Showing papers on "Collision avoidance published in 2005"

Evaluation of automotive forward collision warning and collision avoidance algorithms

Abstract: Collision warning/collision avoidance (CW/CA) systems target a major crash type and their development is a major thrust of the Intelligent Vehicle Initiative. They are a natural extension of adaptive cruise control systems already available on many car models. Many CW/CA algorithms have recently been proposed but the existing literature mainly focuses on algorithm development. Evaluations of these algorithms have been usually based on subjective ratings. The main contribution of this paper is the utilization of a naturalistic driving data set for the evaluation of CW/CA algorithms. We first collect manual driving data from the ICCFOT project, then process the data by Kalman smoothing, and finally identify ‘threatening’ and ‘safe’ data sets according to vehicle brake inputs and vehicle range behavior. Five CW/CA algorithms published in the literature are evaluated against the identified data sets. The performance of these algorithms is determined through a performance metric commonly used in signal detecti...

Collision Avoidance Theory : with Application to Automotive Collision Mitigation

Abstract: Avoiding collisions is a crucial issue in most transportation systems as well as in many other applications. The task of a collision avoidance system is to track objects of potential collision risk ...

Collision avoidance system

Abstract: A method of collision avoidance. The method includes receiving a signal indicative of a potential collision of a vehicle. The method also includes generating a haptic collision alert in response to the signal.

Toward 30-gram Autonomous Indoor Aircraft: Vision-based Obstacle Avoidance and Altitude Control

Abstract: We aim at developing autonomous micro-flyers capable of navigating within houses or small built environments. The severe weight and energy constraints of indoor flying platforms led us to take inspiration from flying insects for the selection of sensors, signal processing, and behaviors. This paper presents the control strategies enabling obstacle avoidance and altitude control using only optic flow and gyroscopic information. For experimental convenience, the control strategies are first implemented and tested separately on a small wheeled robot featuring the same hardware as the targeted aircraft. The obstacle avoidance system is then transferred to a 30-gram aircraft, which demonstrates autonomous steering within a square textured arena.

Cooperative vehicle collision avoidance using inter-vehicle packet forwarding

Abstract: This paper proposes a broadcast based packet forwarding mechanism for intra-platoon cooperative collision avoidance (CCA) using dedicated short range communication (DSRC) links. The paper first motivates the needs for broadcast forwarding as opposed to unicast routing for transporting inter-vehicle data for safety-critical applications. Then it introduces an implicit acknowledgement mechanism for reducing the amount of broadcast traffic for enhanced packet delivery rate. We have developed a discrete event hybrid simulator InventSim, which is capable of jointly simulating DSRC based vehicular wireless networks, highway vehicle traffic with car following logic and various drivers' reaction models, and ITS application interface to the wireless network. Performance of the proposed broadcast forwarding for a CCA system has been characterized using InventSim. Reported results demonstrate that with inter-vehicle spacing of nearly one second, the proposed mechanism is capable of saving up to 90% of vehicles in a platoon from chain crashes following emergency events at the front of the platoon. The system has been also evaluated for a wide range of parameters including vehicle spacing, drivers' reaction time, and the amount of background non-CCA traffic

A new method of ship routing on raster grids, with turn penalties and collision avoidance

Abstract: The article introduces a method of finding optimal routes on raster planes. The method presented takes advantage of a new algorithm that tends to minimize a number of direction changes within a route, while steering clear of the obstacles. Two different schemes, suitable for restricted area Vessel Traffic Service (VTS) system and collision avoidance system located on the own ship are described. The VTS-oriented scheme supports VTS priority policy that may extend or override international give-way regulations. The own-ship routing scheme in a give-way situation is capable of determining the shortest safe path to the destination point. The method takes into account own ship dynamics. It has linear time and space complexities and therefore is sufficiently fast to perform real-time routing on the raster grids. Both the general method and the algorithm it uses are presented in detail in the paper. Implementation issues are also discussed.

