MPP: Multiscale Path Planning for UGV Navigationin Semi-Structured Environments

Autonomous navigation of unmanned ground ve- hicles (UGVs) in structured road and indoor environments has made significant progress in recent years. However, navigation in outdoor semi-structured environments remains a challenge. This paper presents the multiscale path planning (MPP) method for UGV navigation in semi-structured environments. MPP leverages global, mid-layer and local planners to obtain global path and handle local obstacles of different sizes. First, the global planner provides guidance based on road connection relationships, selecting optimal connections by evaluating the distance between road nodes. Next, the mid-layer planner perceives large-scale obstacles and constructs the costmap, generating a mid-layer path that offers a general direction for the UGV. Finally, a local trajectory planning algorithm, namely terrain-considering timed elastic band (TC-TEB), is used to obtain local trajectory. This algorithm incorporates terrain-velocity constraints into the TEB algorithm to ensure the vehicle’s vertical stability. We demonstrate the safety and effectiveness of MPP through experiments in both simulated and real-world environments.