Design and analysis of a remotely-actuated cable-driven neurosurgical robot

Minimally invasive neurosurgical robotic procedure performed under real-time MRI can be achieved with a robot that is head-mounted and fits in a standard MRI bore. The design of a remotely-actuated cable-driven robotic system is presented in this work. A head mounted insertion module has been developed to advance the robot module towards the target brain tumor. The robot module is formed by snapping together a reusable part that leads to the remotely-placed actuators and a disposable part which includes the previously developed spring-based MINIR-II robot. Gear transmission mechanism was implemented in the robot module to transmit the force from the actuators to the end effectors of the robot. The robot module and the insertion module are lightweight and compact with a total weight of 250 g and a total height of 222 mm. This allows the entire setup to be placed vertically on a patient's head in a closed MRI bore. The compact design of the robot module has been achieved, significantly due to the innovative modifications made to the structure of standard spur gears and smart routing of the cables around the gears. The completely MRI-compatible Bowden cable module has been implemented to allow transmission of significant force of around 10 N required for the actuation of the robot. A static friction model has been used to estimate the friction coefficient for the Bowden cable module as a preliminary step towards the complete modeling of the entire robotic system. The relationships between the input displacement and force of the cable at the actuator end and those at the middle and end robot segments were determined through experiments and discussed. A functional robotic system has been presented with the robot being inserted into the phantom tissue and only the end segment actuated back and forth.