Showing papers on "Guidance system published in 2007"

Method and system for performing invasive medical procedures using a surgical robot

Abstract: A method and system for performing invasive procedures includes a surgical robot which is controlled by a guidance system that uses time of flight calculations from RF transmitters embedded in the robot, surgical instrument, and patient anatomy. Sensors around the room detect RF transmissions emitted by the RF transmitters and drive the robot according to a preprogrammed trajectory entered into the guidance system.

Path Planning and Following Algorithms in an Indoor Navigation Model for Visually Impaired

Abstract: This paper describes, path planning and following algorithms for use in indoor navigation for the blind and visually impaired. Providing indoor navigational assistance for this type of users presents additional challenges not faced by conventional guidance systems, due to the personal nature of the interactions. The algorithms are part of an overall Indoor Navigation Model that is used to provide assistance and guidance in unfamiliar indoor environments. Path planning uses the A* and Dijkstra's shortest path algorithms, to operate on an "Intelligent Map", that is based on a new data structure termed "cactus tree" which is predicated on the relationships between the different objects that represent an indoor environment. The paths produced are termed "virtual hand rails", which can be used to dynamically plan a path for a user within a region. The path following algorithm is based on dead reckoning, but incorporates human factors as well as information about the flooring and furnishing structures along the intended planned path. Experimental and simulating results show that the guiding/navigation problem becomes a divergent mathematical problem if the positional information offered by the positioning and tracking systems does not reach a certain requirement. This research explores the potential to design an application for the visually impaired even when to- date 'positioning and tracking' system cannot offer reliable position information that highly required by this type of application.

Experiment on Underwater Docking of an Autonomous Underwater Vehicle `ISiMI' using Optical Terminal Guidance

Abstract: An AUV (Autonomous Underwater Vehicle) being able to dock without surfacing to a launcher or an underwater station can give us long-time duration. It is important for the AUV to be guided to the dock safely. This paper introduces a test bed platform AUV named ISiMI and her optical terminal guidance system. ISiMI uses the optical terminal guidance system for underwater docking. The guidance system consists of a hardware part and a software part. One CCD camera and a frame grabber constitute the hardware part. An image process and a final approach algorithm based on visual servo control are the software part. A dock center which is a final approach target position of ISiMI is estimated by the image process and a reference yaw and pitch are generated by the final approach algorithm. We developed, also, an auxiliary controller to reinforce the final approach algorithm. This additional controller is necessary because there is an area where ISiMI cannot see the target lights near the dock. This makes the performance of docking better. Underwater docking experiments were conducted and the results are included in this paper.

Near-Optimal Missile Avoidance Trajectories via Receding Horizon Control

Abstract: The paper introduces a receding horizon control scheme for obtaining near-optimal controls in a feedback form for an aircraft trying to avoid a closing air-to-air missile. The vehicles are modeled as point-masses. Rotation kinematics of the aircraft are taken into account by limiting the pitch and roll rates as well as the angular accelerations of the angle of attack and the bank angle. The missile utilizes proportional navigation and it has a boost-sustain propulsion system. In the proposed scheme, the optimal controls of the aircraft over a short planning horizon are solved on-line by the direct shooting method at each decision instant. Thereafter, the state of the system is updated by using only the first controls in the sequence, and the process is repeated. The performance measure defining the objective of the aircraft can be chosen freely. In this paper, six performance measures consisting of the capture time, closing velocity, miss distance, gimbal angle, tracking rate, and control effort of the missile are considered. The quality of the receding horizon solutions computed by the scheme is validated by comparing them to the off-line computed optimal open-loop solutions.

Integrated estimation/guidance design approach for improved homing against randomly maneuvering targets

Abstract: Interceptor missiles, designed against aircraft, have substantial speed and maneuverability advantage over their targets. Thus, by exploiting the technological progress, even simple guidance concepts yielded satisfactory performance. For the interception of antisurface missiles, higher guidance precision is required. Using conventional guidance and estimation concepts, existing missile defense systems have demonstrated hit-to-kill accuracy against nonmaneuvering targets. Guaranteeing a similar performance against maneuvering targets can be achieved only if the estimation errors against such targets are minimized. This paper introduces a new, logic-based estimation/ guidance algorithm, that explicitly uses the time-to-go in the estimation process and modifies the guidance law to reduce the consequence of estimation errors. The successful outcome of the new approach is illustrated by an extensive Monte Carlo simulation study.

