• 로봇학회논문지
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• 제8권3호
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• pp.173-178
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• 2013

We present six-degree-of-freedom (6DoF) haptic rendering algorithms using translational ($PD_t$) and generalized penetration depth ($PD_g$). Our rendering algorithm can handle any type of object/object haptic interaction using penalty-based response and makes no assumption about the underlying geometry and topology. Moreover, our rendering algorithm can effectively deal with multiple contacts. Our penetration depth algorithms for $PD_t$ and $PD_g$ are based on a contact-space projection technique combined with iterative, local optimization on the contact-space. We circumvent the local minima problem, imposed by the local optimization, using motion coherence present in the haptic simulation. Our experimental results show that our methods can produce high-fidelity force feedback for general polygonal models consisting of tens of thousands of triangles at near-haptic rates, and are successfully integrated into an off-the-shelf 6DoF haptic device. We also discuss the benefits of using different formulations of penetration depth in the context of 6DoF haptics.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.106.6-106
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• 2001

In this paper, a four-degree-of-freedom non-linear model is developed to study the dynamic response of vehicle that is caused by the disturbance from the road. The chaotic vibration of the model is investigated with numerical simulation. The model displays complicated dynamic responses including harmonic motions and chaos. It is found that changing of the damping coefficients of the system can eliminate the chaotic response.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
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• pp.129-131
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• 2000

The moving vehicle with disturbances has the 6 degree of freedom motion in the pitching, Yawing, and rolling directions of two independent axes. The control system in such a moving vehicle has to perform disturbance rejection. This paper present PID controller with disturbance rejection function, low sensitivity filter and notch filter for bending frequency rejection. The performance of a designed system has been certified by the simulation and experiment and experiment results.

• 한국자동차공학회논문집
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• 제7권6호
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• pp.91-105
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• 1999

Dynamic simulation techniques are developed to analyze the shift characteristics of vehicle powertraisn with automatic transmission. In this study, the mathematical modeling of powertrain components such as engine , clutch system, planetary gear system and road load , is presented for the simulation. The clutch engagement condition, which determines the degree of freedom for the system, is also proposed .By using a detailed nonlinear model of torque converter, it is possibile to accurately analyze the extremely transient state such as the shift. Dynamo-based experiments are carried out to prove the validity of the proposed simulation techniques. Using the developed simulation program, the effects of the dynamic design variables and the control conditions , focused on the shift, are evaluated to improve the driving comforability.

• 한국시뮬레이션학회논문지
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• 제8권4호
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• pp.25-31
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• 1999

To analyze the impulsive response of a motorcycle helmet, a simulation is performed using the finite element method. Based upon the simulation result, an equivalent one degree of freedom vibrational system is adapted, and transient impulsive responses are analysed to investigate the influence of engineering parameters such as damping, natural frequency, and impact velocity on the impulsive response of the helmet. Maximum gravitational acceleration reduces as the damping factor value increases. When the damping factor value is around 0.6 or larger, the maximum acceleration does not change. With respect to the natural frequency and the impact velocity, it increases linearly. The relationship between head injury criterion(HIC) and maximum gravitational acceleration is also presented. The scheme of this study is expected to be utilized to economize the design process of high quality motorcycle helmets.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.47-54
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• 2003

The rotating of rotatory unit with its structural unbalance mass and laundry is making the main vibration problem in a vertical axis washing machine. For reducing vibration problem total washing system hung on the case by its suspension system which is constitute of spring, damper and suspension bar and hydraulic balancer is attached at the upper rim of spin basket. In this paper, we make the dynamic model of washing system of its rigid body motions by 6 degree of freedoms. Hydraulic balancer is modeled by one degree of freedom like auto ball balancer. Elastic motions of washing system have found by method of analytic, experimental and FEM. And we consider first bending mode of each suspension bar and first circumferential mode of assy tub. So, the total washing system is modeled by 12 degree of freedoms. Equations of motion for total washing system have derived, and we perform the dynamic simulation tests.