Modeling of driver's collision avoidance maneuver based on controller switching model

Abstract: This paper presents a modeling strategy of human driving behavior based on the controller switching model focusing on the driver's collision avoidance maneuver. The driving data are collected by using the three-dimensional (3-D) driving simulator based on the CAVE Automatic Virtual Environment (CAVE), which provides stereoscopic immersive virtual environment. In our modeling, the control scenario of the human driver, that is, the mapping from the driver's sensory information to the operation of the driver such as acceleration, braking, and steering, is expressed by Piecewise Polynomial (PWP) model. Since the PWP model includes both continuous behaviors given by polynomials and discrete logical conditions, it can be regarded as a class of Hybrid Dynamical System (HDS). The identification problem for the PWP model is formulated as the Mixed Integer Linear Programming (MILP) by transforming the switching conditions into binary variables. From the obtained results, it is found that the driver appropriately switches the "control law" according to the sensory information. In addition, the driving characteristics of the beginner driver and the expert driver are compared and discussed. These results enable us to capture not only the physical meaning of the driving skill but the decision-making aspect (switching conditions) in the driver's collision avoidance maneuver as well.

A collision mitigation system using laser scanner and stereovision fusion and its assessment

Abstract: Road traffic incidents analysis has shown that 52% of them are caused by a collision between two vehicles or between a vehicle and an obstacle. In this paper, a collision mitigation system is proposed and evaluated towards various typical road situations. The aim of the system is to decrease the kinetic energy of the collision through automatic emergency braking that occurs 1 second before the collision. This emergency braking is triggered by an alarm coming from a decision unit taking into consideration the results of a generic obstacles detection system -based on fusion between stereovision and laser scanner- and a warning area in front of the vehicle. The different sub-systems are presented. Various typical dangerous road situations are then introduced. The behavior of the collision mitigation system towards these situations is presented through real tests carried out in the context of the ARCOS French project. These experiments show the reliability, the genericity and the efficiency of the system. In particular, the false alarm rate is low, the detection rate is high and the system proves to be reactive.

Radiosurgery x-ray system with collision avoidance subsystem

Abstract: The present invention provides a radiosurgery and/or radiotherapy x-ray system including a collision avoidance subsystem for detecting and avoiding obstacles during treatment. The system includes an x-ray source having an emission head at a distal end of an articulated arm assembly extending from a base unit, with the head being adapted for selectively emitting an x-ray beam along a beam axis, and including an associated controller for selectively orienting the head whereby the beam extends along a succession of treatment axes. The system further includes a collision avoidance subsystem including means for preventing the head and arm assembly from effecting a collision with an object in one or more pre-computed exclusion zones.

The obstacle-restriction method for robot obstacle avoidance in difficult environments

Abstract: This paper addresses the obstacle avoidance problem in difficult scenarios that usually are dense, complex and cluttered. The proposal is a method called the obstacle-restriction. At each iteration of the control cycle, this method addresses the obstacle avoidance in two steps. First there is procedure to compute instantaneous subgoals in the obstacle structure (obtained by the sensors). The second step associates a motion restriction to each obstacle, which are managed next to compute the most promising motion direction. The advantage of this technique is that it avoids common limitations of previous obstacle avoidance methods, improving their navigation performance in difficult scenarios. Furthermore, we obtain similar results to the recent methods that achieve navigation in troublesome scenarios. However, the new method improves their behavior in open spaces. The performance of this method is illustrated with experimental results obtained with a robotic wheelchair vehicle.

Inter-vehicle communication and warning apparatus

Abstract: A short-range inter-vehicle communication and warning apparatus comprises a forward radar and a backward radar. The apparatus uses the radars to generate Frequency Modulation/Continuous Wave (FMCW) signals, uses amplitude shift keying for data modulation and arranges a special packet format, to realize such a low cost and fast response device of collision avoidance for vehicles. The invention has the dual capabilities of detecting and communicating simultaneously. It can also measure the relative speed of a preceding/rear vehicles and the relative inter-vehicle distance. The invention also exchanges the real-time traffic information with the preceding/rear vehicles at the same time. It is applicable to a one-to-one or one-to-many inter-vehicle channel model.

