A Calibration Procedure for Robotic Ultrasound Systems

Abstract

With the rise of collaborative robots, there has been a growing interest in integrating ultrasound imaging with robotic systems in medical applications. This integration allows the system to receive real-time visual information, enabling the robot to move based on relevant anatomical features. However, for the visual information to be used accurately, it is essential to calibrate the pose of the ultrasound image in the robot’s coordinate frame. This paper presents a calibration technique that eliminates the need for external trackers and minimizes sources of error. The proposed method involves scanning a straight wire phantom with an unknown arrangement to constrain the set of possible solutions. By optimizing the cost function associated with the wires’ straightness, we can estimate the pose of the B-scan in the robot flange coordinate frame precisely and reliably without significant limitations, e.g., complex scanning trajectories. The technique shows an average precision of 0.8 mm and an accuracy of 1.72 mm with a scaling factor of 0.2778 mm/pixel.