Concentric Tube Robot Design and Optimization Based on Task and Anatomical Constraints

Abstract

Concentric tube robots are catheter-sized continuum robots that are well suited for minimally invasive surgery inside confined body cavities. These robots are constructed from sets of pre-curved superelastic tubes and are capable of assuming complex 3D curves. The family of 3D curves that the robot can assume depends on the number, curvatures, lengths and stiffnesses of the tubes in its tube set. The robot design problem involves solving for a tube set that will produce the family of curves necessary to perform a surgical procedure. At a minimum, these curves must enable the robot to smoothly extend into the body and to manipulate tools over the desired surgical workspace while respecting anatomical constraints. This paper introduces an optimization framework that utilizes procedureor patient-specific image-based anatomical models along with surgical workspace requirements to generate robot tube set designs. The algorithm searches for designs that minimize robot length and curvature and for which all paths required for the procedure consist of stable robot configurations. Two mechanics-based kinematic models are used. Initial designs are sought using a model assuming torsional rigidity. These designs are then refined using a torsionally-compliant model. The approach is illustrated with clinically relevant examples from neurosurgery and intracardiac surgery.

On-line collision-free inverse kinematics with frictional active constraints for effective control of unstable concentric tube robots

“…The kinematic models are currently based on boundary value problems, solving differential equations iteratively [12] which is computationally intensive [15], [16]. Using the torsionally compliant model the Jacobian has to be determined numerically [17].…”

“…The manipulation of tissue through narrow and sometimes torturous surgical corridors is particularly problematic in endoscopic intraventricular and transventricular surgery. Therefore the use of concentric tube robots [12], and the incorporation of active constraints [19], may allow for improved effectiveness and safety respectively. Eleven participants (seven male, ten right-handed, six familiar with haptic devices, all novices regarding the medical procedure) took part in a user study to navigate through hydrocephalic ventricles to simulate electroclautery of thirteen targets.…”

“…Fundamental mechanics modelling and control of concentric tube robots has seen extensive research, and recent advances focus on computationally designing optimal patient-and surgery-specific robots [10]- [12], following optical paths [13]- [15]. While most methods consider the latest mechanics models that account for tube bending and twisting, the elastic instabilities that arise in certain elongated highly-curved concentric tube robot configurations have only been considered so far in [12], [14].…”

“…While most methods consider the latest mechanics models that account for tube bending and twisting, the elastic instabilities that arise in certain elongated highly-curved concentric tube robot configurations have only been considered so far in [12], [14]. Instability consideration is crucial, since it causes sudden release of elastic energy through rapid tube untwisting.…”

Implicit active constraints for safe and effective guidance of unstable concentric tube robots

“…These instabilities cause uncontrollable tube motion, which, if it occurs intraoperatively, may cause severe tissue trauma. For this reason, computational design, path-planners, and inverse kinematics solvers consider criteria not only to avoid such configurations but also to guide the human operator away from them [10], [11], [12], [13].…”