Experimental investigation of a twisted string actuation for usage in active catheter.

Abstract

The improvement of the steerability and controllability of catheters is highly required because catheter-based interventional diagnosis and therapy have become increasingly popular. However, active catheters are often complex and expensive. This study attempts to control catheter tip by a twisted string actuator. Experiments are carried out to analyze the full actuation and bending characteristics of the active catheter. It is indicated that the expected bending motion can be achieved by twisting the strings. Hysteresis behavior in backward and forward motion is also discussed. High repetitive positional accuracy and reverse position accuracy can be obtained when the number of rotation is low. When the number of turns is 25, the maximum tip position errors are 4, 1.8 and 1 mm in X, Y and Z directions, respectively. It is expected that the presented method will prove useful for the application of twisted string active catheter.