Earticle

많은 수의 제어면을 가지고 있는 F-18 Super Hornet, F-35 JSF(Joint Strike Fighter) 및 F-22 Rapter와 같은 대부분의 고기동 전투기는 항공기 시스템의 제약을 고려하여 항공기의 가속 도를 달성하기 위한 제어면 명령을 계산하기 위해, 보다 진보된 조종력 할당 방식을 요구 한다. 요구되는 항공기 응답 특성에 기반하여 가속도를 생성하는 동적 모델역변환제어 및 모델추종제어와 같은 조종력 할당 방법을 사용하는 많은 다른 형태의 제어 구조가 있다. 본 논문에서는 동적 모델역변환 제어 구조를 기반으로 하여 여분의 제어면에 조종명령을 재분배하는 조종력 할당 방식을 기술한다. 제안된 방식은 구조 하중 문제와 제어면의 포화 를 보상하기 위해 Daisy Chain을 통합한 CGI(Cascaded Generalize Inverse) 접근 방식을 기 반으로 한다. 고등훈련기 모델을 이용한 평가 결과, 제안된 방식은 저속 및 고속 비행영역 에서 성능 달성의 용이함을 보여준다.

Most of the highly maneuverable fighter aircraft such as F-18 Super Hornet, F-35 JSF(Joint Strike Fighter) and F-22 Rapter with a large number of actuators will require advanced CA(Control Allocation) methods to compute the actuator commands needed to achieve a specified set of vehicle accelerations while respecting system constraints. There are many different types of control architectures that utilize a control allocation methodology such as DMI(Dynamic Model Inversion) control or MFC(Model Following Control) that generates a set of desired acceleration outputs based upon aircraft's specific response characteristics. This paper addresses a control allocation method by redistributing control command to the redundant control surfaces based on DMI control architecture. The proposed method is based on a CGI(Cascaded Generalized Inverse) approach with integrated of daisy chain for the compensation of actuators saturation and structural load problem. A set of simulation results with an advanced trainer demonstrate that the proposed method can achieve adequate performance in low and high speed flight envelope.

비행제어법칙의 내부루프 설계는 불안정하게 설계된 항공기의 안정성을 보장하고, 전비행영역에서 만족스러운 조종성을 부과한다. 대부분의 전투기는 성능이 기 검증된 고전제어방식을 채택하고 있으며, 최근에 운용되고 있는 항공기의 경우에는 고전적인 설계접근 방식을 보완한 모델역변환제어를 적용하고 있는 추세에 있다. 이러한 예로, 초음속 고등훈련기는 종축의 제어법칙에 선형모델을 활용한 모델역변환 제어방식, F-35의 경우에는 종, 횡-방향축 전체의 제어법칙을 비선형 모델을 활용한 모델역변환 제어를 적용한 바 있다. 본 논문에서는 전투기급 항공기의 제어법칙 개발사례를 분석하고, 고기동 전투기에서 필요로 하는 내부루프 비행제어법칙을 제시하고자 한다. 아울러, 고등훈련기 모델을 기반으로 하여 횡-방향축 모델역변환제어를 설계하고, 군사규격서 기반의 요구도를 기준으로 평가한 결과를 제시하였다.

The aim of designing the inner-loop flight control law is to satisfy the stability of the RSS(Relaxed Static Stability), and to achieve adequate the handling quality requirement in overall flight envelopment. Traditionally, aircrafts have adopted classical control method of which performances have been verified. However, for modern aircraft, the DMI(Dynamic Model Inversion) is considered as the primary flight control system to improve the design techniques from the previous one; for example, the linearized DMI for longitudinal control of the supersonic advanced trainer, and the nonlinear DMI for lateral-directional control of the F-35. In this paper, flight control laws for various fighter aircrafts are analyzed first, and then the inner-loop flight control law for highly performance aircraft is proposed. Moreover, the DMI is designed as the lateral-directional controller of the advanced trainer; finally, the performance test results based on the requirements established by military specification are provided.

