• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.6
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• pp.505-516
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• 2011

The concept of the IGC(Integrated Guidance and Control) has been introduced to overcome the performance limit of the SGC(Separated Guidance and Control) loop. A new type of IGC with impact angle constraint has been proposed in this paper. Angle of attack, pitch angle rate, pitch angle and line of sight angle are considered as state variables. A controllability analysis and equilibrium point analysis have been carried out to investigate the control characteristic of the prposed IGC. The LQR(Linear Quadratic Regulator) has been adopted for the control law and detailed explanations about the adoption has been provided. The performance comparison between the IGC and the SGC has been carried out. The result of numerical simulations shows that the IGC guarantees better guidance performance than the SGC when the agile maneuver is needed for a specific guidance geometry.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.12
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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.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.1
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• pp.90-98
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• 2012

In this paper, the Integrated Guidance and Control (IGC) law is proposed for the Rotary Unmanned Aerial Vehicle (RUAV). The objective of the IGC law is to consider the nonlinear dynamic characteristics of the RUAV and to design a guidance law which takes into consideration the nonlinear relationship between kinematics and dynamics. In order to control the RUAV system, sliding mode control scheme is adopted. As the RUAV is an under-actuated system, a slack variable approach is used to generate the available control inputs. Through the Lyapunov stability theorem, the stability of the proposed IGC law is proved. In order to verify the performance of the IGC law, numerical simulations are performed for waypoint tracking missions.

• 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.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.115-118
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• 2003

In recent years, a receding horizon guidance law based on receding horizon control and optimal control is proposed. A receding horizon guidance law considering autopilot lag and constraints is proposed. The performance of receding horizon guidance law in the presence of target maneuvers is confirmed by simulation results. Through many simulation, a suitable selection of weighting matrix can minimize effect of disturbance, target acceleration. which is meaning of this paper.

• International Journal of Control, Automation, and Systems
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• v.6 no.3
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• pp.460-466
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• 2008

This paper deals with the stability analysis of a missile guidance loop employing an integrated proportional navigation guidance law. The missile guidance loop is formulated as a closed-loop control system consisting of a linear time-invariant feed-forward block and a time-varying feedback gain. Based on the circle criterion, we have defined the concept of absolute stability margins and obtained the gain and phase margins for the system assuming 1 st order missile/autopilot dynamics. The correlation between the absolute stability margins and the margins derived from the frozen system analysis is also discussed.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.1
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• pp.16-23
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• 2011

In this paper, nonlinear model predictive control (NMPC) is addressed to develop formation guidance for multiple unmanned aerial vehicles. An NMPC algorithm predicts the behavior of a system over a receding time horizon, and the NMPC generates the optimal control commands for the horizon. The first input command is, then, applied to the system and this procedure repeats at each time step. The input constraint and state constraint for formation flight and inter-collision avoidance are considered in the proposed NMPC framework. The performance of NMPC for formation guidance critically degrades when there exists a communication failure. In order to address this problem, the modified optimal guidance law using only line-of-sight, relative distance, and own motion information is presented. If this information can be measured or estimated, the proposed formation guidance is sustainable with the communication failure. The performance of this approach is validated by numerical simulations.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.3
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• pp.273-278
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• 2007

In this paper, a performance comparison between CLOS(Command to Line-of-Sight) guidance law and PN(Proportional Navigation) guidance law is made, based on a short range surface-to-air missile simulation program called KNUCLOS. This simulation program has a full nonlinear aerodynamic missile model, a tracker model for missile and target, and target model. According to the simulation results, the PN guidance law has a better performance than CLOS guidance law under various target speed.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.59-64
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• 1989

In this paper, the launch trajectory of the Japan scientific satellite M-3H-3 from launch to orbit injection is investigated. For the terminal conditions at a guidance target point, a guidance and control system is used. An open-loop and a closed-loop guidance schemes are used simultaneously. For the closed-loop guidance scheme, the velocity polynomial algorithm represented by the velocity difference between the target point and present velocity is used. A PD control system is used for activating gimbal type engines. The simulation result shows that all the terminal position and velocity conditions are satisfied and the trajectory for the M-3H-3 scientific satellite is reasonable.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.525-530
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• 2007

In this paper, a performance comparison between traditional TPN (true proportional navigation) guidance law and PPN(pure proportional navigation) guidance law is made, based on a short range surface-to-air missile simulation program. This simulation program has a nonlinear aerodynamic missile model, a roll stabilized autopilot, a nonlinear radar model, and a target model, According to the simulation results, the PPN guidance law has better performances than TPN guidance law under the condition of evasive target.