This paper proposes an event-based method to ensure a collision-free movement of two mobile objects. The vehicles are locally controlled and connected by a communication network. In the hierarchical structure considered, a stand-on object can freely change its trajectory, whereas a give-way object has to plan its trajectory so as to avoid collisions with the stand-on object. The give-way object is provided with an event-based collision avoidance unit, which predicts the behaviour of the stand-on object, generates events and plans collision-free trajectories. A method for trajectory planning is introduced that is based on Bezier curves. The trajectory of the stand-on object is communicated to the give-way object, with which the trajectory of the give-way object can be adapted so as to avoid collisions. As the stand-on object can change its trajectory at any time under system limitations, its possible future positions are estimated by the give-way object to be able to react on the current movement of the stand-on object. If the spatial separation between the two objects deceeds a threshold, communication is invoked by the give-way object. In contrast to the existing literature this approach is performed online and with a low communication effort. The effectiveness of the method is demonstrated by a simulation study with two quadrotors.The main result is the guaranteed collision-free movement of the objects if the give-way object generates events with an appropriately chosen event threshold. The events are separated from each other by a determined minimum period of time. (C) 2020 European Control Association. Published by Elsevier Ltd. All rights reserved.
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