• International Journal of Aeronautical and Space Sciences
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• 제11권2호
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• pp.69-79
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• 2010

This paper describes the experimental framework for the control system design and validation of a rotorcraft unmanned aerial vehicle (UAV). Our approach follows the general procedure of nonlinear modeling, linear controller design, nonlinear simulation and flight test but uses an indoor-installed multi-camera system, which can provide full 6-degree of freedom (DOF) navigation information with high accuracy, to overcome the limitation of an outdoor flight experiment. In addition, a 3-DOF flying mill is used for the performance validation of the attitude control, which considers the characteristics of the multi-rotor type rotorcraft UAV. Our framework is applied to the design and mathematical modeling of the control system for a quad-rotor UAV, which was selected as the test-bed vehicle, and the controller design using the classical proportional-integral-derivative control method is explained. The experimental results showed that the proposed approach can be viewed as a successful tool in developing the controller of new rotorcraft UAVs with reduced cost and time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권6호
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• pp.2859-2872
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• 2019

Interference alignment (IA) has been a powerful approach to achieve the maximum degree of freedom (DoF) for K users multiple-input-multiple-output (MIMO) interference channels. However, due to the feasibility constraint, aligning all the interference signals at each receiver is impractical for large K without symbol extension. In this paper, we propose two best-effort interference alignment (BEIA) schemes that the network selects the maximum number of interfering transmitters to align their signals given the feasibility conditions when each transmitter-receiver pair has a constant number of data streams. Besides, in case of not all interfering signals aligned at each receiver, an upper bound of the average throughput is derived. Simulation results show that the proposed schemes have superiority over the traditional methods, such as time division multiple access (TDMA) and cluster IA(CIA), in low and moderate signal-to-noise ratio (SNR) region in terms of average user throughput. In addition, the proposed max-min relative interference distance alignment scheme outperforms the proposed scheme of equal interfering transmitters number alignment in terms of both average user throughput and minimum user throughput.

• 한국해양공학회지
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• 제20권6호
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• pp.114-122
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• 2006

The most important thing in the container terminal is to handle the cargo effectively in a limited time. To achieve this objective, many strategies have been introduced and applied. If we consider the automated container terminal, it is necessary that the cargo handling equipment is equipped with more intelligent control systems. From the middle of the 1990s, an automated rail-mounted gantry crane (RMGC) and rubber-tired gantry crane (RTG) have been developed and widely used to handle containers in the yards. Recently, in these cranes, equipment like CCD cameras and sensors have been mounted to cope with the automated terminal environment. In this paper, we try to support the development of more intelligent automated cranes that make the cargo handling be performed effectively in the yards. For this plant, we ought to consider modeling, tracking control, anti-sway system design, skew motion suppressionand complicated motion control and suppressing problems. In this paper, the system modeling and a tracking control approach are discussed, based on a two-degree-of-freedom (2DOF) servo-system design. From the simulation results, the good control performance of the designed control system is evaluated.

• 한국지능시스템학회논문지
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• 제22권3호
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• pp.267-272
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• 2012

본 논문에서는 6 방향 자유도를 지닌 능동 자기베어링 시스템의 강인 디지털 퍼지 제어에 대한 내용을 다루고자 한다. 6방향 자유도에 대한 기본 모델은 회전자 구조와 원뿔형의 능동 자기베어링 시스템의 자기력 간의 상관관계에 의해 결정된다. 구성된 모델은 비선형 동적방정식으로 구성되기 때문에, 제어 목적을 달성하기 위한 제어 입력 신호의 설계가 어려우며, 외부 환경의 영향에 따른 시스템 파라미터 변화율에도 많이 민감한 편이다. 이를 보완하기 위하여, 획득한 동적방정식을 기반으로 TS 퍼지 모델에 기반 한 디지털 제어 목적에 적합한 구조로의 변환이 이루어진다. 여기서 말하는 제어 목적이란, 회전자의 회전을 외부의 물리적 접촉 없이 자기장의 힘만으로 동작하도록 베어링의 위치를 최대한 센터에 위치케 하는 것을 말한다. 본 논문에서는 6자유도를 지닌 능동 자기베어링 시스템의 비선형성에 대한 해석 방안으로 퍼지 모델링을 통해 시스템을 재해석하게 되며, 외부 파라미터 변화에 따른 대응을 위하여 강인 제어기 설계를 목적으로 한다. 제안된 강인 제어 알고리즘은 시뮬레이션 과정을 통해 검증된다.