Feedback Guidance Research Articles

Study on multi-scheme analysis and evaluation method for concrete sequence placement of high arch dam

A complete scheme for solving the key scientific problems of how to make concrete sequence placement scheme of high arch dam reasonable and feasible and how to meet the need of construction process was presented. First, based on a coupling analysis of concrete sequence placement system of high arch dam, a mathematical model considering complex construction constraints was established. Second, a multi-scheme computational analysis method for concrete sequence placement of high arch dam was proposed based on dynamic simulation. Third, a multi-scheme evaluation method for concrete sequence placement was put forward based on analytic hierarchy process. Fourth, feedback guidance for progress control and management in the high arch dam construction process was proposed. Finally, these methods were applied to a practical project to show that the methods can analyze and evaluate multi-scheme for concrete sequence placement of high arch dam effectively, optimize the process of dam concrete sequence placement, and recommend engineering measures. These methods provide new theoretical principles and technical measures for real-time progress control in the high arch dam construction.

A cooperative guidance law for target estimation by multiple unmanned aerial vehicles

A new cooperative guidance law is proposed for target estimation of multiple unmamed aerial vehicles (UAVs) without involving numerical computational work. The guidance law derivation is based upon the Fisher Information Matrix (FIM) to quantify the amount of target information. For two UAVs, an analytical one-step determinant of FIM is introduced, which sufficiently reflects the trend of previous well-known optimal manoeuvers. Therefore, by considering only one-step information, as opposed to accumulated total information, a new feedback guidance law with intuitive physical analysis is induced and then its validity is verified by comparing it with the results of previous approaches. To apply the proposed idea to more multiple UAVs, a generalized formulation is derived as a weighted combination of each guidance law. Also, for more realistic application, the proposed guidance law is modified to deal with an avoidance problem of risk zone.

Visual Tracking in Wind with Field of View Constraints

This paper addresses the problem of tracking a ground-based target with a fixed camera pointing out the wing of a micro air vehicle that is subjected to constant wind. Rather than planning explicit trajectories for the vehicle, a nonlinear image-based feedback guidance strategy is developed that maintains the target in the field-of-view of the camera. We show that under ideal conditions, forcing the target to the center of the image results in flight paths that are elliptical trajectories. We also show that if the target is allowed to move in the image plane, circular orbits are possible. Both simulation and flight tests are used to demonstrate the effectiveness of the proposed algorithm and its robustness to wind gusts.

Optimal guidance for reentry vehicles based on indirect Legendre pseudospectral method

Development of a feasible guidance scheme for reentry vehicles is a challenge because of its significant nonlinearity and multi-constraints. A method for the implementation of three-degree-of-freedom guidance for constrained reentry vehicle is presented in the paper. First, the constrained trajectory is generated by Legendre pseudospectral method (LPM) and then the feasibily of the trajectory is validated. Based on the obtained reference trajectory, the guidance problem is converted into a trajectory state regulation problem which is a linear time varying system. A robust state feedback guidance law is generated in real time using indirect Legendre pseudospectral feedback method. Finally, simulation results illustrate that the overall guidance scheme can lead to a very accurately controlled flight with all the constraints satisfied even in the presence of initial state uncertainty.

Conceptual unifying constraints override sensorimotor interference during anticipatory control of bimanual actions

Traditional approaches to research on bimanual coordination focus on sensorimotor interference, motor programming, and effects of perception and feedback guidance; surprisingly, little is known about high-level conceptual constraints that might unify separate movements into coordinated actions. We investigated two possible forms of high-level unifying representations on anticipatory control (i.e., reaction time: RT) in two-limb (bimanual) movements. Specifically, we adapted a paradigmatic bimanual task involving reaching to targets by adding two novel manipulations. One involved a visual-perceptual manipulation in which target-objects were presented either separately (i.e., two circles) or as a unified object (i.e., two circles connected by a bar). The other involved variants on language representation to elicit separate action plans (i.e., separate instructional commands joined by 'and') or unified action plans (i.e., a single verb applying to both hands). Typical forms of sensorimotor interference were virtually abolished when these unifying constraints were available. These findings provide strong support for the theoretical account that unifying conceptual representations are primary forms of bimanual constraint. Findings further suggest that the organization and content of the language used to form action representations can strongly influence anticipatory planning of bimanual actions.

