Modeling of and Experimenting with Concentric Tube Robots: Considering Clearance, Friction and Torsion

Abstract

Concentric tube robots (CTRs) are a promising prospect for minimally invasive surgery due to their inherent compliance and ability to navigate in constrained environments. Existing mechanics-based kinematic models typically neglect friction, clearance, and torsion between each pair of contacting tubes, leading to large positioning errors in medical applications. In this paper, an improved kinematic modeling method is developed. The effect of clearance on tip position during concentric tube assembly is compensated by the database method. The new kinematic model is mechanic-based, and the impact of friction moment and torsion on tubes is considered. Integrating the infinitesimal torsion of the concentric tube robots eliminates the errors caused by the interaction force between the tubes. A prototype is built, and several experiments with kinematic models are designed. The results indicate that the error of tube rotations is less than 2 mm. The maximum error of the feeding experiment does not exceed 0.4 mm. The error of the new modeling method is lower than that of the previous kinematic model. This paper has substantial implications for the high-precision and real-time control of concentric tube robots.

Toward Bionic Arthroscopy: A Comprehensive Perspective of Continuum Robotics Principles and Prototypes for the Inception of Arthroscopic Surgery Robots

“…Rigid continuum structures refer to the mode of force and torque transmission directly through rigid elements. [59] Driven by the demand for high flexibility and small scale in medical intervention surgeries, there has been a great deal of innovation in the design of rigid continuum robots, [21,24,60] which can be classified as steerable needles, [61][62][63] concentric tubes, [64][65][66][67][68] notch tubes, [69][70][71] and backbone-based (hinged or continuous) robots. [30,[72][73][74][75] Figure 2 illustrates examples of implementations using these design principles.…”

“…Originally published by and used with permission from Dove Medical Press Ltd., b) typical concentric tube design. Reproduced with permission [68]. Copyright 2023, MDPI, c) notched tube.…”