Minyoung Sung

Design and Implementation of a Delay-Guaranteed Motor Drive for Precision Motion Control

This paper proposes a systematic design approach for a precision-guaranteed motion control system. We develop a delay-guaranteed motor drive with our new software implementation and real-time Ethernet, which can be used as a building block to build up a multi-axis motion control system. Our drive software implementation provides a probabilistic guarantee on drive-local processing delays to motor actuation, while real-time Ethernet provides a deterministic guarantee on message communication delays from a motion control host to each drive. In the paper, we address the precision of a motion control system in two terms: host cycle time and simultaneous actuation deviation. The host cycle time is a period with which the host can periodically release motor control messages while the average drive utilization does not exceed 1, and the simultaneous actuation deviation is the difference between the earliest and the latest actuation at different drives in response to the same message. In our approach, the main objective is to minimize the periods of tasks in each drive, using our stochastic analysis, which gives us a minimum possible host cycle time. Together with an existing delay analysis of real-time Ethernet, we analyze the end-to-end delay from message release to motor actuation and in turn the simultaneous actuation deviation. Through experiments, we show that for various requirements on the deadline miss probabilities of the tasks, we can successfully reduce the host cycle time and evaluate the resulting distribution of the simultaneous actuation deviation depending on the number of drives.

An EtherCAT-based motor drive for high precision motion systems

Industrial Ethernet-based motor drives offer many advantages for motion applications. This paper presents the implementation and analysis of a motor drive with the EtherCAT, an open real-time Ethernet standard, for high-precision motion systems. Considering the characteristics of the multitasked software and the network interface, we analyze the delay in actuating the motor in response to a command from the control host. Based on a response time analysis and the times measured from the developed drive, we discuss performance characteristics of the drive in respect of the end-to-end delay and the maximum achievable throughput for non-real-time traffic when the drive is controlled in position, velocity, or torque mode.

An open-source development environment for industrial automation with EtherCAT and PLCopen motion control

Standards conformance and integrated development are key features of modern automation systems. This paper introduces an integrated development environment (IDE) that enables high-speed EtherCAT communication and standardized motion programming. On the basis of our previous work, we extended and customized open-source software components to provide a completely open architecture IDE, that is compliant with the relevant industrial standards. The major components of our IDE are IEC 61131-3 and PLCopen TC6 compliant editor, EtherCAT communication support, and PLCopen TC2 compliant motion control library. Since the whole procedures from the project setup to run-time monitoring are highly automated, the presented IDE allows developers to integrate coordinated motion with control logics seamlessly and efficiently.

A rich media framework for communication-broadcasting converged IPTV

As the trend toward communication and broadcasting convergence grows, a hybrid Internet Protocol television (IPTV) that supports both IP network-based video and traditional TV broadcast is attracting increasing attention. This paper proposes a rich media framework for hybrid IPTV with support of the latest H.264 codec. The problem of software incompatibility along with the resource constraints of IPTV set-tops limits the adoption of rich media technologies in IPTV environment. Aiming for portability and performance, we propose a media component for hybrid IPTV that features an efficient application interface and sophisticated media processing schemes. Using the media interface, we developed a rich media runtime whose design enables it to fully utilize the built-in graphics acceleration hardware. Through demonstration and experiments, we validate the performance and flexibility of the proposed framework. Our schemes that include ring-structured media stream abstraction, I-frame prefetch via vectored I/O, and adaptive I-frame search proved to greatly enhance the VCR functions in respect of the fulfillment of the requested playback speed and the download throughput. The proposed framework is believed to provide a useful insight into the design of vector graphics and the playback of hybrid media in the applications of IPTV-based advertising, education, and Video-on-Demand (VoD).

