Bilateral telemanipulation of a flexible catheter in a constrained environment

This paper describes some novel research results on bilateral teleoperation of a flexible catheter in a constrained environment. The dynamics of the catheter in a constrained environment is highly nonlinear and is affected by a large number of factors such as friction, flexibility of the catheter, force of insertion, shape and size of the catheter, etc. As a result, the distal end of the catheter almost never follows the actuated end of the catheter which could cause fatigue to the clinician/user attempting to insert the catheter in a blood vessel. In addition, there is a time delay of up to 0.8 second before the distal end of the catheter advances after the near end is actuated. This delay is sufficient to cause instability in the control loop. We have developed a teleoperation framework using wave variables to perform robot- assisted catheter insertion in a constrained environment while reflecting the forces at the tip of the catheter to the clinician. Experimental results showing the effect of different factors such as the velocity and stroke length of insertion on the delays introduced in control loop and errors between the master and slave position are included. To the best of our knowledge, this work is among the first to attempt to provide an understanding of the effects of various factors on the flexing of the catheter. In addition, master-slave insertion of a catheter instrumented with shape memory alloys (SMA) has also been performed and the results are included in this paper.