Research On Master-Slave Control Of Robotic Catheter System

With the increasing of patients suffering from cardiac diseases, endovascular minimally invasive surgery serves as an effective solution in clinical surgeries, due to its merits of little trauma, less blood, fast recovery and less recurrence. However, conventional minimally invasive surgery has many limitations, which confine its development. So with the advancement of computer assistance and the fusion with many cross subjects, our research team proposes an idea to construct a robotic catheter system. This dissertation is based on the developed results to focus on the system's master-slave control, force feedback and local area network(LAN) remote control.The kinematic analysis is carried out for the devised steerable catheter through the D-H method, so two-dimension and three-dimension kinematic spaces are acquired. Considering the master handle and steerable catheter, the open-loop increment map and close-loop point-to-point map are established, then the open-loop increment control and close-loop inverse Jacobian control are designed. The former is to control the master handle with the reciprocation motions to perform the pulling/pushing, bending/recovering and rotating independently, and during this procedure the operator takes the dominant role; the latter takes the Jacobian matrix to build the relationship between the operating room velocity and joint room velocity, in order to track the position of master handle, so during the procedure the operator just needs to provide the position coordinates of target point. As well, the positioning accuracies of two control methods are tested, and the comparison between them are performed in several aspects.Force feedback of the robotic catheter system is studied, which has realized the force feedback from interventional mechanisms, the distal tip of catheter and virtual guiding restriction. The force feedback from interventional mechanisms can reflect the whole effect of insertion force during the catheterization, which is displayed using the progress bar and numerical value in the navigation software; the force feedback from the catheter's distal tip can reflect the tactile force between it and surrounding vessels and tissues, which is displayed with the fusion with navigation software, and the colors are provided to identify the range of external force; virtual restriction force is proposed to assist the close-loop inverse Jacobian control, which can present a series of reference circles with the centers on the centerlines of vessles to restrict the motion of master handle, so as to keep the target point provided by the master handle in the circles.LAN remote control of the robotic catheter system is studies, and a method of remote desktop has been established to realize the catheterization with the open-loop increment control in the LAN, also a method of double local image is proposed and discussed to establish the basis for perfecting and improving the subsequent performance of remote control.The research results mentioned above are integrated into the robotic catheter system in order to complement and improve the system's functions. Experiments of catheterization has been carried out in the thorax vascular model, which indicated the proposed control methods'feasibility and applicable conditions, and validated the force feedback's assistant effectiveness during the procedure, meanwhile experiments of LAN remote control are also carried out to verify its feasibility, then analysis and comparisons about the proposed operation modes are performed from several aspects.