Guidance Design Research Articles

Entry Guidance With Terminal Time Control Based on Quasi-Equilibrium Glide Condition

The terminal constraints in entry guidance design are generally position and velocity constraints. In this study, the terminal time constraint is also taken into account. The estimates of time-to-go and range-to-go are discussed based on the quasi-equilibrium glide condition. Further analysis reveals that only two among the time-to-go, range-to-go, and terminal velocity are independent. Based on this observation, a guidance method is designed, which provides a new aspect to exploit the potential of entry guidance.

Dynamic Guidance by Colored Running Lights and Affordance: Route Choices of Adults and Older Children

Abstract Guidance to emergency exits play an important role for safe evacuation. Dynamic route guidance by colored flashing lights and strobe lights at emergency exits has been tested [1–3], but the effects of dynamic lights to support route choices need to be determined in more detail. Also, the guidance effects of different colors need to be examined and the reaction of various groups of evacuees. The paper analyzes the effects of red and green running lights on route choice in subway stations comparing adults and older children (10 to 12 years old). Data was gathered in a laboratory experiment, focusing on the concept of affordance [4, 5]. Participants were asked to make a decision about the safest direction between two alternative directions. Their choice was either unsupported or supported by red or green running lights. In general, an interaction between color and direction of the running light was found. Green running lights influenced route choices of both participant groups and led participants clearly into the direction indicated by the lights. Red running lights influenced route choices of both participant groups, but red lights lead to ambiguous decisions. Architectural elements such as stairs influenced route choices of both participant groups (functional affordance). But green running light offered a stronger indication to a safe route (cognitive affordance) than a visible staircase (functional affordance). Green lights even led participants to modify their route preference. In contrast, red running lights had an aversive effect: older children chose against the lights and preferred the other direction than the red lights were directing to. Implications for design of dynamic route guidance are discussed. This includes colored running lights to lead evacuees to a safe exit and to implement the influence of running lights on route choice and movement in simulations.

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.

Analytical cooperative entry guidance for Rendezvous and formation flight

The cooperative entry guidance design is difficult for Hypersonic Glide Vehicles (HGVs), because the motions of hypersonic glider in longitudinal- and lateral-planes are seriously coupled as they lack adjustable thrust to offset the complex influence of lateral maneuvers on longitudinal motion, whereas formation flight requires that the two motions can be controlled independently. However, by exploring and exploiting the weak capability of HGVs in controlling the longitudinal and lateral motions independently, we propose a feasible flight mode named Rendezvous & Formation Flight (R&FF) mode, in which the vehicles are only required to fly in formation through a relatively short range. This flight mode is also of great value in fast cooperative detection of key area. The flight mode divides the entry flight into Rendezvous Phase (RP) and Formation Flight Phase (FFP), and the corresponding guidance scheme is designed to be of two layers: offline planning layer and online guidance layer. In the offline planning layer, the coordinated reference trajectories of all the vehicles for all the phases are fast planned beforehand by the mix use of the trajectory simulations and analytical solutions to 3-D hypersonic glide problem. In the online guidance layer, a weak-tracking guidance is posed for RP, which allows the HGVs to fly relatively freely for anti-interference, but should meet the rendezvous conditions strictly. By contrast, in FFP, a strong-tracking guidance is put forward to track the 3-D reference trajectories closely in order to maintain the formation configuration.

A Semi-Physical Platform for Guidance and Formations of Fixed-Wing Unmanned Aerial Vehicles.

Unmanned Aerial Vehicles (UAVs) have multi-domain applications, fixed-wing UAVs being a widely used class. Despite the ongoing research on the topics of guidance and formation control of fixed-wing UAVs, little progress is known on implementation of semi-physical validation platforms (software-in-the-loop or hardware-in-the-loop) for such complex autonomous systems. A semi-physical simulation platform should capture not only the physical aspects of UAV dynamics, but also the cybernetics aspects such as the autopilot and the communication layers connecting the different components. Such a cyber-physical integration would allow validation of guidance and formation control algorithms in the presence of uncertainties, unmodelled dynamics, low-level control loops, communication protocols and unreliable communication: These aspects are often neglected in the design of guidance and formation control laws for fixed-wing UAVs. This paper describes the development of a semi-physical platform for multi-fixed wing UAVs where all the aforementioned points are carefully integrated. The environment adopts Raspberry Pi’s programmed in C++, which can be interfaced to standard autopilots (PX4) as a companion computer. Simulations are done in a distributed setting with a server program designed for the purpose of routing data between nodes, handling the user inputs and configurations of the UAVs. Gazebo-ROS is used as a 3D visualization tool.

