Local Path Planner for Mobile Robot in Dynamic Environment based on Distance Time Transform Method

For unknown field explorations in disaster areas, mobile robots that can replace human workers in dangerous environments can greatly improve disaster response efforts by reducing additional risk to human life. However, realizing such robot systems requires various technologies. In particular, path planning is quite important because mobile robots in the real world are surrounded by dynamic obstacles such as people, which may hinder a robot’s activities. In this research, we propose a collision avoidance method for a mobile robot in dynamic environments, considering the near-term motion and “personal space” of dynamic obstacles. Our method consists of the following three steps: “estimation,” “conversion,” and “planning.” In the estimation step, dynamic and static obstacles are recognized and their future positions are estimated from their previous motions. Next, in the conversion step, a time axis is added to construct a 3-D time-space coordinate system. Finally, in the planning step, a distance-time transform is applied to plan a safe 3-D path from the robot’s current position to the desired goal. The proposed method has been implemented on our mobile robot and mobile robot simulator and experiments were conducted to verify its usefulness. keywords: mobile robot, path planning, collision avoidance, personal space, distance time transform