Jong-Koo Park

Technical Communique: Dynamic observers for linear time-invariant systems

An alternative state estimator structure for linear time-invariant systems named for dynamic observer is presented, which can be considered as an extension of the usual observer in its configuration. As a possible design method for the dynamic observer, an efficient and plausible design algorithm is also provided. The mechanism of the proposed dynamic observer design is the dual of the output feedback controller design. The essential characteristics of the dynamic observer to be qualified as an effective observer are addressed.

Dynamic anti-windup method for a class of time-delay control systems with input saturation

An anti-windup-based approach is newly attempted to deal with time-delay control systems with input saturation. Following the anti-windup paradigm, we assume that controllers have been designed beforehand for time-delay control systems based on existing design techniques which will show desirable performance. Then, an additional compensator is designed to provide graceful performance degradation under control input saturation. By taking the difference of controller states in the absence and presence of input saturation as a performance index, a dynamic compensator which minimizes it is derived. The resulting anti-windup compensator is expressed in plant and controller parameters. The proposed method not only provides graceful performance degradation, but also guarantees the stability of the overall systems. Illustrative examples are provided to show the effectiveness of the proposed method. Copyright

Brief Dynamic anti-windup based control method for state constrained systems

Based on the dynamic anti-windup strategy, an alternative control methodology for state constrained systems is presented. The proposed method is an a posteriori approach for state constrained systems, which is differentiated from the usual a priori approach. That is, first a linear controller is designed to show a desirable nominal performance by ignoring state constraints. Then, an additional compensator is introduced to account for state constraints. By minimizing a reasonable performance index, a dynamic compensator is derived explicitly, which is expressed in plant and controller parameters. The proposed method not only provides a graceful performance degradation, but it also guarantees the total stability of the resulting systems. An illustrative example is given to show the effectiveness of the proposed method.

The concept and design of dynamic state estimation

The concept of a dynamic state estimator as an alternative to a static state estimator is introduced. Efficient and plausible design algorithms are also provided. The dynamic estimator is an extension of the usual static estimator. Both the model based and generalized dynamic estimators are considered. The essential characteristics of the dynamic estimators to be qualified as an effective estimator design scheme are addressed.

Cost effective location management scheme based on hierarchical mobile IPv6

Recently MIP becomes more important for the macro mobility support in the emergence of the global system such as IMT-2000. However this protocol suffers from many weaknesses on the location management. MIPv4 regional registration is presented for the local registration of MNs. MIPv6 can benefit from the reduced mobility signaling with external networks by employing a local MAP, that is called HMIPv6. The total signaling cost of HMIPv6 is rapidly increased by the number of CNs of an MN when the MN moves around between MAPs. In this paper, we propose a new location management scheme in MIPv6 that reduces the total signaling cost in the location update based on HMIPv6. Here the MN does not send the BU to CNs and HA when it moves around between MAPs. Instead it informs the current location by transferring the modified BU to the previous MAP. According to the results of the performance analysis, we determine the upper bound for the number of forwarding links allowed among adjacent MAPs without the BU information.

Static anti-reset windup method for saturating control systems with multiple controllers and multiloop configuration

Presents an anti-reset windup (ARW) compensation method for saturating control systems with multiple controllers and/or multiloop configuration. The proposed ARW method is motivated by the concept of equilibrium point. The design parameters of the ARW scheme is derived explicitly by minimizing a reasonable performance index. In the event of saturation, the resulting dynamics of the compensated controller reflects the dynamics of a linear closed-loop system. The proposed method guarantees the total stability of resulting control systems under a certain condition.

Product-Service Systems (PSS) Design Process and Design Support Systems

This paper presents a new PSS design process and associated design support systems being developed by the PSS Design Project Consortium sponsored by the Korean Ministry of Knowledge Economy. Six procedural steps are included in the PSS design process. For design support systems, the activity modelling system is developed for a complete description of activity with context elements. The PSS function modelling system can support the definition of functions and service providers/receivers and their decompositions. The modified service blueprint system is also developed to address relations among activities and functions. Finally, the PSS DesignScape is used to capture and visualize the PSS design process. Sample case example is presented to show the effectiveness of the PSS design support systems.

Simulation Based Functional and Performance Evaluation of Robot Components and Modules

This paper presents a simulation based test method for functional and performance evaluation of robotic components and modules. In the proposed test method, function test procedure consists of unit, state, and interface tests which assess if the functional specifications of robot component 1 or module 2 are met. As for performance test, simulation environment provides a down scaled virtual work space for performance test of robot module accommodating virtual devices in conformity with the detailed performance specifications of real robot components. The proposed method can be used for verification of reliability of robot modules and components which prevents faults of them before their usage in real applications. In addition, the developed test system can be extended to support various test conditions implying possible cost saving for additional tests.

Geomagnetic localization of mobile robot

In the present paper, a method is proposed that uses the geomagnetic field to estimate the positions of mobile robots in indoor environment. The reinforced concrete, H-beams, and power systems in buildings distort the geomagnetic field and these characteristics are used as regional features to estimate the positions of mobile robots. Another method is also proposed that prepares geomagnetic field maps using the model information obtained from the characteristics of sensors mounted on mobile robots and the position information to efficiently access the database. The extended Kalman filter is used to fuse robot motion models with geomagnetic field sensor models. The performance of the proposed algorithm is verified through Ground Truth experiments.

Deciding Optimal Information Dispersal for Parallel Computing with Failures

Supporting availability, integrity, and confidentiality of data is crucial for parallel computer systems. The parallel computer systems require to encode and distribute data over multiple storage nodes to survive failures and malicious attacks. Information Dispersal Scheme(IDS) is one of the most efficient schemes allowing high availability and security with reasonable overhead. In this paper we propose an algorithm determining an optimal IDS in terms of availability.