Compound continuum manipulator for surgery: Efficient static-based kinematics.

BACKGROUND: The combination of various continuum manipulators is a potential solution to break the bottleneck of continuum manipulators. However, continuum manipulators dissatisfy the constant curvature assumption due to the influence of joints. METHODS: In this paper, a mechanics-based kinematic model of the compound continuum manipulator is proposed, which indicates that the curvature is non-constant. The static model of the manipulator is established, and the relationship of the bending angles is obtained. An efficient static-based Inverse Kinematic Algorithm using Polynomial Curve (IKAPC) of the manipulator is proposed. The polynomial curve is used to fit the end trajectory of the first manipulator. RESULTS: The simulation results show that the IKAPC is 354 times faster than the Levenberg-Marquardt algorithm. The experimental results show that the mechanics-based model improves the position accuracy by 3.75 times over the constant curvature method. CONCLUSION: This paper is critical for solving the inverse kinematics of the compound continuum manipulator.

Coupling Analysis of Compound Continuum Robots for Surgery: Another Line of Thought.

The compound continuum robot employs both concentric tube components and cable-driven continuum components to achieve its complex motions. Nevertheless, the interaction between these components causes coupling, which inevitably leads to reduced accuracy. Consequently, researchers have been striving to mitigate and compensate for this coupling-induced error in order to enhance the overall performance of the robot. This paper leverages the coupling between the components of the compound continuum robot to accomplish specific surgical procedures. Specifically, the internal concentric tube component is utilized to induce motion in the cable-driven external component, which generates coupled motion under the constraints of the cable. This approach enables the realization of high-precision surgical operations. Specifically, a kinematic model for the proposed robot is established, and an inverse kinematic algorithm is developed. In this inverse kinematic algorithm, the solution of a highly nonlinear system of equations is simplified into the solution of a single nonlinear equation. To demonstrate the effectiveness of the proposed approach, simulations are conducted to evaluate the efficiency of the algorithm. The simulations conducted in this study indicate that the proposed inverse kinematic (IK) algorithm improves computational speed by a significant margin. Specifically, it achieves a speedup of 2.8 × 103 over the Levenberg-Marquardt (LM) method. In addition, experimental results demonstrate that the coupled-motion system achieves high levels of accuracy. Specifically, the repetitive positioning accuracy is measured to be 0.9 mm, and the tracking accuracy is 1.5 mm. This paper is significant for dealing with the coupling of the compound continuum robot.