• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.137-144
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• 2006

The objective of this paper is to present trajectory guidance and control system with a dynamic inversion for a small unmanned aerial vehicle (UAV). The UAV model is expressed by fixed-mass rigid-body six-degree-of-freedom equations of motion, which include the detailed aerodynamic coefficients, the engine model and the actuator models that have lags and limits. A trajectory is generated from the given waypoints using cubic spline functions of a flight distance. The commanded values of an angle of attack, a sideslip angle, a bank angle and a thrust, are calculated from guidance forces to trace the flight trajectory. To adapt various waypoint locations, a proportional navigation is combined with the guidance system. By the decision logic, appropriate guidance law is selected. The flight control system to achieve the commands is designed using a dynamic inversion approach. For a dynamic inversion controller we use the two-timescale assumption that separates the fast dynamics, involving the angular rates of the aircraft, from the slow dynamics, which include angle of attack, sideslip angle, and bank angle. Some numerical simulations are conducted to see the performance of the proposed guidance and control system.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.3
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• pp.281-292
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• 2014

We propose a novel cooperative guidance law design method based on the finite time disturbance observer (FTDO) for multiple near space interceptors (NSIs) with impact time control. Initially, we construct a cooperative guidance model with head pursuit, and employ the FTDO to estimate the system disturbance caused by target maneuvering. We subsequently separate the cooperative guidance process into two stages, and develop the normal acceleration command based on the super-twisting algorithm (STA) and disturbance estimated value, to ensure the convergence of the relative distance. Then, we also design the acceleration command along the line-of-sight (LOS), based on the nonsingular fast terminal sliding mode (NFTSM) control, to ensure that all the NSIs simultaneously hit the target. Furthermore, we prove the stability of the closed-loop guidance system, based on the Lyapunov theory. Finally, our simulation results of a three-to-one interception scenario show that the proposed cooperative guidance scheme makes all the NSIs hit the target at the same time.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.1
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• pp.96-106
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• 2002

Many modern guided weapon systems employ sophisticated target sensors as well as powerful computing systems. Due to such advanced features, they are required to achieve better guidance accuracy, and at the same time other guidance objectives for better weapon effectiveness and survivability. In this paper, we overview some of the technical considerations in such advanced guidance algorithm development, and briefly look at some related research works. More specifically, we discuss impact angle control, time-varying nature of the guidance system, time-to-go estimation, guidance loop stability, effect of autopilot lag and physical limitations in control variables, parasitic paths in guidance loops, etc. We also briefly look at some advanced concepts such as integrated guidance and control loop design, target adaptive guidance, guidance law development based on dual control concept, and terminal evasive maneuver.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.522-534
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• 2017

According to the characteristics of salvo attack for the multiple flight vehicles (MFV), the design of cooperative guidance law can be converted into the consensus problem of multi-vehicle system through the concept of multi-agent cooperative control. The flight vehicles can be divided into leader and followers depending on different functions, and the flight conditions of leader are independent of the ones of followers. The consensus problem of leader-follower multi-vehicle system is researched by graph theory, and the consensus protocol is also presented. Meanwhile, the finite time guidance law is designed for the flight vehicles via the finite time control method, and the system stability is also analyzed. Whereby, the guidance law can guarantee the line of sight (LOS) angular rates converge to zero in finite time, and hence the cooperative attack of the MFV can be realized. The effectiveness of the designed cooperative guidance method is validated through the simulation with a stationary target and a moving target, respectively.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.13 no.4
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• pp.307-314
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• 2013

We designed and implemented a fork-type automatic guided vehicle (AGV) with a laser guidance system. Most previous AGVs have used two types of guidance systems: magnetgyro and wire guidance. However, these guidance systems have high costs, are difficult to maintain with changes in the operating environment, and can drive only a pre-determined path with installed sensors. A laser guidance system was developed for addressing these issues, but limitations including slow response time and low accuracy remain. We present a laser guidance system and control system for AGVs with laser navigation. For analyzing the performance of the proposed system, we designed and built a fork-type AGV, and performed repetitions of our experiments under the same working conditions. The results show an average positioning error of 51.76 mm between the simulated driving path and the driving path of the actual fork-type AGV. Consequently, we verified that the proposed method is effective and suitable for use in actual AGVs.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.4
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• pp.638-647
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• 1994

This paper describes the real time Hardware-In-the Loop Simulation(HILS) that is an efective tool for design, testing and performance evaluation of the guidanc eflight system. The real time HILS was performed by using a 3-axis flight motion simulator, real time computer, I/O system and flight control system hardware along with the assumed flight trajectory of the guidance flight system. Also, we proved the validity of the real time HILS is the guidance flight system by comparing its simulation results with the software simulation data and telemetry data.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.6
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• pp.478-488
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• 2003

A guidance scheme that is suitable for controlling the aircraft flight path is proposed. The concept of miss distance which is commonly used in the missile guidance laws, and Lyapunov stability theorem are effectively combined to obtain the aircraft's trajectory-tracking guidance law. Guidance commands are given in terms of speed and flight path angles, but they perfectly reflect any position and velocity errors between real aircraft trajectory and reference one. The proposed guidance law is easily integrated into the existing flight control system. The new guidance law was extensively tested with various mission scenarios and the fully nonlinear 6-DOF aircraft model. Furthermore, the new guidance law was compared with previous guidance schemes in nonlinear simulation. Results from the numerical simulation show that the proposed guidance law yields better performance than previous ones.

• International Journal of Railway
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• v.8 no.1
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• pp.21-29
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• 2015

This study focuses on the performance enhancement of the levitation and guidance control system in urban and medium-to high-speed magnetic levitation trains. A levitation control system, which is currently being tested in Yeongjongdo, is a single controller that is neither designed nor produced on the basis of redundancy. Hence, vehicular stability and reliability should be improved for the situation in which levitation failure occurs because of a breakdown in a controller during vehicle operation. In addition, the control system should be developed to control electromagnetic levitation considering changes in normal force according to changes in the driving force of the propulsion system.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.3
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• pp.366-377
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• 2016

This paper presents a vision-based guidance method that allows a fixed-wing aircraft to orbit around a target at a given radius. The guidance method uses a simple formula that regulates a relative side-bearing angle estimated by a vision system. The global asymptotic stability of the associated guidance law is demonstrated, and a linear analysis is performed to facilitate the proper selection of the relevant control parameters. A flight experiment is presented to demonstrate the feasibility and performance of the proposed guidance method.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.4
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• pp.430-435
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• 2011

In this paper, a navigation technology of an unmanned vehicle using relative localization and magnetic guidance is proposed. Magnetic guidance system had been developed as a robust autonomous driving technology as long as magnetic fields on the path are detected. Otherwise, if magnetic fields were not detected due to some reasons, the vehicle could not drive. Therefore, in order to overcome the drawback, we propose that relative localization would be combined to magnetic guidance system. To validate the usefulness of the proposed method, a robotic vehicle was set up with the magnetic guidance system and the relative localization. In addition, the unmanned driving test was realized on the road without the magnetic fields so that the proposed method is verified by the experiment.