Passive Ranging for UAV Sense and Avoid Applications

Abstract: *† ‡ Unmanned Air Vehicles (UAVs) are currently not authoriz ed by the Federal Aviation Administration to operat e freely within the National Airspace (NAS) due to the lack of an onboard system capable of providing an “equivalent level of safety ” (ELOS) to manned aircraft regarding the ability to “sense and avoid ” (SAA) other aircraft. This paper describes the effort s t o integrate component technologies developed for electro -optical (EO) camera -based aircraft detection system into a SAA capability for High Altitude Long Endurance (HALE) UAVs such as Global Hawk and Predator B . The major technology gap preventing EO m easurements from be ing directly us ed with a collision avoidance system is the lack of range information. In this paper, the authors investigate the feasibility of estimating the range and velocity of other air t raffic by performing a small self -maneuver . The authors explore the performance of ra nge estimation while subject to the ownship maneuverability and other mission and operational constraints such as staying within the assigned Air Tra ffic Control (ATC) corridor . Furthermore, the authors investigat e the effects of range estimat ion errors on the collision avoidance performance .

The car-following and lane-changing collision prevention system based on the cascaded fuzzy inference system

Abstract: A new design for the collision prevention system based on cascaded fuzzy inference system (CFIS) for lane-changing maneuver and car-following is proposed. The lane-changing is combined with car-following to save the processing time of the lane-changing maneuver. The distance and speed relative to the vehicle in front or in target adjacent lane are measured by the spread spectrum radars and applied to the collision prevention system. The output acceleration or deceleration rate obtained from the CFIS collision prevention system is based on the characteristics of the vehicles. Monte Carlo simulations were conducted to demonstrate that the CFIS collision prevention system could provide a safe, reasonable, and comfortable drive for car-following and lane-changing. The system characteristics for car-following, lane-changing, and emergency braking are verified.

A collision avoidance warning and taxi guidance device

Abstract: The present invention relates to a collision avoidance warning system for an aircraft (1). The system comprises a light source (8, 9), sensors (10, 11, 12) mounted on the aircraft (1) and processing means for determining the dimensions and location of an object (15) relative to the aircraft (1) so as to determine whether a collision alert is to be given. The present invention is particularly suited to providing collision alert warnings on the ground, such as when the aircraft (1) is taxiing and manoeuvring on runways and in aircraft hangars.

Roadmap Based Pursuit-Evasion and Collision Avoidance

Abstract: We study pursuit-evasion games for mobile robots and their applications to collision avoidance In the first part of the paper, under the assumption that the pursuer and the evader (possibly subject to physical constraints) share the same roadmap to plan their strategies, we present sound and complete strategies for three different games In the second part, we utilize the pursuit-evasion results to post-process the workspace and/or configuration space and obtain a collision probability map of the environment Next, we present a probabilistic method to utilize this map and plan trajectories which minimize the collision probability for independent robots

Self-collision avoidance motion control for human robot cooperation system using RoBE

Abstract: We have proposed a real-time self-collision avoidance control method for the robot which is used for human-robot cooperation. In this method, we represent the body of the robot by using elastic elements referred to as "RoBE (representation of body by elastic elements)". The self-collision avoidance motion could be realized based on a reaction force generated by the contacts between the elastic elements before the actual self-collision of the robot. In this paper, especially, we consider task constraints and environmental constraints during the self-collision avoidance motion, and propose two priority functions for robots to realize the several kinds of tasks in an environment based on the force/moment applied by a human. By using this control algorithm, we could apply the proposed control algorithm to any robot systems used for human-robot cooperation. The proposed motion control algorithm is implemented in a human-friendly robot, referred to as "MR Helper", and experiments are done for illustrating the validity of the proposed self-collision avoidance motion.

