Sight Angle Research Articles

An Intelligent Bait Delivery Control Method for Flight Vehicle Evasion Based on Reinforcement Learning

During aerial combat, when an aircraft is facing an infrared air-to-air missile strike, infrared baiting technology is an important means of penetration, and the strategy of effective delivery of infrared bait is critical. To address this issue, this study proposes an improved deep deterministic policy gradient (DDPG) algorithm-based intelligent bait-dropping control method. Firstly, by modeling the relative motion between aircraft, bait, and incoming missiles, the Markov decision process of aircraft-bait-missile infrared effect was constructed with visual distance and line of sight angle as states. Then, the DDPG algorithm was improved by means of pre-training and classification sampling. Significantly, the infrared bait-dropping decision network was trained through interaction with the environment and iterative learning, which led to the development of the bait-dropping strategy. Finally, the corresponding environment was transferred to the Nvidia Jetson TX2 embedded platform for comparative testing. The simulation results showed that the convergence speed of this method was 46.3% faster than the traditional DDPG algorithm. More importantly, it was able to generate an effective bait-throwing strategy, enabling the aircraft to successfully evade the attack of the incoming missile. The strategy instruction generation time is only about 2.5 ms, giving it the ability to make online decisions.

A priori parameter estimation of space SAR operating in the sliding spotlight scan mode and in the terrain observation mode by progressive scans

In the detailed mode of operation of the synthetic aperture radar (SAR), an improved level of geometric resolution of the terrain in a small frame is achieved. If, however, the frame length exceeds the size of the bottom trace in the azimuthal direction, then it is necessary to use a sliding spotlight operation mode (SSL), in which antenna pattern is scanned in the swath along the azimuth angle. To increase the width of the swath, ScanSAR mode is used. In the traditional implementation of this mode, image serration occurs. This effect can be eliminated by using terrain observation by progressive scans mode (TOPS)). In this mode, when shooting a frame, the antenna pattern runs quickly and alternately through all the specified partial swath bands. Despite the presence of a large number of publications in domestic and foreign literature devoted to the analysis of the main parameters of SAR operating in SSL and TOPS modes, there is a need to clarify calculation methods and increase the number of system parameters issued by them, which generally determine the basic appearance of the equipment. The purpose of the work is to clarify and detail the presentation of the methodology for a priori estimation of an increased number of parameters describing the main system characteristics of space SAR operating in SSL and TOPS. The paper develops and describes in detail a methodology with an exhaustive list of calculation ratios for a priori estimation of parameters describing the main system characteristics of space SAR operating in SSL and TOPS. Based on it, algorithms and software modules have been developed that allow you to perform calculations and display the results in a visual graphical form. Examples of computer calculations of 12 system parameters dependencies on the angle of sight of space radars operating in these two modes are given. The application of the developed methodology makes it possible to quickly perform an a priori assessment of a variety of basic system parameters of space radars operating in SSL and TOPS modes, which facilitates the selection of the most acceptable basic appearance of the equipment for practical implementation.

Effect of boundary angle on aero-optical imaging deviation of the blunt-headed side-window vehicle.

This paper defines the intersection angle between the tangent plane at the boundary of aero-optical flow field and the body axis as the boundary angle and focuses on the influence of the boundary angle on the imaging deviation. This paper shows that the boundary angle of the aero-optical flow field is different at different flight conditions, which means the location of the zero value of imaging deviation is different. With the increase of the line of sight angle, the imaging deviation decreases first and then increases in the opposite direction. After the change of flight conditions, the boundary angle decreases with the increase of the compression of the flow field. The imaging deviation increases if the incident light is on the right side of the normal and decreases in the opposite direction.

