A novel robot-assisted electrical impedance scanning system for subsurface object detection

Abstract

Submerged elements, such as cracks inside concrete material or hidden pathological tissue, can potentially threaten safety and health. Thus, the detection of abnormal objects internally is of importance and frequently required. In this study, we propose a novel electrical impedance measurement method with the assistance of a robotic system. Specifically, the proposed measurement method is able to perform subsurface object detection effectively, noninvasively, flexibly and autonomously. The measurement system is developed based on a tripolar impedance sensing configuration. Specifically, a current-source electrode and a voltage-measurement electrode are attached to different robots, and directed to a series of preset positions on the object’s surface. By injecting current into the object and measuring voltages around the current source, the apparent resistivity of the internal structure of the object can be calculated using the proposed algorithm. The related circuit hardware and autonomous control strategy are developed. Subsequently, the proposed system is evaluated through a series of water tank experiments. The experimental results demonstrate that the proposed system can detect a subsurface heterogeneous object effectively and efficiently. In addition, the reconstructed results allow us to discriminate the location of the subsurface object with about 90% accuracy.