Chang-Eun Lee

Design of a universal middleware bridge for device interoperability in heterogeneous home network middleware

The paper proposes the design of a software universal middleware bridge (UMB) that can be used to solve seamless interoperability problems caused by the heterogeneity of several kinds of home network middleware. The proposed UMB dynamically maps physical devices in all the different middleware domains into virtually abstracted devices in the UMB domain and enables all home devices overlaid on heterogeneous networks to be seen as virtually the same physical devices in the same middleware domain, as well as to detect and control each other.

Comparison of localization methods using CSS-UWB WPAN for mobile robots

Ultra Wideband (UWB) techniques are utilized to localize mobile robots in indoor environment. Although there are many methods, such as IR-UWB, CSS-UWB, and AWGN-UWB, it is hard to make it smaller. CSS-UWB technique is a viable solution, since it has a chip solution. By utilizing chirp signal, ranging counter, and SDS-TWR technique, CSS-UWB acquires under-meter ranging measurements. To solve position with these measurements in severe indoor condition, robust location algorithm should be exploited. Gauss-Newton (GN) method shows good performance compared to other algorithms. However, GN method has a chance to diverge in poor geometry condition. Moreover, different anchor heights could cause divergence problem in three-dimensional condition. The quadratic corrected least square (QCLS) method is introduced to alleviate this divergence problem. Not only classical QCLS method, but also other methods such as modified QCLS (MQCLS) are introduced. The performances of these algorithms are analyzed by both simulation and experimental results. MQCLS algorithm shows better performance for the edge of the geometry.

Cooperative seamless communication with collective intelligent robots

In collective intelligent robots, communication capability is considered as a key feature to decide how to design the collaboration policy. A cooperative routing robot system is suggested to maintain the communication capability in between robots and an algorithm to establish a seamless global communication is proposed. The proposed algorithm is composed of two steps. At the first step, the communication links are monitored and the disconnection of network is predicted by analyzing RSSI (Received Signal Strength Indicator) and LQI (Link Quality Indicator) among cooperative robots. Then, the robots are driven forward inside a safety region of communication using virtual force model on the basis of the strength of the networking signal. Experiments with routing robots and sensing system verify our proposed system and algorithm are valid in real environment.

Design of the Autonomous Fault Manager for learning and estimating home network faults

This paper proposes a design of software Autonomous Fault Manager (AFM) for learning and estimating faults generated in home network. Most of the existing researches employ rule-based fault processing mechanism, but those works depend on the static characteristics of rules for a specific home environment. Therefore, we focus on a fault estimating and learning mechanism that autonomously produces a fault diagnosis rule and predicts an expected fault pattern in the mutually different home environment. For this, the proposed AFM extracts the home network information with a set of training data using the 5W1H (Who, What, When, Where, Why, How) based contexts to autonomously produce a new fault diagnosis rule. The fault pattern with high correlations can then be predicted for the current home network operation pattern.

Implementation of a seamless communication scheme using cooperative routing robots for teleoperation

In collective intelligent robots, communication capability is considered as a key feature to decide how to design the collaboration policy. A cooperative routing robot system is suggested to maintain the communication capability in between human and robots and an algorithm to establish a seamless global communication is proposed. In this paper, implementation of seamless communication between human and the robots using cooperative routing robots is shown in real environment.

Realization of Fault-Tolerant Home Network Management Middleware with the TMO Structuring Approach and an Integration of Fault Detection and Reconfiguration Mechanisms

A middleware model named ROAFTS (Real-time Object-oriented Adaptive Fault Tolerance Support) has been evolving in the UCI DREAM Lab. over the past decade as the core of a reliable execution engine model for fault-tolerant (FT) real-time (RT) distributed computing (DC) applications. It is meant to be an integration of various mechanisms for fault detection and recovery in a form that meshes well with high-level RT DC object-/component- based programming, in particular, TMO (Time-triggered Message-triggered Object) programming. Using ROAFTS as a backbone and low-layer middleware, we developed a model and a skeleton implementation for FT DC middleware providing efficient FT execution services for component-based home network applications. Capabilities for management of home information processing devices, including health monitoring of home devices, reconfiguration of device connections, and servicing queries on device status, were added to ROAFTS. Those additions were first designed as a network of high-level RT DC components, i.e., TMOs. Then the TMO network was extended into an FT TMO network by applying the replication scheme called the PSTR (Primary-Shadow TMO Replication) scheme and incorporating a component responsible for reconfiguring TMO replicas. This extension of ROAFTS is called ROAFTS-HNE (Home Network Extension) and its architecture is presented here. In addition, during the development of the ROAFTS-HNE model, we formulated a new approach for applying the PSTR scheme to RT DC components supported by ROAFTS. Finally, evaluations of the recovery times of a prototype implementation have been conducted.

