Robot-assisted ultrasound scanning promises to advance autonomous and accessible medical imaging. However, ensuring patient safety and compliant human-robot interaction (HRI) during probe contact poses a significant challenge. Most existing systems either have high mechanical stiffness or are compliant but lack sufficient force and precision. This paper presents a novel single-degree-of-freedom end-effector for safe and accurate robotic ultrasound imaging, using a quasi-direct drive actuator to achieve both passive mechanical compliance and precise active force regulation, even during motion. The end-effector demonstrates an effective force control bandwidth of 100 Hz and can apply forces ranging from 2.5N to 15N. To validate the end-effector's performance, we developed a novel ex vivo actuating platform, enabling compliance testing of the end-effector on simulated abdominal breathing and sudden patient movements. Experiments demonstrate that the end-effector can maintain consistent probe contact during simulated respiratory motion at 2.5N, 5N, 10N, and 15N, with an average force tracking RMS error of 0.83N compared to 4.70N on a UR3e robot arm using conventional force control. This system represents the first compliant ultrasound end-effector tested on a tissue platform simulating dynamic movement. The proposed solution provides a novel approach for designing and evaluating compliant robotic ultrasound systems, advancing the path for more compliant and patient-friendly robotic ultrasound systems in clinical settings.

Computer pioneer Alan Kotok, an MIT alumnus who helped create both the first video game and the gaming joystick, died of a heart attack in his home in Cambridge, Mass., on Friday, May 26. A native of Philadelphia, he was 64. Kotok (S.B. 1962) entered MIT at age 16 and became swiftly involved in developing chess-playing computer programs, designing new systems for MIT's Tech Model Railroad and, with a group of friends, coming up with their original video game, Spacewar. Tim Berners-Lee, founder and director of the World Wide Web Consortium (W3C), which is housed in MIT's Computer Science and Artificial Intelligence Laboratory, described Kotok as "one of the early wise men of computer science." The unflappable Kotok was "not only technically adept well beyond the norm, but also possessed a childlike delight in all things ingenious or intriguing. Wit, wisdom and sheer human warmth defined him, yet he commanded total respect. He would humbly take on anything which simply needed doing," Berners-Lee said.