Ahmad Yusairi Bani Hashim

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.

Design of super twisting sliding mode control for single axis direct drive motor

Chattering effect is often associated negatively with the application of the robust nonlinear sliding mode control. This paper compares the tracking responses of system controlled with different controllers and demonstrates the ability of super twisting sliding mode control in chattering suppression and enhancement of tracking performance against classical controller and traditional sliding mode control. The controller was numerically analyzed and experimentally validated on a direct drive single axis positioning system which is described as a second order single-input-single-output system. Three controllers, namely; PID, pseudo sliding mode control and super twisting sliding mode control were designed, analyzed and compared. A Kalman-Bucy filter was designed for velocity estimation to reduce noises from numerical differentiation of position measurement. Results showed the superiority of super twisting sliding mode controller in smoothing the control input and suppressing the chattering effect compared to pseudo sliding mode control. Additional investigation was performed by replacing the signum function using a hyperbolic tangent function. However, only slight improvement in tracking performance was recorded. The results displayed the novelty of super twisting algorithm in chattering suppression making it an attractive option for real-time application.

Digraph Representations of Machine Vision Workspace for Monitoring Worker’s Behavior

If motions are repeated normally for every few seconds, and for prolonged periods about an 8-h shift, fatigue and muscle strain may occur. Suppose that we have a worker who is operating a machine. We need to monitor the worker’s behavior through real-time video streaming. Our challenge is to approximate the locations to place the tripods. We propose workspace geometry and workspace configuration so that, there is a proper methodology for designating the operator’s initial position, the machine position as the origin of the workspace. We deduce that, for a typical local manufacturing setting, there is a generalized workspace configuration usable for a wide-ranging machine operators’ height measurement. Implementing the proposed procedures, the camera placement is therefore defined by digraphs.

Fatigue on Upper Quadrant Human Body: The Psychophysical Experience among Drivers

Upper body discomfort has become one of the issues to drivers nowadays. In this modern era, majority of Malaysian workers drive to work daily. This paper aims to find the most uncomfortable upper body part, as well as the effect of time, body mass index (BMI) and length of arm towards upper body discomfort for drivers. Sixteen volunteers were requested to complete the questionnaire soon after they completed driving the car simulator for three duration of times (30 minutes, 60 minutes and 90 minutes). Time is proven to be the main factor affecting the upper body comfort level, with the upper arm and lower arm being the most affected part during driving, [F(2,237) =14.37, p<0.01] compared to BMI and length of arm. It can be concluded that the upper body discomfort can be caused by driving for a long time. Nevertheless, the BMI and length of arm is not the issue for upper body discomfort.

Comparison on Techniques for Multiple Video Streaming via Webcam for Manufacturing Engineering Purpose

Multiple video streaming can be used for many functions and there are two techniques that can be used for streaming. The first is the use of the on-the shelf software which is ready-made and can be downloaded. The second technique is a self-programming technique using open source software. In this paper, both techniques were compared to investigate their capabilities in the manufacturing process. Some experiments were conducted to verify the affordability of the techniques. The focus of comparison for both techniques is to detect the image of real-time motion and generate report of the motion. In this research, the capabilities and differences between the two techniques are also identified.

Synthesis of Four Bar Slider Mechanism for Finitely Three Separated Positions

Movement of the heliostat tracking sun is able to achieve through simple four bar mechanism. Design methods for four bar linkage encompass a mathematical approach, trial and error method, function generation, motion synthesis and path synthesis. The paper presents a study of motion synthesis of four bar slider mechanism applies to heliostat movement. Mathematical equations used for the synthesis are presented and the results are compared with the graphical method. Procedure of various methods to determine the length and position of the links in case of desired positions of the coupler are presented. As a conclusion, both methods are able to achieve wanted results with an acceptable degree of accuracy. However, the graphical method is helpful to provide better insight of the system during designing the solution compared to the mathematical method.

Analysis of unimorph piezoceramic patches on damped square shaped plate

Active damping using piezoelectric element is one of the effective techniques to counter vibration problems. A 3D finite-element model is developed as part of investigation for damping control. The piezoelectric patches are surface bonded on quadrilateral thin plate and supported with spring damper elements. The main goal of this paper is to investigate mechanical characteristics of piezoceramic array on membrane and the effect of force excitation using small motor and electric excitation on the system. The system setup produced small vibration displacement and does not displace the plate beyond elastic strain region. The results show the linear behavior of piezoceramic and the correlation between electric excitation, motor vibration and displacement at the centre of the plate at different frequency range. The mode shapes and natural frequencies at low frequency spectrum are also presented. Therefore, the results can be used as reference to develop damping system with aid of piezoelectric patches.

Development of lumped-input access system

Passwords, smart cards, and biometrics that act as inputs are common approaches in security systems design. The operational and functional methodologies of these systems are, however, distinct from one another. There is increasing number of specialists in the field due to widespread use of passwords, smart cards, and biometrics authentication systems. Therefore, the technologies are becoming open secrets. As a result, security systems that apply these technologies are vulnerable to intrusions unless unorthodox methods are fused together to make the systems least exposed. Typical systems design approaches involve estimations on how well they should perform. It is uncommon to model them in an abstract way. Modeling by abstraction, if properly performed can create powerful algorithms that can be difficult to decode. This paper presents abstract formulation style to system design. It shows the formulations of a lumped password-biometrics input; explains how definitions to every components are made, the flow of information, and the execution style.