A MAC parameter optimization scheme for IEEE 802.11e-based multimedia home networks

Enhanced Distributed Channel Access (EDCA) is a channel access scheme adopted by the IEEE 802.11e draft standard for QoS-enabled wireless local area networks. It classifies traffic into separate Access Categories (ACs) and achieves service differentiation by allowing each AC to have its own values of channel access parameters, i.e. minimum and maximum Contention Window (CW) and InterFrame Space (IFS). Since the network performance is highly sensitive to these parameters, their values should be carefully determined. The IEEE 802.11e specification, however, includes only default recommended values and does not deal with run-time optimization. This paper proposes a scheme to dynamically adapt the EDCA parameters to traffic environment so that they both maximize the throughput of non real-time traffics and meet the delay and throughput constraints of real-time traffics. For this purpose, we develop a design time algorithm for efficient exploration of the EDCA parameter space. Using the algorithm, we derive a Pareto curve for delay-throughput trade-off in each anticipated traffic environment. The Pareto database can then be used to optimally adjust the parameter according to the traffic environment and administrative policies. Simulation results show that compared with the default parameter configuration, the proposed scheme is better for delay, throughput guarantee and can improve the throughput of non real-time traffics by 12% on average.

Comparative performance evaluation of Java threads for embedded applications: Linux thread vs. Green thread

Despite the portability and platform independence of Java programs, their performance depends on the threading mechanisms of the host operating system. In this paper, we measure the performance of Java threads for two different multithreading implementations, Linux Thread and Green Thread, using PersonalJava (TM) on a Linux-based platform. The experimental results show the relative strengths and weaknesses of the two threading mechanisms with respect to synchronization overhead, I/O efficiency, and thread control.

A QoS-enabled service discovery and delivery scheme for home networks

For an end-to-end QoS-enabled service, the service discovery and delivery mechanisms are required to be aware of QoS and be able to differentiate its behavior according to the negotiated QoS level. This paper presents a work-in-progress scheme for achieving quality of service in service discovery and delivery networks. Based on the universal plug & play standard, we propose an architecture which provides actions for QoS negotiation and effectively prioritizes service tasks through heuristics to assign process priority and allocate server processes. Using a prototype, we plan to conduct experiments to demonstrate the efficiency and correctness of the proposed schemes.

Machine-learning-integrated load scheduling for peak electricity reduction

The scheduling of household electrical loads can contribute to a significant reduction in peak demand. This paper introduces a load scheduling scheme that integrates an SVM (Support Vector Machine) model for demand prediction. The experiment results confirm the strength of the proposed scheme, showing its ability to achieve the intended performance in consideration of the trade-off among peak reduction, temperature band violation, and switch count.

Design and Implementation of a RIA Framework for IPTV Set-Top Boxes

As increasing emphasis is being placed on user experience design, the RIA (Rich Internet Application) technology is now widely deployed for user interface and software execution on embedded devices including cell phones, PMPs and TVs. In particular, RIA-based IPTVs are recently gaining attraction in that they enable creation of various sophisticated contents via animation and interactivity. This paper proposes a RIA framework for IPTV set-top boxes. We design and implement a programming interface for media playback in IPTV environments. Based on the interface, we develop a prototype of Adobe Flash-compatible RIA run-time with the support of IPTV media. The runtime was carefully designed to fully utilize the builtin graphic acceleration hardware in media processors. It is therefore able to render sophisticated vector graphics in the resource-constrained IPTV systems. Demonstration and extensive experiments validate the proposed framework.

Machine-learning-integrated load scheduling for reduced peak power demand

Load scheduling over cyclic electrical devices can reduce the peak power demand. In this paper, we propose a machine-learning-integrated load control (MILC) scheme for improved performance and reliability. By dynamic capacity adjustment and interactive load heuristic, MILC tries to reduce the power deviation while keeping the temperature violation ratio and switching counts within an acceptable range. A prototype of the proposed scheme has been implemented and, through experiments using load traces from a real home, we evaluate the performance of MILC. The results show that MILC reduces the peak demand from 4993 W to 4236 W and successfully decreases the power deviation by 12.1% on average.