Variable Stiffness Mechanism in Robotized Interventional Radiology

Abstract

During the last two decades, a large number of robotic assistants have been developed to help surgeons place surgical tools. Until now, research in this field has mostly focused on rigid robotic structures, which make safety issues difficult to deal with. In this paper, we consider a new collaborative manipulation approach based on a variable stiffness mechanism. By controlling the stiffness perceived by the user when he/she manipulates the device, it then becomes possible to guide his/her gesture in a safe way. This strategy is first presented, before detailing the design, optimization and experimental validation of the proposed mechanism based on leaf springs.

Appendix: \(c_{i}\) Expressions

$$\begin{aligned} c_1&= 8 E I (\delta -\lambda ) \delta [ (2 \delta +6 \lambda ) p^3+ (9 r \lambda +9 \lambda r-18 \lambda ^2+3 \delta r+3 \delta r) p^2 +(18 \lambda r^2-18 \lambda ^2 r-18 r \lambda ^2 \\&+18 \lambda ^3+6 \delta r^2-6 \lambda ^2 \delta ) p + (-6 \lambda ^4-3 r \lambda ^2 \delta -3 \delta \lambda ^2 r+9 \lambda ^3 r-18 r^2 \lambda ^2+4 \lambda ^3 \delta +9 \lambda ^3 r)] \\ c_4&= -\delta (\lambda -p)^3 (\delta -\lambda ) (3 \delta \lambda +\delta p-3 \lambda ^2+3 \lambda p) \end{aligned}$$