Self Guided Catheter
Senior Project Proposal
Derek Carlson & Caleb Anderson
Dr. Dempsey & Dr Stewart
12/12/06
Project Summary: In surgical operations that require the use of a catheter, multiple guidewires must be used in order to direct the catheter through the patients 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.
Detailed description: Below is the high-level functionality block diagram:
Figure 2 1 High Level Block Diagram
Figure 21 shows that there will be both keyboard and joystick input into the control system. Both will input via USB or PS/2 to Simulink. Simulink will then be used to supply the signal to the motor controller board running the two stepper motors, and the voltage to the polymer at the tip of the catheter. Visual feedback will be implemented through the use of a webcam. This will allow the surgeon to operate from a remote location.
At this point, it is not known whether the signal to the electroactive polymer will be PWM, DC voltage, or otherwise, but further testing will reveal this detail. The polymer tip will act as an actuator as well as a sensor. This sensor will provide the surgeon with feedback regarding the radius of curvature. Also, there will be a pivotal motor that will rotate the tip so the surgeon can achieve 360 degree control of the polymer. While Dr. Chiou has not requested a motor for advancement of the guidewire through the body, a stepper motor will be implemented for this feature. This is above the scope of what a surgeon may require, but will allow for other possible applications of this same technology.
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 roughly 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.
Schedule:
Weeks 1-3
Stepper motor Simulink interface (Derek)
Webcam Simulink interface (Caleb)
RS-232 Simulink interface (Derek)
Weeks 4-6
GUI for user input (Both)
Joystick functionality in Simulink (Caleb)
Develop polymer electrical characteristics (Both)
Weeks 7-8
Develop power electronics to actuate polymer (Derek)
Possible polymer shielding concerns (Caleb)
Weeks 9-10
Stepper motor physical interface (Caleb)
Guidewire drive system (propulsion, rotation, etc.) (Derek)
Weeks 11-14
Build test system (Both)
Finalize report & Presentation(Both)
Bibliography:
Polymer material source
http://www.environmental-robots.com
Patent information
http://www.patentstorm.us/patents/6997870.html
Motor Control Board Source
Equipment List:
(2) 1 degree stepper motors
(1) Bistep Motor Controller Board
(1) Electroactive polymer tip
(1) Surgical Guidewire
(1) DC voltage source
(1) PC USB Webcam
(1) Logitech Wingman Pro Attack 2 Joystick
TBA mechanical system to test guidewire