检索结果-内蒙古大学图书馆

作者： Sarani, Siamak Jet Propulsion Laboratory California Institute of Technology Pasadena CA 91109-8099 Mail Stop 230-104D Avionic Systems Engineering Section 4800 Oak Grove Drive

Upon arrival at Saturn, Cassini will execute numerous low-altitude flybys of Titan and a few targeted icy satellite flybys. At the closest approach altitudes, the spacecraft must use its thrusters in order to overcome the external torques, maintain attitude control, and perform the required science slews. Because of the uncertainties associated with Titan atmospheric density model, as well as other uncertainties, the adequacy of thruster control authority at the closest approach must carefully be assessed to ensure that Cassini will not tumble out of control. The results indicate that even with conservative assumptions, there still exists adequate control authority margin.

关键词： Astrophysics

来源：评论

学校读者我要写书评

暂无评论

Surveyor spacecraft automatic landing system

Surveyor spacecraft automatic landing system

引用

27th Annual AAS Rocky Mountain Guidance and Control Conference

作者： Thurman, Sam W. Avionic Systems Engineering Section M/S 156-142 NASA/Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena CA 91109-8099

The Surveyor Project accomplished five successful lunar landings between 1966 and 1968, following an intensive five-year development effort. One of the many significant accomplishments made by Surveyor was the development and validation of the first-ever automated soft-landing system. This paper provides a historical overview of Surveyor, with emphasis on the guidance and control aspects of the spacecraft's terminal descent system. Driving requirements and other important design considerations are described, along with the configuration and operational sequence of the actual flight system.

关键词： Spacecraft landing

来源：评论

学校读者我要写书评

暂无评论

On-board autonomous attitude maneuver planning for planetary spacecraft using genetic algorithms

On-board autonomous attitude maneuver planning for planetary...

引用

AIAA Guidance, Navigation, and Control Conference and Exhibit 2003

作者： Kornfeld, Richard P. Avionic Systems Engineering Section Jet Propulsion Laboratory California Institute of Technology Pasadena CA 91109 United States

ISBN: (纸本)9781624100901

A key enabling technology that leads to greater spacecraft autonomy is the capability to autonomously and optimally slew the spacecraft from and to different attitudes while operating under a number of celestial and dynamic constraints. The task of finding an attitude trajectory that meets all the constraints is a formidable one, in particular for orbiting or fly-by spacecraft where the constraints and initial and final conditions are of time-varying nature. This paper presents an approach for attitude path planning that makes full use of a priori constraint knowledge and is computationally tractable enough to be executed on-board a spacecraft. The approach is based on incorporating the constraints into a cost function and using a Genetic Algorithm to iteratively search for and optimize the solution. This results in a directed random search that explores a large part of the solution space while maintaining the knowledge of good solutions from iteration to iteration. A solution obtained this way may be used 'as is' or as an initial solution to initialize additional deterministic optimization algorithms. Two case examples are presented involving a generic Europa Orbiter spacecraft in cruise as well as in orbit around Europa. The search times are typically on the order of minutes, thus demonstrating the viability of the presented approach. The results are applicable to all future deep space missions where greater spacecraft autonomy is required. In addition, onboard autonomous attitude planning greatly facilitates navigation and science observation planning, benefiting thus all missions to planet Earth as well. © 2003 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Genetic algorithms

来源：评论

学校读者我要写书评

暂无评论

A randomized attitude slew planning algorithm for autonomous spacecraft

A randomized attitude slew planning algorithm for autonomous...

