Design of a soft, parallel end-effector applied to robot-guided ultrasound interventions

Medical ultrasound imaging robotics systems often comprise of complex control architectures and hardware integration to enable safe human robot interaction. In this paper, we investigate the applicability of a soft robotic end-effector for ultrasound intervention. A novel, parallel design is derived based on the medical requirements, which addresses common shortcomings in both robotic ultrasound systems and soft robotic devices. Individual actuators are developed and characterized and the performance of the overall platform is evaluated in regards to its stiffness and steerability. It is shown that the platform comprises relatively high longitudinal and transversal stiffness, while still being compliant enough to ensure the safety of the patient. The shear stiffness of the platform is 4.2 times greater than the shear stiffness of an individual actuator. The platform is capable of applying loadings of 10N along its longitudinal axis, which makes it suitable for the given application. Furthermore, the workspace of the platform is suitable to robot-guided ultrasound with a maximum platform rotation range of ±14.8°, while only moving ±7mm in space.