Precise implant insertion technology for measuring dental implant placement

Identifying the ideal implantation site is important for the long-term stability and effectiveness of follow-up restorations. Implant surgical guide and navigation are used to determine the implantation site in clinic and improve the precision of implantation. However, due to difficulties in digital methods, such as multiple procedures, high cost, and actual accuracy of more than 1 mm, many physicians still prefer to operate with free hand. In preoperative, intraoperative, and postoperative procedures, time-saving and practical methods for implant site evaluation are lacking. In many cases, oral physicians found that the position deviates only by cone beam CT, which was costly to modify the position. In this article, we presented a precise implantation insertion technology that is guided by a measurable technique throughout the implantation application for all implant systems. This method was guided by a dynamic control measuring ruler, which functions together with the measuring and intraoperative locating rulers. The 3D space of the operative area was measured by a measuring ruler prior to operation, and the implant plan and quantitative guidance design were conducted according to the measured and cone beam CT data. The whole implantation process was guided by the dynamic control measuring ruler, and measuring verification results were also considered. This method can realize the quantification of the entire preoperative space analysis, intraoperative precise implantation guidance, and postoperative site measurement and evaluation. This practical technique also helps to adjust the position, improve the implantation accuracy and is suitable in generalizing dental implantation.

Sustainable Traffic Management in an Urban Area: An Integrated Framework for Real-Time Traffic Control and Route Guidance Design

This paper focuses on the presentation of an integrated framework based on two advanced strategies, aimed at mitigating the effect of traffic congestion in terms of performance and environmental impact. In particular, the paper investigates the “operational benefits” that can be derived from the combination of traffic control (TC) and route guidance (RG) strategies. The framework is based on two modules and integrates a within-day traffic control method and a day-to-day behavioral route choice model. The former module consists of an enhanced traffic control model that can be applied to design traffic signal decision variables, suitable for real-time optimization. The latter designs the information consistently with predictive user reactions to the information itself. The proposed framework is implemented to a highly congested sub-network in the city center of Naples (Italy) and different scenarios are tested and compared. The “do nothing” scenario (current; DN) and the “modeled compliance” (MC) scenario, in which travelers’ reaction to the information (i.e., compliance) is explicitly represented. In order to evaluate the effectiveness of the proposed strategy and the modeling framework, the following analyses are carried out: (i) Network performance analysis; (ii) system convergence and stability analysis, as well as the compliance evolution over time; (iii) and emissions and fuel consumption impact analysis.

Design of intelligent traffic guidance display system based on internet of vehicles

In order to solve the problem of inaccurate detection of road space occupation, an intelligent traffic guidance and display system based on vehicle network is designed. Firstly, the real-time acquisition and prediction of vehicle and path environment data are realised by using navigation information data acquisition module. Secondly, the traffic guidance information is used to publish the model, edit the data, and send the traffic guidance information display module. Then, the set theory method is used to detect the traffic volume of RFID readers set up on the road. Finally, the average space speed, space occupation rate and road delay time are calculated to complete the traffic guidance. The experimental results show that the system can quickly balance the delay in road network and shows powerful guidance display performance with instantaneity larger than 95% and dynamics high 0.97 in ten kinds of traffic congestions in different roads.

Design of intelligent traffic guidance display system based on internet of vehicles

Design of intelligent traffic guidance display system based on internet of vehicles

A New Midcourse Guidance Design for Near Space Target Interceptor

This study proposes a new midcourse guidance method, combining the trajectory optimization approach and the optimal sliding mode method, to decrease the larger relative velocity between the near space target and the interceptor. Firstly, the midcourse trajectory optimization model is established. Then, the trajectory optimization guidance law based on a sampling scheme is proposed to decrease the larger relative velocity and satisfy multiple constraints at the end time of the midcourse guidance phase. Thirdly, the optimal sliding mode guidance law is introduced to deal with the target maneuverability. Finally, numerical simulations were performed to verify the performance of the midcourse guidance law.