New and handoff calls control mechanisms are the key point to wireless cellular networks. In this paper, we present an adaptive algorithm for dynamic channel allocation scheme with guard channels and also with handoff calls waiting queue ensuring that handoff calls take priority over new calls. Our goal is to find better tradeoff between handoffs and new calls blocking probabilities in order to achieve more efficient channel utilization. Simpy is a Python based discrete event simulation system. We use Simpy to build our simulation models to get analytical data.

Objective To investigate the postural control factors influencing the automatic (reflex-controlled) and attentional (high cortical) factors on dual task.Methods We used a dual task model to examine the attentional factors affecting the control of posture, subjecting test subjects to vibration stimulation, one-leg standing and verbal or nonverbal task trials. Twenty-three young, healthy participants were asked to stand on force plates and their centers of pressure were measured during dual task trials. We acquired 15 seconds of data for each volunteer during six dual task trials involving varying task combinations.Results We observed significantly different sway patterns between the early and late phases of dual task trials, which probably reflect the attentional demands. Vibration stimulation perturbed sway more during the early than the late phases; with or without vibration stimulation, the addition of secondary tasks decreased sway in all phases, and greater decreases in sway were observed in the late phases, when subjects were assigned nonverbal tasks. Less sway was observed during the nonverbal task in a sequential study.Conclusion The attentional and automatic factors were analyzed during a sequential study. By controlling the postural control factors, optimal parameters and training methods might be used in clinical applications.

In this paper, we propose a resource allocation and Tx power control scheme, called resource allocation and power control (RAPC) in an LTE-Advanced device-to-device (D2D) network. In the proposed scheme, the macro base station (mBS) and D2D senders (D2DSs) service macro user equipment (mUEs) and D2D receivers (D2DRs) use the different frequency bands and Tx power chosen as D2D links’ locations in inner and outer zones to reduce interference substantially. We analyze and compare the proposed scheme and random resource allocation (RRA) scheme with fractional frequency reuse (FFR) systems in terms of the system throughput for DL and outage probability according to the number of D2D user’s (D2DR) traffic density. Simulation results show that the RAPC scheme has better performance than the random resource allocation (RRA) scheme performance in terms of the system throughput and outage probability for mUEs and D2DRs.

In this letter, optimal power control and time resource allocation schemes are considered in wireless relay network, which two users communicate with each other assisted by an energy harvesting relay that gathers energy from the received signal by applying a time switching scheme and forwards the received signal by using the harvesting energy. It is focused on the optimal power control and time resource allocation for the system to cooperate the power transfer and information transmission among three nodes in Decode-and-Forward (DF) mode. Specifically, time ratios for three transmission phases are firstly investigated. Then, we proposed to formulate the power optimization problem with energy constraint. Since the transmission duration of the transmitter is not fixed, the energy constraint instead of power constraint is more reasonable to evaluate the system performance. Through some variables substitution, we demonstrate that it is a convex problem. It can be solved efficiently by convex optimization technology. Simulation results are demonstrated that the performance of the proposed algorithm outperform than the fixed and semi-fixed traditional methods.

This paper proposes a fuzzy logic control based dynamic channel allocation (DCA) to ECMA-368 based WiMedia UWB networks, which aims to support mixed high-quality video traffic and shipboard control data traffic with high reliability and priority as well. The DCA method applied in this paper is to flexibly vary the portions of time slots of either the prioritized contention access (PCA) or the distributed reservation protocol (DRP), according to traffic condition and priority. Furthermore, the proposed DCA with the fuzzy logic control algorithm can intelligently divide the portion of time slots and allocate channels to both PCA and DRP, resulting in support of both HD-video stream services and shipboard instrument control data. It is shown that the proposed fuzzy logic controlled DCA with WiMedia UWB MAC protocol can provide reliable mixed video and shipboard control data traffic as well, and it can provide better performance of the aggregated throughput than that of without fuzzy logic control algorithm.

