A Novel Actuating Mechanism for Concentric Tube Robots based on Universal Friction Wheel Sleeves

Concentric tube robots (CTR) are a type of flexible robot with a small size. Conventional CTR is normally actuated by lead-screws. Such actuation method normally has a limited movement speed as well as a large weight. This paper addresses these challenges by proposing a novel actuating mechanism based on universal friction wheel sleeves, which can be used to actuate CTR. A teleoperated control system is designed to control the CTR. Kinematic analysis of the mechanism is also derived in this work. The results of validation experiments reveal a high accuracy of the actuating mechanism. The translation error could reach less than 0.1mm, while the rotation error is less than 0.05° with closed-loop control. The repeatability of this mechanism is proven to be high with an average error of about 0.1mm. The actuating mechanism also has high stability, which can move stably at a speed up to 50 mm/s. Finally, a preliminary study with the deployed concentric tubes is carried out to demonstrate the bending, translation and rotation motion of the CTR system. To sum up, the movement speed can be improved by using this novel actuating mechanism while maintaining a high control accuracy. This could potentially improve the performance of the interventions/surgeries. In addition, the mechanism can be used to build a handheld CTR due to its lightweight and modularized design.