Enrique J. Bernabeu

Hough transform for distance computation and collision avoidance

A new technique for collision detection based on the application of the Hough transform is presented in this paper. As a consequence of applying this technique, a method for computing the minimum translational distance (MTD) between two spherically extended polytopes is introduced. This distance algorithm is based on the Gilbert-Johnson-Keerthi (GJK) algorithm. Parameters returned by the MTD algorithm hold collision-free configurations that avoid a predicted collision.

Collision prediction and avoidance amidst moving objects for trajectory planning applications

A methodology for computing a collision-free trajectory for mobile robots amidst moving objects is presented. This planner is based on a technique for computing the minimum translational distance between two mobile objects. This distance is then used for predicting and avoiding a collision. The computation of this distance is based on the application of the GJK algorithm to a particular subset of the Minkowski difference set of the involved objects. This subset states the separation or penetration distance between two objects along their given motions. When a collision is predicted, a collision-free intermediate temporal-position is generated avoiding such a collision.

Optimal geometric modeler for robot motion planning

Planning collision-free trajectories under real-time restrictions is a challenging topic in robotics. In order to reduce computational cost in the collision avoidance process, some authors have proposed different model representations. This article presents an optimal method able to generate automatically geometric models of the objects in a robotic system. For each object, two models are obtained, i.e., the minimum outer and the maximum inner models. Availability of both models allows one to face more successfully robot motion applications. The geometric modeler is focused on the generation of spherically extended polytopes. Each object to model is represented by a set of points taken from its surface. Models are generated through the application of an iterative process based on the Hough transform. When both outer and inner models have been generated, a parameter for evaluating the quality of the models is introduced. This parameter can be used by a rule-based system for increasing the complexity of the model generated and improving, therefore, the accuracy of the representation. 2000 John Wiley & Sons, Inc.

Real-time generation of collision-free paths for a mobile sphere

A novel and fast technique for solving the basic motion-planning problem is introduced. Obstacle avoidance is based on the computation of minimum translational distances that allows one to obtain collision-free intermediate configurations. When path planning is constrained to two degrees of freedom, Hough transform is applied to such configurations. After that, several collision-free paths are generating by joining different sets of selected intermediate configurations. These selections are obtained by applying the technique called minimum volume locus. Complexity of this path planner is linear with the number of obstacles. Object representation is based on spherically extended polytopes.

Multi-Agent Systems Platform for Mobile Robots Collision Avoidance

This paper presents a multi-agent platform to simulate a new methodical approach to the problem of collision avoidance of mobile robots, taking advantages of multi-agents systems to deliver solutions that benefit the whole system. The proposed method has the next phases: collision detection, obstacle identification, negotiation and collision avoidance. In addition of simulations with virtual robots, in order to validate the proposed algorithm, an implementation with real mobile robots has been developed.

Collision Avoidance of Mobile Robots Using Multi-Agent Systems

This paper presents a new methodical approach to the problem of collision avoidance of mobile robots taking advantages of multi-agents systems to deliver solutions that benefit the whole system. The proposed method has the next phases: collision detection, obstacle identification, negotiation and collision avoidance. In addition of simulations with virtual robots, in order to validate the proposed algorithm, an implementation with real mobile robots has been developed. The robots are based on Lego NXT, and they are equipped with a ring of proximity sensors for the collisions detections. The platform for the implementation and management of the multi-agent system is JADE.

Fast generator of multiple collision-free trajectories in dynamic environments

This paper presents a fast technique for obtaining a set of collision-free trajectories for a mobile robot under a continuous time approach. Given a mobile-robot path, a set of speeds for the mobile robot is generated with the constraint of avoiding collision with the moving obstacles in sight. Afterwards, this set of speeds is easily updated, when a change in the original mobile-robot path is applied. Collision-free trajectories that do not verify the dynamic constraints of the mobile robot are simply rejected

A navigation system for unmanned vehicles in automated highway systems

In this paper, a new method for generating a set of collision-free maneuvers for unmanned vehicles in automated highway systems is introduced. The low computational cost of the proposed maneuver planner allows its execution as frequent as the new positions and speeds of vehicles (obstacles) in sight are received. This planner is based on the computation of the minimum translational distance between two mobile objects. This distance is then used for predicting and avoiding a collision, generating (if it is possible and safe), overtaking (changing to the left and right lane), braking and keeping-the-lane maneuvers. These maneuvers can be provided to a decision-making process for selecting the most suitable one.

Distance Computation Between Non-Holonomic Motions with Constant Accelerations

A method for computing the distance between two moving robots or between a mobile robot and a dynamic obstacle with linear or arc-like motions and with constant accelerations is presented in this paper. This distance is obtained without stepping or discretizing the motions of the robots or obstacles. The robots and obstacles are modelled by convex hulls. This technique obtains the future instant in time when two moving objects will be at their minimum translational distance - i.e., at their minimum separation or maximum penetration (if they will collide). This distance and the future instant in time are computed in parallel. This method is intended to be run each time new information from the world is received and, consequently, it can be used for generating collision-free trajectories for non-holonomic mobile robots.

Continuous distance computation for motions with constant accelerations

A method for computing the distance between two mobile objects following linear or arc-like motions with constant accelerations is introduced in this paper. This distance is obtained without stepping or discretizing any objects motion. Objects are modeled by bi-dimensional convex hulls. The distance- computation algorithm obtains the instant in time when two mobile objects are at their minimum translational distance of separation or penetration. The distance and the instant in time are parallely computed. This method is so fast that can be run as frequent as new information from the world is received.