Speech-Based Interactive Information Guidance System using Question-Answering Technique

Abstract: This paper addresses an interactive framework for information navigation based on document knowledge base. In conventional audio guidance systems, such as those deployed in museums, the information flow is one-way and the content is fixed. In order to make an interactive guidance system, we propose the application of question-answering (QA) techniques. Since users tend to use anaphoric expressions in successive questions, we investigate appropriate handling of contextual information based on topic detection, together with the effect of using N-best information in ASR output. Moreover, we apply the QA technique to generation of system-initiative information recommendation. A navigation system on Kyoto city information was implemented. Effectiveness of the proposed techniques was confirmed through a field trial by a number of real novice users.

Device for aiding the piloting of an aircraft during an approach phase for the purpose of landing

Abstract: Device for aiding the piloting of an aircraft during an approach phase for the purpose of landing. The device (1) comprises a guidance system (8) for aiding guidance of the aircraft, in the event of the actuation of a control means (11A, 11B, 11n), both during an initial phase in accordance with a first guidance mode and during a terminal phase in accordance with a second guidance mode, the transition between these first and second guidance modes being achieved automatically by the guidance system (8).

Autonomous UAV Control Using a 3-Sensor Autopilot

Abstract: An autopilot system for a small unmanned vehicle is described which consists only of a single axis rate gyro, an absolute pressure sensor, and a GPS receiver. The structure of a control system is described which is able to estimate all necessary information to provide stabilization and guidance for a small flying wing UAV. A vector field guidance system is discussed that is able to navigate the aircraft from any initial location to a stable loiter around a point given only the coordinates of the desired point and the desired radius. Warping of the simple circular loiter into a racetrack shape is discussed. Modifications to the autopilot to achieve autonomous takeoff and landing are discussed. Experimental results of the successful implementation of all aspects of this autopilot system are shown, as well as an example flight where the only human interaction is to send a ‘takeoff’ and ‘land’ command.

Data fusion and path-following controllers comparison for autonomous vehicles

Abstract: This paper presents a comparative study of two path-following controllers developed for guiding autonomous vehicles in semi-structured outdoor environments. Part of this paper is focused on the performance of two path-following controllers, which are implemented using two different approaches, the first using fuzzy logic and the second using chained systems theory. The control effort and the errors magnitude along the path are evaluated in a comparative way. A magnetic guidance system for autonomous vehicles navigation in semi-structured outdoor environments is also described, integrating redundant encoders data and absolute positioning data provided by on-board magnetic sensors and magnetic markers buried in the road. Simulation and experimental results are presented showing the effectiveness of the overall control system.

A simple and adaptive on-line path planning system for a UAV

Abstract: This paper presents a guidance algorithm for an unmanned aerial vehicle (UAV). It combines a nonlinear lateral guidance control law, originally designed for UAVs tracking circles for mid-air rendezvous, with a new simple adaptive path planning algorithm. Preflight path planning only consists of storing a few way points guiding the aircraft to its targets. The paper presents an efficient way to model no-fly zones, to generate a path in real-time to avoid known or "pop-up" obstacles, and to reconfigure the flight path in the event of reduced aircraft performance. Simulation results show the good performance of this reconfigurable guidance system which, moreover, is computationally efficient.

Adaptive Disturbance Rejection Controller for Visual Tracking of a Maneuvering Target

Abstract: This paper presents an adaptive disturbance rejection control architecture for a flying vehicle to track a maneuvering target using a monocular camera as a visual sensor. Viewing the target’s velocity as a time-varying disturbance, the change in magnitude of which has a bounded integral, a guidance law is derived that guarantees asymptotic tracking of the target in the presence of measurement noise and an intelligent excitation signal in the reference input. Implementation of the guidance law is done via conventional adaptive block backstepping. Simulations illustrate the benefits of the method.

Stochastically Optimized Monocular Vision-Based Guidance Design

Abstract: This paper designs a relative navigation and guidance system for unmanned aerial vehicles for monocular vision-based control applications. Since 2-D vision-based measurement is nonlinear with respect to the 3-D relative state, an extended Kalman fllter (EKF) is applied in the navigation system design. It is well-known that the vision-based estimation performance highly depends on the relative motion of the vehicle to the target. Therefore, a main objective of this paper is to derive an optimal guidance law to achieve given missions under the condition that the EKF-based relative navigation outputs are fed back to the guidance system. This paper suggests a stochastic optimal guidance design that minimizes the expected value of a cost function of the guidance error and control efiort subject to the EKF prediction and update procedures. A one-step-ahead suboptimal optimization technique is implemented to avoid iterative computations. The approach is applied to vision-based target tracking and obstacle avoidance, and simulation results are illustrated.

