Using continuum robots for force-controlled semi autonomous organ exploration and registration

To perform semi-automated surgical tasks or to assign virtual fixtures for telemanipulated surgical procedures, accurate correspondence between preoperative and intraoperative organ geometry is required. To overcome organ deformation and shift relative to pre-operative images, this paper proposes using force-controlled exploration to update organ geometry using a deformable registration of a pre-operative model to the surgical scene. Since continuum robots can offer deep access into the anatomy, we explore the unique challenges associated with their use to achieve force-controlled exploration. A mixed feedback control law is proposed whereby joint-level and end-effector position measurements are used to satisfy a reference motion trajectory. A hybrid force/position controller is presented using sensory input from magnetic tracking and force sensing. Validation of the proposed control algorithms is achieved on the IREP (a single port access surgical system). Experimental results show that, despite deformation of an organ, the surgical plan can be deformably registered using force-controlled exploration data via an implementation of coherent point drift registration. Future work includes integrating intrinsic force sensing, updating virtual fixture laws in the presence of organ deformations or swelling, and semi-automation of surgical tasks.