Ungrounded haptic-feedback for hand-held surgical robots

Abstract

Surgical robotic technology has evolved over the last few decades: from autonomous systems, to master-slave and cooperatively-controlled assistive robots. Whilst these various approaches have proven to be technically successful, clinical adoption of robotic technology remains moderate, largely as a result of the financial cost of such technology. An alternative approach that has been recently explored is the integration of mechatronic technology in to surgical devices that are held by the hands of the surgeon and are unattached to a grounding frame. These ungrounded hand-held devices exploit the existing dexterity of the surgeon’s hand that allows them to be simpler, physically compact, lower cost, more easily integrated in to the surgical workflow and with fewer barriers to clinical translation. This thesis explores the use of mechatronic technology in ungrounded, hand-held surgical tools for the purpose of augmenting a surgeon’s haptic perception. During microsurgery in particular, the tool-tissue manipulation forces are often so low that they cannot be perceived by the operating surgeon. This thesis initially proposes a hand-held device that can amplify these sub-threshold forces to magnitudes that can be perceived by human subjects. The mechatronic force amplification concept is further evolved for use in microsurgical forceps designs. In this case, haptic perception is diminished by the elastic spring return of the forceps which is significantly greater in magnitude than the micro-scale manipulation forces. Having investigated the force amplification concept, vibrotactile-based feedback of predefined force-thresholds is investigated. The concept is studied through the clinical exemplar of microneurosurgery: a device is proposed which can inform the operating surgeon if they are exerting excessive force based on a force threshold at which iatrogenic injury of neurovascular tissue is known to occur. Finally, an ungrounded force-feedback strategy is investigated for use with a hand-held device that incorporates position-based active constraints of the tool tip.