Integrated robust navigation and guidance for the kinetic impact of near-earth asteroids based on deep reinforcement learning

The defense against near-Earth asteroids (NEAs) using kinetic impact is faced with various challenges, including limited maneuverability of the impactor, inaccurate dynamic models, poor observability of relative navigation, and control execution errors. To address these challenges, an integrated robust navigation and guidance method for the kinetic impact of NEAs based on deep reinforcement learning (DRL) is proposed in this paper, which can directly map angle measurements by a monocular camera to guidance maneuvers. Firstly, a discrete partial observable Markov decision process (POMDP) is modeled for the integrated navigation and guidance problem of NEA interception. To address the situation where impactors are usually only equipped with aiming cameras and only the line of sight (LOS) angle is measured, past and current LOS measurements are concatenated into a one-dimensional state observation vector to directly introduce the memory of historical state information. A shaping reward function design based on potential energy has also been proposed to solve the problem of sparse reward as the main goal. Subsequently, proximal policy optimization (PPO) is used to solve the established POMDP model, obtaining an integrated navigation and guidance policy that directly maps from the original output of the navigation sensor to the guidance command. The potentially hazard asteroid (PHA) Bennu is used as the target and a typical kinetic impact defense scenario is designed to simulate and verify the model and method proposed in this paper, considering the influence of multiple factors. Numerical simulation results show that the proposed method achieves an interception accuracy of 203.58 m (mean value). The proposed method abandons the traditional separate design of navigation and guidance algorithms, and its robustness has been tested and verified in a wide range of uncertain environments.

An assessment of the effectiveness of acoustic treatments for balconies and open spaces as required by Queensland State Assessment and Referral Agency

This study examines the effectiveness of acoustic treatments required to fulfill “Queensland State Assessment and Referral Agency (SARA)” conditions for balconies or private open spaces in apartment units above the ground floor. SARA SDAP State Code 1 Performance and Acceptable Outcome PO42 mandates developers to use a combination of continuous, solid, gap-free structures or balustrades and highly acoustically absorbent material treatments for such locations. The study explores the relevance of SARA conditions to balconies and highlights the absence of specific statistical noise level criteria for upper-floor private open spaces affected by traffic noise from state-controlled roads in Queensland. Furthermore, the Code requires these measures for balconies “adjacent” to state-controlled roads, which DTMR defined to be within 100 m of a state transport corridor and/or infrastructure. To investigate these aspects, computational noise modeling was undertaken to predict and assess the impact of road traffic noise on balconies, considering factors such as diffraction, reflection, and direct noise propagation paths. The study also analyzes the potential benefits of acoustic treatments, which were found to be dependent on sight angles to and distances from state-controlled road. In certain cases, minimal acoustic benefits are observed. It is recommended that there is a shift from prescriptive acoustic requirements to performance-based and building-specific requirements within the SARA framework.

Integrated Design of Multi-Constrained Snake Maneuver Surge Guidance Control for Hypersonic Vehicles in the Dive Segment

Focusing on the large maneuver penetration of the hypersonic glide vehicle with multiple constraints and uncertain disturbance, a robust integrated guidance and control law, which can achieve the snake-shape maneuver, is designed. A snake-shape maneuver acceleration command, in the framework of sine function, determined by the altitude, target declination of the line of sight and the missile-target distance, is discussed. The integrated guidance and control law includes the terminal guidance law with multiple constraints, attitude control law and angular velocity control law. In the terminal guidance law design, the sliding mode control is adopted while the adaptive technique is applied to estimate the disturbance. The selected sliding mode surface has variable gain determined by the estimated time-to-go. With the designed terminal guidance law, using the snake-shape maneuver acceleration command as the bias item, the angular rate of the line of sight will converge to zero and the line of sight angle will converge to the expected value, simultaneously. The attitude control law and angular velocity control law are designed to track the expected attack and bank angles. The stability of the whole system is proved with the application of the Lyapunov theorem. The effectiveness and robustness of the proposed integrated guidance and control law is verified by simulation.

