Control of Tip Actuated Steerable Needles

Control of Tip Actuated Steerable Needles

Nanut, I.

van den Dobbelsteen, J. (mentor)
van de Berg, N.J. (mentor)
Dankelman, J. (mentor)

Mechanical, Maritime and Materials Engineering

BioMechanical Engineering

2013-09-19

Percutaneous procedures are minimally invasive medical procedures that use needles to locally operate on a target in a patient’s body. The precise placement of the needle in the body is a challenging task that can affect the quality and efficiency of these procedures. Needle insertion accuracy may be improved by robot-assisted control of steerable needles. The type of steerable needles considered in this study are needles that are being developed at the Delft University of Technology (TUD) and are intended to be used in liver biopsy procedures. The goal of this research is to prove that these needles are able to reach a predetermined target accuracy during straight needle insertion. First, the uncontrolled insertion is tested in different tissue stiffness samples and with different insertion speeds. The results show that the target is reached with an accuracy that is smaller than 1 mm only when the insertion speed and the tissue stiffness are low. Other conditions require a control of the needle steering during its insertion, so that its deviations from the straight path can be corrected for. Two controllers are applied and tested. They both use direct position feedback that comes from optical strain sensors in the needle stylet and act on the servomotors with a proportional controller. The first controller only takes into account the end-point of the needle, while the second one takes into account its whole trajectory. Results show that both controllers improve the needle insertion accuracy with respect to the uncontrolled insertion at the tested conditions, allowing to reach the target with a position error that is smaller than 1 mm. The trajectory control gave better performance than the end-point control, which is to be expected, considering that the needle is a nonholonomic system. Overall, this study proved that under specified conditions, the TUD tip actuated steerable needles are able to reach a target on a straight trajectory within a position error that is smaller than 1 mm.

steerable needles
precise needle tip placement
nonholonomic control

http://resolver.tudelft.nl/uuid:114b4e15-b294-4bcf-bbf6-dcdf5103bb7e

2014-09-19

Student theses

master thesis

(c) 2013 Nanut, I.