引用

AIAA Guidance, Navigation, and Control Conference and Exhibit 2001

作者： Frazzoli, E. Dahleh, M.A. Feron, E. Kornfeld, R.P. Laboratory for Information and Decision Systems Massachusetts Institute of Technology Cambridge MA United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA United States Department of Aeronautics and Astronautics Massachusetts Institute of Technology Cambridge MA United States Avionic Systems Engineering Section Jet Propulsion Laboratory Pasadena CA United States

ISBN: (纸本)9781563479786

The ability to autonomously generate and execute large angle attitude maneuvers, while operating under a number of celestial and dynamical constraints, is a key factor in the development of several future space platforms. In this paper we propose a randomized attitude slew planning algorithm for autonomous spacecraft, which is able to address a variety of pointing constraints, including bright object avoidance and ground link maintenance, as well as constraints on the control inputs and spacecraft states, and integral constraints such as those deriving from thermal control requirements. Moreover, through the scheduling of feedback control policies, the algorithm provides a consistent decoupling between low-level control and attitude motion planning, and is robust with respect to uncertainties in the spacecraft dynamics and environmental disturbances. Simulation examples are presented and discussed. © 2001 by the American Institute of Aeronautics and Astronautics. Inc. All rights reserved.

关键词： Space platforms

来源：评论

学校读者我要写书评

暂无评论

Minimalist hardware architecture for using commercial microcontrollers in space

Minimalist hardware architecture for using commercial microc...

引用

Proceedings of the 1997 16th AIAA/IEEE Digital avionics systems, DASC. Part 1 (of 2)

作者： Caldwell, D.W. Rennels, D.A. Avionic Systems Engineering Section Pasadena United States

Microcontrollers provide very dense functionality for embedded applications ranging from telephones to automobiles. The acceptance of these devices for space applications has been hindered by their manufacture which often uses multiple semiconductor fabrication techniques and thereby compromises radiation tolerance. If such concerns could be mitigated, microcontrollers would provide a substantial increase in performance for builders of spacecraft electronics. This paper presents hardware considerations for using commercial microcontrollers in space applications. The motivations for starting with commercial devices and the concerns associated with their use are presented. The advantages of software versus hardware voting schemes to mitigate single-event effects are discussed. Interprocess communications approaches and schemes for improving I/O robustness are presented.

关键词： Control equipment

来源：评论

学校读者我要写书评

暂无评论

A distributed spacecraft thermal control architecture using the Dallas Semiconductor MicroLan products

A distributed spacecraft thermal control architecture using ...

引用

Conference on Digital avionics systems (DASC)

作者： D.W. Caldwell Avionic Systems Engineering Section Pasadena CA USA

Distributing the functionality associated with low-level sensing and actuation, particularly for highly granular functions like thermal control, has been difficult because of the overhead associated with local signal processing and communications functions. The MicroLAN/sup TM/ serial data protocol and architecture implemented by the Dallas Semiconductor DS1820 Digital Thermometer and DS2407 Dual Addressable Switch provide an interesting approach implementing this functionality on spacecraft. Very low-power devices provide simple sophisticated serial bus interfaces which allow significant reductions in configuration management and cable mass. A detailed application architecture for temperature sensing and control is presented. Radiation effects test data, limitations and mitigation techniques are discussed. An application which demonstrates the virtues of one device, the DS1820, on the New Millennium Program's Deep Space One mission is described.

关键词： Space vehicles Distributed control Communication system control Switches Signal processing Protocols Communication switching Temperature sensors Temperature control Radiation effects

来源：评论

学校读者我要写书评

暂无评论

A minimalist hardware architecture for using commercial microcontrollers in space

A minimalist hardware architecture for using commercial micr...

引用

Conference on Digital avionics systems (DASC)

作者： D.W. Caldwell D.A. Rennels Jet Propulsion Laboratory Avionic Systems Engineering Section Pasadena CA USA Los. Angeles School of Engineering and Applied Science Department of Computer Science Jet Propulsion Laboratory Avionic Equipment Section University of California Los Angeles CA USA

Microcontrollers provide very dense functionality for embedded applications ranging from telephones to automobiles. The acceptance of these devices for space applications has been hindered by their manufacture which often uses multiple semiconductor fabrication techniques and thereby compromises radiation tolerance. If such concerns could be mitigated, microcontrollers would provide substantial increase in performance for builders of spacecraft electronics. This paper presents hardware considerations for using commercial microcontrollers in space applications. The motivations for starting with commercial devices associated with their use are advantages of software versus hardware voting schemes to mitigate single-event effects are discussed. Interprocess communications approaches and schemes for improving I/O robustness are presented.

