Robust Map-Based Visual Localization System for Container Ports

The Hong Kong University of Science and Technology
Department of Computer Science and Engineering


PhD Thesis Defence


Title: "Robust Map-Based Visual Localization System for Container Ports"

By

Mr. Bohuan XUE


Abstract:

This thesis addresses the challenge of precise state estimation for Intelligent 
Guided Vehicles (IGV) in the dynamic, structurally complex environments of 
container ports. Central to this work is the development of a sophisticated 
visual localization system that dynamically adapts to environmental changes and 
interference from large metal structures, thereby enhancing navigation and 
operational planning.

A crucial innovation of this research is the application of a scaled quadratic 
pose estimation problem (sQPEP) solver for accurate calibration of camera 
extrinsics. To ensure high precision in response to varying loads, a physical 
model correlating vehicle payload changes to sensor z-axis height variations 
was developed. This model has been proven equivalent to a Multilayer Linear 
Network (MLN), enabling precise computation of the sensor's z-axis adjustments. 
This MLN-based approach facilitates the effective resolution of the scale-less 
hand-eye calibration problem, crucial for the accurate recovery of camera 
extrinsics relative to the vehicle control center.

The core methodology integrates deep learning with geometric analysis to detect 
ground markers and lane lines accurately, supplemented by a robust outlier 
exclusion mechanism. Furthermore, an automated map construction scheme is 
proposed to minimize manual interventions, enhancing system scalability and 
reliability. Wheel encoders are integrated as odometry inputs to ensure 
reliable performance even when visual data is limited.

After more than two years of operation at Nansha Port, the system has 
demonstrated its capability to adapt and perform reliably, contributing 
positively to the efficiency of port operations.


Date:                   Wednesday, 29 May 2024

Time:                   10:00am - 12:00noon

Venue:                  Room 4475
                        Lifts 25/26

Chairman:               Prof. Yaping GONG (MGMT)

Committee Members:      Prof. Yangqiu SONG (Supervisor)
                        Prof. Qiong LUO
                        Prof. Huamin QU
                        Prof. Jun ZHANG (ECE)
                        Prof. Jiwen LU (Tsinghua Univ.)