The Action Point Angle of Sight: A Traffic Generation Method for Driving Simulation, as a Small Step to Safe, Sustainable and Smart Cities

Computer simulations of traffic and driving provide essential solutions to reduce risk and cost in traffic-related studies and research. Through nearly 90 years of simulation development, many research projects have attempted to improve the various aspects of realism through the use of traffic theory, cameras, eye-tracking devices, sensors, etc. However, the previous studies still present limitations, such as not being able to simulate mixed and chaotic traffic flows, as well as limited integration/interoperability with 3D driving simulators. Thus, instead of reusing previous traffic simulators, in this paper, we define relevant concepts and describe the development and testing of a novel traffic generator. First, we introduce realistic aspects to improve traffic generation, including interactive physics (i.e., interactions based on physics among the vehicles, infrastructure, and weather) and natural traffic behaviors (e.g., road user behaviors and traffic rules), allowing the self-driving vehicle behaviors to mimic human behaviors under stochastic factors such as random vehicles and speed. Second, we gain experiences from the technical deficiencies of existing systems. Third, we propose methods for traffic generation based on the action point angle of sight (APAS) formula, which adheres to these constraints and is interoperable with modern driving simulators. We also conducted quantitative evaluations in two experiments (comprising 250 trials), in order to prove that the proposed solution can effectively simulate mixed traffic flows. Moreover, the approaches presented in this study can help self-driving cars to find their way at an intersection/T-junction, as well as allowing them to steer automatically after an accident occurs. The results indicate that traffic generation algorithms based on these new traffic theories can be effectively implemented and used in modern driving simulators and multi-driving simulators, outperforming previous traffic generators based on repurposed technologies.

Seeker head geometric parameters influence on the hypersonic aero-optical effect.

The aero-optical effect of hypersonic flight vehicles creates serious distortion on the imaging system. In this paper, based on the 2D model of a typical optical seeker, flow field density data are obtained by numerical simulation with different optical seeker head radii, cone angles, and relative positions of incident rays reaching the window as variables. Through a series of evaluation parameters, the aero-optical effect under different conditions is quantitatively computed by a ray tracing method. The results show that with the increase of the line of sight (LOS) angle, image deviation decreases. When the optical seeker radius is 40mm and the cone angle is more than 20°, image deviation will not change with the increase of the cone angle. In the case of a small cone angle, the bore sight error (BSE) decreases gradually with the increase of LOS angle. The BSE decreases with the increase of the cone angle, and tends to be stable when the cone angle is above 40°. The variation of the optical path difference with respect to the flow field density is more sensitive than the distance from the shock wave region to the optical seeker window. The Strehl ratio decreases with the increase of the optical seeker cone angle, indicating that the larger the cone angle, the worse the imaging quality.

Cooperative Guidance Law for the Mother-Cabin of the Anti-UAV Cluster Mother-Son Missile

This article investigates a novel operational pattern for intercepting UAV clusters over the range of middle and far distances using mother-son missiles. To address the guidance issue of the mother-cabin in the operational pattern, a special cooperative guidance law, which takes into account acceleration constraint and satisfies the constraints of impact time, speed, and zero line of sight angle (LOS), is proposed. Based on consistency theory and sliding mode control theory, the proposed cooperative guidance law is specifically designed for the mother-cabin of the mother-son missile. This approach offers several advantages, including a simple structure and smooth controller output, and smooth flight trajectory. Finally, numerical simulations are presented to demonstrate the effectiveness and applicability of the cooperative guidance law.

Synthesis of Line of Sight Angle Coordinate Filter with Three Different Target Models

Synthesis of Line of Sight Angle Coordinate Filter with Three Different Target Models

