Novel claw-type continuum robots: design, modeling, and control

This study addresses the challenges of tendon-driven continuum robots in terms of high-performance joint design, high-accuracy and -efficiency mechanical modeling, and inverse kinetostatic-based control. First, a general design framework for rigid–flexible coupled continuum robots is proposed inspired by the Freedom and Constraint Topology theory. Based on this framework, a novel claw-type continuum robot with high torsion resistance, high-precision positioning, and excellent anti-buckling performance is developed. Consequently, a novel kinetostatic model named the separated beam equilibrium model (SBEM) is proposed by solving the equilibrium equations for each unit individually rather than recursively, which achieves high modeling accuracy and efficiency. Finally, an iterative inverse kinetostatic-based control method involving mechanic factors is proposed. Comparative experimental results demonstrate that the claw-type continuum robot outperforms the twin-pivot continuum robot in terms of torsion resistance by more than 300 times. Moreover, the SBEM achieves high morphology estimation accuracy with errors less than 2.91% of manipulator length and high efficiency with more than 20 times improvement for computation reduction compared with the conventional chained beam constraint model. Furthermore, the iterative inverse kinetostatic model-based control obtains a tip error less than 3.70% of manipulator length by only using the open-loop method. The proposed design, modeling, and control method exhibits vast potential for continuum robots when tackling challenging tasks such as inspection, maintenance, and medical surgery in confined and unstructured environments including engine flow paths, nuclear conduits, and human body cavities. (Figure presented.).