Secondly, the aim of this article is to focus on the fundamental aspect on how to analyze the open loop and closed loop behavior for both velocity and position loop in the control structure by extracting the mathematical formulation of the controller. The outcome from this paper which is in the form of mathematical formula is beneficial and exceptionally significant during the validation and verification stage. The theoretical analysis involved are analysis on gain and phase margin, bandwidth frequency, sensitivity function, position error and finally analysis on dynamic stiffness of the system which is in this case the XY Table Ballscrew drive system. The strength of this controller is the self-adjusting mechanism towards variable disturbance cutting forces. Based on mathematical formulation, it is observed that the designed nonlinear cascade feedforward offer more flexibility and robustness in terms of the ability to compensate the tracking errors at variable disturbances.

Design and Implementation of Cascade NP/PI Controller for Feed Table Ball Screw Driven Milling Machine

This paper presents improvements on conventional cascade P/PI position control structure with implementation of nonlinear function onto the existing control structure resulting in cascade NP/PI controller. The controller design process involved three main steps, namely; (i) design of PI controller for the speed loop, (ii) design of P controller for the position loop, and (iii) design of the nonlinear function. The speed and position controllers were designed based on gain margin and phase margin considerations. There were three main elements involved in the design of the nonlinear function, namely; rate of variation of nonlinear gain (KO), maximum value of error, (emax) and sampling frequency, (δ). Results obtained from implementation on the x-axis of a milling machine feed table shows that the proposed cascade NP/PI controller generated an improvement of 1.3% in tracking performance in term of RMS error values compared to the classical cascade P/PI controller.

Investigating the Influences of Automated Material Handling System (AMHS) and Effect of Layout Changing in Automotive Assembly Process

The material handling equipment adds utilization to the performance level of the manufacturing process. Thus, by investigating the influences of AMHS and at the same time seeing the effect of changing its layout in automotive assembly process help the research in improvising the system easier and guaranteed to be success. A case study focus at the material flow of warehouse to assembly shop is done and the result show the work is done manually and has a lot of time are wasted. From the case study, an approach tool are used to simulate the system by using Delmia Quest simulation software. 4 models are simulated which consist of AGV and tugger train as transportation system, 2 layouts which are the current used layout in case study and new layout, and the supply order system which are picking list and pick-to-light system. The result shows the number of part deliveries highly increase by the changed of layout in the system in model 4. The deliveries able to achieve 3 times value from the current old system in the factory. As the system improves with the change of supply order system and layout in model 3 and 4, the idle time reduce to below 0.5 h and maintain linearly in the system. Lastly, it can be summarized that the improvement shows the influences of automated material handling system and facility layout in increasing the performance of the automotive assembly factory.