Showing papers on "Collision avoidance published in 1998"

A hybrid collision avoidance method for mobile robots

Abstract: Proposes a hybrid approach to the problem of collision avoidance for indoor mobile robots. The /spl mu/DWA (model-based dynamic window approach) integrates sensor data from various sensors with information extracted from a map of the environment, to generate collision-free motion. A novel integration rule ensures that with high likelihood, the robot avoids collisions with obstacles not detectable with its sensors, even if it is uncertain about its position. The approach was implemented and tested extensively as part of an installation, in which a mobile robot gave interactive tours to visitors of the "Deutsches Museum Bonn." Here our approach was essential for the success of the entire mission, because a large number of ill-shaped obstacles prohibited the use of purely sensor-based methods for collision avoidance.

Navigation guided by artificial force fields

Abstract: This paper presents a new technique for controlling a user’s navigation in a virtual environment. The approach introduces artificial force fields which act upon the user’s virtual body such that he is guided around obstacles, rather than penetrating or colliding with them. The technique is extended to incorporate gravity into the environment. The problem of negotiating stairs during a walk-through has also been investigated with the new approach. Human subjects were tested in experiments in which they experienced three different kinds of navigation: unconstrained, simple constrained and assisted by force fields. Theresults demonstrate that the force-field technique is an effective approach for effective, comfortable navigation. KEY’VirORDS: 3D interfaces, virtual environments, collision avoidance, navigation, force fields.

Path planning for autonomous vehicles driving over rough terrain

Abstract: This paper presents a multiresolutional architecture of planners for obstacle avoidance in outdoor mobility. The planner makes use of off-line dynamical simulations results to efficiently find paths that avoid obstacles. The trajectories are generated by sets of steering velocity commands. This approach of building the search space for the planner results in realistic cost and trajectories for the vehicle. An implementation of the planner was developed and tested in a vehicle at the National Institute of Standards and Technology (NIST) with promising results.

Application of radio frequency identification systems to collision avoidance in metal/nonmetal mines

Abstract: Collisions between haulage equipment and pedestrian workers or other vehicles claim an average of five lives each year in surface and underground metal/nonmetal mining operations. Many more workers are severely injured, Although technologies exist that could prevent these collisions, (radar, closed-circuit TV, and backup alarms), they do have limitations and are not being used widely. New developments in radio-frequency identification (RFID) systems show promise for reducing the number of collisions. This paper, originally presented in 1998, describes tests conducted on off-the-shelf RFID systems and the subsequent development of a custom RFID system that could be used for both surface and underground mining equipment.

Multilayered reinforcement learning for complicated collision avoidance problems

Abstract: We have proposed the collision avoidance methods in a multirobot system based on the information exchanged by the "LOCISS: Locally Communicable Infrared Sensory System", which is developed by the authors. One of the problems in the LOCISS based methods is that the number of situations which should be considered increases very much when the number of the robots and stationary obstacles in the working environment increases. In order to reduce the required computational power and memory capacity for such a large number of situations, we propose, in this paper, a multilayered reinforcement learning scheme to acquire appropriate collision avoidance behaviors. The feasibility and the performance of the proposed scheme is examined through the experiment using actual mobile robots.

The potential of precision maps in intelligent vehicles

Abstract: In this paper, the authors discuss the concept of using probe vehicles with positioning capabilities and communications for mapping a road network with high accuracy. Positioning technology and map refinement are first discussed. Techniques for collecting position data and characteristics of the collected data are then described. Example applications are discussed briefly. Some of these include lane- keeping, collision avoidance, curve warning, and obstacle detection. Additional applications that are discussed include precision positioning, sensor fusion, and low communication latency. The paper concludes with a discussion regarding problems faced in using the proposed technology.

Advanced collision warning systems

Abstract: The paper outlines the framework under which Jaguar is carrying out its collision warning and avoidance research. It shows the history of the work, the progression from conventional cruise control to adaptive cruise control and then on to collision warning and intervention. The approach used by Jaguar to develop and check on the user needs/requirements for collision warning systems is described. The strategies being adopted for the warnings and intervention are discussed, as are issues related to the sensor and scenario prediction. The planned trials to evaluate the system and the possible saleable product are then briefly discussed.

