Synthesis of a High-Precision Missile Homing System with an Permissible Stability Margin of the Normal Acceleration Stabilization System

The proportional guidance method-based missile homing systems (MHS) have been widely used the real-world environments. In these systems, in order to destroy the targets at different altitudes, a normal acceleration stabilization system (NASS) is often utilized. Therefore, the MHS are complex and the synthesis of these systems are a complex task. However, it is necessary to synthesize NASS during the synthesis of the MHS. To simplify the synthesis process, a linear model of the NASS is used. In addition, we make use of the available commands in Control System Toolbox in MATLAB. Because the Toolbox has the commands to describe the transfer function, determine the stability gain margin, and the values of the transient respond of the linear automatic systems. Thus, this article presents two methods for synthesizing the missile homing systems, including (i) a method for synthesizing the MHS while ensuring the permissible stability gain margin of the NASS, and (ii) a method for synthesizing the MHS while ensuring the permissible stability margin of the NASS by overshoot. These techniques are very easy to implement using MATLAB commands. The synthesis of the proposed MHS is carried out by the parametric optimization method. To validate the performance of the proposed techniques, we compare them withthe MHS synthesized by ensuring the stability margin of the NASS bythe oscillation index. The results show that, two our proposed methods and the existing method provide the same results in terms of high-precision. Nevertheless, the proposed methods are simple and faster than the conventional method. The article also investigates the effect of gravity, longitudinal acceleration of the rocket, andblinding of the homing head on the accuracy of the synthesized MHS. The results illustrate that they have a little effect on its accuracy.

Factors Affect Slipping of Automobiles

This paper presents analysis for the slipping phenomenon in automobiles; the parameters affects slipping of automobiles are discussed. An analytical equation is constructed to relate all factors affect slipping ratio. Some relations are predicted to show the factors affect the slipping in automobiles. It is found that the parameters affect slipping can be summarized as: radius of curvature of the curve, angle of the curve (slope), RPM of the tire, radius of the tire in addition to the nature of the road. It is found that: as the normal acceleration increases the slipping ratio decreases, as the RPM of the tire increase the slipping ratio increases and as the radius of the tire increases the slipping percent increases. It is obvious that as the path slope (tan θ) increases the slipping value decreases. It is noticed that: as the radius of curvature increase the slipping % decrease which is logic, since the slipping on straight dry path is nearly close to zero. Also it is noticed that: as the tire radius decreases the slipping % increases.

OPTIMIZATION OF LONG-RANGE TRAJECTORY FOR AN UNPOWERED FLIGHT VEHICLE

This report presents problems of optimization of long-range trajectory for an unpowered flight vehicle at subsonic and transonic speed. The results may be recommended to have a new long range trajectory. The optimization problem is solved by numerical experiments while the normal load factor (normal acceleration) is used as optimization variables with compliance to flight constraints. The focus problem of this study is the investigation of the possibility of trajectory expansion according to the criteria of the maximum range in the first stage of the trajectory.

OPTIMIZATION OF LONG-RANGE TRAJECTORY FOR AN UNPOWERED FLIGHT VEHICLE

This report presents problems of optimization of long-range trajectory for an unpowered flight vehicle at subsonic and transonic speed. The results may be recommended to have a new long range trajectory. The optimization problem is solved by numerical experiments while the normal load factor (normal acceleration) is used as optimization variables with compliance to flight constraints. The focus problem of this study is the investigation of the possibility of trajectory expansion according to the criteria of the maximum range in the first stage of the trajectory.

Normal acceleration response to canard control with wind for spin-stabilized projectiles

In this investigation, the normal acceleration response to the control inputs of spin-stabilized projectiles considering the atmospheric wind with the coupled effects of canard control, gravity, and aerodynamic forces, being an important reference for the guidance design of low-cost guided projectiles with less measurement information (only translational motion), is deduced and analyzed. Based on the approximate formulas predicting the angle of attack under canard control and considering the atmospheric wind obtained by a linear model of the pitch and yaw motion, estimated expressions for the normal acceleration response to canard control are deduced and analyzed. To analyze the cross-coupling between pitch and yaw and simplify the design of guidance and control, the acceleration response is divided into controllable and uncontrollable parts. The phase shift between the controllable acceleration response and the direction of the control input is defined to represent the coupling effect between the pitch and the yaw; this is found to be strongly dependent on the projectiles' state parameters rather than the control parameters. The results indicate that the acceleration and phase are dramatically altered under different control directions. This condition adversely affects guidance and control because uncontrollable directions arise when the deflection angle is smaller than the critical angle.