Educational Supervision Appropriate for Psychiatry Trainee's Needs

The authors studied the regularity and content of supervision sessions in one of the U.K. postgraduate psychiatric training schemes (Mid-Trent). A questionnaire sent to psychiatry trainees assessed the timing and duration of supervision, content and protection of supervision time, and overall quality of supervision. The authors examined the views of respondents based on their most recent experience of supervision. Almost all psychiatry trainees received regular, time-tabled supervision, and a majority went into supervision sessions with a preset agenda. Clinical case discussion was found to be the mainstay of the supervision session as reported by 94.7% of the respondents. One-third of the trainees used the supervision sessions to seek guidance regarding teaching medical students. They also sought advice on preparation for academic presentations in addition to developing administrative and management skills. A majority of trainees received personal and careers guidance and regular feedback on their performance. The average score for the overall quality of supervision was 7.88 out of 10. Supervision remains a unique learning experience for the psychiatry trainees. This study indicates that trainee psychiatrists want regular supervision sessions for discussion about various training issues. Educational supervision should be seen as an essential element in psychiatry training and assessed as part of the quality assurance monitoring of psychiatry training schemes.

Facilitating Children's Learning of Dynamic-Display AAC Devices: The Effect of two Instructional Methods on the Performance of 6- and 7-year-olds with Typical Development Using a Dual-Screen Prototype

This study compared the operation of a dynamic-display AAC device in two instructional conditions: corrective feedback (CF) and dual-screen guidance (DSG). In the CF condition prompts/feedback were provided for incorrect responses; the DSG condition used errorless guided instruction only. Twenty-one children with typical development – ten 6-year-olds and 11 7-year-olds – were randomly assigned to one instructional condition and completed five sessions: three learning/testing, one generalization, and one maintenance. The children were required to reproduce visual sentence stimuli on the AAC device. Differences were found in accuracy and efficiency of 6- and 7-year-olds. The 7-year-olds were more accurate and quicker than the 6-year-olds. Differences due to instructional condition were observed for 6-year-olds only. All children generalized and maintained learning.

Robust Nonlinear Optimal Solution to the Lunar Landing Guidance by Using Neighboring Optimal Control

A closed-loop time-optimal control strategy for the highly nonlinear problem of the lunar landing mission by using the perturbation technique is developed in this study. The first part of the study considers analytical solution for an optimal control policy of variable mass spacecraft, while it descents on the surface of the moon in the variable gravitational field of it. To validate the accuracy of perturbation solution, a numerical approach based on steepest descent method is employed. The second part considers analytical derivation of an optimal feedback guidance solution by employing the neighboring optimal control (NOC) law when effects of imperfection in the dynamic model or disturbing noises have been taken into account. The technique of NOC produces time-varying feedback gains that minimize the performance index to the second order for perturbations from a nominal optimal path. The robustness of the designed NOC law is examined with applying sinusoidal noises. From the study of the simulation results, it may be concluded that the developed optimal guidance laws may be used in real world spacecraft applications.

A task-driven intelligent workspace system to provide guidance feedback

We introduce a vision-based human–computer interaction system which collaborates with a user by providing feedback during user activities. We design an intelligent workspace system that analyzes the context of a user’s tasks and generates appropriate feedback guiding the user to complete the tasks correctly. While a user is performing the high-level activity, our system analyzes what sub-events the user has already completed and what sub-events are needed next in order for the user to finish the activity. Based on this analysis, the system generates hierarchical feedback messages to assist the user. We test our system on three different types of tasks: tightening nuts on a wheel of a car, assembling a toy spaceship with LEGO blocks, and assembling a laptop computer with its parts. Experimental results demonstrate the accuracy of the vision-based activity analysis, and a comparative user study shows that our system’s feedback enables users to complete assembly tasks with significantly improved efficiency.

