• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.688-696
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• 2017

This paper presents an integrated roll-pitch-yaw autopilot using an equivalent based sliding mode control for skid-to-turn nonlinear time-varying missile system with lumped disturbances in its six-equations of motion. The considered missile model are developed to integrate the model uncertainties, external disturbances, and parameters perturbation as lumped disturbances. Moreover, it considers the coupling effect between channels, the variation of missile velocity and parameters, and the aerodynamics nonlinearity. The presented approach is employed to achieve a good tracking performance with robustness in all missile channels simultaneously during the entire flight envelope without demand of accurate modeling or output derivative to avoid the noise existence in the real missile system. The proposed autopilot consisting of a two-loop structure, controls pitch and yaw accelerations, and stabilizes the roll angle simultaneously. The Closed loop stability is studied. Numerical simulation is provided to evaluate performance of the suggested autopilot and to compare it with an existing autopilot in the literature concerning the robustness against the lumped disturbances, and the aforesaid considerations. Finally, the proposed autopilot is integrated in a six degree of freedom flight simulation model to evaluate it with several target scenarios, and the results are shown.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.98-106
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• 2011

This paper is summarized for designing launch vehicle autopilot structure with attitude angle command from guidance algorithm and for evaluating performance of autopilot using launch vehicle six-degree of freedom simulation program. The suggested autopilot has heritage from KSR-III/KSLV-I upper stage autopilot designing experience, and it has two design point. The one is, it must have same performance with KSR-III/KSLV-I upper stage autopilot, the other is, it must be simple autopilot structure and use low number of variable to apply on-board system. It is evaluated the performance using launch vehicle six-degree of freedom simulation program in case of roll maneuvering and no roll control flight condition.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1492-1495
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• 1996

In this paper, an approach to autopilot design based on the robust nonlinear dynamic inversion method is proposed. Both unknown parameters and uncertainty bounds are estimated and parameter estimates are used in the fast inversion. Furthermore, to get more robustness slow inversion is incorporated with MRAC(Model Reference Adaptive Control) and sliding mode control where the estimates of uncertainty bounds are used. The proposed method is applied to the pitch autopilot design of a missile system and excellent performance is shown via computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.40.3-40
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• 2002

Unmanned Aerial Vehicle(UAV) needs autonomous flight capability to accomplish various mission objectives. For this objective, the autopilot is a key element in the UAV system design. The principal goal of autopilot is to guide the aircraft under varying external disturbances throughout the mission phases. The external disturbances include gravity effect, wind gust, and other unexpected obstacles. The gust affects the aircraft flight performance to a significant extent. UAV's low speed, light weight, and the absence of human judgment makes un predictable gust more dangerous. Autopilot design in general takes the gust effect into account to satisfy flight performance requirement. In this study..

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.82-86
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• 1989

In this paper, digital autopilot design methods are investigated and a new method is suggested in order to improve existing problems. The method is based on .delta. transform (1) and overcome numerical problems occurring in the process of discretization. We illustrate design procedures using .delta. transform and suggest a hardware and software structure for digital autopilot implemented by microprocessor.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.653-657
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• 1990

Since linearized equations of notion have much modelling errors, robust controller for disturbances and noises Is necessary for autopilot. In this paper, notion equations for underwater vehicle with six degree-of-freedom are derived and linearized. And robust autopilot for this system is designed by using LQG/LTR methodology.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.547-549
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• 1987

The purpose of this paper is to present an efficient and practical method for a Hissle autopilot design problem. The method emphasizes on the use of a modern design technique to classical flight control specifications and the trade-off between dynamic performance and robustness of the Missle autopilot control system.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1864-1866
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• 1997

Uncertainties in the aerodynamic coefficients or time delay effects in implementing an autopilot algorithm can make a Flight Control System(FCS) unstable. When a FCS enters unstable state, the actuator or sensor limiters in FCS make the unstable system not diverge but be in the state of stable limit cycle. If an autopilot recognize the FCS to be in the stable limit cycle phenomenon, it woudl be better to adjust autopilot gains to stabilize the FCS. A novel method to stabilize a FCS using parameter estimation and maintenance of given phase margin is proposed. The method is applied to roll control loop and verified its performance.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.3
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• pp.231-238
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• 2002

In this paper, we present a new approach to autopilot design for skid-to-turn missiles which may have severe aerodynamic cross-couplings and nonlinearities with angle of attack. The model of missile motion is derived in the maneuver plane and, based on that model, pitch, yaw, and roll autopilot are designed. They are composed of a nonlinear term which compensates for the aerodynamic couplings and nonlinearities and a linear controller driven by the measured outputs of missile accelerations and angular rates. Besides the outputs, further information such as Mach number, dynamic pressure, total angle of attack, and bank angle is required. With the proposed autopilot and simple estimators of bank angle and total angle of attack, it is shown by computer simulations that the induced moments and some aerodynamic nonlinearities are properly compensated and that the performance is superior to that of the conventional ones.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.8
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• pp.633-638
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• 2002

We study how the missile autopilot with three loop acceleration structure is related to the aerodynamic characteristics. First, the relationships between the response characteristics of wingless-tail controlled missile and aerodynamics are derived. Next the maximum allowable performance limit of autopilot and the design direction for a missile shape are indicated using the property of zero. The method proposed in this paper may give a help to the missile autopilot system design and determination of the shape of aerodynamic. Also, the validity of proposed method is demonstrated via numerical example.