A Self-Assembling Extendable Tendon-Driven Continuum Robot With Variable Length

• Published in: IEEE robotics and automation letters Vol. 8; no. 12; pp. 8518 - 8524
• Main Authors: Fischer, N., Becher, M., Holtge, L., Mathis-Ullrich, F.
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.12.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Actuators; Bending; Confined spaces; dexterous manipulation; flexible robotics; Flexible structures; Manufacturing engineering; mechanism design; Robotics; Robots; Segments; Self-assembly; Tendon/Wire mechanism; Tendons; Workspace
• DOI: 10.1109/LRA.2023.3325781
• ISSN: 2377-3766

Tendon-driven continuum robots offer enhanced dexterity for intricate tasks within confined spaces. Nevertheless, when exclusively relying on remote access points, the entire fixed-length robotic system must be precisely repositioned to insert the robotic structure. Conversely, existing methods incorporating extendability tend to introduce complex design requirements, often resulting in a larger spatial footprint. Here, we present a novel design featuring a self-assembling continuum robotic structure during extension process with variable section- and segment lengths. We investigate a compact actuator unit (<inline-formula><tex-math notation="LaTeX">\text{240} \,\text{mm}\times \text{140} \, \text{mm} \times \text{145} \,\text{mm}</tex-math></inline-formula>, <inline-formula><tex-math notation="LaTeX">\text{1.5} \,\text{kg}</tex-math></inline-formula>) assembling a robotic structure smaller than <inline-formula><tex-math notation="LaTeX">15.4 \,\text{mm}</tex-math></inline-formula> in diameter, with a three-tendon configuration and two omnidirectional bendable segments, able to extend up to <inline-formula><tex-math notation="LaTeX">240 \,\text{mm}</tex-math></inline-formula>. A reliable assembly performance was found with repeatability errors below <inline-formula><tex-math notation="LaTeX">2 \,\text{mm}</tex-math></inline-formula> during extension, while workspace and dexterity of the continuum robot achieved a median error of <inline-formula><tex-math notation="LaTeX">2.39 \,\text{mm}</tex-math></inline-formula> for bending. Our scalable approach reaches state-of-the-art dexterity and workspace range, showing great potential to be used for existing and future tendon-driven robotic systems.