Collision avoidance for highway vehicles using the virtual bumper controller

Abstract: In this paper, the authors describe a concept described as a virtual bumper which integrates steering, braking and acceleration control in response to incursions into a programmable region around a vehicle. The dynamic behavior is designed to be compatible with normal driving behavior, vehicle and human dynamic constraints, and acceptable response to unpredicted emergency situations. The authors discuss longitudinal and lateral impedance control, and describe the demonstration of the virtual bumper control strategy in a real-time simulation.

Development of collision avoidance systems at delphi automotive systems

Abstract: This paper describes a systems engineering approach to the design and development of collision avoidance systems. It discusses the evolution of a collision avoidance system, and identifies the first component as an adaptive cruise control (ACC) system. This is then followed by a discussion regarding the need for data acquisition systems (DAS).

Collision-avoidance: nature's many solutions.

Abstract: How does the brain sense looming danger? A new study shows that specialized visual neurons in pigeons carry out several different computations in parallel to analyze signals from approaching objects such as predators.

Benefit Evaluation of Crash Avoidance Systems

Abstract: A five-layer hierarchy to integrate models, data, and tools is proposed for benefits assessment and requirements development for crash avoidance systems. The framework is known as HARTCAS: Hierarchical Assessment and Requirements Tools for Crash Avoidance Systems. The analysis problem is multifaceted and large-scale. The driving environment is diverse and uncertain, driver behavior and performance are not uniform, and the range of applicable collision avoidance technologies is wide. Considerable real-world data are becoming available on certain aspects of this environment, although the collection of experimental data on other aspects is constrained by technological and institutional issues. Therefore, analyses of collision avoidance systems are to be conducted by collecting data on nominal operating conditions to the greatest extent possible and by using such data to build models for analysis of the rare, abnormal conditions. HARTCAS provides a framework within which to structure the collection and use of...

Trials of automotive radar and lidar performance in road spray

Abstract: The European Prometheus project had as two of its aims the development and evaluation of vehicle radar and lidar sensors as sources of control signals for: autonomous intelligent cruise control; and collision avoidance. The trial described arose from realisation in the European automotive industry that in designing mm wave and infra-red range-measuring sensors for use in such systems, there was a lack of experimental data about any degradation of their performance caused by road spray. This spray arises principally from other road vehicles in front of the sensor-fitted vehicle and could thus affect the detection of such vehicles and other objects. Accordingly, a joint European experiment was framed under the Prometheus programme to acquire quantitative data under controlled conditions with stationary and mobile radars and lidars.

Obstacle Avoidance in Multi-Robot Systems, Experiments in Parallel Genetic Algorithms

Abstract: Overview parallel computing path planning search techniques inverse kinematics collision detection collision avoidance examples discussion, conclusions and future work.

Avoidance of moving obstacles through behavior fusion and motion prediction

Abstract: We propose a novel approach of fusing the fuzzy control actions of the obstacle avoidance, goal seeking and steering behaviors, in which the steering behavior is derived from motion prediction. As such, the navigator is more capable to steer clear of the zone of high collision probability. Through simulation, it has been confirmed that the navigator having this steering behavior can tackle multiple moving obstacles successfully at much higher speed compared with those without. Furthermore, it does not require any a priori knowledge of the obstacle motion.

On-line Planning for Collision Avoidance on the Nominal Path

Abstract: In this paper a solution to the obstacle avoidance problem for a mobile robot moving in the two-dimensional Cartesian plane is presented The robot is modelled as a linear time-invariant dynamic system of finite size enclosed by a circle and the obstacles are modelled as circles travelling along rectilinear trajectories This work deals with the avoidance problem when the obstacles move in known trajectories The robot starts its journey on a nominal straight line path with a nominal velocity When an obstacle is detected to be on a collision course with the robot, the robot must devise a plan to avoid the obstacle whilst minimising a cost index defined as the total sum squared of the magnitudes of the deviations of its velocity from the nominal velocity The planning strategy adopted here is adjustment of the robot’s velocity on the nominal path based on the time of collision between the robot and a moving obstacle, and determination of a desired final state such that its Euclidean distance from the nominal final state is minimal Obstacle avoidance by deviation from the nominal path in deterministic and random environments is based on the work presented here and is investigated in another paper

AMADEUS: a mobile, autonomous decentralized utility system for indoor transportation

Abstract: The authors have developed a mobile, autonomous decentralized utility system for indoor transportation, called AMADEUS. This paper explains how we put it to practical use. AMADEUS is a system designed around transportation agents. We eliminated centrally managed vehicle allocation and routing plans by implementing autonomous vehicle allocation negotiations and collision avoidance between agents. The transportation agent's collision avoidance function enables the bi-directional movement of vehicles on a single-track thereby making efficient, space-saving transportation possible. This paper introduces the concept of AMADEUS and describes the transportation agent architecture by focusing on installing the collision avoidance function.

