The Effect of Haptic Feedback on Efficiency and Safety During Preretinal Membrane Peeling Simulation.

PurposeWe determine whether haptic feedback improves surgical performance and outcome during simulated a preretinal membrane peeling procedure.MethodsA haptic-enabled virtual reality preretinal membrane peeling simulator was developed using a surgical cockpit with two multifinger haptic devices. Six subjects (three trained retina surgeons and three nonsurgeons) performed the preretinal membrane peeling surgical procedure using two modes of operation: visual and haptic feedback, and visual feedback only.ResultsTask completion time, tool tip path trajectory, tool-retina collision force, and retinal damage were all reduced with haptic feedback used and compared to modes where haptic feedback was disabled.ConclusionsHaptic feedback improves efficiency and safety during preretinal membrane peeling simulation.Translational relevanceThese findings highlight the potential benefit of haptic feedback for improving performance and safety of vitreoretinal surgery

Semiautomated optical coherence tomography-guided robotic surgery for porcine lens removal.

PurposeTo evaluate semiautomated surgical lens extraction procedures using the optical coherence tomography (OCT)-integrated Intraocular Robotic Interventional Surgical System.SettingStein Eye Institute and Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, USA.DesignExperimental study.MethodsSemiautomated lens extraction was performed on postmortem pig eyes using a robotic platform integrated with an OCT imaging system. Lens extraction was performed using a series of automated steps including robot-to-eye alignment, irrigation/aspiration (I/A) handpiece insertion, anatomic modeling, surgical path planning, and I/A handpiece navigation. Intraoperative surgical supervision and human intervention were enabled by real-time OCT image feedback to the surgeon via a graphical user interface. Manual preparation of the pig-eye models, including the corneal incision and capsulorhexis, was performed by a trained cataract surgeon before the semiautomated lens extraction procedures. A scoring system was used to assess surgical complications in a postoperative evaluation.ResultsComplete lens extraction was achieved in 25 of 30 eyes. In the remaining 5 eyes, small lens pieces (≤1.0 mm3) were detected near the lens equator, where transpupillary OCT could not image. No posterior capsule rupture or corneal leakage occurred. The mean surgical duration was 277 seconds ± 42 (SD). Based on a 3-point scale (0 = no damage), damage to the iris was 0.33 ± 0.20, damage to the cornea was 1.47 ± 0.20 (due to tissue dehydration), and stress at the incision was 0.97 ± 0.11.ConclusionsNo posterior capsule rupture was reported. Complete lens removal was achieved in 25 trials without significant surgical complications. Refinements to the procedures are required before fully automated lens extraction can be realized

Adaptive Control of a MEMS Steering Mirror for Suppression of Laser Beam Jitter

Abstract-This paper presents an adaptive control scheme for laser-beam steering by a two-axis MEMS tilt mirror. Disturbances in the laser beam are rejected by a µ-synthesis feedback controller augmented by the adaptive control loop, which determines control gains that are optimal for the current disturbance acting on the laser beam. The adaptive loop is based on an adaptive lattice filter that implicitly identifies the disturbance statistics from real-time sensor data. Experimental results are presented to demonstrate that the adaptive controller significantly extends the disturbancerejection bandwidth achieved by the feedback controller alone

Rejection of repeatable and non-repeatable disturbances for disk drive actuators

ABSTRACT This paper presents an application of two-parameter robust repetitive control (TPRRC) in disk drive servo control, where the repeatable rrmout (RRO) and non-repeatable runout (NRRO) are rejected simultaneously. The repeatable disturbances are rejected by tbe internal model structure of TPRRC, while the nonrepeatable disturbances are attenuated by the robust performance specification. The design procedure of TPRRC is given. A simple structure of tbe robust performance weighting function WP(j@ is proposed and the relationship between the coefficients of WP@iS) and the performance specification over the non-repeatable disturbance is discussed too. The simulation results using the measured position error signals (PES) of a disk drive as output disturbance are presented to show the effectiveness of the disturbance rejection of disk drive servo control and demonstrate that it is a cost effective way to improve the track density of disk drives

Control of Magnetic Bearings for Rotor Unbalance With Plug-In Time-Varying Resonators

Rotor unbalance, common phenomenon of rotational systems, manifests itself as a periodic disturbance synchronized with the rotor's angular velocity. In active magnetic bearing (AMB) systems, feedback control is required to stabilize the open-loop unstable electromagnetic levitation. Further, feedback action can be added to suppress the repeatable runout but maintain closed-loop stability. In this paper, a plug-in time-varying resonator is designed by inverting cascaded notch filters. This formulation allows flexibility in designing the internal model for appropriate disturbance rejection. The plug-in structure ensures that stability can be maintained for varying rotor speeds. Experimental results of an AMB–rotor system are presented