Implementation of Cooperative Routing Robot System for Long Distance Teleoperation

Cooperative robots are more efficient than a robot when the assigned task is complex and the workspace is large. To meet with the task efficiency and successful control of Cooperative robots, sensing and networking of the robot are necessities. To ensure stable communication, the cooperative routing robot system is implemented. Our system is an autonomous reactive router that responds to change in strength of a signal and a quality of link among cooperative robots. The routing robot is driven toward a safety region of network using virtual force model or change into a router. A result of our approach was shown as an experiment. A tank robot was continuously teleoperated from ROC (remote operate center); thereby condition of network was proven to be stable. In addition, the ROC continuously acquired a remote video and positions. As a result, the cooperative routing robot system help you teleoperate a robot about long distance.

Poster Abstract: An Iterative Approach for Non-Line-of-Sight Error Mitigation in UWB Localization

Ultrawideband (UWB) based localization has the potential to be used in a variety of applications due to its high accuracy. For robust and high performance in real environment, the most challenging issue is the detection and mitigation of noise from non-line-of-sight (NLOS) signals. Current researches use channel state information, particle or Kalman filter, and statistics based approaches for the NLOS noise detection and mitigation. These solutions show high accuracy in some applications; however, they need additional hardware and work in static environment only. We propose an NLOS mitigation algorithm that does not need any additional hardware andworks in dynamic environment with mobile obstacles. The main idea of the algorithm are to estimate the NLOS bias by repetitively comparing the intersection of the hyperbolas with intersections of circles. The proposed approach is tested for Decawave UWB testbed. Experimental results show that the proposed scheme works well in different dynamic scenarios as compared to the localization scheme without NLOS noise mitigation.

An iterative approach for non-line-of-sight error mitigation in UWB localization: poster abstract

Ultrawideband (UWB) based localization has the potential to be used in a variety of applications due to its high accuracy. For robust and high performance in real environment, the most challenging issue is the detection and mitigation of noise from non-line-of-sight (NLOS) signals. Current researches use channel state information, particle or Kalman filter, and statistics based approaches for the NLOS noise detection and mitigation. These solutions show high accuracy in some applications; however, they need additional hardware and work in static environment only. We propose an NLOS mitigation algorithm that does not need any additional hardware and works in dynamic environment with mobile obstacles. The main idea of the algorithm are to estimate the NLOS bias by repetitively comparing the intersection of the hyperbolas with intersections of circles. The proposed approach is tested for Decawave UWB testbed. Experimental results show that the proposed scheme works well in different dynamic scenarios as compared to the localization scheme without NLOS noise mitigation.

Analysis of Error Propagation in Two-way-ranging-based Cooperative Positioning System

Alternative radio-navigation technologies aim at providing continuous navigation solution even if one cannot use GNSS (Global Navigation Satellite System). In shadowing region such as indoor environment, GNSS signal is no longer available and the alternative navigation system should be used together with GNSS to provide seamless positioning. For soldiers in battlefield where GNSS signal is jammed or in street battle, the alternative navigation system should work without positioning infrastructure. Moreover, the radio-navigation system should have scalability as well as high accuracy performance. This paper presents a TWR (Two-Way-Ranging)-based cooperative positioning system (CPS) that does not require location infrastructure. It is assumed that some members of CPS can obtain GNSS-based position and they are called mobile anchors. Other members unable to receive GNSS signal compute their position using TWR measurements with mobile anchors and neighboring members. Error propagation in CPS is analytically studied in this paper. Error budget for TWR measurements is modeled first. Next, location error propagation in CPS is derived in terms of range errors. To represent the location error propagation in the CPS, Location Error Propagation Indicator (LEPI) is proposed in this paper. Simulation results show that location error of tags in CPS is mainly influenced by the number of hops from anchors to the tag to be positioned as well as the network geometry of CPS.