Design of agile two-wheeled robot with machine vision

Mobile two-wheeled self-balancing robots have been built and widely investigated since 2002 by many parties for research, leisure and commercial purposes. This paper details the design and construction of a small autonomous two-wheeled robotic platform. The robot is agile, able to navigate itself in unstructured environment with the aid of multiple on-board sensors, able to overcome small obstacles and has short and long range wireless communication capabilities. One of the highlights is the on-board single camera machine vision module, which help the robot to identify obstacles. It is hoped that this disclosure will assist other researchers working on similar projects to improve their design of such machines

Modeling Of Electromagnetic Wave Propagation In Printed Circuit Board And Related Structures

The objective of this thesis is to develop a systematic framework for modeling electromagnetic wave propagation in a printed circuit board (PCB) assembly and related structures. The PCB assembly contains discrete components (both active and passive), integrated circuits, copper traces, sockets and connectors. Related structures imply this framework can be generalized to environments such as Monolithic Microwave Integrated Circuit (MMIC) and the semiconductor itself. The proposed method-of-choice for approximating a solution to the Maxwell's equations for this environment is the Finite-Difference Time-Domain (FDTD) approach, which was originally proposed by K.S.Yee in 1966 (Yee 1996). The method approximates the differentiation operators of the Maxwell equations with finite difference operators in time and space. This method is suitable for finding the approximate electric and magnetic field in a complex three-dimensional structure in the time domain. This thesis puts forward a collection of algorithms, mathematical tools and a computer program for approximating the Maxwell's equations with a finite-difference counterpart under various conditions encountered in a typical PCB assembly. The author consolidates the results obtained by previous researchers in this area, puts forward a few improvements and also derives new stability theorems suitable for a general PCB model. The stability theorems are intended to check whether the numerical algorithm is "well-behaved" or not. This is important for the FDTD approach, which like many iterative numerical methods, are susceptible to a condition where the solution gradually increases without limit as simulation progresses. The computer program developed in this thesis can be used to simulate various microwave circuits before actual prototyping , thus cutting down the cost and saving valuable time. This project is self-encompassing, it provides the theoretical basis for the method, the details of the implementation on a digital computer and finally the software itsel

On-chip slew-rate control for low-voltage differential signalling (LVDS) driver

A low-voltage differential signaling (LVDS) driver with 3-bit programmable slew-rate control has been designed and fabricated in 0.13um complementary metal oxide semiconductor (CMOS) process. On-chip programmable capacitors allow cost saving compared to external capacitors and fine tuning to driver output slew-rate. This enables system designers with the flexibility to optimize driver slew-rate for wider range of applications. Slew-rate adjustment procedures are simple and yield accurate measurement results which meet the TIA/EIA-644-A standard

A study on the stability of bipolar-junction-transistor formulation in finite-difference time-domain framework

Recently, a new stability result has been put forward for three-dimensional finite-difference time-domain (FDTD) framework by deriving a discrete energy relation similar to the Poynting Theorem in electromagnetism. In this paper, the result is used to show how stability analysis of an FDTD model containing three-terminal nonlinear components can be performed. Here the bipolar junction transistor (BJT) is used to illustrate the idea. It is shown that instability can be due to the BJT contributing numerical energy to the system during simulation, thus causing the E- and H-field components to blow up. This paper also shows how we can prevent instability by identifying the operating region of the device where it is contributing numerical energy. By preventing the device from contributing numerical energy to the system, dynamical stability can be maintained. Formulation, which can source and sink numerical energy, is called conditionally proper. The BJT formulation in FDTD is such an example

A finite-difference time-domain FDTD) software for simulation of printed circuit board (PCB) assembly

This paper describes the design of a three-dimensional (3D) finite-difference time-domain (FDTD) simulation software for printed circuit board (PCB) modeling. The flow, the dynamics and important algorithms of the FDTD simulation engine will be shown. The software is developed using object-oriented programming (OOP) approach, to enable code reuse and ease of upgrade in future. The paper begins by looking at how a 3D PCB structure is created using cubes, and proceed to show the inclusion of various lumped components such as resistors, capacitor, inductor and active semiconductor components into the model. The architecture of the FDTD simulation program is then carefully explained. Finally a few sample simulation examples using the software will be illustrated at the end of the paper

A dual-receiving visible-light communication system for intelligent transportation system

Wireless communication has been identified as the key enabling technology in Intelligent Transportation System (ITS). Visible-light communication (VLC) presents an alternative to other existing wireless technologies to enable infrastructure-to- vehicle communication in ITS. In this paper, we identify the major limitations in implementing VLC on outdoor environment. Next, we introduce a new and innovative receiver design with dual reception and effective ambient-light rejection capabilities. Simulation results show that our newly proposed receiver is able to achieve greater communication range and receivable information with an average improvement of 20 m and 10 Mbits during daytime, respectively