複数設計点法を利用した飛しょう体のオンライン誘導則

This paper deals with design procedure of online guidance law for future missiles that are required to have agile maneuverability. For the purpose, the authors propose to mount high power side-thrusters on a missile. The guidance law for such missiles is discussed from a point of view of optimal control theory in this paper. Minimum time problem is solved for the approximated system. It is derived that bang-bang control is optimal input from the necessary conditions of optimal solution. Feedback guidance without iterative calculation is useful for actual systems. Multiple design point method is applied to design feedback gains and feedforward inputs of the guidance law. The numerical results show the good performance of the proposed guidance law.

A Suboptimal Guidance Design using Continuous-time MPSP with Input Inequality Constraint in a Hypersonic Mission

AbstractA newly developed nonlinear continuous-time model predictive static programming (MPSP) technique with input inequality constraints is presented in this paper for a carrier launch vehicle in a hypersonic mission, which leads to a closed form solution of the necessary guidance command. The proposed optimal guidance algorithm can be implemented online and leads to computational efficient. In this paper, the trajectory of the launch vehicle from launch point to terminal injection point is divided into two segments. In the first segment, a nonlinear feedback guidance loop using dynamic inversion is incorporated to assure vertical raise in presence of wind disturbance, thrust misalignment etc for launch clearance. In the second segment, the proposed guidance algorithm is incorporated to ensure the desired terminal conditions within a tight error bound with minimum control effort and to satisfy the others path constraints like desired control (angle of attack) effort in the transonic zone and high dynamics pressure region. The promising simulation results suggest that the proposed guidance algorithm with input inequality constraints is quite successful in obtaining the performance of the carrier launch vehicle.

Quality of closed chest compression on a manikin in ambulance vehicles and flying helicopters with a real time automated feedback

Context Automated verbal and visual feedback improves quality of resuscitation in out-of-hospital cardiac arrest and was proven to increase short-term survival. Quality of resuscitation may be hampered in more difficult situations like emergency transportation. Currently there is no evidence if feedback devices can improve resuscitation quality during different modes of transportation. Objective To assess the effect of real time automated feedback on the quality of resuscitation in an emergency transportation setting. Design Randomised cross-over trial. Setting Medical University of Vienna, Vienna Municipal Ambulance Service and Helicopter Emergency Medical Service Unit (Christophorus Flugrettungsverein) in September 2007. Participants European Resuscitation Council (ERC) certified health care professionals performing CPR in a flying helicopter and in a moving ambulance vehicle on a manikin with human-like chest properties. Interventions CPR sessions, with real time automated feedback as the intervention and standard CPR without feedback as control. Main outcome measures Quality of chest compression during resuscitation. Results Feedback resulted in less deviation from ideal compression rate 100 min −1 (9 ± 9 min −1, p < 0.0001) with this effect becoming steadily larger over time. Applied work was less in the feedback group compared to controls (373 ± 448 cm × compression; p < 0.001). Feedback did not influence ideal compression depth significantly. There was some indication of a learning effect of the feedback device. Conclusions Real time automated feedback improves certain aspects of CPR quality in flying helicopters and moving ambulance vehicles. The effect of feedback guidance was most pronounced for chest compression rate.

