• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.469-473
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• 1992

The conventional closed-loop guidance commands are generated from a simplified point mass model for real time operations. In real situations, the generated guidance commands are applied to the original rigid body. This can cause attitude instability of the vehicle. In this paper, in order to solve the attitude instability problem in the guidance system sense, the influence of the guidance commands on a launch vehicle attitude is derived quantitatively. The checking method of the attitude stability conditions that uses Liapunov theorem is proposed, and the attitude stabilizing method is also proposed. The attitude stability is accomplished by subtracting the influence of the guidance commands that destabilize the vehicle attitude. The closed-loop guidance commands generated from the simplified point mass model may destabilize the vehicle attitude, which is verified through simulations. In this case, the vehicle attitude can be always stabilized with the proposed attitude stabilizing method without additive fuel consumption.

• 제어로봇시스템학회논문지
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• 제14권12호
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• pp.1253-1259
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• 2008

This paper presents a landing controller and guidance law for net-recovery of fixed-wing unmanned aerial vehicles. A linear quadratic controller was designed using the system identification result of the unmanned aerial vehicle. A pursuit guidance law is applied to guide the vehicle to a recovery net with imaginary landing points on the desired approach path. The landing performance of a pure pursuit guidance, a constant pseudo pursuit guidance, and a variable pseudo pursuit guidance is compared. Numerical simulation using an unmanned aerial vehicle model was performed to verify the performance of the proposed landing guidance law.

• 대한조선학회논문집
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• 제42권4호
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• pp.299-306
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• 2005

To determine a guidance law which is suitable for Target Tracking System(TTS) of an underwater vehicle, the performance (hitting probability) of TTS were calculated with four different guidance schemes, considering underwater vehicle's manoeuvrability and characteristics of seeking equipment such as sonar To evaluate the performance of TTS with each guidance law, numerous target-tracking simulations of underwater vehicle were performed under the condition of target's various motion scenario. Furthermore, the effect of sonar characteristics to the performance of guidance law in TTS was studied by changing parameters of sonar such as frequency of ping and detecting error of target. The pursuit-tail guidance law showed the best performance among four different guidance laws. Complex motion of target from straight line to turning circle and zigzag movement, low frequency of sonar ping and large detecting error of target decreased the hitting probability.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.533-539
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• 1993

In this paper, two side-attack guidance laws for an underwater vehicle are considered. In order to find the guidance command, we first make use of the optimal guidance law with terminal impact angle constraint. Secondly, the optimal solution of tracking problem is used. This paper shows some brief theory which is used in deriving the side-attack guidance laws, and the method of computing these guidance laws. Simulations on underwater vehicle for a constant moving target prove that the suggested side-attack guidance laws have enhanced side attack performance over the optimal guidance law with miss distance weighting only. Furthermore, from simulation results. we conclude that the guidance law using the optimal solution of tracking problem is more efficient for the side-attack guidance than the optimal guidance law with terminal impact angle constraint.

• Journal of Biosystems Engineering
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• 제31권6호
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• pp.489-499
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• 2006

Since the application of chemicals in confined spaces under the canopy of an orchard is hazardous work, it is needed to develop an autonomous guidance system for an orchard sprayer. The autonomous guidance system developed in this research could steer the vehicle by tracking an overhead guidance rail, which was installed on an existing frame structure. The autonomous guidance system consisted of an 80196 kc microprocessor, an inclinometer, two interface circuits of actuators for steering and ground speed control, and a fuzzy control algorithm. In addition, overhead guidance rails for both straight and curved paths were devised, and a trolley was designed to move smoothly along the overhead guidance rails. Evaluation tests showed that the experimental vehicle could travel along the desired path at a ground speed of 30 $\sim$ 50 cm/s with a RMS error of 5 cm and maximum deviation of less than 12 cm. Even when the vehicle started with an initial offset or a deflected heading angle, it could move quickly to track the desired path after traveling 2 $\sim$ 3 m. The vehicle could also complete turns with a curvature of 1 m. However, at a ground speed of 50 cm/s, the vehicle tended to over-steer, resulting in a zigzag motion along the straight path, and tended to turn outward from the projected line of the guidance rail.

• 제어로봇시스템학회논문지
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• 제7권2호
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• pp.173-182
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• 2001

Ascent trajectory optimization and optimal explicit guidance problems for a satellite launch vehicle in a 2-dimensional pitch plane are studied. The trajectory optimization problem with boundary conditions is formulated as a nonlinear programming problem by parameterizing the pitch attitude control variable, and is solved by using the SQP algorithm. The flight constraints such as gravity-turn are imposed. An optimal explicit guidance algorithm in the exoatmospheric phase is also presented, the guidance algorithm provides steering command and time-to-go value directly using the current states of the vehicle and the desired orbit insertion conditions. To verify the optimality and accuracy of the algorithm simulations are performed.

• 전기학회논문지
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• 제60권6호
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• pp.1229-1238
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• 2011

This paper deals with the lateral dynamic model of an all-wheel steered articulated vehicle to design a guidance controller. Nonlinear dynamic model of articulated vehicle is developed by complementing the model about the BRT system of California PATH in U. S. A. and the Phileas system of the APTS in Netherlands. Linear lateral dynamic model has been derived from the nonlinear dynamic model under some assumptions associated with the driving conditions. To design a guidance controller, we derive a transfer function that is steering angle as input and lateral acceleration as output from the linear lateral dynamic model by applying the parameter of vehicle that is developed by Korea Railroad Research Institute. To validate the dynamic model, nonlinear dynamic model has been compared with a vehicle model that has been programmed in ADAMS, and linear dynamic model has been compared with a nonlinear dynamic model under sime assumptions.

• 대한전기학회논문지:전력기술부문A
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• 제48권7호
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• pp.881-888
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• 1999

Target pointing guidance steers a vehicle to point at a target point at a given range Rs. In this paper, vehicle's motions relative to the target point are modeled by differential equations. Then a target pointing guidance law is derived using optimal control theories. In addition, it is shown that the proposed guidance law can achieve the goal of target pointing guidance whatever initial headings are.

• 한국지능시스템학회논문지
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• 제21권4호
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• pp.430-435
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• 2011

본 논문에서는 상대위치인식과 자계기반 안내를 결합한 무인주행 차량의 주행기법을 제안한다. 자계기반 주행은 이동하는 경로에 자계가 항상 계측되면 안정적인 자율주행이 가능하다. 하지만 외부요인으로 인해 자계가 검출되지 않으면 예측 불가능한 상황이 발생하는 단점이 있다. 따라서 상대위치인식을 이용한 무인주행을 통해 자계가 검출되지 않는 구간을 극복하는 방법을 제안하였다. 제안한 방법의 유용함을 검증하기 위하여 차량을 개발하고 자계기반 주행 실험하였다. 또한 자계가 없는 구간에서의 상대항법을 이용한 무인주행 실험을 실시하고 결과를 분석하여 문제점 극복의 가능성을 확인하였다.

• 전기학회논문지
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• 제57권11호
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• pp.2074-2079
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• 2008

This paper presents a software toolbox with $Matlab^{(R)}$ developed for the various performance analysis of an automatic guidance system of the Bimodal Tram. The Bimodal Tram is a new kind of transportation vehicle which could be an all-wheel steered multiple-articulated vehicle. This vehicle has to be equipped with an automatic guidance, traction/braking, and docking system, In the stage of developing such a system, its validities and performances should be verified under various operation conditions. For the purpose of doing these things through simulation, this toolbox has been developed and demonstrated well by applying it to the KRRI model.