A FastSLAM Approach Integrating Beamforming Maps for Ultrasound-Based Robotic Inspection of Metal Structures

Abstract

We present a novel FastSLAM approach for a robotic system inspecting structures made of large metal plates. By taking advantage of the reflections of ultrasonic guided waves on the plate boundaries, it is possible to recover, with enough precision, both the plate shape and the robot trajectory. Contrary to our previous work, this approach takes into account the dispersive nature of guided waves in metal plates. This is leveraged to construct beamforming maps from which we solve the mapping problem through plate edges estimation for every particle, in a FastSLAM fashion. It will be demonstrated, with real acoustic measurements obtained on different metal plates, that such a framework achieves better results in terms of convergence and accuracy, while the complexity of the algorithm is sensibly reduced.

On-plate autonomous exploration for an inspection robot using ultrasonic guided waves

“…As in [2], echo detection and plate geometry reconstruction are based on a propagation model which is used to construct ẑ(r, t), the expected signal that would be received if the incident wave is reflected at a distance r to the transducers. Given measurement z i (t), the correlation signal:…”

“…While precise localization of a mobile agent on a platebased metal structure has been identified as a fundamental requirement to long-range robotic inspection [1], Ultrasonic Guided Waves (UGWs) have proven to be useful for both plate geometry reconstruction and on-plate robot localization, yielding an innovative solution to the SLAM problem [2]. Yet, this solution has been assessed without using a real robotic platform and with pre-defined paths.…”

“…1 Ayoub Ridani, Othmane-Latif Ouabi, Nico F. Declercq and Cédric Pradalier are with the International Research Lab Georgia Tech -CNRS, IRL 2958, Metz, France. {aridani, oouabi, cedric.pradalier}@georgiatech-metz.fr 2 Nico F. Declercq is also with Georgia Institute of Technology, Atlanta, GA 30332-0250, USA. declercq@gatech.edu From a robotic perspective, plate geometry reconstruction and defect detection can be considered as a mapping problem, for which autonomous solutions are desirable [1].…”

“…In [2], a map building technique is presented in which we estimate the boundaries of a rectangular plate. Here, we aim at pursuing this work by introducing an autonomous exploration technique integrating UGWs and exploiting the estimated plate geometry while limiting ourselves to flat rectangular plates.…”

“…1) A demonstration of the utility of using the In-plate Points Grid map in combination with the geometry estimator [2] to map a "safe space" that ensures the sensor remains on the plate during robot motion. 2) An integration of UGWs sensing modality with the frontier exploration approach that balances information gain and travel cost.…”