Browsing by Author "Chang, Hsung-Pin"

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Design of applying FlexRay-bus to federated archiectecture for triple redundant reliable UAV flight control system
(2017-01-01)
Wu, Chang-Han
;
Chen, Ti-Jui
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Hsu, Terng-Yin
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Tsai, Shang-Ho
;
Chang, Hsung-Pin
For an Unmanned Aerial Vehicle (UAV) performing a mission, any failure of the flight control system can result in fatal disaster. Therefore, reliability requirement for UAV flight control system becomes increasingly important and then the redundancy technology is considered as a solution to enhance system reliability. This paper studies the designs of reliability, system architecture, and redundancy management logic for UAV flight control system. Therefore, a reliable federated architecture design for triple redundant UAV flight control system is introduced, in which the distributed hardware design combined with centralized software framework was adopted as well. The number of subsystems in the case study is more than that of centralized architecture and less for distributed architecture. Next, the fault detection and fault tolerant design can be achieved, and simultaneously the design problems associated with distributed software framework was reduced. Furthermore, by using the distributed hardware, system's reliability requirement of single hardware module was decreased. Consequently, the goal of high reliability for the entire system reached. Finally, FlexRay bus with time-trigger mechanism was chosen to simulate the communication of such a federated architecture designed. The experimental results show that the design is reasonable and satisfy the high reliability, high performance-price ratio and high expandability requirements of UAV flight control system.
GSR: A global seek-optimizing real-time disk-scheduling algorithm
(2007-02-01)
Chang, Hsung-Pin
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Chang, Ray-I
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Shih, Wei-Kuan
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Chang, Ruei-Chuan
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資訊工程學系
Earliest-deadline-first (EDF) is good for scheduling real-time tasks in order to meet timing constraint. However, it is not good enough for scheduling real-time disk tasks to achieve high disk throughput. In contrast, although SCAN can maximize disk throughput, its schedule results may violate real-time requirements. Thus, during the past few years, various approaches were proposed to combine EDF and SCAN (e.g., SCAN-EDF and RG-SCAN) to resolve the real-time disk-scheduling problem. However, in previous schemes, real-time tasks can only be rescheduled by SCAN within a local group. Such restriction limited the obtained data throughput. In this paper, we proposed a new globally rescheduling scheme for real-time disk scheduling. First, we formulate the relations between the EDF schedule and the SCAN schedule of input tasks as EDF-to-SCAN mapping (ESM). Then, on the basis of ESM, we propose a new real-time disk-scheduling algorithm: globally seek-optimizing rescheduling (GSR) scheme. Different from previous approaches, a task in GSR may be rescheduled to anywhere in the input schedule to optimize data throughput. Owing to such a globally rescheduling characteristic, GSR obtains a higher disk throughput than previous approaches. Furthermore, we also extend the GSR to serve fairly non-real-time tasks. Experiments show that given 15 real-time tasks, our data throughput is 1.1 times that of RG-SCAN. In addition, in a mixed workload, compared with RG-SCAN, our GSR achieves over 7% improvement in data throughput and 33% improvement in average response time. (C) 2006 Elsevier Inc. All rights reserved.
Wireless LAN medium access controller supporting mode change and mode change method thereof
(2006-04-27)
Lin, Yen-Liang
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Chang, Hsung-Pin
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Chang, Ruei-Chuan
A wireless LAN medium access controller supporting mode change and the mode change method thereof are proposed. A physical layer detects signal strength in the environment and writes a mode index value of the stronger signal into a register. When the written mode index value is different from a mode index value in the communication system, a medium access controller is informed to perform mode change. The physical layer then sends out an interrupt signal to a central processor and sends the mode index value to the central processor for comparison via a DMA module and a memory. An interface module is used to access the mode index value in the memory for providing an external interface for the medium access control layer. When the mode index value doesn't conform to the signal in the environment, a software layer in the medium access controller is used for mode change.