Research On The Invasive-Surgery Active-Catheter Navigating Robot Drive And Control Techniques

An active catheter is an independent minimally invasive surgery equipment to control it's own realization of the front sports deflection in vitro .It can help catheter to reach the surgery position in the minimally invasive surgery, reduce operational difficulties and reduce its risks caused by errors operate. Navigating robot is installed in front of the catheter initiative to achieve bending and steering function devices.Based on the shape-memory effect, the structure of the robot and the principles of robot's orientation are discussed in detail in this paper .And a navigating robot is developed. The navigating robot revolved in this paper is contained by four SMA (Shape Memory Alloy) actuators and the bias spring bending in the middle , it can achieve different directions and bending angles .The size of the robot is 20 mm long, 1.3 mm and the diameter of it is1.3 mm.To improve the SMA actuator response speed, and enhance controllability of the SMA actuator in the phase of transition temperature range, and avoid degradation of shape memory effect of the SMA actuator caused by the overheating, in this paper, we use PWM to drive the navigating robot, and select the resistance and temperature as feedback variables, design two sets of corresponding feedback control system. The control system hardware and software design are discussed in detail.On base of the AURORA posture sensor platform of NDI company of Canada, we use VC++6.0 to develop a sensor position and orientation tracking system software, from which the PC to send orders to AURORA sensor system, access sensor configuration information within the work space. To make sure that the data transmitted is correct, the CRC check is used to ensure that the communications and data transmitted are carried out correctly.Test the overall performance of the navigating robot, obtain the relations between PWM duty cycle and the navigating robot bending angle, and the relations between heating electricity and bending angles, providing accurate parameters for the control of SMA actuator. In the thoracic vascular model with coronary artery, we simulate the cumulating process in the interposition surgery. In light of the scheduled surgery route, the navigating robot entered the target vas ramous successfully under the control of resistance-feedback system and temperature-feedback system. The results of the test testify the veracity and quickness in the cumulating process. As a result, the difficulty in the surgery operation is reduced and the rate of success is improved.