Chun-Hyon Chang

HELISCOPE Project: Research Goal and Survey on Related Technologies

In this paper, we introduce the target scenario of our HELISCOPE project with the emphasis on the four modes for flying-camera task. We also explain the control points that are considered as the interfaces where the on-flight embedded software and mechanical implementation of the unmanned helicopter are contacted for the autopilot necessarily used in performing such as various modes of flying-camera tasks. Being related to real-time issues, we are developing a real-time S/W platform based on TMO (time-triggered and message-triggered object) scheme. We, in this paper, explain the clues in becoming to use the TMO mode with the survey of other on-flight real-time S/W platform researches.

Experimental Feasibility Analysis of ROI-Based Hough Transform for Real-Time Line Tracking in Auto-Landing of UAV

Autonomous landing for fixed-wing aircraft is one of issues in smart Unmanned Aerial Vehicles (UAV). In this paper, we present a robust real-time line tracking algorithm for UAV using image processing. In the proposed algorithm, we first reduce computation region, and then transform to Hough space to detect lines in frame. Finally, the line tracking is performed. Experimental model has been designed in MATLAB Simulink environment and evaluated with several landing video clips. We took tolerance boundary test to check robustness. Experimental results indicate this approach is applicable in real uses.

Design and Implementation of an Operational Flight Program for an Unmanned Helicopter FCC Based on the TMO Scheme

HELISCOPE is the name of a project support by MKE (Ministry of Knowledge & Economy) of Korea to develop flying-camera services that transmits the scene of a fire by an unmanned helicopter. In this paper, we introduce the design and implementation of the OFP (Operational Flight Program) for the unmanned helicopters navigation based on the well-known TMO scheme. Navigation of the unmanned helicopter is done by the commands on flight mode from our GCS (Ground Control System). As the RTOS on the FCC (Flight Control Computer), RT-eCos3.0 that has been developed based on the eCos3.0 to support the basic task model of the TMO scheme is being used. To verify this navigation system, a HILS (Hardware-in-the-loop Simulation) system using the FlightGear simulator also has been developed. The structure and functions of the RT-eCos3.0 and the HILS is also introduced briefly.

An Efficient Task Serializer for Hard Real-Time TMO Systems

Timeliness-guaranteed computing considering the worst case can hardly be accomplished at run time because of the uncertainty caused by resource sharing, asynchronous events and conflicting timing constraints between tasks. An easier way to reach it is to do some off-line analysis from design time with predictable characteristics of tasks. The TMO model supporting time-triggered (SpM) and message-triggered (SvM) member-threads is a well-known real-time object-oriented task model that aims the design-time guaranteed computing. In this paper, a new efficient task serializer that allocates the executions of time-triggered periodic tasks of multiple TMOs without delay and preemption to avoid resource conflicts is presented. The serializer tries to find scheduling scenarios in that each SpM is executed at its exact trigger-time without delay based on the given WCET. This is done by recasting the initial offsets of SpMs to avoid overlaps of executions. And several methods to handle SvMs according to the types of SvMs using the serializer are also proposed.

Experimental Reliability Analysis of Multi-UAV Simulation with TMO-Based Distributed Architecture and Global Time Synchronization

In developing multi-UAV (Unmanned Aerial Vehicle) system, a simulation environment is essential to verify the functionalities of the whole system with higher productivity and reduced risks of accidents. Simulations of multi-UAV systems are usually accomplished by using distributed systems where multiple standalone simulators are connected via a network. Thus, in order to achieve an improved reality in such distributed simulation environments, the whole multi-UAV simulator should be guaranteed real-time and synchronized behaviors among the connected systems. In this paper, we discuss about the necessity of two important real-time features, i.e., the periodicity of computations and the clock synchronization among standalone simulators. We also propose an architecture based on TMO(Time-triggered and Message-triggered Object) model as a multi-UAV simulation platform with our preliminary experimental results showing its potential feasibilities.

