A Miniaturized Tendon-Driven Continuum Robot for Direct Laser Deposition

Abstract

Direct laser deposition, a form of additive manufacturing, shows potential in numerous high-value applications such as aeroengine blade repair. However, conventional setups are bulky and unsuitable for in-situ repair, requiring costly engine disassembly. This letter presents a miniaturized high-repeatability tendon-driven robot that showed good potential for delivering additive manufacturing equipment for in-situ processes like direct laser deposition. The integrated actuation and ruggedized control unit make the robot portable and compatible with various aeroengines. The actuation design prevents excessive fiber optic bending and damage. While continuum robots have the advantage of flexible and redundant structures, they often lack accuracy and repeatability. The optimized kinematics and actuation of the robot presented permitted to achieve in controlled laboratory conditions an excellent repeatability with a standard deviation of 0.02 mm on a linear path and below 0.1 mm on a path that simulates the reconstruction of a blade. The robot showed excellent linearity on each segment of the path with a coefficient of determination to the 3D best-fit line of 0.999, while maintaining the commanded end effector velocity magnitude with a standard deviation of 0.05 mm/s along the whole path.