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.

Dynamic Obstacle Avoidance for an Omnidirectional Mobile Robot

Abstract: We have established a novel method of obstacle-avoidance motion planning for mobile robots in dynamic environments, wherein the obstacles are moving with general velocities and accelerations, and their motion profiles are not preknown. A hybrid system is presented in which a global deliberate approach is applied to determine the motion in the desired path line (DPL), and a local reactive approach is used for moving obstacle avoidance. A machine vision system is required to sense obstacle motion. Through theoretical analysis, simulation, and experimental validation applied to the Ohio University RoboCup robot, we show the method is effective to avoid collisions with moving obstacles in a dynamic environment.

ODE-based obstacle avoidance and trajectory planning for unmanned surface vessels

Abstract: A new method for real-time obstacle avoidance and trajectory planning of underactuated unmanned surface vessels is presented. In this method, ordinary differential equations (ODEs) are used to define transitional trajectories that can avoid obstacles and reach a final desired target trajectory using a robust tracking control law. The obstacles are approximated and enclosed by elliptical shapes. A transitional trajectory is then defined by a set of ordinary differential equations whose solution is a stable elliptical limit cycle defining the nearest obstacle on the vessel's path to the target. When no obstacle blocks the vessel's path to its target, the transitional trajectory is defined by exponentially stable ODE whose solution is the target trajectory. The planned trajectories are tracked by the vessel through a sliding mode control law that is robust to environmental disturbances and modeling uncertainties and can be computed in real time. The method is illustrated using a complex simulation example with a moving target and multiple moving and rotating obstacles and a simpler experimental example with stationary obstacles.

Method for controlling running of self-running robot

Abstract: PURPOSE: To make a self-running robot closer to a wall by turning only running direction of wheels by 90° without changing of the direction of the self-running robot and making the robot run sideways along the wall or an obstacle when the self-running robot comes close to the wall and it can not carry out a U-turn. CONSTITUTION: When the self-running robot comes so close to the wall of a room or the obstacle that it can not execute the U-turn, it is made to run sideways along the wall or the obstacle by turning only directions of the wheels 1 and 4 by 90° without changing the direction of the robot. The running distance in running sideways is changed according to the distance from the robot's own position to the wall of the room or the obstacle. COPYRIGHT: (C)1988,JPO&Japio

How Obstacles Perturb Population Fronts and Alter Their Genetic Structure.

Abstract: As populations spread into new territory, environmental heterogeneities can shape the population front and genetic composition. We focus here on the effects of an important building block of heterogeneous environments, isolated obstacles. With a combination of experiments, theory, and simulation, we show how isolated obstacles both create long-lived distortions of the front shape and amplify the effect of genetic drift. A system of bacteriophage T7 spreading on a spatially heterogeneous Escherichia coli lawn serves as an experimental model system to study population expansions. Using an inkjet printer, we create well-defined replicates of the lawn and quantitatively study the population expansion of phage T7. The transient perturbations of the population front found in the experiments are well described by a model in which the front moves with constant speed. Independent of the precise details of the expansion, we show that obstacles create a kink in the front that persists over large distances and is insensitive to the details of the obstacle’s shape. The small deviations between experimental findings and the predictions of the constant speed model can be understood with a more general reaction-diffusion model, which reduces to the constant speed model when the obstacle size is large compared to the front width. Using this framework, we demonstrate that frontier genotypes just grazing the side of an isolated obstacle increase in abundance, a phenomenon we call ‘geometry-enhanced genetic drift’, complementary to the founder effect associated with spatial bottlenecks. Bacterial range expansions around nutrient-poor barriers and stochastic simulations confirm this prediction. The effect of the obstacle on the genealogy of individuals at the front is characterized by simulations and rationalized using the constant speed model. Lastly, we consider the effect of two obstacles on front shape and genetic composition of the population illuminating the effects expected from complex environments with many obstacles.