346 research outputs found

    Pitch-Axis Identification for a Guided Projectile Using a Wind-Tunnel-Based Experimental Setup

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    International audienceThis paper details the identification of a pitchaxis model for an 80-mm fin-stabilized canard-guided projectilethrough a hardware-in-the-loop experimental setup. This setup is based on an autonomous functional projectileprototype installed in a subsonic wind tunnel by the means of a three-degree-of-freedom gimbal mount. A nonlinear dynamical model is first derived from flight mechanics principles;then, a linearized model is obtained through Taylorseries expansion. The a priori and a posteriori identifiabilityof the proposed linear model are assessed, and the associatedexperimental input signals are accordingly designed.The model parameters are then estimated using a numericaloptimization procedure, and the associated uncertainty isobtained through a boostrapping method. The results andtheir implication on the projectile flight control design arefinally discussed

    Pitch Axis Control for a Guided Projectile in a Wind Tunnel-based Hardware-in-The-Loop Setup

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    This article details the design of a pitch axis autopilot for an 80mm fin-stabilized, canard-guided projectile and its validation on a Hardware-In-the-Loop test setup. This setup is built around an autonomous projectile prototype, which is installed in the test section of a wind tunnel by the means of a 3-DoF gimbaled structure. The autopilot design is based on a family of linearized dynamic models of the projectile, whose parameters were estimated from experimental data. Several control approaches are considered. Using the H1 robust control framework, a full-order disturbance rejection controller is designed, taking into account the limited actuator dynamics. A fixed-order, fixed-structure controller of lower complexity with the same performance objective is also designed, using a nonsmooth H1 technique. The tracking performance of these controllers is improved with the addition of a feedforward controller. A final approach considers the disturbance rejection and reference tracking as a multi-objective problem, where the feedback and the feedforward controllers are designed in a single step. The performance of these approaches is then assessed and compared using numerical simulation as well as experimental results gathered from the Hardware-In-the-Loop setup

    Experimental and theoretical control of a smart projectile fin using piezoelectric bimorph actuator

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    The goal of this work is to develop efficient control algorithms for the control of a smart projectile fin. Smart fins are deployed as soon as the projectile reaches the apogee and are used to steer the projectile towards its target by controlling the rotation angle of the fin. The fin is actuated using the piezoelectric macro-fiber composite (MFC) bimorph actuator which is completely enclosed within the aero-shell. The actuator is composed of two Macro Fiber Composites (MFC\u27s), manufactured by Smart Material Co. The presented smart fin design minimizes the volume and weight of the unit; Two different models of the smart fin are developed. One is mathematical model that uses finite element approach to describe dynamics of the smart fin system. This model includes the aerodynamic moment which is a function of the angle of attack of the projectile. Second model is based on system identification approach. A linear model of the actuator and fin is identified experimentally by exciting the system using a chirp signal. Comparison is done between these two models based on open-loop step response of the smart fin system; In this dissertation, five kinds of control systems based on fuzzy logic, inverse dynamics and adaptive structure theory are developed. The aerodynamic disturbances and parameter uncertainties are considered in these controllers. The simulation results illustrate that asymptotic trajectory tracking of the fin angle is achieved, in spite of uncertainties in the system parameters and presence of aerodynamic disturbance. A prototype model of the projectile fin is developed in the laboratory for real-time control. The designed controllers are validated using the subsonic wind tunnel at University of Nevada, Las Vegas (UNLV) for various wind speeds. Experimental results show that the designed controllers accomplish fin angle control

    Guidance, navigation, and control for munitions

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    The United States Army is currently looking for new methods of guiding munitions, which would allow the military to employ guided munitions in place of traditional munitions. This will give the US Army an edge on the battle eld and also allow the use of munitions in areas where traditional mortars and artillery cannot be used, including dense urban environments where collateral damage is not acceptable.In this thesis, an innovative approach to Guidance, Navigation, and Control (GN&C) is developed for a spinning projectile that utilizes a single axis canard actuation system. Utilizing the projectiles spin, the controller can provide a full range of aerodynamic forces, over the 360o of rotation, that provides maneuverability using only one actuator. This technique minimizes the need for multiple actuators and maintains the inherent aerodynamic stability provided by the spin.The GN&C system design described in this thesis consists of a tracking regulator for sinusoidally oscillating the canard system, a nonlinear state estimator for attitude measurement, and a guidance law to guide the projectile to a target. By combining the three components, we can demonstrate a closed-loop guidance system that will hit a target accurately at distances normally not achieved by an unguided projectile.Ph.D., Mechanical Engineering -- Drexel University, 200

    Soft Target for Advanced Emergency Braking System Daimler Trucks

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    This report provides an overview of the AEBS Soft Target project delivered to Daimler Trucks North Amer- ica as part of the 2016-2017 Mechanical Engineering Senior Design class at California Polytechnic State University, San Luis Obispo. The purpose was to build a soft target to test Advanced Emergency Braking Systems, or AEBS, on Daimler 0 s large trucks. Though this design is for Daimler specifically, there may be other interested parties such as highway safety groups and rival auto manufacturers. Currently, there are no suitable alternative products that satisfy every requirement for Daimler to validate their systems. They require a target that must not damage their trucks, visible to their sensor systems, mountable to a moving frame, can be reset quickly, and is a cheaper long term testing solution than their current setup. The team was able to build a target that had improved car profile and appearance compared to preexisting targets while producing the target for a very low cost. The truss, bumpers, and tarp proved durable in Cal Poly’s testing environment. However, the base connections are a weak point of the design and failed when run over in testing. Fortunately these pieces are extremely quick and inexpensive to replace. Further full scale testing would better validate these results for truck impact

    Fourth International Symposium on Magnetic Suspension Technology

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    In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Fourth International Symposium on Magnetic Suspension Technology was held at The Nagaragawa Convention Center in Gifu, Japan, on October 30 - November 1, 1997. The symposium included 13 sessions in which a total of 35 papers were presented. The technical sessions covered the areas of maglev, controls, high critical temperature (T(sub c)) superconductivity, bearings, magnetic suspension and balance systems (MSBS), levitation, modeling, and applications. A list of attendees is included in the document

    Aeronautical Engineering, a continuing bibliography with indexes, supplement 173

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    This bibliography lists 704 reports, articles and other documents introduced into the NASA scientific and technical information system in March 1984

    Experiments in Planetary and Related Sciences and the Space Station

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    Numerous workshops were held to provide a forum for discussing the full range of possible experiments, their science rationale, and the requirements on the Space Station, should such experiments eventually be flown. During the workshops, subgroups met to discuss areas of common interest. Summaries of each group and abstracts of contributed papers as they developed from a workshop on September 15 to 16, 1986, are included. Topics addressed include: planetary impact experimentation; physics of windblown particles; particle formation and interaction; experimental cosmochemistry in the space station; and an overview of the program to place advanced automation and robotics on the space station

    Aeronautical Engineering: A continuing bibliography with indexes

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    This bibliography lists 529 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in May 1980

    AFIT School of Engineering Contributions to Air Force Research and Technology Calendar Year 1973

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    This report contains abstracts of Master of Science Theses, Doctoral dissertations, and selected faculty publications completed during the 1973 calendar year at the School of Engineering, Air Force Institute of Technology, at Wright-Patterson Air Force Base, Ohio
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