Multimodal Motion Control of Magnetic Continuum Robot for Endovascular Intervention Navigation

Advances in robotic technology have been adopted in various subspecialties of both open and minimally invasive surgery, offering benefits such as enhanced steerability and reduced fatigue of the surgeon. Despite the advantages, magnetic robot applications of percutaneous coronary intervention (PCI) have yet to be sufficiently explored. In this article, a multimodal magnetic continuum robot (MMCR) with segment control and deformation capabilities is proposed. This is achieved by coaxially embedding three magnets with different magnetization directions within its body, and designing a thermoplastic urethane coating and polyvinylpyrrolidone skin on the MMCR's surface. Three magnets are interconnected using a magnetic polymer, enabling the magnetically controllable portion to extend from a single magnet node to encompass the entire MMCR, achieving deflection angles greater than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$20^{\circ }$</tex-math></inline-formula> within controlled domains of 235.5 mm (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i>-axis), 271.65 mm (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i>-axis) and 249.05 mm (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z</i>-axis). The hydrophilic polyvinylpyrrolidone coating (25.15–88.56 μm) reduces the water contact angle from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$102.526^{\circ }$</tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$84.096^{\circ }$</tex-math></inline-formula>. In addition, the model of MMCR is constructed, including the combination analysis of elastic potential energy and magnetic energy, the quantitative modeling of gravity influence, the optimization design algorithm based on gradient descent, and the comparative analysis of multimagnet arrangement. Experimental results show that the MMCR can achieve several shapes useful in medical procedures, exhibiting sufficient flexibility in complex navigation tasks and showing significant advantages in terms of manipulation success rate and time.