The Comprehensive Handling of Safety in an Autonomous Robot Capstone Project

A systematic approach to safety issues is described in the context of an autonomous robot capstone project. The treatment of safety should not be an ad hoc or an after-thought aspect of design projects. Engineering students need to consider safety as an integral component of the design process and to identify and address hazards systematically in each stage of project work. Appropriate actions include researching professional standards and regulations, incorporating safety best practices, developing safety checklists and operating protocols, and providing significant safety documentation. Formal safety components were added to a capstone design project for electrical and computer engineering undergraduates in which an R2D2-like robot was designed and built. The work provides project examples, lessons learned, and student feedback related to the safety treatment

Analysis of a PWM Resonant Buck Chopper for Use as a Ship Service Converter Module

The Navy's interest in implementing a DC Zonal Electric Distribution System (DC ZEDS) in the next generation of surface combatant has motivated considerable research work into dc-dc converters. The switching frequency of a hard-switched dc-dc converter is limited by the maximum admissible switching losses allowed by the switch, heat sink, and cooling process. Also, hard- switched converters contribute significant Electromagnetic Interference (EMI) concerns for the system. This study provides a background analysis into resonant converters which utilize zero-voltage-switching and zero-current-switching techniques to mitigate the aforementioned concerns and facilitate high-bandwidth control loops. In particular, one candidate circuit is identified which can be readily realized using existing hardware and a straightforward control. The report documents the modes of operation of the circuit, sets forth the governing differential equation and mode-transition conditions, examines an ACSL simulation representation of the circuit, formulates design criteria for component selection, identifies key fabrication nuances, and documents a PSpice simulation of the circuit. Both simulation models are used to explain the operating modes of the circuit, provide insight into parameter selection, and ultimately to design the proper control of the circuit.Prepared for: Naval Surface Warfare Center (NSWC) Annapolis Det.N00167-98-WR-80279Approved for public release; distribution is unlimited

The Control of Parallel-Connected Inverters for U.S. Navy Shipboard Applications

Concepts such as the Integrated Power System (IPS) and the DC Zonal Electric Distribution System (DC ZEDS) have motivated the study of power inverter control and paralleling strategies by the U.S. Navy. For example, in DC ZEDS a Ship Service Inverter Module (SSIM) converts DC power into AC power for use within a zone. For reasons of redundancy and logistics, multiple paralleled inverter submodules are used to implement the SSIM. The current effort supports ongoing SSIM hardware development by the SatCon Corporation. This report documents the modeling and control analysis of a set of parallel-connected PWM inverters. Although initially focusing on a static three-phase R-L load, the analysis is extended to three-phase symmetrical induction machine loads and three-phase round- rotor permanent-magnet synchronous machine loads. In each case, an algorithm for designing the local inner current control is developed by employing reference frame theory, replacing the paralleled inverters by an equivalent unit, and executing a nonlinear pole-placement strategy. Upon reviewing the equations necessary for AC machine vector control, the report concludes by documenting the analysis and design of a simple speed control loop for this aformentioned machine loads.This report was sponsored by the Naval Surface Warfare Center Carderock Division

PEBB Feedback Control Law Library, Volume 1: Three-Phase Inverter Control Algorithms

The Navy is actively engaged in developing Power Electronic Building Blocks (PEBBs) for its initiatives into DC Zonal Electric Distribution (DC ZEDS) . DC ZEDS is a key element of the Integrated Power System (IPS) effort which seeks to modify the current surface combatant so that both ship service and ship propulsion electrical loads are powered from a common set of prime movers. Presently, the current generation of PEBB-like devices include high-power, fast- switching, high-bandwidth dc-dc converters and dc-ac inverters. This report summarized the algorithms required to control a conventional three-phase inverter. First, implementation issues regarding the Sine-Triangle Pulse-Width- Modulation and Space-Vector Modulation are presented with an emphasis placed on digital realizations. Then, two current control schemes are documented via analysis, design example, and simulation. Next, a complex voltage-control scheme is documented, a design example proffered, and simulation studies conducted to illustrate dynamic response. The report concludes with detailed analyses, designs, and simulations of two three-phase induction machine startup and speed control algorithms.Prepared for: Naval Surface Warfare Center Carderock Divisiodhnapolis DetechmentN0016796WR60488Approved for public release; distribution is unlimited

The analysis and reduced-order modeling of a proposed aerospace electric drive

The aerospace industry has expressed increased interest in replacing hydraulic actuators with electromechanical actuators to capitalize on the savings in weight, efficiency, maintenance, and cost. The proposed drive has these qualities but is difficult to analyze because of the high system order, the large separation in time scales between the electrical and mechanical systems, and the considerable harmonic distortion injected into the link by the load converter. In this work, component and an end-to-end reduced-order models are developed to investigate the salient features of this drive. The end-to-end model eliminates the large separation of time scales which facilitates rapid simulation of mechanical dynamics and mechanical control systems. The model is validated for both operating point and transient conditions. In developing the component models, several potential system improvements were discovered and reported on

Comparison of Binary and Multi-Level Logic Processing for an Optical Encoder

The measurement of rotation is required for many sensor systems. Rotary optical encoders are a rugged option for such measurements and gray code systems help prevent ambiguous values during transitions. A complex interface task is selected to compare binary and multi-level logic implementations in which a five-bit, encoder gray code maps to seven-segment displays. An optimized binary gate implementation is compared to a functional equivalent using a multi-level, memory-based logic approach. CMOS circuit implementations are compared with respect to transistor count, propagation delay, and power usage. The suitability of the multi-level, memory-based approach for low-power, dedicated instrumentation is discussed

4. TITLE AND SUBTITLE Design Of A Ship Service Converter Module For A Reduced-Scale

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"SEA ARCHER" Distributed Aviation Platform

Includes supplementary material.This report outlines the results of a two quarter Total Ship Systems Engineering (TSSE) Capstone design project undertaken by the students at the Naval Postgraduate School. The project was under the direction of Professors C.N. Calvano and R.Harney.Currently, no system exists that provides a sea-based distributed aviation platform capability. The emergence of Unmanned Air Vehicles (UAVs) / Unmanned Combat Air Vehicles (UCAVs), the continued U.S. Navy focus on the littorals, the desire for force distribution, the need for operational cost reductions, and the advent of Network Centric Warfare (NCW) all continue to support the requirement to re-evaluate how littoral operations will be conducted in the future. Given this background, a bottom-up design of a ship supporting a primarily UAV/UCAV air wing in a low to medium threat environment is of significant interest. SEA ARCHER meets this interest. This report outlines a design that meets the future needs for distributed aviation with a high-speed, highly automated platform. Large gains in reduced manning through automated systems for both operation and damage control helpmeet the demanding needs for the future of the Navy at reduced operational costs. The report will outline both the Mission Needs Statement (MNS) and Operational Requirements Document (ORD) for the ship that was developed. The analysis of alternatives that was conducted to determine relative size requirements for the ship in presented in the next section. The concept design that resulted as a result of the Total Ship Systems Engineeing process in then presented. Finally, a detailed look at the analysis and trade studies that were conducted in presented in order to show the more detailed analysis that was conducted in designing the ship.http://archive.org/details/seaarcherdistrib109457277US Navy (USN) authorsHellenic Navy authorTurkish Navy authorsSingapore Defense Science and Technology Agency author (civilian)Approved for public release; distribution is unlimited