Spring-Based Tendon-Driven Continuum Robots for Compact Modular Designs in Endoluminal Applications

Continuum robots have gained significant attention for endoluminal deployment due to their ability to operate in constrained environments. However, the complexity of many continuum robotic design approaches creates challenges in adapting robot geometry, dexterity, stiffness distribution, and functional integration to the requirements of specific medical procedures and/or patient-specific anatomy. This article presents a modular and adaptable design approach for the development of compact, multisegment tendon-driven continuum robots. The design strategy employs a compliant helical spring backbone with inner and outer self-anchoring spacer disks, enabling simple reconfiguration of segments and actuation tendons without increased manufacturing complexity. A design framework is introduced to formalize disk–spring integration, and a two-segment, seven-tendon example is presented for robotically assisted bronchoscopy. The design achieves a minimum diameter of 4.2 mm with a 2.4-mm working channel housing a camera and biopsy tool. An adapted piecewise constant curvature model is presented to predict shape and tip pose, with a mean tip error of 4.0 mm. Navigation trials within a bronchial phantom reached predefined targets for biopsy needle deployment with an average positioning error and navigation time of 2.4 mm and 75 s, respectively. The presented approach offers a versatile strategy for developing compact continuum robots for endoluminal interventions.