Collision monitoring within satellite clusters

Abstract: An autonomous online collision avoidance methodology for satellite clusters is developed and simulated. Contours of probability, defined using state uncertainty ellipsoids, are used to monitor and predict potential collisions over time. The methodology integrates three approaches in order to reduce online computation for autonomous operations while still producing accurate predictions: 1) monitoring distances between bounded probability ellipsoids, which are used to evaluate when and how fast a collision may occur, 2) monitoring ellipsoids as they intersect, then calculating an outer bound of collision probability, and 3) numerical evaluation of collision probability using a three-dimensional (3-D) convolution integral to evaluate conservatism and insure accuracy. The approach assumes the initial state error (relative position and velocity), sensor error, and disturbance function are bounded by ellipsoids to a known level of probability. The methodology can be applied in the presence of different control schemes and system faults. If a collision is imminent, a control reconfiguration can then occur in order to move the healthy satellites to parking orbits. Simulation results show the proposed methodology to not be overly conservative. In addition, results show that satellite clusters with a close proximity will require a backup system that is accurate and gives measurement updates at least every few minutes.

Ground vehicle guidance along collision-free trajectories using elastic bands

Abstract: Latest developments in automotive sensor technology promise an unbroken innovation thrust for driver assistance systems. Accordingly, future vehicles might be able to navigate autonomously. For autonomous vehicles collision avoidance systems (CAS) are essential. Key elements of CAS are automatic path planning, path following and model based estimation of the driving conditions of a CAS-equipped car. For this purpose, a path planning technique using modified elastic bands is presented. Furthermore, a possible overall CAS-structure including path following control and driving condition estimation is discussed. Finally, simulation results for an evasion maneuver are given.

Distributed Model Predictive Control for Multi-Vehicle Formation with Collision Avoidance Constraints

Abstract: This paper presents a distributed model predictive control (MPC) method for unicycles information with collision avoidance constraints The proposed method first stabilizes the system by using a feedback linearization, and then a collision avoidance method based on MPC is applied to the linearized system One of the features of the proposed method is that each vehicle sequentially solves its optimal control problem at different time step Unlike other MPC collision avoidance methods in which all vehicles solve optimal control problems at every time step, only one vehicle can solve its optimization problem at one time step We derive a condition for the proposed method to ensure the feasibility of the optimization method and stability of the closed-loop system The effectiveness of the method is also investigated by experiments

A fuzzy-neural inference network for ship collision avoidance

Abstract: The basic structure of a fuzzy-neural inference network model for ship collision avoidance in sight one another is presented in this article. The model has three subnets. There are the subset of classifying ship encounter situations and collision avoidance actions, the subset of calculating membership function of speed ratio, and the subset of inferring alteration magnitude and action time. The weight values of former two subsets are obtained by self-learning from a number of samples, while those of last one subset are obtained form experience. All of these weight values can be adjusted respectively and conveniently according to practical needs. The test results show that by the inference of the model, some valuable decisions can be made from initial input data.

Decentralized stabilization and collision avoidance of multiple air vehicles with limited sensing capabilities

Abstract: Motivated by the needs of distributed air traffic management, we extend the decentralized navigation function methodology, established in previous work for navigation of multiple holonomic agents with global sensing capabilities to the case of local sensing capabilities. Each agent plans its actions without knowing (i) the destinations of the others and (ii) the positions of agents outside its sensing neighborhood. A nonsmooth decentralized navigation function is used for each agent. The collision avoidance and global convergence properties are verified through simulations.

Airport runway collision avoidance system and method

Abstract: Systems and methods for avoiding runway collisions. In a disclosed embodiment of the invention, a collision avoidance system includes a position-sensing device that is operable to determine a position of the aircraft, and a communications system operable to support two-way communications between the aircraft and other similarly configured aircraft. A collision avoidance processor is coupled to the position-sensing device and the communications system that is configured to generate a message if the aircraft moves into a restricted zone positioned proximate to the airport.

