An efficient approach to mobile robot motion planning in dynamically unknown environments

This paper presents an efficient reactive approach to mobile robot motion planning in dynamically unknown environments featuring multi-shaped obstacles moving with varying velocities both in direction and in magnitude. In order to endow the mobile robot with real-time response capability, the entire motion planning duration is divided into tiny time slices during each of which a control input is determined for the mobile robot. We present a concept of a conservative collision-free state and mathematically define a collision-free state area as a feasible solution space which guarantees the safety in such a way that, as long as the center of the mobile robot is located in the solution space, a collision with any obstacles will never occur until the current time slice expires. Then, a reasonable oriented point is rapidly selected from the feasible solution space through a greedy principle based upon an equal angle-interval sampling method. In order to improve the escape capability of the mobile robot operating in a crowded environment, we present an urgency strategy by establishing a virtual repulsive force field around the mobile robot and determining the escape orientation via a potential energy function defined in the force field. Simulation results show that this reactive approach is very effective and well-suited for mobile robot motion planning in dynamically unknown environments.