Model-Free Synchronous Motion Generation of Multiple Heterogeneous Continuum Robots

Heterogeneous continuum robots (HCRs) with different structures have been designed for different purposes, whereas the coordination of multiple HCRs has received little attention. On one hand, multiple HCRs coordination brings the possibility of performing complicated tasks. On the other hand, the structural diversity of HCRs poses great difficulties to their modeling and control. This article proposes a model-free scheme for the synchronous motion control of multiple HCRs. The control problem is formulated as two convex optimization problems in a model-free closed-loop framework, including control quantity estimation and Jacobian matrix estimation. The proposed approach aims at addressing the synchronous motion problem of multiple HCRs in a decentralized way. The design of model-free feedback control guarantees the high adaptability of the proposed method for a wide range of HCRs. Simulation studies are performed to verify the effectiveness and adaptability of the proposed scheme for multiple HCRs. Comparative studies verify that the tracking error synthesized by the proposed method is about two-thirds lower than that of the existing method while the computational cost is similar, which reveals the merit of the proposed method in terms of accuracy. Finally, the feasibility and effectiveness of the proposed method are also verified by hardware-in-loop simulations and physical experiments on the synchronous motion control of a cable-driven continuum robot and a concentric-tube robot.