Self Guided Catheter

 

Functional Requirements

 

 

 

Derek Carlson & Caleb Anderson

 

Dr. Dempsey & Dr Stewart

11/7/06

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

            In surgical operations that require the use of a catheter, multiple guidewires must be used in order to direct the catheter through the patient’s arteries.  The goal of this project is to eliminate the need for different guidewires and to add precision control to the guidewire itself.  Also, the surgeon will be able to control the guidewire from a remote location simply by viewing the patient through a camera.    Control will be implemented using a joystick interfaced with Simulink using RS-232 as an output.  This will drive the controller board that will run two stepper motors.  These stepper motors will be used for lateral motion and guidewire advancement.  A voltage reactive polymer will be used for precision tip control.  Certain specifications for this project will be provided by Dr. Andy Chiou of Proctor Hospital, though the scope of the project will greatly outreach this.

            Below is the high-level functionality block diagram:

 

 

Figure 2 – 1 High Level Block Diagram

Functional Requirements:  The subsystems of this project are: User Input, PC Target running Simulink, Serial Motor Control, and the Polymer Control System.  The user input system will use joystick and keyboard control for rotational and lateral movement of the catheter through the use of two stepper motors.  The stepper motors will require a step size of rougly 1 degree.  This will allow for 0.5 degrees of resolution by using the half-stepping feature of the Motor Control Interface Board.  The Motor Control Interface Board will use 19200 baud serial communication in order to send and receive data from the PC Simulink Target.  This Motor Control Interface Board will control two stepper motors that are either two or four phase up to a maximum voltage of 34 volts.  The tip of the polymer will operate at voltage levels between +-9 Volts.  Roughly 5 volts will achieve a 90 degree bend.  The radius of curvature of the tip will need precision of roughly +-10 degrees. 

            Further testing of the polymer is required to estimate its precision more accurately.  At this point, testing has not shown the voltage to curvature characteristics, so the value of 10 degrees may change substantially.  The mechanical engineering students will assist in some of the measurements of the characteristics of the polymer.