Method and system for defense against incoming rockets and missiles

Abstract: An interception system for intercepting incoming missiles and/or rockets including a launch facility, a missile configured to be launched by the launch facility, the missile having a fragmentation warhead, a ground-based missile guidance system for guiding the missile during at least one early stage of missile flight and a missile-based guidance system for guiding the missile during at least one later stage of missile flight, the missile-based guidance system being operative to direct the missile in a last stage of missile flight in a head-on direction vis-a-vis an incoming missile or rocket.

Predictive Guidance and Control for a Tail-Sitting Unmanned Aerial Vehicle

Abstract: This paper is concerned with the research and development of a predictive control and guidance system for a tail sitting, unmanned aerial vehicle (UAV). The vehicle in question is the T-wing and it is a tail-sitting UAV. The T-Wing can fly in vertical and horizontal flight modes, using propeller wash over the control surfaces for control in vertical flight. These two flight conditions and the fundamentally different vehicle dynamics between them give rise to a challenging control problem. The predictive control and guidance strategy developed in this research synthesises non-linearity by creating a new linear model from a non-linear vehicle model at every time step. This methodology allows the use of efficient quadratic programming techniques to find the control solution. The continuous linearization ensures that the current linear problem is always a close approximation to the current nonlinear situation. This predictive controller has been successfully flight-tested in the vertical flight mode, running in real-time on a 400 MHz, PC-104 flight computer using xPC Target software.

Aerodynamic and Mission Performance of a Winged Balloon Guidance System

Abstract: A winged balloon guidance system exploits the natural wind-field variation with the altitude available in planetary atmospheres to generate passive lateral control forces on a balloon using a tether-deployed aerodynamic surface below the balloon. Several balloon guidance system topics are discussed, including development status, physics and aerodynamics, systems performance, concept of operations, and the near-space applications of this technology for scientific, communications, and defense applications.

Approach to Time Dependence and Reliability in Dynamic Route Guidance

Abstract: This paper presents a methodology for increasing the reliability of route suggestions in route guidance systems. The procedure, based on the A* path-finding algorithm and Chen's link penalty method, involves penalizing links with a high risk of being congested and obtaining a set of reliable route suggestions. Time dependence of travel times is considered by adapting the flow-speed model technique accordingly. The structure of the path-finding algorithms is also modified to account for real road network features. Finally, experiments using simulated travel time and reliability data are carried out on a road network, and the results are discussed.

Fault-tolerant flight control and guidance systems for a small unmanned aerial vehicle

