Robotized measurements : automated acoustic characterization of structures

Overview & Synopsis

This thesis aims at developing a tool for automated acoustic characterization using robotized measurements. Leveraging advancements in robotics, mechanics, and applied mathematics, the work focuses on employing a robotic arm equipped with sensors to estimate the sound field emitted by unknown structures. Since the accuracy of the measurements depends on the precise positioning of the sensor, discrepancies between the nominal and actual models of the robotic arm must be corrected. To address this, a comprehensive geometric calibration procedure is proposed and experimentally validated through two case studies involving three robotic arms and two types of sensors. Notably, significant improvements in accuracy are achieved by incorporating task-specific and sensor-infused features. The theoretical and numerical foundations of Sound Field Estimation (SFE), which aims at reconstructing the acoustic field radiated by an unknown source based on a limited set of measurements, are then explored. Among the reviewed methods, the Boundary Elements Method (BEM) stands out for its efficiency and flexibility despite its computational cost. Numerical simulations allow for the validation of the method's performances and the analysis of its robustness in the presence of external disturbances, highlighting the importance of robot calibration to ensure reliable results. Finally, to support the experimental implementation of our tool, a framework based on the ROS middleware is introduced to manage interfaces between the robot, sensors, and their environment. Prior to acoustic measurements, a robotized geometric characterization process is presented to determine the shape and position of the studied object. The robotized setup developed to automate acoustic measurements is then presented, with particular focus on the effects of the robot on the measurements. Under conditions where these effects are minimized, two autonomous measurement campaigns led to a successful reconstruction of the sound field radiated by an unknown loudspeaker, demonstrating the potential of the proposed tool.