Stretched backboneless continuum manipulator driven by cannula tendons

Purpose The purpose of this paper is to present a stretched backboneless continuum manipulator, which aims to provide sufficient inner room for potential transportation of objects or fixture of necessary devices, and to reduce the number of motors for reduction of the weight of the system. Design/methodology/approach A mathematical model of the presented manipulator is established in this paper. To verify the presented theory, the position of the free end was recorded by a high-resolution digital camera in experiment. According to the comparison of experimental values and theoretical values, the error is less than 2.5 per cent. It shows that the mathematical model and theoretical analysis are reasonable; the presented continuum manipulator can reach to desired postures and positions. Findings This paper presents a new stretched backboneless continuum manipulator supported and driven by cannula tendons. The cannula tendons are composed of rubber tubes and glass fibers. The upper section and the lower section of the presented manipulator are driven by same motors. For steering the manipulator, switched driving strategy is developed based on the presented kinematics model. The presented manipulator possesses six degrees of freedom (DOFs) and has good performance in dealing with complex working environment. The experiment verifies the presented driving strategy. Research limitations/implications The presented backboneless continuum manipulator has only two sections and is supported by cannula tendons. Extending this structure to further more sections is a challenge and is left for future research. Originality/value The value of this study is to propose a stretched backboneless continuum manipulator, which can provide inner room as large as possible for potential usage and halve the number of motors, for which a switched driving strategy is put forward. As a result, the weight and complexity of the manipulator are decreased. The presented manipulator is able to move in potential complex environments and approach its objects in different postures in virtue of its high flexibility and its six DOFs.