Sea Fall Point Measurement Method Based on Cone Angle Intersection

The naval gun strikes against the sea need to measure the deviation of the fall point to determine the accuracy and hit probability. In order to improve the accuracy of measuring the fall point position of the naval gun, this paper proposes a maritime fall point measurement method based on cone angle intersection, which does not need to use the axis angle data of the equipment and eliminates the dependence on the equipment’s axis angle data when measuring accuracy. Firstly, the photographic measurement method is used to achieve automatic optical intersection of single equipment at different moments, using two observation stations and one cooperative target ship. Then, the image data within 10 km from the measured target are collected using two observation stations. The line of sight directions and angles of the two observation stations are combined to measure the target object and the cooperative target ship at each observation station. The constraint of the approximate equal radius of the Earth ellipsoid is added under close range conditions. The cone angle intersection model mapping relationship is established. Finally, the coordinate position of the target object in three-dimensional space is calculated using field tests at sea and compared with the actual position for analysis.The experimental results show that the measured fall point is within 5 m in the range of 700 m with a ratio of more than 75%. This has increased the range of measurement accuracy processing and proved the feasibility of the measurement method. The method can be used for calibrating large and medium caliber naval gun firing to the sea to improve the firing accuracy of the weapon. It has guiding significance for measuring the fall point position of naval guns at sea.

Dynamic Line of Sight Shaping for Impact Time and Angle Control Guidance

This paper presents a novel guidance law enabling to control together of the impact time and angle for planar engagement scenarios. The developed guidance command has a form of biased proportional navigation, and the bias term employs the angle and time constraints at the terminal phase. Specifically, the bias term with nonlinear expression contains the second derivative of the line of sight angle. Thus, shaping a Bézier curve with the C2 continuity guarantee allows us to meet final constraints. Besides, one extra design variable is needed to remove the impact time error related to angle error arising from nonlinearity. Control point locations of resulting 4th degree Bézier curve are determined by boundary conditions, except one being determined using an offline Newton iteration method to eliminate the error. Simulation studies, including a comparison study, are conducted to show the effectiveness of the proposed ITACG law.

Development of 3D Model and Display on Web Using Open-Source Technology

It is basically done on the concept for bringing the 2D area view to 3D area view . The problem arises in the 2D view area is that there is only perspective angle of sight which may occurs problem after some time if we use it as a blueprint. 3D-model overcome this problem. As 3D model has various perspective angle of sight . If in the blueprint there is any such model which is not suitable at that location, we can easily remove it from there and place it on the new location where it is needed. For this we use Blender for 3D modelling and later on displayed on the web using Cesium and Three.js.

A new three-dimensional adaptive sliding mode guidance law for maneuvering target with actuator fault and terminal angle constraints

In this paper, an adaptive terminal sliding mode guidance law is designed to intercept the maneuvering target with terminal line of sight angle constraints in three-dimensional space, and the actuator failure is considered. First, the relative kinematics model of three-dimensional space missile target considering fault is established. Then, the guidance law is designed by using the nonsingular fast terminal sliding mode method, which makes the tracking error and rate converge in finite time; Aiming at the problem of uncertain disturbance and fault in the model, the adaptive method is used to evaluate online. Finally, the Lyapunov stability theorem is used to prove that the missile target system is closed-loop stable under the proposed guidance law. Simulation results verify the performance of the proposed guidance law.

Three-dimensional prescribed performance sliding mode guidance law for intercepting maneuvering target

This article describes three-dimensional sliding mode guidance laws with prescribed performance. The proposed guidance laws can ensure that the line of sight (LOS) angle converges according to the prescribed performance, and the convergence rate, the steady-state error and the maximum overshoot can be preset in advance. By combining the LOS tracking error with the performance constraint function, a new error variable function is designed, and then the prescribed performance control problem is transformed into that of the boundedness of the error variable function. The key concept in this approach is to design a new sliding mode surface to ensure that the error variable function is bounded, so as to ensure that the system state converges according to the prescribed performance. Additionally, this article discusses the problem whereby the upper bound of the aggregate uncertainty, including the target information, is unavailable. An adaptive guidance law is presented for this scenario. Finally, simulations comparisons are conducted with other forms of guidance laws. Simulation results show that the guidance laws proposed in this article achieve effective performance.

An Improved Unscented Kalman Filter for Maneuvering Target Tracking*

The photoelectric pod provides angular information and distance information for the UAV (Unmanned Aerial Vehicle), and the UAV uses it to estimate the status information of the moving target. Since the measurement information of the photoelectric pod is the angle of sight and relative distance, the measurement equation contains some nonlinear functions in the Cartesian coordinate system, and the output frequency of the photoelectric pod is low. The improved unscented Kalman filter combines the function of prediction and correction, introduces the prior information of the target acceleration constraint, and uses the offline data to obtain steady gain, and then estimates the target state online. The simulation result show that the algorithm can track the target and need less time compared with the traditional unscented Kalman filter.

