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مقالة‌ تحقیقی‌ (پژوهشی‌)
Dynamic Terminal Sliding Mode Control for an Aerospace Launch Vehicle

علیرضا علیخانی؛ سیدعلی اکبر کسائیان

دوره 8، شماره 4 ، دی 1394، صفحه 1-7

چکیده
  Tracking guidance commands for a time-varying aerospace launch vehicle during the atmospheric flight is considered in this paper. Hence, the dynamic terminal sliding mode control law is constructed for this purpose and dynamic sliding mode control is utilized. The terminal sliding manifold causes the dynamic sliding mode to converge asymptotically to zero in finite-time. The actuator and rate gyro dynamics are included in the model of launch vehicle. Dynamic sliding mode control accommodates unmatched disturbances, while the terminal sliding mode control is used to accelerate the system to reach ...  بیشتر

مقالة‌ تحقیقی‌ (پژوهشی‌)
A New Backstepping Sliding Mode Guidance Law Considering Control Loop Dynamics

وحید بهنام گل؛ احمدرضا ولی؛ علی محمدی

دوره 8، شماره 4 ، دی 1394، صفحه 9-17

چکیده
  In this paper, a new procedure for designing the guidance law considering the control loop dynamics is proposed. The nonlinear guidance loop entailing a first order lag as the control loop dynamics is formulated. A new finite time and smooth backstepping sliding mode control scheme is used to guarantee the finite time convergence of relative lateral velocity. Also in the proposed algorithm the chattering is removed and a smooth control signal is produced. Moreover, the target maneuver is considered as an unmatched uncertainty. Then a robust guidance law is designed without requiring the precise ...  بیشتر

Equilibrium Effects on the Hypersonic Laminar Boundary Layer Flow over Axisymmetric Bodies

رامین کمالی مقدم؛ محمدرضا سلیمی

دوره 8، شماره 4 ، دی 1394، صفحه 19-27

چکیده
  An accurate and efficient computational procedure is developed to predict the laminar hypersonic flowfield for both the perfect gas and equilibrium air around the axisymmetric blunt body configurations. To produce this procedure, the boundary layer equations utilize the integral matrix solution algorithm for the blunt nose and after body region by using a space marching technique. The integral matrix procedure enables us to create accurate and smooth results using the minimum grid in the boundary layer and to minimize the computational costs. This algorithm is highly appropriate for the design ...  بیشتر

مقالة‌ تحقیقی‌ (پژوهشی‌)
Hot Air Gun Identification by Inverse Heat Transfer

امیر مهدی تحسینی؛ سمانه تدین موسوی

دوره 8، شماره 4 ، دی 1394، صفحه 29-34

چکیده
  The aim of this paper is to identify the unknown properties of an industrial hot air gun using inverse heat transfer approach. A combination of experiments and numerical analyses is used to define the convection coefficient and the produced temperature of this device. A numerical solver is developed by employment of a straightforward and powerful inverse heat transfer method: “The conjugate gradient method for parameter estimation”. The variation of temperature versus time in a fixed point of a steel-304 rod is sensed by a thermocouple and is given as an input to the numerical solver. ...  بیشتر

مقالة‌ تحقیقی‌ (پژوهشی‌)
Optimal Control of a Tri-axial Spacecraft Simulator Test bed Actuated by Reaction Wheels

حجت طائی؛ مهران میرشمس؛ مهدی قبادی؛ محمد امین وحید دستگردی؛ حسن حقی

دوره 8، شماره 4 ، دی 1394، صفحه 35-44

چکیده
  This article describes the details of a Tri-axial Spacecraft Simulator Testbed (TSST) that has been developed as part of a research program on spacecraft multi-body rotational dynamics and control in Space Research Laboratory (SRL) at K. N. Toosi University of Technology. This dumbbell style simulator includes a variety of components: spherical air-bearing, inertial measurement unit (IMU), rechargeable battery, reaction wheels (RW), on-board computer (OBC) and balancing masses. In this paper, an attitude control problem for the spacecraft simulator actuated by three reaction wheels is studied. ...  بیشتر

مقالة‌ تحقیقی‌ (پژوهشی‌)
INS Alignment Improvement Using Rest Heading and Zero-Velocity Updates

مهدی فتحی؛ علی محمدی؛ نعمت الله قهرمانی

دوره 8، شماره 4 ، دی 1394، صفحه 45-51

چکیده
  In this paper the feasibility of rapid alignment and calibration of a static strapdown inertial navigation system (INS) is evaluated. Resting conditions including zero-velocity update and a known initial heading direction as virtual external measurement data are integrated with INS data. By comparing the virtual external measurements with the estimates of those generated by the aligning INS, estimates of the velocity and heading errors can be obtained and these errors will be propagated in the INS as a result of alignment inaccuracies. An extended Kalman filter based on an augmented process model ...  بیشتر