Complementary Model Update: A Method for Simultaneous Registration and Stiffness Mapping in Flexible Environments

Abstract

Registering a surgical tool to an a priori model of the environment is an important first step in computer-aided surgery. In this paper we present an approach for simultaneous registration and stiffness mapping using blind exploration of flexible environments. During contact-based exploration of flexible environments, the physical interaction with the environment can induce local deformation, leading to erroneous registration if not accounted for. To overcome this issue, a new registration method called complementary model update (CMU), is introduced. By incorporating measurements of the contact force, and contact location, we minimize a unique objective function to cancel out the effect of local deformation. We are thus able to acquire the necessary registration parameters using both geometry and stiffness information. The proposed CMU method is evaluated in simulation and then experimentally on silicone models and an ex vivo organ.