In this paper, we propose a joint distributed rate control algorithm and distributed resource allocation algorithm in multiradio multichannel multihop wireless networks with network coding. Our formulation provides a method of finding active links from the source to the destination and utilizing the resources from the available ones in order to maximize the network utility. Distributed schemes are used to approximate the upper bound within the feasible solution region of the optimization problem. The performance evaluation results show that the proposed scheme can effectively exploits multiple radios and channels.

A technical prerequisite for a converged network is a common service delivery platform that is independent from the access networks below. The 3GPP SIP-based IP Multimedia Subsystem is defined for this purpose. By specification, IMS is the first implementation towards reaching converged communications which allows users to communicate with video, audio and multimedia content, via any fixed, mobile and wireless access network type, with controllable QoS. This article analyses the mechanisms of resource allocation and admission control by employing logical interfaces that carry SIP messages.

It is the common issue for all of countries that lots of safety risk accidents happen in large scale engineering projects. To save cost, generally, no enough resource is booked, or not very qualified resource is selected, which is one of the import safety risk factors in large scale engineering projects. But less scientific strategies are available to balance between safety risk values and safety risk investment. In the large scale engineer safety risk management filed, currently most of methods are qualitative, so it is a hot and difficult topic that constructs a quantitative model for practical problems, especially based on optimal control theory. In this paper, we will take both advantages of maximum principle and dynamic programming to solve the large scale engineering project safety risk issues caused by resource numbers and resource quality. Firstly, by maximum principle, establishes safety risk model considering resource numbers, and give iterative steps of the gradient descent method for numerical solution; Secondly, by dynamic programming, establishes safety risk economic model which takes into account the quality of resource; In the end, both the models are validated in one practical equipment case by combining the advantages of each algorithms .

This paper considers WiMedia UWB network based wireless ship area network (WSAN) so as to support high-quality multimedia video data services and important shipboard control data. In this paper, prioritized contention access (PCA) and distributed reservation protocol (DRP) based on WiMedia UWB (ECMA- 368) MAC protocols are combined and proposed to support mixed high-quality video traffic and shipboard control data traffic applying varying DRP and PCA data periods according to channel condition and link parameter ptimization. It is shown that the proposed dynmaic channel allocation of WiMedia UWB MAC protocol can provide reliable mixed video and shipboard control data traffic as well.

현재 차량 내 네트워크에서 주로 쓰이는 CAN 프로토콜은 네트워크 내에 다수의 노드가 연결되어 동작하는 경우 우선순위가 낮은 메시지의 전송지연이 심각하게 발생할 수 있다. 이를 해결하기 위해 다양한 제어 방법들이 제안되어 시험되고 있는데, 본 논문에서는 동적 ID 할당 기법을 연료전지 하이브리드 자동차 네트워크 시스템에 적용하여 각 장치들 간의 메시지 전송 지연문제를 해결 하며, 또한 이로 인해 발생하는 차량 내 네트워크 시스템의 수행 주기 변화의 문제점을 샘플링 주기 결정 기법을 이용하여 효율적으로 해결하였다.

To improve efficiency of inter-module communication in vehicle, a new CAN-based control system and scheduling algorithm which uses dynamic ID allocation and sampling period decision method is proposed. Experiments are conducted to evaluate the properties of the proposed system using a hardware simulator.

지금까지 논의된 지역간 재정조정은 지역간 자원배분의 효율성과 형평성에만 초점을 맞추었다. 하지만 본고는 향후 지역간 재정조정 과정에서 지역간 자원배분의 효율성과 형평성뿐 아니라 지역간 경제력의 균형과 지역경제성장의 극대화를 추구할 필요성을 제기하였다. 그리하여 지역간 경제력 격차를 조정하고 지역경제성장을 극대화하기 위해서는 지방재정배분 과정에서 지역간 경제연관구조를 고려해야 한다는 논리적 근거를 최적제어기법을 적용한 수치실례를 통해 입증하고 그 개선방향을 모색하였다. 그 결과 지역경제 규모가 큰 지역이 작은 지역에게 부(-)의 성장 파급효과를 미칠 경우, 작은 지역이 동일 목표를 달성하는데 필요한 지방재정 액은 급격히 증가함과 동시에 규모가 큰 지역의 지방재정 액도 상당 규모로 감소하였다. 이는 지역경제력 규모가 작은 지역에 과다 배분되는 지방재정 액을 절감하고 규모가 큰 지역의 필요 성장마저 저해하는 악순환을 타파하기 위해서는 지역상생형 경제구조로 개선해야함을 시사하고 있다.

