A multi-function force sensing instrument for variable admittance robot control in retinal microsurgery

Abstract

Robotic systems have the potential to assist vitreoretinal surgeons in extremely difficult surgical tasks inside the human eye. In addition to reducing hand tremor and improving tool positioning, a robotic assistant can provide assistive motion guidance using virtual fixtures, and incorporate real-time feedback from intraocular force sensing ophthalmic instruments to present tissue manipulation forces, that are otherwise physically imperceptible to the surgeon. This paper presents the design of an FBG-based, multi-function instrument that is capable of measuring mN-level forces at the instrument tip located inside the eye, and also the sclera contact location on the instrument shaft and the corresponding contact force. The given information is used to augment cooperatively controlled robot behavior with variable admittance control. This effectively creates an adaptive remote center-of-motion (RCM) constraint to minimize eye motion, but also allows the translation of the RCM location if the instrument is not near the retina. In addition, it provides force scaling for sclera force feedback. The calibration and validation of the multi-function force sensing instrument are presented, along with demonstration and performance assessment of the variable admittance robot control on an eye phantom.

Toward robotically assisted membrane peeling with 3-DOF distal force sensing in retinal microsurgery

“…Future investigation will use more realistic phantoms under a simulated sclerotomy constraint. Additional force sensing at the sclerotomy [12] can be integrated to update the RCM constraint in real time.…”

Haptics in Robot-Assisted Surgery: Challenges and Benefits

“…The experiments were however performed on a single user. Later He et al [139] extended the work by adding an additional force sensor to a variable admittance controlled cooperative robot, to provide force feedback from both tool tip and sclera entry point. The work was based on the idea that in freehand manipulation, the surgeon can often sense the contact force at the sclera entry point, and utilizes it as an indicator to guide the desired motion.…”

Robotic Vitreoretinal Surgery

“…Similarly, in ophthalmology, electromagnetic tracking systems and force-sensing tools can quantify surgical movements by providing the amplitude and rate of forces being generated during tissue manipulation, the distance of the instrument tip and shaft from ocular structures, or the velocity movement of instruments by the surgeon (44, 45). This information can be used to develop a library of quantified movements for any surgical procedure, thus creating a “language of surgery”.…”