The 7th IFAC Symposium on Intelligent Autonomous Vehicles 2010

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Guidance Based Collision Free and Obstacle Avoidance of Autonomous Vehicles under Formation Constraints

Xianbo Xiang
LIRMM/CNRS
France

Bruno Jouvencel
LIRMM/CNRS
France

Abstract:
In the framework of nonlinear path following based formation control for autonomous vehicles, the reactive behaviors of obstacle avoidance and collision free are considered in this paper. For instance, if there are some obstacles appearing on the predefined paths or closing to the paths, how could the vehicles avoid obstacles while following the paths and keeping the formation? And how could the vehicles keep away from each other if they move on the same path and have to exchange the relative positions in the whole fleet. A guidance based method is proposed to address the problem. This idea is triggered by the concept of approaching angle in the control design for individual path following, which plays the similar role of Line-of-sight guidance angle. This control design guarantees that the vehicle always moves towards and converges to the path via the guidance. When one vehicle meets obstacles or another vehicle, the primary job is to avoid these barriers (obstacles or another vehicle) and following the path would be the secondary job. Therefore, it is natural to directly change the guidance angle while avoiding the barrier, and then go back to the nominal guidance angle when there are no barriers any more. A Gaussian function mainly based on the Euclid distance between the vehicle and the barrier, is chosen to introduce the additional part of the nominal guidance angle, which generating a Gaussian-like deviated route to avoid the barrier. Simultaneously, the geometric formation constraints will be realized by the Lyapunov-based nonlinear design. Finally, a simulation test is given to validate this idea. The behaviors of obstacle avoidance and collision free while following the paths with a specific formation, are clearly presented in the simulation result.

 

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