Matrix Probe Offset Calibration for Robotic Arm Scanning

Robotic arms are increasingly used in Non-Destructive Testing (NDT) to automate ultrasonic inspections, especially with matrix array probes for 3D imaging. Accurate knowledge of the Tool Center Point (TCP) offset is essential for precise probe positioning. This work presents a method to estimate the six TCP offset parameters (three translational and three rotational) using only ultrasound data acquired in immersion. Time-of-flight (ToF) analysis of echoes from a planar reflector is used to estimate both rotational and translational errors. The latter are further refined by minimizing interference in compounded Total Focusing Method (TFM) images. The proposed method enables spatial compounding across multiple probe orientations without external tracking or image registration, improving image quality and simplifying the workflow.