Stable force/position control of a robotic endoscope holder for constrained tasks in nasal surgery

In this paper we employ passivity-based control techniques to guarantee the stable manipulation of a constrained robotic endoscope holder. The system´s modelling and the control synthesis are realised under the port-Hamiltonian formulation. Where a desired form of the closed-loop energy is enforced such that its local equilibrium implies the application of the desired force to the environment (patient´s nostril), while regulating the endoscope unconstrained position and orientation inside the nasal cavity. This allows to set a specific energetic relation between the controlled robot and the environment, which in turn means a safer interaction with the tissue. Simulation and experimental results are presented to validate the theoretical concepts.