Development of a Low-Cost Mobile Stereometric Mapping System for Unmanned Vehicles.

摘要

This thesis details the development of a cost-effective mobile stereometric mapping system (MSMS) suitable for use onboard unmanned ground and aerial vehicles. The MSMS is intended to perform direct-georeferencing based mapping in time-critical operations that are unsafe for human presence, such as monitoring dangerous situations, mapping unknown and potentially hostile environments, and tracking objects of interest. As such, the MSMS is uniquely designed as a portable and light-weight payload that is quickly and easily transferred to different platforms for deployment in a wide variety of situations.;The MSMS provides a simple yet effective mapping solution by integrating a single-frequency GPS receiver, a MEMS-based IMU, and a MEMS-based magnetometer to directly georeference imagery collected from two consumer grade digital cameras in stereometric alignment. The GPS is used in RTK (Real-Time Kinematic) mode to provide the cameras' position at the image exposure times, while the IMU and magnetometer provide the cameras' attitude and heading. The estimated exterior orientation parameters are then used in a photogrammetric space intersection to estimate 3D georeferenced coordinates of objects in mapping frame. Sensor and system calibration techniques are used to improve the performance of the low-cost sensors. To further increase the mapping accuracy, advanced filtering techniques are integrated with photogrammetric algorithms to optimally estimate object mapping coordinates and mitigate measurement noise. The design and implementation of the system are detailed and a proof-of-concept-test is performed to assess the system's performance.;The MSMS achieves mapping accuracies comparable to current low-cost mobile mapping systems without the use of ground control points. Specifically, the system is capable of positioning objects in the mapping frame with an accuracy ratio in the range of 1/100 (i.e., 1 metre error for a point 100 metres away) with respect to the given control framework.