A Robust Autonomous Following Method for Mobile Robots in Dynamic Environments

Autonomous following is one of the key issues in mobile robotics with a wide range of applications in commercial, industrial and military areas. To achieve autonomous following, the robot needs not only to robustly detect and track the target, but also efficiently follow the target while avoiding obstacles. In this paper, we propose a method that combines a Line-of-sight sensor (a 2D laser range finder) and a Non-line-of-sight sensor (a low-cost Angle-of-Arrival (AOA) tag) to identify, track and follow the target person in dynamic environments. First, in order to get smooth and continuous moving trajectory of the target person, a Kalman Filter is used to fuse person tracking information from AOA data and laser data. Then, a real-time robot-centric rolling grid map is constructed using the laser data. On top of the rolling grid map, a target potential field is generated by using the fast marching method, and then a direction gradient field is created based on the target potential field. With the rolling grid map, the target potential field and the direction gradient field, an improved dynamic window algorithm, FMM-DWA, is proposed to control the robot to move towards the target. The proposed method considers not only the distance between the robot and the target, but also the difference between the heading of the robot and the reference direction provided by the direction gradient field, to avoid falling into the local optimum. To validate the performance of the proposed method, a series of person following experiments are carried out in complex dynamic environments. The experimental results show that the proposed following algorithm can effectively deal with the occlusion problem and robustly follow the target person while quickly avoiding the static and dynamic obstacles.