# Topological Navigation and Localization in
## 6 Conclusions  
The proposed topological navigation and localization system for LHDs was developed and tested in simulation, field trials, and finally, in a production tunnel of a copper, underground, sublevel stoping mine. Using this system, the LHD was able to navigate safely inside the mine, maintaining a safe distance between the LHD and the tunnel's walls at all times.  
Parameterization of the navigation conditions for each individual TM node was crucial for achieving the desired behavior on the underground industrial tests. The software modularization allowed the development of specific software components for tackling the different challenges of the autonomous navigation. The _Navigation Control_ module manages the mission requests and the overall navigation behavior. _Deliberative Path Planning_ generates local driving trajectories for the _Guidance_ module to follow, while avoiding the tunnel walls and obstacles. _Command Executor_ maintains a queue of consistent and smooth commands to guarantee short-term operation, while simultaneously maintaining system safety. Finally, global and local localization allows maintaining an estimation of the pose of the LHD inside the mine.  
When comparing the automation system with a seasoned human operator, it shows a slightly slower performance (about 10% in terms of average instant speed), which is not that serious when taking into consideration all the safety and operational benefits of the system. Besides being faster, the human operator showed smoother driving and more control of the LHD, but this did not necessarily reflect on the performance of the system, or at least it was not noticeable when supervising the operation. It needs to be considered that the tunnel was very narrow and the system needed to be tuned to drive very near to the walls, at a distance of about 10 [cm], in order to be able to drive through some parts of the tunnel (the LHD manufacturer recommends a minimum distance of 50 [cm] to each side of the tunnel).  
One of the major problems during testing on site was the lack of a wireless communication infrastructure with the capabilities of high speed roaming. This caused preemptive stops and/or speed reductions while going through the tunnel, hindering the optimizing process of the system and hurting the overall performance. A video showing the operator's graphic interface while the system is driving the LHD autonomously through the tunnel can be found at [[https://youtu.be/4Q34N25](https://youtu.be/4Q34N25) XjpA]([https://youtu.be/4Q34N25](https://youtu.be/4Q34N25) XjpA) (accessed on 14 July 2021).  
The system is now being installed and tested in a room and pillar mine in Germany, where a more robust, and better performing, network infrastructure will be used.  
Conceptualization, M.M., I.P.-T., C.T. and J.R.-d.-S.; methodology, M.M., I.P.-T., C.T. and J.R.-d.-S.; software, I.P.-T. and C.T.; validation, M.M., I.P.-T. and C.T.; resources, J.R.-d.-S.; data curation, M.M.; writing--original draft preparation, M.M., C.T. and J.R.-d.-S.; writing--review and editing, M.M., I.P.-T., C.T. and J.R.-d.-S.; funding acquisition, J.R.-d.-S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Chilean National Research Agency ANID under project grant Basal AFB180004 and FONDECYT 1201170.  
Not applicable.  
The data presented in this study is contained in the article itself.  
We thank [PERSON] for the valuable discussions and support for on-site execution of the experiments, and [PERSON] and [PERSON] for their valuable help in computing metrics for the results section. We acknowledge Compania Minera San Geronimo for providing the mine infrastructure for testing the system, and GHH Chile for supplying the LHD machine needed for this work.  
The authors declare no conflict of interest.