Adaptive steering control for an azimuth thrusters-based autonomous vessel

ABSTRACTThe proposed paper presents the design and development of the combined guidance and control strategies for the autonomous navigation of unmanned vessels characterised by azimuth-based thrust architecture. Autonomous marine vehicles (AMVs) are consolidated technological tools commonly employed for different tasks such as exploration, sampling and intervention. With the final aim of autonomous shipping, the AMVs capabilities have to be migrated and adapted towards the reliable and safe control of commercial-like unmanned vessels. These last are spreading thanks to a number of technological research projects. The employment of unconventional hull shapes combined with propulsive layout based on azimuth thrusters requires robust guidance techniques to provide precise and reliable motion control during navigation. The paper introduces a dual-loop guidance and control scheme able to provide advanced navigation capabilities. An inner control loop, devoted to the actuation of the azimuth thrusters, allows the tracking of reference course angle (namely the autopilot). Such a control loop is characterised by a modified PD regulation scheme, where a novel adaptive derivative component is inserted in order to improve the convergence curve towards the required course reference. The outer guidance loop, based on Lyapunov and virtual-target approach, allows the vessel to track generic desired paths, thus enhancing the autonomous navigation capabilities. The paper will provide a deep design and analysis approach for the developed techniques, as well as simulation results of the combined guidance and control scheme, proving the reliability of the proposed approach in different operative conditions.

LSTM Model for Trajectory Design of Missile-Borne BFSAR Imaging Guidance

LSTM Model for Trajectory Design of Missile-Borne BFSAR Imaging Guidance

Analytical solution of field-of-view limited guidance with constrained impact and capturability analysis

An analytical missile guidance law is derived to meet both the impact time and angle constraints as well as the limit of reduced seeker field-of-view that is required to maintain the lock-on condition for a strap-down seeker. Specifically, an auxiliary variable related to the seeker look angle is introduced as an independent variable to design the relative range and line-of-sight (LOS) angle polynomial profiles. The first-order derivative of the LOS profile is designated positive to guarantee that the seeker's look angle decreases monotonically from its initial value to zero at the collision point. By transforming the guidance equations in terms of the auxiliary variable and integrating them with boundary constraints, an analytical impact time and angle guidance law is obtained and presented in the open-loop and closed-loop forms that are similar to the well-known proportional navigation guidance law with a time-varying gain. Moreover, the achievable impact time and angle sets are analytically determined for capturability analysis based on the initial engagement conditions. This technique is user/designer friendly in that it involves no heuristic tuning of guidance design parameters and error-prone estimate of time-to-go. Numerical simulations with comparisons under different terminal constraints are conducted to validate the effectiveness and advantages of the proposed guidance law.

Theory of Fractional-Polynomial Powered Descent Guidance

The notion and the theory of constructing planetary powered descent guidance laws based on fractional polynomials are introduced. Along the way a new perspective to the classical Apollo powered descent guidance designs is gained. As a foundation of this work, a theory is first developed on how to derive an explicit powered descent guidance law by selecting the feedback gains in a unique way in an implicit tracking guidance law. Then by employing a particular profile of the reference thrust acceleration in the tracking law with a special set of gains, a large family of powered descent guidance laws is obtained that offer the flexibility in trajectory shaping and thrust characteristics by two adjustable parameters. An equivalence theory is established to show that each in this family of guidance laws is actually the explicit guidance law from a fractional-polynomial thrust acceleration profile. This insight provides a perfect explanation to the predictable behavior and good targeting performance of these guidance laws. The well-known Apollo lunar descent guidance and E-guidance laws are revealed to be two members of this much broader class of fractional-polynomial powered descent guidance laws.

Computer-Based Scaffolding Targeting Individual Versus Groups in Problem-Centered Instruction for STEM Education: Meta-analysis

Computer-based scaffolding (CBS) has been regarded as an effective way to help individual students complete and gain skill at completing complex tasks beyond their current ability level. Previous meta-analyses also have demonstrated that CBS for collaborative learning leads to positive cognitive outcomes in problem-centered instruction for STEM education. However, while separate synthesis efforts have been conducted on CBS and collaboration guidance, little work has examined the intersection of these approaches. This study addresses this gap by examining the extent to which the effect of CBS is moderated by the group size in which students work, which type of CBS intervention was used in groups or individually, and whether CBS includes supports for both individual and group works or only individual learning. Results from 145 studies indicate that CBS leads to statistically significant cognitive learning effects when students solve problems individually, as well as working in pairs, triads, and small groups. Moderator analyses indicated that (a) effect sizes are higher when students worked in pairs than when they worked in triads, small groups, or individually; (b) the effect size of metacognitive scaffolding on group activity is higher than other types of scaffolding intervention; and (c) the effect size is higher for groups when scaffolding was present but collaboration support was absent. These results suggest that elaborated design and integration of CBS and collaboration guidance are considered to maximize students’ learning in problem-centered instruction within STEM education.

