Topic
Obstacle
About: Obstacle is a research topic. Over the lifetime, 9517 publications have been published within this topic receiving 94760 citations. The topic is also known as: impediment & barrier.
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01 Feb 1995
TL;DR: The development of the kinematic constraints and with motion planning under these constraints are dealt with and a new inverse kinematics is presented that provides joint motion for robots under contact constraints.
Abstract: A new robot path planning methodology, called obstacle accommodation, has been introduced for robots in cluttered environments. This methodology does not attempt to avoid physical contact between the robot and obstacles. Instead, it controls the contact to prevent damage to the robot. Obstacle accommodation represents a new robotic paradigm in which obstacles can contact robots at unspecified positions, i.e., a contact point can be at any point on any link. Obstacle accommodation requires analysis in kinematics, motion planning, dynamics, and control. This paper deals with the development of the kinematic constraints and with motion planning under these constraints. We begin by providing a general formulation of the motion constraints due to contact with obstacles. Next, a new inverse kinematics is presented that provides joint motion for robots under contact constraints. Finally, the new motion planning algorithm for robot motion in a cluttered environment is provided. The motion planning algorithm is verified by two examples, one on a linkage robot and the other on a mobile robot. >
29 citations
TL;DR: In this article, an asymptotically stable point-mass system governed by differential equations is proposed for point stabilization of a planar mobile car-like robot moving in the presence of a static obstacle.
Abstract: Artificial potential fields, which are widely used in robotics for path planning and collision avoidance, are normally beset by difficulties arising from the existence of local minima. This article proposes a solution that involves an asymptotically stable point-mass system governed by differential equations. The system represents a planar point robot moving from its initial position to the desired goal whilst avoiding a static obstacle. Because the system is asymptotically stable, its Lyapunov function, which produces artificial potential fields around the goal and the obstacle, has no local minima other than the goal configuration in the pathwise-connected proper subset of free space which contains the goal configuration. As an application, we consider the point stabilization of a planar mobile car-like robot moving in the presence of a static obstacle.
29 citations
Patent•
27 Feb 2001
TL;DR: In this paper, a decision logic and control circuit processes the signals and determines whether the user and the obstacle are close enough and there is sufficient closing velocity to present a hazard to the user.
Abstract: A sensor transmits a pulse in the direction of travel of a user and receives reflections from any obstacle in the path. The sensor provides two signals which indicate the relative range and the relative velocity between the user and the obstacle. A decision logic and control circuit processes the signals and determines whether the user and the obstacle are close enough and there is sufficient closing velocity to present a hazard to the user. When the circuit determines there is a hazard, the circuit activates a warning device. An activation signal is also generated when the circuit determines that the user cannot avoid the obstacle. This signal is supplied to an automatic protection system which includes an air bag located on the front portion of a jacket worn by the user. The air bag is inflated by the activation signal to protect the user when colliding with the obstacle.
29 citations
15 Jun 1993
TL;DR: A new model is derived for the quality of a simple obstacle detection algorithm that predicts the probability of detecting obstacles and the probabilities of false alarms, as functions of the size and distance of the obstacle, the resolution of the sensor, and the level of noise in the range data.
Abstract: Statistical modeling and evaluation of the performance of obstacle detection systems for unmanned ground vehicles (UGVs) is essential for the design, evaluation, and comparison of sensor systems. This issue is addressed for imaging range sensors by dividing the valuation problem into two levels, i.e., the quality of the range data itself and the quality of the obstacle detection algorithms applied to the range data. Existing models of the quality of range data from stereo vision and AM-CW laser range-finders (LADAR) are reviewed. These are used to derive a new model for the quality of a simple obstacle detection algorithm. This model predicts the probability of detecting obstacles and the probability of false alarms, as functions of the size and distance of the obstacle, the resolution of the sensor, and the level of noise in the range data. These models are evaluated experimentally using range data from stereo image pairs of a gravel road with known obstacles at several distances. The results show that the approach is a promising tool for predicting and evaluating the performance of obstacle detection with imaging range sensors. >
29 citations