A Miniaturized Tendon-Driven Continuum Robot for Direct Laser Deposition

Abstract

Direct laser deposition, a specialized form of additive manufacturing, shows good potential in numerous high-value applications such as the repair of aeroengine blades. However, the traditional setup for this technique is bulky and not suited for in-situ repair, requiring the costly disassembly of the aeroengine. This letter presents a miniaturized high-repeatability tendon-driven robot that showed good potential for delivering additive manufacturing equipment for in-situ techniques like direct laser deposition. The integrated actuation and ruggedized control unit make the robot portable and suitable for a variety of aeroengines. The design of the robot actuation prevents excessive bending and damage to the fiber optic. Continuum robots have the advantage of flexible and redundant structures but present limited accuracy and repeatability. The optimized kinematics and actuation of the robot presented permitted to achieve 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 velocity magnitude of the end effector with a standard deviation along the whole path of 0.05 mm/s.