Microtunneling is a trenchless construction method that is highly adequate to install pipelines beneath roads, rail roads, dams, harbours and environmentally sensitive areas. Microtunneling could be understood as a remotely-controlled, guidance operation of a MicroTunneling Boring
Machine (MTBM), where references are provided by a human operator from the surface. A review of current technologies and main working principles of traditional guidance systems used to determine the position and orientation of the drill head of the MTBM during tunneling will be presented. Practical limitations and drawbacks will be discussed. A special attention will be given to those systems based on a laser-generated reference. In this paper a new video target system developed to improve the current performance of guidance systems will be presented. As it will be detailed, improving target processing of laser’ incidence allow us to extend the minimum range to achieve a distance over 400 m, without having to displace the total reference stations which are guiding the path during tunnel execution. The new target sensing principle, the implementation approach, the image processing and pose estimation algorithms will be discussed. Additionally, some preliminary results of the prototype in its current testing phase in real scenarios, gathered in parallel with commercial units, and its comparison will be presented.
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