Finding lost wrenches: Using continuum robots for contact detection and estimation of contact location

This paper presents a novel modeling framework for contact detection and estimation of contact location on multi-backbone continuum robots. The paper presents modified kinematics for constrained continuum robots and introduces the concept of Fixed Centrode Deviation (FCD) for continuum robots. It is shown that the change in fixed centrode locus may be used for detection of contact and for contact location estimation. An alternative method for contact detection using Joint Force Deviation (JFD) is investigated and a lower bound for contact detectability is derived while considering uncertainties in joint forces. An estimation framework for the location of contact is presented based on FCD and the constrained kinematics Jacobian of the continuum robot. These methods are validated by simulation and experiments. This framework may be used for enhancing the safety of robotic surgical slaves and for exploration of unknown environments such as in scenarios of search and rescue.