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Article
Publication date: 18 October 2011

Jungguk Kim, Agus Budiyono, Dong‐Min Kim, Ho‐Geun Song and Doo‐Hyun Kim

The purpose of this paper is to introduce a new danger‐aware Operational Flight Program (OFP) for the unmanned helicopter's auto‐navigation based on the well‐known time‐triggered…

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Abstract

Purpose

The purpose of this paper is to introduce a new danger‐aware Operational Flight Program (OFP) for the unmanned helicopter's auto‐navigation based on the well‐known time‐triggered message‐triggered object (TMO) model.

Design/methodology/approach

In this design with the TMO, the danger‐awareness means two things. First, an unmanned helicopter maneuvers on safe altitudes to avoid buildings or mountains when navigating to the target position. It is assumed that minimum safe altitudes are given on evenly spaced grids and on the center points of every four adjacent grids. A three‐dimensional (3D) path‐finding algorithm using this safe‐altitude information is proposed. Second, a helicopter automatically avoids a zone with very high temperature caused by a fire.

Findings

Since the auto‐flight control system requires componentized real‐time processing of sensors and controllers, the TMO model that has periodic and sporadic threads as members, has been used in designing the OFP. It has been found that using the TMO scheme is a way to construct a very flexible, well‐componentized and timeliness‐guaranteed OFP.

Practical implications

As the RTOS, RT‐eCos has been used. It was developed a few years ago based on the eCos3.0 to support the real‐time thread model of the TMO scheme. To verify this navigation system, a hardware‐in‐the‐loop simulation (HILS) system also has been developed.

Originality/value

Designing an OFP by using the real‐time object model TMO and the proposed 3D safe path finding algorithm is a whole new effective deadline‐based approach. And the developed OFP can be used intensively in the phase of disaster response and recovery.

Details

Aircraft Engineering and Aerospace Technology, vol. 83 no. 6
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 18 October 2011

Nodir Kodirov, Doo‐Hyun Kim, Junyeong Kim, Seunghwa Song and Changjoo Moon

The purpose of this paper is to make performance improvements and timely critical execution enhancements for operational flight program (OFP). The OFP is core software of…

432

Abstract

Purpose

The purpose of this paper is to make performance improvements and timely critical execution enhancements for operational flight program (OFP). The OFP is core software of autonomous control system of small unmanned helicopter.

Design/methodology/approach

In order to meet the time constraints and enhance control application performance, two major improvements were done at real‐time operating system (RTOS) kernel. They are thread scheduling algorithm and lock‐free thread message communication mechanism. Both of them have a direct relationship with system efficiency and indirect relationship with helicopter control application execution stability through improved deadline keeping characteristics.

Findings

In this paper, the suitability of earliest deadline first (EDF) scheduling algorithm and non‐blocking buffer (NBB) mechanism are illustrated with experimental and practical applications. Results of this work show that EDF contributes around 15 per cent finer‐timely execution and NBB enhances kernel's responsiveness around 35 per cent with respect to the number of thread context switch and CPU utilization. These apply for OFP implemented over embedded configurable operating system (eCos) RTOS on x86 architecture‐based board.

Practical implications

This paper illustrates an applicability of deadline‐based real‐time scheduling algorithm and lock‐free kernel communication mechanism for performance enhancement and timely critical execution of autonomous unmanned aerial vehicle control system.

Originality/value

This paper illustrates a novel approach to extend RTOS kernel modules based on unmanned aerial vehicle control application execution scenario. Lock‐free thread communication mechanism is implemented, and tested for applicability at RTOS. Relationship between UAV physical and computation modules are clearly illustrated via an appropriate unified modelling language (UML) collaboration and state diagrams. As experimental tests are conducted not only for a particular application, but also for various producer/consumer scenarios, these adequately demonstrate the applicability of extended kernel modules for general use.

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Article
Publication date: 31 December 2004

Inkyo Cheong

The government of Korea considers the promotion of Free Trade Agreements (FTA) as necessary to develop its economy into an open trading nation. As for the countries with which the…

280

Abstract

The government of Korea considers the promotion of Free Trade Agreements (FTA) as necessary to develop its economy into an open trading nation. As for the countries with which the Korean government is actively investigating possible FTAs, there are Japan, Singapore, the Association of South East Asian Nations (ASEAN,) and Mexico. For the time-being, the FTA with Japan seems to be a critical one in practicing Korea s FTA policy. Recently, Korean industries show negative positions against a Korea-Japan FTA, with strong opposition from the labor union insisting that it is evident that Korea will sustain damages in the short-run and the dynamic (long-term) benefits are still ambiguous and uncertain. Regardless of whether their argument is correct or not, it will be difficult for Korea to conclude the FTA with Japan unless there is concrete confidence of balanced economic gains through the FTA between the two countries.

Details

Journal of International Logistics and Trade, vol. 2 no. 2
Type: Research Article
ISSN: 1738-2122

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