I. Introduction
Simultaneous localization and map building (SLAM) is one of the key research contents in the field of mobile robots, and it is the key technology to realize autonomous navigation of robots in unknown environments [1]. According to the types of sensors used, SLAM algorithms can be divided into lidar SLAM and visual-based SLAM [2]. Visual SLAM is easily affected by light and texture, which leads to the decrease of accuracy and the lack of all-weather working ability [3]. Lidar SLAM, which takes lidar as the main sensor, is not limited by illumination, and has high accuracy and stability [4], so it has been widely used in the field of navigation and positioning. However, lidar SLAM algorithms is prone to precision degradation when working in scenes with insufficient geometric features [5].