Collision avoidance using potential fields

Abstract: Control of manipulator collision avoidance by using computer‐aided potential field method is studied. A repulsive force is artificially created using the distances between the robot links and obstacles, which are generated by a distance computation algorithm. Typical approaches for definition of link coordinate frames and kinematics computations are adopted. Control gains in the potential field control model are selected with respect to the ranges of the angular velocity and angular acceleration of an industrial robot. Results on collision detection and collision avoidance control are presented. Using a high‐speed personal computer, real‐time manipulator control was achieved. From the results, changing repulsive force gain can change the safety distance. This makes the safety zone adjustable and provides greater intelligence for robotic tasks under the ever‐changing environment.

Realization of autonomous navigation in multirobot environment

Abstract: In this paper, we discuss autonomous navigation in multirobot environment based on local communication. To carry out cooperative tasks using multiple autonomous robots, navigation systems should be implemented to the robots because mutual alignment of their positions and collision avoidance to each other become important. Therefore, it seems a collision avoidance and a self-localization are indispensable as elemental techniques for the navigation. Although these techniques need to recognize situation of robots surrounding environment, conventional devices to acquire information around them can not work sufficiently in such environment. For this problem, we propose techniques based on the local communication and the navigation system by combining them for multirobot environment. It is shown that robots can arrive their goal precisely without collision among them through proposed navigation systems.

Collision avoidance by a ship with a moving obstacle: computation of feasible command strategies

Abstract: A ship moving from a point A to a point B detects a moving small obstacle at close range. Hence, the ship has to perform a maneuver to avoid collision with the moving obstacle. Using a realistic model of a tanker ship, a method is proposed for computing feasible rudder command strategies for performing the collision-avoidance maneuver.

Application of nonlinear control to a collision avoidance system

Abstract: The design of a collision avoidance (CA) algorithm is presented. Previous work relied on a simple CA algorithm which used on/off brake control. This work is extended by using nonlinear control techniques to improve brake control and minimize driver discomfort. First, a quarter car model suitable for control design is described. Then, a multi-surface sliding controller with on/off hysteresis is developed. The on/off hysteresis is modified to include a switch with 1st order dynamics in an attempt to minimize large initial accelerations. Finally, the simulation results of the CA algorithms are given. For the covering abstract see IRRD E102946.

Mobility planning for autonomous navigation of multiple robots in unstructured environments

Abstract: We describe an approach to mobility planning for autonomous navigation of multiple vehicles in unstructured environments. At the lowest level, this approach uses command arbitration in order to combine command recommendation from driving behaviors. Driving behaviors include local behaviors such as obstacle avoidance or goal tracking, and strategic behavior such as route planning to distant goals. Obstacle avoidance is performed by evaluating a fixed command set with respect to a terrain map built from 3D sensors. Route planning is based on the D* dynamic route planner which evaluates the command set based on the currently optimal path to the next goal. An additional planner, called GRAMMPS, is used to continuously analyze the outputs of the route planners running on each of the vehicles and re-computes optimally the allocation of goals to vehicles in order to minimize time and distance travelled. This approach has be exercised extensively with two vehicles using stereo and LADAR for obstacle detection and map building.

On-line Collision Avoidance for Multiple Robots Using B-Splines

Abstract: Real world assembly sequences consists of multiple assembly steps, many of which can be performed in parallel. In practice this parallelism is often not exploited because of the complexity involved in avoiding collisions between all of the robots. In this paper we describe a simplified method of achieving smooth collision free paths for multiple robots within a single assembly workcell. Our method is simple because we exploit properties of B-splines to reduce the problem to path planning without moving robots. We develop a path planner to compute an initial linear path. Using that path as input, a trajectory generation tool creates a collision free path of any desired continuity. We exploit three properties of B-splines: (i) continuity for smooth paths, (ii) convex-hull for collision avoidance, and (iii) locality for dynamic course alteration without loss of continuity. In addition, our system runs in real-time, easily accommodating multiple robots. Finally, we describe a user level visualization tool for this system.

