Optimal Sensor Location and Observation Policy under Constraint in Detecting Anomalous Lump Objects in Shield Construction Method

Abstract

Using acoustic sensors, the authors previously proposed an effective detection system of anomalous objects in tunnel excavation with shield tunneling machines to prevent the machine from getting damages. Not many observation data being available in the detection, optimal observation policy is important. From this viewpoint, the authors next considered an optimal sensor location on the cutter plane of the machine and also the optimal observation policy, for the case where three receiving transducers were used to detect lump objects. The optimal location of the receiving transducers was shown to be given as arbitrary equally-spaced points on the outer circle of the cutter plane. The optimal rotating angles were also found to be arbitrary. In applications, however, it is often difficult to locate sensors at arbitrary positions of the cutter plane. This paper thus considers the optimal observation policy for detecting anomlous lump objects effectively under the practical constraint that the sensors are located only along a diameter of the cutter plane.