An ungrounded hand-held surgical device incorporating active constraints with force-feedback

This paper presents an ungrounded, hand-held surgical device that incorporates active constraints and forcefeedback. Optical tracking of the device and embedded actuation allow for real-time motion compensation of a surgical tool as an active constraint is encountered. The active constraints can be made soft, so that the surgical tool tip motion is scaled, or rigid, so as to altogether prevent the penetration of the active constraint. Force-feedback is also provided to the operator so as to indicate penetration of the active constraint boundary by the surgical tool. The device has been evaluated in detailed bench tests to quantify its motion scaling and force-feedback capabilities. The combined effects of force-feedback and motion compensation are demonstrated during palpation of an active constraint with rigid and soft boundaries. A user study evaluated the combined effect of motion compensation and force-feedback in preventing penetration of a rigid active constraint. The results have shown the potential of the device operating in an ungrounded setup that incorporates active constraints with force-feedback. © 2013 IEEE.link_to_subscribed_fulltex

Force-Sensing-Based Multi-Platform Robotic Assistance for Vitreoretinal Surgery

Vitreoretinal surgery aims to treat disorders of the retina, vitreous body, and macula, such as retinal detachment, diabetic retinopathy, macular hole, epiretinal membrane and retinal vein occlusion. Challenged by several technical and human limitations, vitreoretinal practice currently ranks amongst the most demanding fields in ophthalmic surgery. Of vitreoretinal procedures, membrane peeling is the most common to be performed, over 0.5 million times annually, and among the most prone to complications. It requires an extremely delicate tissue manipulation by various micron scale maneuvers near the retina despite the physiological hand tremor of the operator. In addition, to avoid injuries, the applied forces on the retina need to be kept at a very fine level, which is often well below the tactile sensory threshold of the surgeon. Retinal vein cannulation is another demanding procedure where therapeutic agents are injected into occluded retinal veins. The feasibility of this treatment is limited due to challenges in identifying the moment of venous puncture, achieving cannulation and maintaining it throughout the drug delivery period. Recent advancements in medical robotics have significant potential to address most of the challenges in vitreoretinal practice, and therefore to prevent traumas, lessen complications, minimize intra-operative surgeon effort, maximize surgeon comfort, and promote patient safety. This dissertation presents the development of novel force-sensing tools that can easily be used on various robotic platforms, and robot control methods to produce integrated assistive surgical systems that work in partnership with surgeons against the current limitations in vitreoretinal surgery, specifically focusing on membrane peeling and vein cannulation procedures. Integrating high sensitivity force sensing into the ophthalmic instruments enables precise quantitative monitoring of applied forces. Auditory feedback based upon the measured forces can inform (and warn) the surgeon quickly during the surgery and help prevent injury due to excessive forces. Using these tools on a robotic platform can attenuate hand tremor of the surgeon, which effectively promotes tool manipulation accuracy. In addition, based upon certain force signatures, the robotic system can precisely identify critical instants, such as the venous puncture in retinal vein cannulation, and actively guide the tool towards clinical targets, compensate any involuntary motion of the surgeon, or generate additional motion that will make the surgical task easier. The experimental results using two distinct robotic platforms, the Steady-Hand Eye Robot and Micron, in combination with the force-sensing ophthalmic instruments, show significant performance improvement in artificial dry phantoms and ex vivo biological tissues

The Hand-Held Force Magnifier: Surgical Tools to Augment the Sense of Touch

Modern surgeons routinely perform procedures with noisy, sub-threshold, or obscured visual and haptic feedback,either due to the necessary approach, or because the systems on which they are operating are exceeding delicate. For example, in cataract extraction, ophthalmic surgeons must peel away thin membranes in order to access and replace the lens of the eye. Elsewhere, dissection is now commonly performed with energy-delivering tools – rather than sharp blades – and damage to deep structures is possible if tissue contact is not well controlled. Surgeons compensate for their lack of tactile sensibility by relying solely on visual feedback, observing tissue deformation and other visual cues through surgical microscopes or cameras. Using visual information alone can make a procedure more difficult, because cognitive mediation is required to convert visual feedback into motor action. We call this the “haptic problem” in surgery because the human sensorimotor loop is deprived of critical tactile afferent information, increasing the chance for intraoperative injury and requiring extensive training before clinicians reach independent proficiency. Tools that enhance the surgeon’s direct perception of tool-tissue forces can therefore potentially reduce the risk of iatrogenic complications and improve patient outcomes. Towards this end, we have developed and characterized a new robotic surgical tool, the Hand-Held Force Magnifier (HHFM), which amplifies forces at the tool tip so they may be readily perceived by the user, a paradigm we call “in-situ” force feedback. In this dissertation, we describe the development of successive generations of HHFM prototypes, and the evaluation of a proposed human-in-the-loop control framework using the methods of psychophysics. Using these techniques, we have verified that our tool can reduce sensory perception thresholds, augmenting the user’s abilities beyond what is normally possible. Further, we have created models of human motor control in surgically relevant tasks such as membrane puncture, which have shown to be sensitive to push-pull direction and handedness effects. Force augmentation has also demonstrated improvements to force control in isometric force generation tasks. Finally, in support of future psychophysics work, we have developed an inexpensive, high-bandwidth, single axis haptic renderer using a commercial audio speaker