Model Predictive Convex Programming for Constrained Vehicle Guidance

A new model predictive convex programming is proposed in this paper for state and input constrained vehicle guidance design. The proposed method defines a convex optimization framework considering a flexibly designed cost function subject to inequality constraints and a sensitivity relation between state increments and input corrections. This formulated convex optimization problem can be solved in a computationally efficient manner. Simulation studies of nonlinear missile and aircraft landing guidance problems demonstrate the effectiveness of the proposed approach.

Design of an Gain-Scheduled Guidance Scheme for a Guided Projectile

This paper addresses the design of a two-dimensional guidance scheme in the vertical plane, using robust and gain-scheduling control methods, for a fin-stabilized canard-guided projectile. Given that the conventional proportional navigation guidance (PNG) is not completely adequate for target interception with a control-authority-limited weapon, the proposed guidance law is offered as an improvement compared with PNG while respecting a similar parallel navigation guidance principle. The projectile-target engagement kinematics full nonlinear model is discussed, and a linear parameter-varying model, necessary for guidance design, is derived without any approximation. A set of reduced-order mixed-sensitivity controllers with an additional reference model following constraint is designed using a specific computation procedure. The resulting homing closed-loop system is assessed through linear and nonlinear simulations of either nominal or perturbed scenarios. These scenarios include noise or uncertain launch initial conditions, and they also take a simplified or a more realistic autopilot loop into account. The gain-scheduled guidance scheme is finally compared with PNG, and with three other recent guidance laws considering limitations on the acceleration command.

Design and Analysis of a Robust UAV Flight Guidance and Control System Based on a Modified Nonlinear Dynamic Inversion

The work presented in this paper focuses on the design of a robust nonlinear flight control system for a small fixed-wing UAV against uncertainties and external disturbances. Toward this objective, an integrated UAV waypoints guidance scheme based on Carrot Chasing guidance law (CC) in comparison with the pure pursuit and line of sight-based path following (PLOS) guidance law is analyzed. For path following based on CC, a Virtual Track Point (VTP) is introduced on the path to let the UAV chase the path. For PLOS, the pure pursuit guidance law directs the UAV to the next waypoint, while the LOS guidance law steers the vehicle toward the line of sight (LOS). Nonlinear Dynamic Inversion (NLDI) awards the flight control system researchers a straight forward method of deriving control laws for nonlinear systems. The control inputs are used to eliminate unwanted terms in the equations of motion using negative feedback of these terms. The two-time scale assumption is adopted here to separate the fast dynamics—three angular rates of aircraft—from the slow dynamics—the angle of attack, sideslip, and bank angles. However, precise dynamic models may not be available, therefore a modification of NLDI is presented to compensate the model uncertainties. Simulation results show that the modified NLDI flight control system is robust against wind disturbances and model mismatch. PLOS path-following technique more accurately follows the desired path than CC and also requires the least control effort.

Implementation and validation of autopilot design for vertical missile systems

high nonlinearity and deficiency in control at boost-phase due to high angle of attack during maneuver and low velocity in the vertical launched missile. The necessity of high maneuverability and vertical launching require thrust vector control additional to aerodynamic control. effectively increasing the alertness of the missile against air defense threats by using That mixture usage of aerodynamic and thrust vector controls. Critical design of guidance and control is difficult and critical due to requirement and the rapidly changing dynamics of this type of missiles. The aim of this paper is to design autopilot with aerodynamics surfaces(fin)and thrust vector control by system characteristics reflection. by using Missile Lebadev Program (MLP) the model is developed based on the configuration of operating missile. Two control systems are aimed, which usages the command trajectory result optimization and the pitch rate controller which tracks real-time guidance command. The guidance and control strategy are developed through an actuation systems and autopilot design in the two channels pitch and roll based on the poles assignment technique. The investigation of the performance of pitch autopilot and its ability to reject disturbances due to cross-coupling between pitch and roll channels showed that, the pitch channel can reject disturbances within average time 3.5 sec.

Curved Path Following for Unmanned Surface Vehicles With Heading Amendment

This article presents two interrelated problems-along tracking and cross tracking-in guidance design for curved path following for unmanned surface vehicles. Since these two types of directional tracking are interactively constrained in most research work, an iteration mechanism is first put forward to optimize the path parameter in each closed loop such that along tracking will not affect cross tracking in the subsequent time period. An extended line-of-sight (ELOS) guidance principle is then proposed by varying the look-ahead distance with the cross-track error such that sideslip in cross tracking can be promptly compensated through vehicle heading amendment. Both simulation and experimental results verify the effectiveness of the proposed methods, which perform better than the conventional line-of-sight (LOS) and integral LOS (ILOS) guidance laws.