A Psychologically-Based Simulation of Human Behaviour

Abstract: We describe a system designed to simulate human behaviour in crowds in real-time, concentrating particularly on collision avoidance. The algorithms used are based heavi ly on psychology research, and the ways this has been used are explained in detail. We argue that this approac h gives better results than conventional methods, and detail further work to be done.

Vehicle accident avoidance method in which dynamic models of objects in the vehicle surroundings and of the vehicle itself are used to calculate a collision probability and determine a collision avoidance trajectory

Abstract: Method for motor vehicle accident avoidance has the following steps: generation of a digital situation plan of the vehicle and its surroundings by use of the vehicle's surroundings capture system, assignment of a dynamic model to each detected object (4) and to the vehicle (3) itself. Carrying out of a collision prediction based on the dynamic models, determination of a displacement and from it a collision probability. This is used to calculate a trajectory to avoid a collision, which is then implemented as an emergency maneuver. The invention also relates to a corresponding device for implementing the inventive method.

Airborne Collision Avoidance Systems and Air Traffic Management Safety

Abstract: A new ICAO Policy on Airborne Collision Avoidance Systems is needed, which recognizes it to be an integrated part of the air traffic management system's safety defences; and that should be fully included in hazard analyses for the total system's design safety targets.

On Automatic Collision Avoidance Systems

Abstract: In future automotive collision avoidance systems (CAS) collision-free path planning will be required. For this reason, two possible path planning techniques are compared. The first method is based on the mathematical theory of differential games, the second method focuses on so-called elastic bands. However, the method of elastic bands is essentially modified to provide solutions in complex driving situations. Furthermore, it is shown how path planning, path following control and driving condition estimation can be embedded in a possible overall CAS-setup. Therein, driving conditions are estimated based on the characteristic velocity. Finally, simulation results for an emergency maneuver are presented.

Collision Avoidance for Operational ESA Satellites

Abstract: Since more than 10 years the European Space Operations Centre (ESOC) has been monitoring close proximities of objects of the US Space Surveillance Network Catalog with operational ESA satellites in low-Earth orbits. In recent years this activity has evolved into an operational service which is provided for the ERS-2 and Envisat remote sensing satellites. In this paper the basic principles of a Catalog based conjunction event detection and collision risk estimation process are explained, associated orbit prediction uncertainties are addressed, operational collision avoidance procedures are outlined, avoidance manoeuvre citeria are explained, and examples of evasive manoeuvres are provided. The observed manoeuvre rate is compared with a statistical manoeuvre frequency assessment, based on collision flux predictions for Catalog size objects by ESA’s MASTER-2001 space debris environment model.

Reactive inflight obstacle avoidance via radar feedback

Abstract: Avoidance of unmapped obstacles is critical to autonomous flight in forested areas and urban canyons. The small vehicles capable of navigating in these spaces necessarily cannot carry the heavy and sophisticated sensor packages carried on large aircraft. We propose simple reactive feedback laws that enable obstacle avoidance for a hover-capable unmanned aerial vehicle (UAV) using a crude low resolution, small field of view radar sensor. The basic component in these laws is the reduction in the velocity component in the direction of the obstacle. We illustrate the performance of these feedback laws on a point mass double integrator model with velocity and acceleration limits. Simulation results in both 2-D and 3-D settings are presented.

AUV experiments in obstacle avoidance

Abstract: Reactive obstacle avoidance (OA) is an important step in attaining greater autonomy in autonomous underwater vehicles (AUV) For AUVs that conduct underwater surveys, avoidance of uncharted obstacles can improve vehicle survivability This paper discusses initial experiments at the Center for AUV Research in obstacle detection and avoidance using the Naval Postgraduate School ARIES AUV with the Blueview Blazed Array forward looking sonar It includes a discussion on evaluating OA optimality, autopilot control design and sonar image processing It concludes with a description of successful results from a recent demonstration