So far, literature has focused only on the efficiency and equity of resource allocation among regions in the process of local finance adjustment. However, this paper additionally raises the necessity to pursue the correction of regional economic inequality and the maximization of regional economic growth. In order to adjust regional economic inequality and to maximize regional economic growth, we provide the rationale for considering inter-regional economic linkages in the process of allocating local finance. We solve the numerical examples using optimal control techniques to find methods to improve local finance adjustment. If a large regional economy has a negative growth effect upon a small region, the amount of local expenditure required for a small region to achieve the same goal sharply increases as well. This suggests that the economic link among regions should be restructured into a win-win relationship in order to overcome the vicious cycle of over-allocation of local financial resources in small regions.

For spacecraft attitude control, reaction wheel (RW) steering laws with more than three wheels for three-axis attitude control can be derived by using a control allocation (CA) approach.1-2 The CA technique deals with a problem of distributing a given control demand to available sets of actuators.3-4 There are many references for CA with applications to aerospace systems. For spacecraft, the control torque command for three body-fixed reference frames can be constructed by a combination of multiple wheels, usually four-wheel pyramid sets. Multi-wheel configurations can be exploited to satisfy a body-axis control torque requirement while satisfying objectives such as minimum control energy.1-2 In general, the reaction wheel steering laws determine required torque command for each wheel in the form of matrix pseudo-inverse. In general, the attitude control command is generated in the form of a feedback control. The spacecraft body angular rate measured by gyros is used to estimate angular displacement also.? Combination of the body angular rate and attitude parameters such as quaternion and MRPs(Modified Rodrigues Parameters) is typically used in synthesizing the control command which should be produced by RWs.¹ The attitude sensor signals are usually corrupted by noise; gyros tend to contain errors such as drift and random noise. The attitude determination system can estimate such errors, and provide best true signals for feedback control.? Even if the attitude determination system, for instance, sophisticated algorithm such as the EKF(Extended Kalman Filter) algorithm?, can eliminate the errors efficiently, it is quite probable that the control command still contains noise sources. The noise and/or other high frequency components in the control command would cause the wheel speed to change in an undesirable manner. The closed-loop system, governed by the feedback control law, is also directly affected by the noise due to imperfect sensor characteristics. The noise components in the sensor signal should be mitigated so that the control command is isolated from the noise effect. This can be done by adding a filter to the sensor output or preventing rapid change in the control command. Dynamic control allocation(DCA), recently studied by Harkegard, is to distribute the control command in the sense of dynamics⁴: the allocation is made over a certain time interval, not a fixed time instant. The dynamic behavior of the control command is taken into account in the course of distributing the control command. Not only the control command requirement, but also variation of the control command over a sampling interval is included in the performance criterion to be optimized. The result is a control command in the form of a finite difference equation over the given time interval.⁴ It results in a filter dynamics by taking the previous control command into account for the synthesis of current control command. Stability of the proposed dynamic control allocation (CA) approach was proved to ensure the control command is bounded at the steady-state. In this study, we extended the results presented in Ref. 4 by adding a two-step dynamic CA term in deriving the control allocation law. Also, the strict equality constraint, between the virtual and actual control inputs, is relaxed in order to construct control command with a smooth profile. The proposed DCA technique is applied to a spacecraft attitude control problem. The sensor noise and/or irregular signals, which are existent in most of spacecraft attitude sensors, can be handled effectively by the proposed approach.