关键词： Hardware Microcontrollers Telephony Automobile manufacture Semiconductor device manufacture Fabrication Aircraft manufacture Aerospace electronics Application software Voting

来源：评论

学校读者我要写书评

暂无评论

Practical applications of concurrent engineering for systems integration

Practical applications of concurrent engineering for systems...

引用

IEEE National Conference on Aerospace and Electronics (NAECON)

作者： D.H. Rhodes C.A. Smith IBM Federal Sector Division Avionic Systems Engineering Section Owego NY USA

The authors focus on how a task force at IBM Federal Sector Division at Owego, NY addressed the practice of concurrent engineering (CE), and the approach taken to strengthen concurrent engineering in the systems integration business. A quality improvement team (QIT) decided to produce a practically oriented CE plan. Two important objectives were established for the plan. First, it must define practical implementations of CE in the form of a checklist with each implementation tied to one or more resultant benefit. Secondly, it must allow the project using the plan to determine, via a set of measurements, if CE was successfully applied. The practical applications derived by the Owego QIT task force represent one attempt of applying a set of generic, practical CE criteria that is virtually program independent. The plan has been developed so that it can be tailored for a particular program if required. The key to implementation is an emphasis on the working relationships among people.< >

关键词： Concurrent engineering systems engineering and theory Costs Design engineering Software testing Product design Proposals Software performance Aerospace electronics Business

来源：评论

学校读者我要写书评

暂无评论

MEASURES OF EFFECTIVENESS AS APPLIED TO MAINTENANCE PRACTICES

引用

NAVAL ENGINEERS JOURNAL 1992年第4期104卷 101-102页

作者： JACOBS, KS ELFONT, M PROCACCINO, V Mark Elfont Ph.D:. is head of the Engineering Analysis Staff at the Naval Ship Systems Engineering Station (NAVSSES). At NAVSSES Dr. Elfont developed the Ships Machinery Analysis and Reporting Technique (SMART) System that utilizes direct access to the Ships 3-M database to calculate the fleet performance of HM&E systems. The SMART process is an automated approach to performance trending and offers the in-service engineers and life cycle managers cost effective information on the performance of equipments and systems in the actual fleet environment. Prior to coming to NAVSSES Dr. Elfont was at the Naval Air Development Center (NADC) for 18 years with most of his service as program manager for various avionic weapon system developments. Dr. Elfont also spent three years as the business manager of a private telecommunication firm. Vincent Procaccino:is the measures of effectiveness coordinator within the Performance and Business Indicators Section of the Equipment Assessment and Alteration Department Naval Ship System Engineering Station (NAVSSES). Mr. Procaccino is responsible for developing processes and techniques for determining the effectiveness of condition assessment efforts primarily the Assessment of Equipment Condition (AEC) program. NAVSSES is the Navy's in service engineering agent for HM&E equipment and is currently pursuing several programs which are in the process of evaluating condition assessment of HM&E systems. The efforts include continuous on-line monitors and expert system applications. Prior to arriving at NAVSSES in December 1988 Mr. Procaccino received a bachelor of science degree in mechanical engineering from Penn State University in August of 1987. He then worked as a project engineer for a small manufacturing firm until his arrival at NAVSSES.

Recent developments in surface ship maintenance strategies have been advanced on the promise of achieving reduced maintenance costs and improving the availability of shipboard systems. Included in the melange of proposed solutions are the Phased Maintenance Concept, Condition Based Maintenance, Expert System Diagnostics, as well as many other variations of these notions. As programs are initiated to evaluate prototype systems, or in some cases install production units, it is crucial that effective measurement procedures be instituted to determine to what extent the respective program goals and objectives are achieved. This paper explores various data sources that offer potential application to evaluation of advanced maintenance concept effectiveness. Also examined are data analysis and reporting techniques to clearly identify the benefits gained from those activities. The authors feel that it is important that the process of effectiveness evaluation, while remaining an objective process, become a part of the maintenance process itself. Maximum use of existing databases and in-place data collection procedures is advocated.

关键词： Naval Vessels

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：