Modeling the dynamic behavior of a shape memory alloy actuated catheter

Abstract

In this paper we investigate the transient behavior of a simple active catheter: a central tube actuated by a single nitinol tendon enclosed by an outer sleeve. Dynamic models are developed to characterize the transient behavior and optimize the design of an experimental prototype. The bending mechanics are derived using a circular arc model and are experimentally validated. Nitinol actuation is described using the Seelecke-Muller-Achenbach model for single-crystal shape memory alloys using experimentally determined parameters. The dynamic characteristics of this active catheter system are simulated and compared with experimental results. Joule heating is used to generate tip deflections, which are computed in real time using a dual-camera imaging system. The effects of outer sleeve thickness on heat transfer and transient response characteristics are studied.

ℒ1adaptive control of a shape memory alloy actuated flexible beam

“…The methods used here can be extended to other single-tendon applications or designs that require antagonistic actuation for increased maneuverability and bandwidth. A complete description of the SMA-actuated flexible beam is presented in (Veeramani, Buckner, Owen, Cook, & Bolotin, 2008).…”

“…Actuation commands are sent via USB communication from the host PC to a microcontroller, which implements pulse-width modulation to regulate Joule heating and temperature-induced strain in the SMA tendon. Real-time bending is calculated from 3D base and tip measurements (trakSTAR 3D Magnetic Tracking System, Ascension Technology Corporation, Burlington, VT) using constant-curvature deflection relationships (Veeramani et al, 2008).…”

Quantification of the Effectiveness of Various Adhesives in Holding an SMA Actuator Wire During Joule Heating

“…Currently there are many application concepts that employ SMA wires as actuators. For example, many biomedical application concepts [1] use small SMA wires as actuation or sensing, including a robotic catheter [2,3], heart valve [4], or an adaptive smart inhaler nozzle that can be deformed to position medication within an inhaled flow without causing a significant obstruction to the flow [5,6]. Five SMA wires are also of interest for applications in the aerospace [7] or MEMS [8][9][10][11] fields, as well as for bio-inspired applications such as an SMA-actuated hand [12,13], fish [14], earthworm [15], or flapping bat [16,17], where the SMA wires become an analog for biological muscles.…”

Path optimization and control of a shape memory alloy actuated catheter for endocardial radiofrequency ablation

“…robotic) catheters have the potential to enhance catheter maneuverability in the heart, reduce procedure times, and increase the range of motion and contact stability during ablation. Previous work has focused on the design, optimization, and fabrication of shape memory alloy (SMA) actuated robotic catheters for endocardial ablation [9], [10]. The SMA-actuated catheter used here (Figure 1) consists of two bending segments: the distal segment containing the catheter tip, and the adjacent proximal segment.…”