Linear Feedback Guidance for Low-Thrust Many-Revolution Earth-Orbit Transfers

TO GUIDE a low-thrust spacecraft to a target orbit, the most commonly used strategy is to frequently uplink control commands to correct orbital deviations. However, this guidance scheme requires a large amount of offline optimal control computations and data communications between the ground and the spacecraft, especially for low-thrust many-revolution Earth-orbit transfer missions (whichmay last several months). For the purpose of reducing ground operational loads, autonomous guidance has to be placed onboard. Kluever developed an inverse dynamics approach [1] and an empirical control law [2] to track reference trajectories, based on the concept of predictive control. These two methods require onboard iterative algorithms to find appropriate control-related parameters. In engineering practice, the implementation of the predictive control guidance usually depends on accurate calibration of thrust magnitude and direction as well as predictive horizon. Another strategy of low-thrust autonomous guidance is based on Lyapunov control laws [3–6] (which, however, usually do not provide optimal solutions). The question of how to select feedback gains of the Lyapunov control laws to achieve optimal or near-optimal performance is still unresolved. In this study, a new linear feedback guidance scheme is proposed for low-thrust Earth-orbit transfers involving large numbers of orbital revolutions. The key concept of this guidance scheme is that the spacecraft tracks the nominal trajectory, which is expressed by mean orbital elements without involving short periodic osculating motion. First, optimal trajectory and control are obtained via a direct optimization method with the consideration of both J2 perturbations and shadowing conditions. Along the optimal trajectory and control, a set of linearized equations of spacecraft motion expressed by mean orbital elements is then developed. At last, the trajectory tracking problem is formulated as a standard time-varying linear control problem, and linear control theory can be readily used for designing the guidance control law. An example transfer from a geostationary transfer orbit (GTO) to a geostationary orbit (GEO) was simulated to verify the guidance performance.

Toward the development of interactive virtual dissection with haptic feedback

Traditional, hands-on dissection of an animal is common practice in many classrooms to aid in the study of anatomy and biology. More specifically, virtual dissection environments have been developed making it possible to study the inner workings of animals without cutting them up. In this paper, we present a novel virtual reality dissection simulator, where a user can dissect an animal (i.e. frog) and its organs using a 3D force feedback haptic device. The simulator uses force feedback as part of a multimodal cue to provide guidance and performance feedback to the user. This paper highlights methodologies which are used for addressing some of the key challenges involved in designing and developing simulators, such as: modelling and mechanics of deformation, collision detection between multiple deformable bodies, and haptic feedback.

Group-Metacognitive Support for Online Inquiry in Mathematics with Differential Self-Questioning

This exploratory study investigated 100 Israeli 9th graders who used two different group-metacognitive support methods in online mathematical inquiry—group feedback guidance (GFG) and self-explanation guidance (SEG)—compared to a control group (CONT). The study evaluated each method's effects on students': (a) mathematical inquiry ability: problem solving, explanations, mathematical feedback in online forum discussions, and transfer ability; and (b) self-regulated learning (SRL) measures (self-report questionnaires and metacognitive feedback in online forum discussions). Metacognitive support methods, based on IMPROVE self-questioning strategies, appeared in pop-up screens and provided the two experimental groups with differential cues for problem-solving processes. Mixed quantitative and qualitative analyses showed that GFG students outperformed SEG students in most mathematical and SRL measures and the CONT students in all measures. In addition, SEG students outperformed the CONT students in mathematical problem-solving but not on mathematical transfer ability or SRL.

Minimum-Time Guidance and Control Law for High Maneuvering Missile

This paper deals with design procedure of online guidance and control law for future missiles that requires agile maneuverability. For the purpose, the missile with high powered side thruster is proposed. The guidance and control law for such missiles is discussed from a point of view of optimal control theory in this paper. Minimum time problem is solved for the approximated system. It is derived that bang- bang control is optimal input from the necessary conditions of optimal solution. Feedback guidance without iterative calculation is useful for actual systems. In this paper. multiple design point method is applied to design feedback gains and feed forward inputs of the guidance and control law. The numerical results show that the proposed guidance and control law has a high -performance for wide-ranging boundary conditions.