Abstract: In this thesis, novel approaches for fault-tolerant flight control systems are investigated. This work focuses on developing algorithms for a small unmanned aerial vehicle. Therefore, the algorithms are designed to be modular, interchangeable, and highly computationally efficient. A nonlinear fault detection and isolation (FDI) system is constructed based on a multiple model scheme, which overcomes the traditional limitations of similar methods. The FDI system is also active, since it generates auxiliary excitation signals in order to systematically check any suspicious behavior of the aircraft, thus increasing the robustness of the detection system. An efficient control allocation module generates actuator control signals in order to achieve the desired roll, pitch, and yaw torque required by the autopilot. The control allocator is reconfigurable based on the fault diagnosis made by the FDI system. The autopilot consists of a turn rate controller on each of the aircraft’s axes, an altitude controller, an airspeed controller, a bank angle controller, and a sideslip angle controller. They are the result of a novel combination of explicit model following, nonlinear dynamic inversion, and nonlinear transformations of selected state variables. A practical methodology is discussed to analyze the stability and the robustness of the controlled system in the presence of model parameter and sensor uncertainties. An innovative approach for an adaptive and reconfigurable guidance system is also presented. It combines a nonlinear guidance control law with a new simple adaptive path planning algorithm. This guidance system avoids autonomously any known or pop-up obstacles. In case of an actuator failure, the flying performance of an aircraft degrades. Therefore, a separate algorithm estimates the new flying performance of the aircraft in order to reconfigure the guidance system. New trajectories are computed on-line by the guidance system, such that the new flight path matches the reduced aircraft performance. Many simulation results on a high-fidelity nonlinear model of a model aircraft demonstrate the successful operation of the reconfigurable flight control system. Résumé Dans ce travail de thèse, de nouvelles approches pour la conception de systèmes de commande tolérants aux fautes sont étudiées et appliquées au contrôle de petits avions sans pilote: les drones. Par conséquent, les algorithmes de commande sont conçus avec un souci particulier de modularité, d’interchangeabilité et de performance de calcul. Un nouvel algorithme non-linéaire et performant pour la détection et la caractérisation des pannes est construit sur le concept des modèles multiples, tout en dépassant les limitations connues de ce genre de méthode. Le détecteur de panne est aussi actif, en ce sens qu’il génère des signaux artificiels d’excitation pour tester systématiquement les organes vitaux de l’avion dès que celui-ci présente un comportement suspect. Un allocateur de commande performant est aussi proposé pour générer la commande sur l’ensemble des actionneurs à partir des commandes de couple générées par l’autopilote sur les axes de roulis, lacet et tangage. L’allocateur de commande est reconfigurable sur la base du diagnostic effectué par le détecteur de panne. L’autopilote du drone est constitué d’un contrôleur de taux de rotation sur chacun des axes de l’avion, d’un contrôleur d’altitude, de vitesse, d’inclinaison, et de “sideslip”. Tous les contrôleurs sont conçus sur la méthode d’inversion dynamique du modèle mathématique non-linéaire de l’avion. De plus, les contrôleurs utilisent une combinaison innovante de transformations non-linéaires de variables d’état choisies avec le suivi d’un modèle de référence. La stabilité et la robustesse des contrôleurs sont étudiées en détail. Un système de guidage novateur est aussi développé dans cette thèse. Il combine une loi de commande non-linéaire pour l’accélération latérale de l’avion avec un générateur de trajectoires simple et adaptatif. Ce système de guidage évite de façon autonome les obstacles et reconfigure les trajectoires de l’appareil en cas de panne pour s’adapter aux nouvelles performances de vol de l’avion. De nombreuses simulations sur un modèle non-linéaire d’avion témoignent du fonctionnement remarquable du système complet de commande et de guidage qui sont reconfigurables en cas de panne. Acknowledgments This thesis was written at the Measurement and Control Laboratory of the Swiss Federal Institute of Technology (ETH Zurich), Switzerland. My first thanks go to my parents and my brother for their continuous and loving support in every possible way during my studies and in life in general. I would like to include the families Paganelli and Corbisiero for their support and encouragement in various domains, and Daniel Tomaszewski for sharing with me his interest and enthusiasm for technical and engineering questions. Special thanks go to my colleagues at the Measurement and Control Laboratory who make the work environment at ETH Zurich very peaceful and friendly and for their constructive inputs. I thank in particular my former office mates from the UAV group and Mikael Bianchi for the many fruitful discussions we had. I also wish to thank Prof. Dr. Lino Guzzella and Dr. Chris Onder, who first welcomed me at ETH for a project dealing with fuel-cell systems. Moreover, I acknowledge the contributions of all the students who collaborated with me during the course of this research project. I wish to thank Hans Ulrich Honegger for his technical support and sharing with me his enthusiasm for his “home made” small flying machines. I wish to express my gratitude to the secretaries Claudia Wittwer, Annina Müller, and Brigitte Rohrbach for their wonderful work, which makes our lives much easier in the Lab. I owe special thanks to Brigitte for the copy-editing of this manuscript, for her invaluable help in many aspects, and for her kindness in general. Additionally, I thank the co-examiners of this thesis for their collaboration. Finally, I am most indebted to my PhD supervisor Prof. Dr. H. P. Geering for offering me this fascinating research project in exceptional working conditions. I gratefully acknowledge his constant support in many different aspects. December 2007 Guillaume Ducard

Evaluation of Reduction in the Performance of a Small UAV After an Aileron Failure for an Adaptive Guidance System

Abstract: After an actuator failure, the performance of an aircraft is degraded. If a fault detection and isolation system is available in the flight control system, the knowledge of the failure can be used to evaluate the new aircraft performance. Based thereon, a supervision system decides whether the mission can still be continued or if it should be aborted and have the aircraft redirected to the base station. In both cases, the aircraft should still be guided along a trajectory that is compatible with the new flying properties of the airplane. This paper focuses on an aileron failure and shows how the degraded flying performance can be evaluated and used to reconfigure the guidance system. Simulation results show that if the reduced performance due to the actuator failure is taken into account, the safety of the mission is improved.

System and method for guiding an aircraft to a stopping position

Abstract: A method for guiding an aircraft toward a stopping position within an aircraft stand of an airport includes receiving a radio frequency (RF) signal from a radio frequency identification (RFID) tag that is carried by the aircraft. The RF signal comprises aircraft-type data that is retrievably stored in an integrated circuit of the RFID tag, the aircraft-type data being indicative of a type of the aircraft. A current location of the aircraft is sensed, and based on the aircraft-type data and the sensed current location of the aircraft, instructions are determined for guiding the aircraft from the current location thereof to a predetermined stopping position for the type of the aircraft. Using a visual docking guidance system (VDGS) associated with the aircraft stand, the instructions are displayed in human-intelligible form for being viewed by a user aboard the aircraft.