Collision avoidance through improved communication between tractor and trailer

Abstract: On September 2 1994, the National Highway Traffic Safety Administration (NHTSA) issued a notice in the Federal Register to promote a cooperative program which would foster the development, evaluation, and deployment of heavy vehicle intelligent communication and powering enhancement system(s). In response to this solicitation, Delco Electronics Corporation, on behalf of its potential project partners, submitted a proposal detailing a collaborative, jointly governed venture between industry and Government to develop and evaluate heavy-duty technology vehicles using two-way communication between the tractor and the trailer. The object of this cooperative agreement was to foster the development, evaluation, and deployment of intelligent communication and powering, also requiring the installation of several advanced electrical sub-systems on the trailers in order to properly exercise these communciation and powering techniques between the tractor and trailer in the real world. Among the devices installed on the vehicles, of particular interest to the government agencies, were the Side Collision Warning System, Brake Stroke Indicator, Head-up Display, and a Rear View Video Camera as collision avoidance devices. A unique feature of this program was the in-fleet operational testing of the systems, using real truck drivers, who faced real driver problems and performance pressures. The drivers introduced a recordable "human factors" element into the evaluation system with regard to the safety and productivity value of many of the tested systems. If something bothered them, it got shutoff or broken. (A) For the covering abstract see IRRD E102514.

Aircraft collision avoidance trajectory generation

Abstract: This paper presents a new approach to the aircraft collision avoidance problem. This approach gives a recommended avoidance trajectory in both the horizontal and vertical planes of motion based on the geometric relationship between aircraft and threats. A new concept, the "threat map", is introduced to describe moving threats as static threats. Thus, motion planning for dynamic threats is reduced to path planning for stationary threat avoidance. At every time interval, the threat map is updated and the velocity direction of the aircraft is calculated to avoid the threats. The "risk space" is used to model a threat By avoiding the risk space, the aircraft avoids the threat while keeping a safe separation. Some simulation studies show the effectiveness of the proposed approach.

Rules and Regulations in Maritime Collision Avoidance: New Directions for Bridge Team Training

Abstract: This paper is based on work done originally for the Chevron Shipping Company, whose agreement to its publication in its present form is gratefully acknowledged.Ever since the International Regulations for Prevention of Collision at Sea (IRPCS) were introduced as a control system for collision avoidance, there have been disputes and arguments about exactly what they mean, and how they should have been applied in particular collision incidents. The principle of deciding by international agreement which ships should be given the duty of keeping clear of other ships generally works well but, as traffic volumes increase, so do situations in which the IRPCS alone do not provide a clear indication of what is expected of the mariner. Various solutions have been addressed to this problem, ranging from proposed radical revisions of the whole principle of collision avoidance, through periodic thoughtful adjustments to the details of the IRPCS, to informal additions and requirements imposed by individual shipowners on their fleets. The residual problem with any solution (except perhaps the first mentioned) is that there will always be exceptions where the rules are unclear or ambiguous. Adding adjustments may reduce these exceptions but, unless all uncertainties can be removed, the adjustments may create a new and even more complex set of exceptions, which are yet more difficult to interpret.

Collision avoidance and resolution multiple access (CARMA)

Abstract: The collision avoidance and resolution multiple access (CARMA) protocol is presented and analyzed. CARMA uses a collision avoidance handshake in which the sender and receiver exchange a request to send (RTS) and a clear to send (CTS) before the sender transmits any data. CARMA is based on carrier sensing, together with collision resolution based on a deterministic tree-splitting algorithm. For analytical purposes, an upper bound is derived for the average number of steps required to resolve collisions of RTSs using the tree-splitting algorithm. This bound is then applied to the computation of the average channel utilization in a fully connected network with a large number of stations. Under light-load conditions, CARMA achieves the same average throughput as multiple access protocols based on RTS/CTS exchange and carrier sensing. It is also shown that, as the arrival rate of RTSs increases, the throughput achieved by CARMA is close to the maximum throughput that any protocol based on collision avoidance (i.e., RTS/CTS exchange) can achieve if the control packets used to acquire the floor are much smaller than the data packet trains sent by the stations. Simulation results validate the simplifying approximations made in the analytical model. Our analysis results indicate that collision resolution makes floor acquisition multiple access much more effective.