Telerobotic Control by Virtual Fixtures for Surgical Applications

Abstract

Summary. We present a new method to generate spatial motion constraints for surgical robots that provide sophisticated ways to assist the surgeon. Surgical robotic assistant systems are human-machine collaborative systems (HMCS) that work interactively with surgeons by augmenting their ability to manipulate surgical instruments in carrying out a variety of surgical tasks. The goal of "virtual fixtures" (VF) is to provide anisotropic motion behavior to the surgeon's motion command and to filter out tremor to enhance precision and stability. Our method uses a weighted, linearized, multi-objective optimization framework to formalize a library of virtual fixtures for task primitives. We set the objective function based on user input that can be obtained through a force sensor, joystick or a master robot. We set the linearized subject function based on five basic geometric constraints. The strength of this approach is that it is extensible to include additional constraints such as collision avoidance, anatomybased constraints and joint limits, by using an instantaneous kinematic relationship between the task variables and robot joints. We illustrate our approach using three surgical tasks: percutaneous needle insertion, femur cutting for prosthetic implant and suturing. For the percutaneous procedures we provide a remote center of motion (RCM) point that provides an isocentric motion that is fundamental to these types of procedures. For femur cutting procedures we provide assistance by maintaining proper tool orientation and position. For the suturing task we address the problem of stitching in endoscopic surgery using a circular needle. We show that with help of VF, suturing can be performed at awkward angles without multiple trials, thus avoiding damage to tissue.

Haptic and visual augmented reality interface for programming welding robots

“…In Rosenberg's work [9], virtual fixtures are overlaid on a workspace as guiding forces that are transmitted to a remote operator via haptic feedback. This approach has since been adopted in robotic surgery [10], micro-scale teleoperation systems [11], maintenance [12] and assembly [13]. Haptic feedback, as an additional perception channel to visual feedback, can provide users with a better spatial understanding of the surfaces and edges of a workpiece.…”

Kinematic design considerations for minimally invasive surgical robots: an overview

“…For instance, Schneider and Troccaz used a six‐axis SCARA robot to perform pericardial puncture in cardiac surgery. Another similar approach is the ‘virtual fixtures’ concept, which can generate the absolute bound of spatial motion (as a cone for the MIS task) to constrain the robot's movement . The non‐mechanical RCMs have a number of advantages such as changeable pivot location and increased maneuverability.…”

Enhancing surgical accuracy using virtual fixtures and motion compensation in robotic beating heart surgery

“…The fixture can be considered as an invisible ruler which exerts forces to the master console, either repelling or attracting, according to some force law. Virtual fixtures have already been investigated in various robotic surgery scenarios [6][7][8][9], showing a positive effect on motion accuracy and task completion time. However, most of these applications only consider static fixtures, applied to environments which do not present deformation.…”