A neuro‐optimal approach for thrust‐insensitive trajectory planning

PurposeThe purpose of this paper is to devise a new approach to synthesize closed‐loop feedback guidance law for online thrust‐insensitive optimal trajectory generation utilizing neural networks.Design/methodology/approachThe proposed methodology utilizes an open‐loop variational formulation that initially determines optimal launch/ascent trajectories for various scenarios of known uncertainties in the thrust profile of typical solid propellant engines. These open‐loop optimized trajectories will then provide the knowledge base needed for the subsequent training of a neural network. The trained network could eventually produce thrust‐insensitive closed‐loop optimal guidance laws and trajectories in flight.FindingsThe proposed neuro‐optimal guidance scheme is effective for online closed‐loop optimal path planning through some measurable and computable engine and flight parameters.Originality/valueDetermination of closed‐loop optimal guidance law for non‐linear dynamic systems with uncertainties in system and environment has been a challenge for researchers and engineers for many years. The problem of steering a solid propellant driven vehicle is one of these challenges. Even though a few researchers have worked in the area of non‐linear optimal control and thrust‐insensitive guidance, this paper proposes a new strategy for the determination of closed‐loop online thrust insensitive guidance laws leading to optimal flight trajectories for solid propellant launch and ascent vehicles.

Design of three-dimensional missile guidance law via tunable nonlinear H ∞ control with saturation constraint

The three-dimensional missile guidance law with saturating actuator is proposed for the pursuit of an unpredictably manoeuvring target. The proposed guidance law achieves a satisfactorily robust performance without having to solve a complicated nonlinear Hamilton–Jacobi partial differential inequality and without relying on Takagi–Sugeno linear fuzzy models. In the proposed guidance scheme, the nonlinear part of the relative motion equations between the missile and target is first cancelled. Then, a tunable state feedback guidance law is designed to eliminate the effect of external disturbance. The conditions of tunable parameters are also proved to achieve the desired goal. The proposed guidance law can achieve reduced interception time than others, yet it is considerably simpler. An example is proposed to confirm it.

Impact of the Visual Environment on the Execution of Aimed Movements

The present study showed that movement execution depends on the direct visual environment. We replicated findings of an earlier study that showed a difference between real time information via a trace of the unfolding trajectory, and cursor feedback constituting real time information about the changing movement location. Detailed analyses involving subdividing a movement into four successive sections revealed that movements governed by trace feedback were typically slower and required more feedback guidance near the occurrence of peak velocity. The present study further showed that movement behavior under the two visual modes diverged even more due to the presence of a static object positioned within the action area of the movement. Movements in the trace feedback condition were affected by the presence of an object in the second half of the movement trajectory when the movement reached peak deceleration. Discussion focuses on the differences between the two modes of online visual information.

Measuring simulation fidelity through an adaptive pilot model

The paper presents a new approach to the quantification of simulation fidelity based on an analysis of pilot guidance strategy. The manoeuvre guidance portrait is conceived as the solution to a low-order equivalent system and to properly allow for pilot adaptation to changing cues and task demands, the model parameters are allowed to vary. Thus the concept of the Adaptive Pilot Model (APM) is proposed and developed. The theoretical foundation to the concept is developed using the familiar spatial variables in flight control, such as distance and speed. Motion is then transformed into temporal variables and drawing on the theory of τ ( t ) -coupling from visual flow theory ( τ ( t ) is the instantaneous time to contact) the APM model is transformed into a much simpler algebraic relationship when the pilot maintains constant τ ˙ during a deceleration. If we make assumptions about the separation of guidance and stabilisation control strategy, pilot guidance feedback gains are then closely related to the frequency and damping of the APM structure. Results are presented from the analysis of simulation trials with pilots flying an acceleration-deceleration manoeuvre that show strong correlation with the τ ( t ) -based guidance strategy. The interpretation of the theory in terms of simulation fidelity criteria is discussed.