Study On Modeling And Path Planning Of A Cable-driven Interventional Active Catheter

Cardiovascular and cerebrovascular diseases have become the one of most serious diseases that threat human health badly. And there are some problems in the traditional interventional operation such as poor controllability, bad universalness and high dependency of surgeons’ experience. Therefore, this thesis presents a cable-driven interventional active catheter system to solve the above-mentioned issues.A single catheter unit consists of a skeleton spring, a silicone tube, a connector and driving cables. And in order to gain more degrees of freedom for a better flexibility and versatility, the multiple segments catheter which is composed of single catheter units in series is usually used. Consequently, it could be suitable to different surgical environments. An assistant control mechanism is devised to free surgeons from the surgery scene and a tension and reeling device of driving cables is devised, according to the drive methods of cables, to ensure the driving accuracy.For further exploration of the catheter‘s bending and deformation mechanism, synthesizing the large deflection hypothesis and the arc hypothesis which are existing, the flexible model of the catheter is established on the ADAMS software and the flexible models of driving cables and skeleton springs are also established according to their different functional features respectively. Comparing and analyzing the results of simulations and the two hypotheses, the applicable ranges and conditions of the two hypotheses is found separately.Based on the analysis of bending characters of the catheter, the kinematic model is built and the rapid forward kinematic calculated algorithms of the multiple segments in series is derivated from the forward kinematics of the single catheter unit. And the inverse kinematics is analyzed. Then, the cable length is decoupled by analyzing and reducing of its coupling relationship.According to the kinematic model from the analysis, the path of the catheter during interventional is planned. And concerning the redundancy characteristic of the multiple segment catheter robot, obstacle avoidance algorithm for the redundant robots is proposed. Thus, working capacity of the robot is improved. Finally, a catheter system is made and experiments are conducted on it to verify the analysis results.