Task coupling based layered cooperative guidance: Theories and applications

Task coupling based layered cooperative guidance design and analysis issues for multiple missiles system are investigated. First, to deal with cooperative guidance problems with multiple task requirements, a task coupling based layered cooperative guidance structure is constructed by the leader layer and the follower layer. Then, for the leader missile layer, the cooperative detection guidance law is designed to achieve the coordination of the detection field of view (FOV) and cooperative interception, while providing the reference trajectories. Third, for the follower missile layer, the time-varying line of sight (LOS) angle formation tracking guidance law is proposed based on the leader missiles’ LOS angle trajectories convex combination. In addition, the design process and stability analysis of the closed-loop system are given. Finally, an equivalent experiment platform based on multiple mobile robots is introduced, which consists of two leaders, three followers, and a target is constructed. The theoretical results are verified by numerical simulation examples, and experimental results are presented on the platform.

Synthesis of Line of Sight Angle Coordinate Filter on the Basis of Interactive Multi-Model Evaluation Algorithm

On the basis of the tracking multi-loop target angle coordinate system, the article has selected and proposed a interactive multi-model adaptive filter algorithm to improve the quality of the target phase coordinate filter. In which, the 3 models selected to design the line of sight angle coordinate filter; Constant velocity (CV) model, Singer model and constant acceleration model, characterizing 3 different levels of maneuverability of the target. As a result, the evaluation quality of the target phase coordinates is improved because the evaluation process has redistribution of the probabilities of each model to suit the actual maneuvering of the target. The structure of the filters is simple, the evaluation error is small and the maneuvering detection delay is significantly reduced. The results are verified through simulation, ensuring that in all cases the target is maneuvering with different intensity and frequency, the line of sight angle coordinate filter always accurately determines the target angle coordinates.

The Effects of the Visual Environment on K-12 Student Achievement

The varying indoor environments among educational buildings can have an impact on students’ ability to learn. This study looks at field data from 220 classrooms in the Midwest, United States, over a two-year period, to analyze the effects of the visual environment on student achievement. The visual environmental metrics considered within this scope include the three new view metrics introduced within the EN 17037 “Daylight of Buildings” standard (Horizontal Sight Angle, Outside Distance of View, and Number of View Layers), as well as standard daylight and electric lighting metrics, focusing on light availability and glare. To capture student achievement, math and reading achievement scores were used, accompanied by auxiliary demographic variables. This allowed for a correlational analysis using multivariate regression. Among the notable results of this study, there was a positive effect of the availability of view on reading achievement. However, another view metric, Horizontal Sight Angle, showed a significant negative interaction with free and reduced lunch recipients on reading achievement, indicating that demographics can also have a significant role in the way the visual environment can affect learning.

Sliding mode lateral stand-off tracking control of finless airship

The paper addresses the stand-off tracking control problem for an underactuated finless airship having uncertainties and wind disturbances. The outer loop design sliding surface is based on the line of sight angle rate and its distance from a target, for the inner control loop, generates the reference heading angle commands, the proposed backstepping sliding-mode controller based on the yaw error angle generating commands by actuating the yaw-gyro propulsion. Theoretical results show that the closed loop system is globally asymptotically stable. With the assumption of target movement as disturbances, this framework is also applied to linear and variable direction moving targets. The numerical simulations are conducted for stand-off tracking control for a stationary and a moving target or targets, having servos dynamics and sensor models with measurement noises and external disturbances, and the results verify the effectiveness of the proposed framework for stand-off target tracking. The results obtained by comparing traditional proportional navigation and LQR design demonstrate the capability of the airship to execute a stand-off trajectory tracking with uncertainties and wind disturbances.