Guidance system for an aircraft

Abstract: The guidance system ( 1 ) comprises a first means ( 2 ) for guiding the aircraft while maintaining a spacing with another aircraft, a second means ( 3 ) for making the aircraft pass through a particular waypoint at a required passing time, and means ( 5 ) for selecting automatically one of said first and second means ( 2, 3 ).

Autonomous mobile vehicle guidance system and method

Abstract: PROBLEM TO BE SOLVED: To provide a system and a method, guiding a vehicle while autonomously moving SOLUTION: In one embodiment of this autonomous mobile vehicle guidance system, a guidance robot guides the vehicle in a parking lot while autonomously moving The guidance robot 100 detects the vehicle 110 (the guided vehicle) to be guided, and acquires outer shape data of the vehicle necessary for the guidance by a sensor or the like Next, the guidance robot 100 calculates a guidance route to a prescribed parking space 120 (for example, designated by a driver) on the basis of environmental data such as empty space information and land form data 130 of the parking lot The guidance robot 100 remotely operates the vehicle along the guidance route, or provides guidance related to driving operation to the driver, while confirming movement of the vehicle COPYRIGHT: (C)2007,JPO&INPIT

Method and device for assisting the flying of an aircraft during an autonomous approach

Abstract: The invention relates to a method and a device for assisting the flying of an aircraft, said method and device being used to determine an approach path and comprising a guidance system for helping to guide the aircraft along this approach path. The inventive method and device define a main approach path (AI) and a corrected approach path that has an extra vertical margin (ΔH) related to the ground over which the craft is flying as compared with a main approach path representing a category 1 precision approach. Said guiding system guides the aircraft following the corrected approach path.

Behavior-Based Path Modification for Shared Control of Robotic Walking Aids

Abstract: Robotic walking aids can provide significant support for elderly users with mobility constraints. Automatic guidance systems help to lead a user to a specific target safely. In order to ensure good support for the user, the robotic walker should adapt to the motion of the user while at the same time not losing the target out of sight. Even though some of the existing active robotic walkers are able to guide their user to a target, during guidance, the input of the user is not considered sufficiently. Therefore, a new guidance system for robotic walkers has been developed. It is able to lead the walking aid user to a given target but at the same time considers his inputs and adapts the path respectively. The guidance system has been implemented and tested on the mobile robot assistant Care-O-bot II. A field test was done in an old people's residence proving the correct function and usefulness of the guidance system.

Towards vehicle trajectory planning for collision avoidance based on elastic bands

Abstract: Vehicle safety and driver assistance systems are an active field of research. Therein, a current trend focuses on guidance systems that link the vehicle to its environment. This paper presents a potential field based guidance strategy, which supports lane keeping and evasion manoeuvres. Therein, potential fields are scaled according to the hazard levels associated to the borders of the road and to other traffic participants. Trajectories of low hazard levels are generated by means of elastic bands that sense the environment like antennae of insects. An important contribution of this predictive motion planning approach is the incorporation of moving obstacles.

A vision system for optic-flow-based guidance of UAVs

Abstract: There is considerable interest in designing guidance systems for UAVs that use passive sensing (such as vision), rather than active sensing which can be bulky, expensive and stealth-compromising. Here we describe and evaluate a sensor that uses optic flow for measurement and control of height above the ground. A video camera is used in conjunction with a specially shaped reflective surface to simplify the computation of optic flow, and extend the range of aircraft speeds over which accurate data can be obtained. The imaging system also provides a useful geometrical remapping of the environment, which facilitates obstacle avoidance and computation of 3-D terrain maps. Laboratory tests of the performance of the device, whilst undergoing complex motions, are described.

Autonomous navigation and guidance for pinpoint lunar soft landing

Abstract: An autonomous navigation and guidance system scheme for pinpoint lunar soft landing is studied in this paper. First, the descriptions of outline of lunar soft landing process are provided. Second, a GNC system scheme for lunar soft landing spacecraft is described. Third, the autonomous navigation based on measurement-updated IMU for lunar soft landing is presented. Fourth, the autonomous explicit guidance for lunar soft landing is provided. Finally, the presented navigation and guidance method are validated by using the simulation and some conclusions are drawn.