Predicting kinematic configuration from string length for a snake-like manipulator not exhibiting constant curvature bending

We have recently developed a snake-like manipulator for use in orthopaedic environments. One example application is the treatment of osteolysis (bone degradation) due to total hip arthroplasty. Recent literature suggest constant curvature models to define manipulator configuration from string (or actuator cable) length; however, our manipulator does not conform to constant curvature bending. In this paper, we present a two-step model to predict the kinematic configuration directly from string length with no assumptions regarding constant curvature bending. We experimentally identify the model parameters and validate the model on an additional experimental data set. The results indicate our model achieved an average maximum error of 1.0 ± 0.90mm in predicting manipulator configuration compared to the ground truth over the test data set.