Continuum robots for multi-scale motion: Micro-scale motion through equilibrium modulation

Existing robots for multi-scale motion (MSM) are unsuitable for micro-surgery in deep surgical sites where miniaturization and traversal of often tortuous anatomical passageways is required. Also, new emerging surgical paradigms for natural orifice surgery and image-based diagnosis and guidance at the micro-scale level promise to provide accurate verification of tumor resection margins. To overcome the limitations of current robot architectures, and to enable image-based biopsy and micro-surgery in confined spaces, we present a new concept of continuum robots with equilibrium modulation (CREM). CREM robots are a modification of multi-backbone continuum robots that achieve micro-motion by using indirect actuation through modulation of their static equilibrium by change of the distribution of their cross-sectional flexural rigidity. As a first step towards modeling the micro-scale kinematics of these robots, solutions for micro-motion tracking are presented and verified to achieve tracking accuracies of better than 2μm. Preliminary evaluation of the micro-motion capabilities of a first prototype demonstrates motion resolutions at 1μm level and hysteresis of less than 10μm - despite the use of inexpensive actuators with significant backlash. Finally, a demonstration of a first effort at integrating such a robot with a custom-made optical coherence tomography (OCT) probe is presented.