Control allocation is an important part of a system. It implements the function that map the desired command forces from the controller into the commands of the different actuators. In this paper, the authors present an approach for solving constrained control allocation problem in vessel system by using multi-parametric quadratic programming (mp-QP) algorithm. The goal of mp-QP algorithm applied in this study is to compute a solution to minimize a quadratic performance index subject to linear equality and inequality constraints. The solution can be pre-computed off-line in the explicit form of a piecewise linear (PWL) function of the generalized forces and constrains. The efficiency of mp-QP approach is evaluated through a dynamic positioning simulation for a vessel by using four tugboats with constraints about limited pushing forces and found to work well.

In this paper, we propose a new approach to ship berthing by using autonomous tugboats. This approach overcomes the nominal effectiveness problem of actuators at slow speed maneuvering to improve the ship operation in the harbor area. The proposed SMC gave us a sliding mode control law that guarantees position tracking with desired velocity in the presence of environmental disturbances. The thrust allocation problem is solved by using a redistributed pseudo-inverse (RPI) algorithm to determine the thrust and direction of each individual tugboat. The main goal of RPI method is to minimize the power supplied to tugboats and increase their controllability. The proposed approach has been simulated on a model of a supply vessel with excellent results.

In this paper, we present a co-design methodology of dynamic optimal network-bandwidth allocation (ONBA) and adaptive control for networked control systems (NCSs) to optimize overall control performance and reduce total network-bandwidth usage. The proposed dynamic co-design strategy integrates adaptive feedback control with real-time scheduling. As part of this co-design methodology, a "closed-loop" ONBA algorithm for NCSs with communication constraints is presented. Network-bandwidth is dynamically assigned to each control loop according to the quality of performance (QoP) information of each control loop. As another part of the co-design methodology, a network quality of service (QoS)-adaptive control design approach is also presented. The idea is based on calculating new control values with reference to the network QoS parameters such as time delays and packet losses measured online. Simulation results show that this co-design approach significantly improves overall control performance and utilizes less bandwidth compared to static strategies.

Cross-layer design is a concept, which captures the dependencies and interactions and enables information sharing among layers in order to improve the network performance and security. There are two key challenges in wireless networks, lossy features of links and power assumption of network nodes. Cross-layer design of congestion control and power allocation in wireless lossy networks has been studied in the existing literature; however, there has been no contribution proposed in the literature that exploits the path diversity. In this paper, we are motivated to develop a cross-layer design of congestion control and power allocation, which takes into account lossy features of wireless links and transmission powers of network nodes and can be implemented in a distributed manner. Numerical simulation is conducted to illustrate the performance of our proposed algorithm and the comparison with current alternative approaches.

This paper proposes a novel cooperative control strategy for voltage restoration and power management in DC microgrids based on the DC bus signaling (DBS) method. In the conventional DBS method, the operation mode is determined according to the voltage deviation. Thus, it is difficult to achieve voltage restoration. To overcome this problem, the conventional DBS method is modified by applying the total power of dispatchable units (DUs) to identify the operation mode instead of the voltage deviation. As a result, the average output voltage of the DUs is restored to its nominal value in all of the operation modes without difficulty. In addition, accurate power sharing is achieved regardless of the line impedance or load change by regulating the voltage magnitude using a simple PI controller. Furthermore, the control performance is theoretically analyzed using a small signal analysis to evaluate the stability of system. The proposed method is validated with results from a lab scale experiment.

클라우드 컴퓨팅은 낭비되는 컴퓨팅 자원들을 클라우드 서버를 통해 처리 가능한 고사양의 컴퓨팅 환경을 제공한다. 클라우드 컴퓨팅은 노드에 가상머신을 할당하여 사용자의 요구를 처리하는데, 노드의 공정한 사용과 사용자 요구사항 충족을 위해 FCFS, 라운드 로빈 등의 가상머신 할당 기법을 사용한다. 본 논문에서는 노드의 효율적인 사용을 위해 클라우드 서버에서 관리 중인 노드들의 성능을 미리 분석하고 가상머신을 할당 혹은 재할당시 분석된 결과를 바탕으로 할당할 노드를 선택하고 관리하는 시스템을 제안한다. 노드의 성능을 미리 분석함으로서 할당을 위한 가상머신 선택을 위한 연산을 줄여 신속하고 효율적인 가상머신 할당이 가능하다.