A Novel Continuum Robot Using Twin-Pivot Compliant Joints: Design, Modeling, and Validation

Background A twisting problem is identified from the central located flexible backbone snake arm robot. Regarding this problem, a design solution is required to mechanically minimise this twisting angle along the backbone. Further, the error caused by the kinematic assumption of previous works is identified as well, which requires a kinematic solution to minimise. Method of approach The scope of this paper is to introduce, describe and test a novel design of snake arm robot which has a twin-pivot compliant joint construction that minimizes the twisting around its axis. A kinematics model is introduced which can be applied to a wide range of twin-pivot construction with two pairs of cables per section design. And according to this model, the approach for minimising the kinematic error is developed. Furthermore, based on the geometry and material property of compliant joint, the work volumes for single/three-section snake arm robot are presented respectively. Results The kinematic analysis has been verified by a three-section prototype of snake arm and adequate accuracy and repeatability tests carried out. And in the test, the system generates relatively small twisting angles when a range of end loads is applied at the end of the arm. Conclusions Utilising the concept presented in this paper, it is possible to develop a snake arm robot which can minimise the twisting angle and be accurately controlled.