Design and integration of a parallel, soft robotic end-effector for extracorporeal ultrasound

In this work we address limitations in state-of-the-art ultrasound robots by designing and integrating the first soft robotic system for ultrasound imaging. It makes use of the inherent qualities of soft robotics technologies to establish a safe, adaptable interaction between ultrasound probe and patient. We acquire clinical data to establish the movement ranges and force levels required in prenatal foetal ultrasound imaging and design our system accordingly. The end-effector's stiffness characteristics allow for it to reach the desired workspace while maintaining a stable contact between ultrasound probe and patient under the determined loads. The system exhibits a high degree of safety due to its inherent compliance in the transversal direction. We verify the mechanical characteristics of the end-effector, derive and validate a kinetostatic model and demonstrate the robot's controllability with and without external loading. The imaging capabilities of the robot are shown in a tele-operated setting on a foetal phantom. The design exhibits the desired stiffness characteristics with a high stiffness along the ultrasound transducer and a high compliance in lateral direction. Twist is constrained using a braided mesh reinforcement. The model can accurately predict the end-effector pose with a mean error of about 6% in position 7% in orientation. The derived controller is, with an average position error of 0.39mm able to track a target pose efficiently without and with externally applied loads. Finally, the images acquired with the system are of equally good quality compared to a manual sonographer scan.

Robotic-assisted Ultrasound for Fetal Imaging: Evolution from Single-arm to Dual-arm System

The development of robotic-assisted extracorporeal ultrasound systems has a long history and a number of projects have been proposed since the 1990s focusing on different technical aspects. These aim to resolve the deficiencies of on-site manual manipulation of hand-held ultrasound probes. This paper presents the recent ongoing developments of a series of bespoke robotic systems, including both single-arm and dual-arm versions, for a project known as intelligent Fetal Imaging and Diagnosis (iFIND). After a brief review of the development history of the extracorporeal ultrasound robotic system used for fetal and abdominal examinations, the specific aim of the iFIND robots, the design evolution, the implementation details of each version, and the initial clinical feedback of the iFIND robot series are presented. Based on the preliminary testing of these newly-proposed robots on 42 volunteers, the successful and re-liable working of the mechatronic systems were validated. Analysis of a participant questionnaire indicates a comfortable scanning experience for the volunteers and a good acceptance rate to being scanned by the robots.