Design and Analytical Modeling of a Double-Joint Catheter Robot With Wire-Reinforced Spring Backbones

Catheter robots show challenges to implement miniaturized design with high dexterity, which are essential to the cardiovascular intervention surgery. To address this issue, a novel double-joint continuum mechanism is designed in this work to implement a miniaturized catheter robot. The mechanism has four controllable bending degrees of freedom (DoFs), where the proximal and distal joints are composed of a wire-reinforced multibackbone mechanism. The multibackbone mechanism with frictional contacts and external loads is a high-DoF underactuated system with complex constraints, whose kinematic relationship is difficult to be obtained. With use of a piecewise-Euler–Bernoulli beam model, a recursive model of the backbone’s curvature distribution is established. By incorporating continuum mechanics, forward kinematics of the catheter robot is analytically developed and its inverse kinematics is numerically solved. Performance tests show that the double-joint mechanism has good actuation decoupling performances. Parameter identification is conducted and model accuracy with external loads is validated. Phantom model experiments show that the catheter robot can complete path-following tasks in a complex heart environment.