Abstract: The cantilever excavator method has several disadvantages when used in water-conveyance tunnels. These include high dust concentration during construction, operational blind spots, and difficulties in controlling over-excavation and under-excavation. To address these issues, the digital capabilities of the cantilever excavator have been upgraded by arranging various sensors. These include a sensor subsystem, a PLC subsystem, a communication subsystem, and an information visualization subsystem, forming an excavating visualization system. A kinematics model for the cantilever excavator is established using the D-H method. By designing a multiparameter coordinate analytic equation, precise analysis of the excavating target coordinates is achieved across various positions. Finally, to improve construction efficiency and adaptability to various conditions, two compensation methods for axis deviation, namely forward calibration and reverse calibration, are proposed. Laser teaching points are arranged on the target surface for calibration testing, with results demonstrating that these methods kept calibration errors within 2 cm, enabling precise positioning of the cantilever excavator under different tunnel wall conditions. A space trajectory recognition test for the cutting head is carried out in the tunnel site. When comparing measurements from laser systems with calculations made via handheld terminal software for the distance between test points, the deviation of the visualization system is within 3.5 cm. The maximum delay rate of the motion response for cutting targets in handheld terminal is 0.2 s.

Key words: water-conveyance tunnel, cantilever excavator, visualization system, precise analysis of coordinate, cutting head, space trajectory