Guidance system

About: Guidance system is a research topic. Over the lifetime, 4282 publications have been published within this topic receiving 45964 citations.

Adaptive noise estimation for homing missiles

Abstract: The presence of a microprocessor makes it possible to utilize a digital filter to process the measurement data and obtain a state estimate to be used in a digital guidance system for tactical homing missiles. Of particular interest is the case of the short-range, air-to-air missile against a highly maneuverable target when angle-only measurements are available. A standard filter for processing the measurements is the extended Kalman filter, the performance of which depends on the value selected for the measurement covariance. It is shown that the performance of this filter can be improved by estimating the,measurement covariance. Two methods for doing so are investigated: the limited-memory and the weighted limited-memory.

On-board computer system for navigation, orientation and route optimization

Abstract: This paper presents a self-sufficient route guidance system for use in both trunk highway systems and inner-city street system.

Trajectory planning and optimal tracking for an industrial mobile robot

Abstract: This paper introduces a unified approach to trajectory planning and tracking for an industrial mobile robot subject to non-holonomic constraints We show (1) how a smooth trajectory is generated that takes into account the constraints from the dynamic environment and the robot kinematics; and (2) how a general predictive controller works to provide optimal tracking capability for nonlinear systems The tracking performance of the proposed guidance system is analyzed by simulation

Flight control system for the automatic landing flight experiment

Abstract: This paper discusses the flight control system developed for the Automatic Landing FLight Experiment, ALFLEX. ALFLEX is an experimental program conducted by the National Aerospace Laboratory and the National Space Development Agency of Japan in order to investigate the automatic landing technology for a future unmanned reentry space vehicle. The ALFLEX vehicle is a dynamically similar sub-scale model of the planned Japanese HII Orbiting Plane, HOPE. Since the HOPE program is in a preliminary conceptual design phase, the ALFLEX vehicle is a scaled model of one of the proposed configurations from 1992 research. The vehicle bare airframe is statically unstable in the pitch axis. In the lateral-directional axes, it has negative weather cock stability and strong dihedral effect, which introduce severe instability. The airframe's instability and the landing performance requirement drive the flight control system design to be one of the key technologies in the HOPE program. Since the vehicle's maximum L/D is approximately 4, it needs the same landing guidance technique as lifting body research vehicles and the Space Shuttle. This paper discusses the flight control design and the design methods applied to ALFLEX, and discusses lessons learned so far. The results from a preliminary flight test are briefly introduced. The series of automatic landing flights are scheduled for the middle of 1996, at Woomera, Australia, and will verify the guidance, navigation and control design. *Head, Control Qualification Lab., member AIAA Senior research engineer, Flight Research Division *^Research engineer, Control Research Division § Associate senior engineer, Winged Space Vehicle Office ^Engineer, Winged Space Vehicle Office *Asistant manager, Nagoya Aerospace Systems **Asistant manager, Nagoya Aerospace Systems Copyright © 1996 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Introduction Automatic landing technology for reentry space vehicles has a long history starting from the lifting body flight experiment at Edwards, California and the US Space Shuttle which demonstrates excellent technology achievement by NASA, e.g. References 1) to 6). Japan has a plan to develop a reentry space vehicle called HOPE, H II Orbiting Plane. Since the HOPE vehicle is unmanned and autonomous, it depends heavily on recent computer technology for flight control. The development project is still in the research phase, and the National Aerospace Laboratory and the National Space Development Agency of Japan are collaboratively conducting research programs in order to develop key technologies for the unmanned reentry vehicle. Among them, ALFLEX, Automatic Landing FLight Experiment, is a research program for the subsonic flight control and automatic landing technology. 7) Technology to be developed in the program breaks down as follows: (1) Integrated navigation system design for automatic landing (2) Automatic landing guidance system design (3) Subsonic flight control system design (4) Subsonic aerodynamics prediction and verification ALFLEX is a research program to study and evaluate design methods to match up-to-date hardware, such as modern computers, sensors and actuators. In the ALFLEX program, however, special hardware has not been developed. Instead, commercially proven avionics and off-the-shelf components are used. An exception is a pseudo-satellite differential GPS system (DGPS), for which the NASDA Tsukuba Space Center developed an onboard receiver and ground system. The DGPS, however, is not a flight critical component, and mainly gives engineering data for off-line analysis in order to use it for a future mission. ALFLEX is a scale model experiment of a future 15 ton reentry space vehicle, HOPE. The vehicle airframe is designed to be dynamically similar to the planned space vehicle. Also the guidance, navigation and control system for ALFLEX is designed to be as similar as possible. Fig. 1 shows three side views of the vehicle, and Fig. 2 shows the primary onboard equipment. The model's length scale is 37 %. In order for HOPE to land on a standard size runway, the runway length specification for ALFLEX is set as 1000 m. According to the similarity rule, where acceleration and mass density are equal for the real and model vehicles, the model's time scale is 60.8%, and the model's velocity scale is 60.8%. The model vehicle's mass should be 5.07%, corresponding to 760 kg; however, it is actually 796 kg, slightly in excess of this figure. The ALFLEX vehicle is released at an altitude of 1500m from a helicopter with a velocity of 46.3m/s (90kt) EAS, the maximum speed for the helicopter's hanging load flight capability. The release altitude is determined in order to achieve an equilibrium flight condition on the glide slope, where approximately 500m altitude will be lost before accelerating to the glide path speed of 84m/s EAS. Ground facilities support the experiment, such as a flight data monitoring system, laser tracker and tracking radar systems. The laser tracker provides reference data for the vehicle position to evaluate the navigation system. The tracking radar provides position data for flight safety. Japanese aerospace manufacturing companies participate in the ALFLEX program. Mitsubishi Heavy Industries Ltd. supports the development of the guidance, navigation and control (GNC) system for ALFLEX. Fuji Heavy Industries, Kawasaki Heavy Industries and TOSHIBA contribute to other parts of the program. The program commenced in 1992, and will be completed with flight tests at Woomera, Australia during 1996. Guidance, Navigation and Control system Design goal The experiment's design goal is safe automatic landing. Quantitative performance requirements are defined for the GNC system design. Automatic landing performance is evaluated by the following measures. 1) Position of touch down, Xtd, Ytd 2) Attitude at touch down, 4>, 0, *P 3) Velocity at touch down, VEAS, VGND 4) Vertical velocity at touch down, Vsink 5) Side-slip angle to the ground at touch down, 6) Pitch rate at nose gear touch down, Qtd(n) 7) Maximum lateral deviation in the ground roll, Ymax 8) Stop position of ground roll, Xstop Table 1 shows the design requirements for the above parameters. Table 1: Landing performances requirement