Design and experimental validation of UAV control system software based on the TMO structuring scheme

The technologies for designing and validating computer-control systems subject to challenging timing and reliability requirements have been advancing slowly. One such type of systems are unmanned aerial vehicle (UAV) control systems. The functional complexity of UAV control systems is steadily increasing. Enabling the design of such complex systems in easily understandable forms that are amenable to rigorous analysis is a highly desirable goal. In this paper, we discuss our experimental application of the Time-triggered Message-triggered Object (TMO) structuring scheme to the design of a UAV control system. The TMO scheme enables high-level structuring together with design-time guaranteeing of accurate timings of various critical control actions with significantly smaller efforts than those required when using lower-level structuring schemes based on direct programming of threads, UDP invocations, etc. An experimental 2-step validation of a UAV control system is also discussed. The first step was to validate the system by use of an environment simulator and then real flight tests were involved only in the second step.

TMO-HILS architecture for real-time control system

Real-Time Simulation is a most important tool that allows for prediction of system behavior in response to operator actions and events via the use of real-time and archived data. Virtual testing of operator actions prior to implementation can reveal potential problems, hence reducing human errors and the risk of service power system interruptions. Hardware-in-the-loop simulation (HILS) assists operators, engineers, and planners in making informed and logical decisions that will reduce operating costs and improve system reliability. There are some kinds of real-time embedded systems, such as UAV (Unmanned Aerial Vehicle) and UGV (Unmanned Ground Vehicle) etc, which require high confidence real-time computation and rigorous analysis to deliver high levels of mission reliability. To measure reliability of these control systems and reduce the risk of costly errors, we present the architecture of a TMO-HILS which can accept from small rapid control prototyping systems to large-scale distributed real-time simulators. To design TMO-HILS, we use a time-triggered message-triggered object (TMO) model which is a well-known real-time object model for distributed and timeliness-guaranteed computing, and makes easy to analyze and design the actual system. TMO-HILS provides easy way to validation of real-time control system like the UAV control system.

Behavior-based portability analysis methodology for Android applications

As Android is an open-source operating system, numerous device-specific updates are frequently published by various developers. Thus, in order to increase the portability of an application, the development of an Android application requires an efficient porting process. However, many analytical time-consuming problems arise when developers convert the application for other versions of platform. In this paper, we propose a behavior-based portability analysis methodology for Android applications. Using this methodology, a developer can extract the ideal behavior of an application and use it to compare the similarity of application flows. We study Android applications to determine whether the proposed methodology can be adopted to detect potential errors. The principal contribution of this paper is to enable developers to use behavior-based analysis for detecting potential errors related to portability by utilizing the porting process easily and quickly.

Design of authenticity evaluation metric for Android applications

For enforcing security, Android platform uses authorizing system which grants permission per application at install-time. With authorized privilege, user applications can modify and delete users personal information. Therefore, inspection of granted permiss ion usage can be used to detect security vulnerabilities. ISO/IEC 25 010 defines software product security characteristic and provides g uidelines to evaluate software product quality. Among sub-characte ristics of security, Authenticity is related to Android permission sys tem. In this paper, we present authenticity metric for android application. This metric can quantify the permission usage of applicatio n and measured information can be used to classify the malware applications. To verify the applicability of metric, we perform evaluat ion to benign and malware application and compare its results.

Design of static execution time analyzer using partial path

Analyzing execution time in static manner is tedious, due to unbounded external inputs in loops and control flow. Parametric WCET analysis uses parameter to get a user input. It can give formula expressed in the input variables of a program during analysis time. This can help an analyzer to offer more accurate and flexible result. But recently, it grows importance to provide information helping developer more than accuracy of dead-line verification at the static execution time analyzer. There are problems to analyze low performance and to provide useful information about flows. Existing analyzers using low level state of control flow graph offer only execution time and hard to use flow information at worst-case. Thus, in this paper, we present static execution time analyzer using partial path for rapid analyzing of WCET and its flow to serve developers. Our purposed analyzer that uses partial path instead of state of control flow graph requires less calculation and easies to check relations between flows and external inputs those were difficult to analyze before.