• Journal of the Korea Institute of Military Science and Technology
• /
• v.24 no.5
• /
• pp.558-568
• /
• 2021

The existing underwater vehicle controller design is applied by linearizing the nonlinear dynamics model to a specific motion section. Since the linear controller has unstable control performance in a transient state, various studies have been conducted to overcome this problem. Recently, there have been studies to improve the control performance in the transient state by using reinforcement learning. Reinforcement learning can be largely divided into value-based reinforcement learning and policy-based reinforcement learning. In this paper, we propose the roll controller of underwater vehicle based on Deep Deterministic Policy Gradient(DDPG) that learns the control policy and can show stable control performance in various situations and environments. The performance of the proposed DDPG based roll controller was verified through simulation and compared with the existing PID and DQN with Normalized Advantage Functions based roll controllers.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.4
• /
• pp.266-278
• /
• 2013

In this paper, to manage the efficient control of IP packet flows crossing multi-provider networks such as Internet, we propose a SDN(Software Defined Networking)-based policy controller. The proposed policy controller leverages the visibility of underlying network and manages both virtual links and ports to inter-connect networking elements. The controller is capable of quickly composing multiple on-demand virtual networks and dynamically managing the composed networks, thus it can provide more flexible and optimized overlay networking environment to end-user applications. More specifically, we first look into the proposed structure and features of policy controller. With two kinds of service applications, we then verify the applicability of the proposed controller by evaluating its service composition time.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.5
• /
• pp.2074-2079
• /
• 2018

Global state space's optimal policy is used for offline controller in the form of table by using Dynamic Programming. If an optimal policy table has a large amount of control data, it is difficult to use the system in a low capacity system. To resolve these problem, controller using the compressed optimal policy table is proposed in this paper. A DCT is used for compression method and the cosine function is used as a basis. The size of cosine function decreased as the frequency increased. In other words, an essential information which is used for restoration is concentrated in the low frequency band and a value of small size that belong to a high frequency band could be discarded by quantization because high frequency's information doesn't have a big effect on restoration. Therefore, memory could be largely reduced by removing the information. The compressed output is stored in memory of embedded system in offline and optimal control input which correspond to state of plant is computed by interpolation with Inverse DCT in online. To verify the performance of the proposed controller, computer simulation was accomplished with a one link inverted pendulum.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.4
• /
• pp.1740-1751
• /
• 2018

This paper proposes a novel fault tolerant tracking control (FTTC) scheme for a class of nonlinear systems with actuator failures based on the policy iteration (PI) algorithm and the adaptive fault observer. The estimated actuator failure from an adaptive fault observer is utilized to construct an improved performance index function that reflects the failure, regulation and control simultaneously. With the help of the proper performance index function, the FTTC problem can be transformed into an optimal control problem. The fault tolerant tracking controller is composed of the desired controller and the approximated optimal feedback one. The desired controller is developed to maintain the desired tracking performance at the steady-state, and the approximated optimal feedback controller is designed to stabilize the tracking error dynamics in an optimal manner. By establishing a critic neural network, the PI algorithm is utilized to solve the Hamilton-Jacobi-Bellman equation, and then the approximated optimal feedback controller can be derived. Based on Lyapunov technique, the uniform ultimate boundedness of the closed-loop system is proven. The proposed FTTC scheme is applied to reconfigurable manipulators with two degree of freedoms in order to test the effectiveness via numerical simulation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.7B
• /
• pp.438-447
• /
• 2007

In the Internet, an identity service must to obtain permission from a user to allow them to share data with requesting service. For that, the privacy policy, which reflects legal regulations and preferences made by the user, is needed. Also, the management interface that aids the user to make the privacy policy and the PDP system that makes admission control and policy decisions in response to a request from an entity wanting to access the personal information are needed. In this paper, the privacy controller system model handled under the internet Identity management system environment is proposed. The system has the easy interface of policy generation and the efficient policy decision process. The system applies and modifies to the XACML of OASIS group. We propose that the privacy policy is divided into the three policies, which are the user policy, the domain policy and the basic offering policy. To resolve the collision between the policies, we also propose the collision resolution policy.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1993.06a
• /
• pp.834-837
• /
• 1993

This paper describes the implementation of an autonomous fuzzy logic controller. The controller is endowed with basic control principles and learning constructs which enable it to autonomously modify its control policy based on system performance. The controller lies dormant when system response is satisfactory but if rapidly initiates adaptation in real time when adverse performance is observed. The autonomous fuzzy controller is implemented on an Intel MCS-51 series micro-controller board using an inexpensive 8-bit Intel 8031 processor. The 11.06 MHz micro-controller operates at a rate exceeding 200 "global" look-up table reinforcements per second. This is important when developing practical on-line adaptive controllers for fast systems. It is also significant because an initial controller look-up table could be incorrect or non-existent. The relatively high learning rate enables the controller to learn to control a system even while it is controlling it.

• The KIPS Transactions:PartC
• /
• v.11C no.4
• /
• pp.429-438
• /
• 2004

This Paper Presents the control structure for incoming traffic from arbitrary node to Provide admission control in policy-based W network management structure using fuzzy logic control approach. The proposed control structure uses scheme for deciding network resource allocation depending on requirements predefined-policies and network states. The proposed scheme enhances policy adapting methods of existing binary methods, and can use resource of network more effectively to provide adaptive admission control, according to the unpredictable network states for predefined QoS policies. Simulation results show that the proposed controller improves the ratio of packet rejection up to 26%, because it Performs the soft adaption based on the network states instead of accept/reject action in conventional CAC(Connection Admission Controller).

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.11
• /
• pp.1118-1124
• /
• 2014

This paper proposes a novel controller design scheme for multimachine power systems based on the explorized policy iteration. Power systems have several uncertainties on system dynamics due to the various effects of interconnections between generators. To solve this problem, the proposed method solves the LQR (Linear Quadratic Regulation) problem of isolated subsystems without the knowledge of a system matrix and the interconnection parameters of multimachine power systems. By selecting the proper performance indices, it guarantees the stability and convergence of the LQ optimal control. To implement the proposed scheme, the least squares based online method is also investigated in terms of PE (Persistency of Excitation), interconnection parameters and exploration signals. Finally, the performance and effectiveness of the proposed algorithm are demonstrated by numerical simulations of three-machine power systems with governor controllers.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.584-588
• /
• 1991

This paper presents a fuzzy adaptive controller which can improve the control policy automatically. Adaptation is achieved by the addition of on-line identification of the fuzzy inverse model using input-output data pairs of the process. Starting with an initial crude control rule, the adaptive controller matches the model to the process to self-tune the controller. The control algorithm needs much less memory of computer than other SOC algorithms.

• 전기의세계
• /
• v.20 no.4
• /
• pp.17-22
• /
• 1971

This paper deals with the analytic structure of feedback controller for linear time invariant discrete systems. On the way of developing the deadbeat controller, some necessary conditions for control policy have been derived. In the case of time delay, it was proved that the q periods delay in the control causes q periods delay in the point at which deadbeat response occurs. Theorems and conclusions are illustrated with some simple nontrivial numerical examples and signal state tracking application problems.