Collision avoidance

About: Collision avoidance is a research topic. Over the lifetime, 8014 publications have been published within this topic receiving 111414 citations.

Obstacle avoidance with sensor uncertainty for small unmanned aircraft

Abstract: The ability to detect, sense, and avoid obstacles in the environment is a critical capability for autonomous groups of unmanned aircraft. The overall obstacle avoidance problem is typically studied as two or three separate subproblems. Unfortunately, such an approach can lead to unrealistic assumptions being made about the other subsystems or specification of unnecessarily high levels of subsystem performance. In this paper, we present an approach to obstacle avoidance in the context of a multilayered, multi-objective control architecture that considers both the aircraft dynamics and sensor limitations in an integrated framework. Specifically, the concept of reachable sets is extended to include the error model of parallel-baseline, stereovision. An analytical solution is presented for the planar motion of a single unmanned aircraft. In addition, the extension to groups of UAV is introduced.

Hierarchical Longitudinal Controller for Rear-End Collision Avoidance

Abstract: Rear-end collision is a very serious problem in modern traffic situations, and there have been a great number of research reports on the longitudinal control method for road vehicles. In many cases, however, the control problem is formulated under platoon configuration and for some predictable noncollision situations. For predictable collision situations, regional and hierarchical approaches have been employed, but these approaches render difficulties due to ignorance for modeling error and logical error in a decision process. In this paper, the vehicle control for collision avoidance is studied with two control objectives, i.e., minimization of the safety distance error and regulation of the relative velocity between two vehicles. For this, a longitudinal controller using terminal sliding mode (TSM) with hierarchical structure is proposed for rear-end collision avoidance. The TSM is employed to achieve convergence in finite time, while the hierarchical approach is used for the system to accommodate the intelligence of the driver to handle various situations. The effectiveness of the proposed control scheme is verified by software simulations

A line of sight counteraction navigation algorithm for ship encounter collision avoidance

Abstract: A new navigation method, called a Line of Sight Counteraction Navigation (LOSCAN) algorithm has been introduced to aid manoeuvre decision making for collision avoidance based on a two-ship encounter. The LOSCAN algorithm is derived from an extension of the basic principle of traditional missile proportional navigation, recognising that the objective of the latter is target capture rather than target avoidance. The basic concept is to derive an acceleration command so as to increase the misalignment between the ships' relative velocity and the line-of-sight. The algorithm includes a risk assessment and the generation of appropriate navigation commands to manoeuvre own ship free of collision if a risk of collision exists. Numerical examples have been used to demonstrate the effectiveness of the algorithm. The relationship between the distance at the closest point of approach with respect to early warning distance, and with the norm of the acceleration, has also been analysed. In operation, the collision avoidance decision making process is a complicated problem, with its solution subject to ship states, practical dynamic constraints, Collision Avoidance Regulations (COLREGS), encountering ship manoeuvre coordination and human decision making factors. The proposed algorithm provides a consistent manoeuvre signal to aid decision-making.

3D Navigation and Collision Avoidance for Nonholonomic aircraft-like vehicles

Abstract: This paper extends the Navigation Function methodology to the case of 3D nonholonomic vehicles, both in single agent and multi-agent problems. The kinematic, nonholonomic, three-dimensional model considered is chosen to resemble the motion of an aircraft by preventing any movement along the lateral or perpendicular axis, as well as preventing high yaw rotation rates. The discontinuous feedback control law used is based on the artificial potential field generated by Dipolar Navigation Functions and steers the agents away from obstacles or each other and towards their destinations, while respecting the nonholonomic constraints present. The convergence properties of the proposed control strategies are formally guaranteed and verified by non-trivial simulation results. Copyright © 2010 John Wiley & Sons, Ltd.

Collision avoidance detector

Abstract: A collision avoidance detector including a transceiver installed in a rear portion of a leading vehicle operative to transmit a signal to and receive a reflected signal from a trailing vehicle, a processor operative to process the signals and derive therefrom information concerning a safe distance criterion between the leading and trailing vehicles and an alarm device, wherein the processor actuates the alarm device if the safe distance criterion is not met.