Kinetostatics-based stiffness analysis of continuum manipulators considering non-constant cross sections

Continuum manipulators are widely used for their compliant and dexterous nature, but their design and modeling are simplified by keeping the cross-section constant. Inspired by biological structures like elephant trunks and octopus tentacles, previous studies have proposed continuum manipulators featuring non-constant cross sections, but few of them study how the cross sections affect the manipulator's properties, such as stiffness. In this paper, a general kinetostatic model and a stiffness model are presented for continuum manipulators with non-constant cross sections and experimental validations are conducted under various actuating and loading conditions. Moreover, comparative stiffness analysis is performed among manipulator designs with different non-constant cross sections. The results indicate a significant impact of cross-section-varying rates on the system stiffness along different directions. This approach and analysis are significant for the structure design and stiffness optimization of continuum manipulators, particularly in applications where stiffness is a primary objective.