Closed-Loop Cross-Scale Motion of Decoupled Light and Tendon Driven Miniature Continuum Robots
Cheng Zhou, Xiaotong Qin, Haoyang Yu, Jingyuan Xia, Zheng Xu, Zecai Lin, Anzhu Gao
AI summary
Problem
Miniature robots in confined spaces struggle to balance rapid macro-range maneuverability with the high positioning accuracy required for delicate local tasks.
Approach
The system decouples macro and micro actuation using function-multiplexed optical fibers, guided by a two-stage image-based visual servoing strategy that tracks a fiducial marker via an external camera.
Key results
- Designed a 1.2 mm decoupled macro-micro continuum robot
- Calibrated laser power-to-contraction mapping for precise micro actuation
- Implemented two-stage image-based visual servoing for closed-loop control
- Demonstrated precise point-tracking across tens-of-microns to millimeter workspaces
Why it matters
Enables high-precision, deep-access manipulation for minimally invasive endoluminal and endocavitary medical interventions.
Abstract
Small-scale robots are rapidly advancing in diverse fields such as industry and medicine. To be effective, they must be capable of accessing narrow, tortuous, or otherwise hard-to-reach environments and performing precise manipulation. This paper presents a vision-based closed-loop motion control scheme for a developed fiber-driven continuum robot for cross-scale motion. Function-multiplexed optical fibers are employed to achieve macro motion through fiber actuation and micro motion through light transmission within the fibers. An external eye-to-hand camera system observes a fiducial tag to estimate its 3D pose relative to the camera frame. The coordinate transformation between the tag and the end-effector is calibrated, along with the mapping between input laser power and light-induced joint contractions. A two-stage image-based visual servoing strategy is then implemented to guide the tag toward the target image position, thereby realizing closed-loop hybrid macro–micro motion through the developed kinematics and visual feedback. Point-tracking experiments demonstrate that the small-scale continuum robot, with an outer diameter of approximately 1.2 mm, can achieve precise cross-scale motion across workspaces ranging from tens of microns to the millimeter scale under the proposed control scheme. This work highlights the potential of hybrid macro–micro motion with visual servoing for deep access and high-precision operation in endoluminal interventions.