Dynamics and wall collision of inertial particles in a solid–liquid turbulent channel flow

The dynamics and wall collision of inertial particles were investigated in non-isotropic turbulence of a horizontal liquid channel flow. The inertial particles were $125~\unicode[STIX]{x03BC}\text{m}$ glass beads at a volumetric concentration of 0.03 %. The bead-laden flow and the unladen base case had the same volumetric flow rates, with a shear Reynolds number, $Re_{\unicode[STIX]{x1D70F}}$, of the unladen flow equal to 410 based on the half-channel height and friction velocity. Lagrangian measurements of three-dimensional trajectories of both fluid tracers and glass beads were obtained using time-resolved particle tracking velocimetry based on the shake-the-box algorithm of Schanz et al. (Exp. Fluids, vol. 57, no. 5, 2016, pp. 1–27). The analysis showed that on average the near-wall glass beads decelerate in the streamwise direction, while farther away from the wall, the streamwise acceleration of the glass beads became positive. The ejection motions provided a local maximum streamwise acceleration above the buffer layer by transporting glass beads to high velocity layers and exposing them to a high drag force in the streamwise direction. Conversely, the sweep motion made the maximum contribution to the average streamwise deceleration of glass beads in the near-wall region. The wall-normal acceleration of the beads was positive in the vicinity of the wall, and it became negative farther from the wall. The investigation showed that the glass beads with sweeping motion had the maximum momentum, streamwise deceleration, and wall-normal acceleration among all the beads close to the wall and these values increased with increasing their trajectory angle. The investigation of the beads that collided with the wall showed that those with shallow impact angles (less than $1.5^{\circ }$) typically slide along the wall. The sliding beads had a small streamwise momentum exchange of ${\sim}5\,\%$ during these events. The duration of their sliding motion could be as much as five times the inner time scale of the unladen flow. The wall-normal velocity of these beads after sliding was greater than their wall-normal velocity before sliding, and was associated with the rotation induced lift force. Beads with impact angles greater than $1.5^{\circ }$ had shorter interaction times with the wall and smaller streamwise and wall-normal restitution ratios.

Orbital plane change maneuver strategy using electric propulsion

The orbital dynamics basis for orbital plane change maneuver using chemical propulsion is the impulsive orbital change theory in practical engineering. The orbital plane change theory using continuous thrust suitable for electric propulsion is studied in this paper. A set of nonsingular orbital variational equations using quaternion is used to investigate the orbital motion of spacecraft under constant normal acceleration departing from a Keplerian circular orbit firstly. Results show that the orbit of spacecraft under continuous constant normal acceleration is a circular orbit over the gravitational center on the same spherical surface as the initial orbit, and it is tangent to the initial circular orbit at the initial position. Continuous and discontinuous maneuver strategies are then designed using the previous theory, and they are validated by numerical simulations. Results indicate that the strategy can work effectively.

Online aircraft velocity and normal acceleration planning for rough terrain following

ABSTRACTThis paper attempts to develop an efficient online algorithm for terrain following in completely unknown rough terrain environments while incorporating aircraft dynamics in the guidance strategy. Unlike most existing works, the proposed algorithm does not generate the flight path directly. The algorithm employs acquired information from the vehicle onboard sensors and rapidly issues appropriate Guidance Commands (GCs) at every point along the way. A suitable dynamic model is developed which takes the lags in the vehicle dynamics into account. The flight path forms gradually as a result of applying the GCs to the vehicle dynamics. Terrain-conforming capability afforded by this approach allows for autonomous and safe low-level flight in unknown mountainous areas. It considerably enhances the autonomy level of the vehicle and in the case of manned aircraft could significantly lead to pilot workload reduction. The proposed scheme is proven to be promising for online applications.