Peter N. Brett

An autonomous surgical robot for drilling a cochleostomy: preliminary porcine trial

Objective:  To produce an autonomous drilling robot capable of performing a bony cochleostomy whilst minimising the damage to the underlying cochlear endosteum.

An approach to optimise the critical sensor locations in one-dimensional novel distributive tactile surface to maximise performance

The distributive approach to tactile sensing is a novel approach. The method relies on the distributed deformation of the surface in response to the applied load to a few sensing points within the surface area. The description of the contacting load is then interpreted into meaningful descriptors typically by using a neural network or fuzzy rules. The method has been shown to interpret descriptors such as load position, load value and load width and relies on strong coupling between the sensory data retrieved. This opposes the design aims in many alternative tactile sensing systems that formulate load description from isolated discrete data detected over an array of sensing elements, or that delineate force descriptions through a structure that minimises coupling on Cartesian axes. For distributive tactile sensors, the performance can be optimised through placement of sensing points such that the obtained information is optimal. This paper examines the effect on performance of sensor location points on an experimental one-dimensional surface designed for this purpose. The algorithm interpreting load descriptors was a back-propagation neural network. The critical parameter of sensor location is optimised using the genetic algorithm (GA) and principal component analysis (PCA) approach. It is shown that when an optimised configuration is used load position can be predicted to within 5% of the full range by using as few as two sensing elements, and that performance is improved by using additional sensor points. The results of this study are a basis for selecting sensor locations to achieve high performance with planar one- and two-dimensional distributive tactile surfaces.

A surgical robot for cochleostomy

In this paper a robotic micro-drilling technique for surgery is described. The device has been deployed in cochleostomy, a precise micro-surgical procedure where the critical stage of controlling penetration of the outer bone tissue of the cochlea is achieved without penetration of the endosteal membrane at the medial surface. The significance of the work is that the device navigates by using transients of the reactive drilling forces to discriminate cutting conditions, state of tissue and the detection of the medial surface before drill break-out occurs. This is the first autonomous surgical robot to use this technique in real-time as a navigation function in the operating room and unlike other fully autonomous surgical robotic processes it is carried out without the use pre-operative data to control the motion of the tool. To control tool points in flexible tissues requires self-referencing to the tissue position in real time. There is also the need to discriminate deflections of the tissue, tissue interface, involuntary patients/ tissue movement and indeed movement induced by the drill itself, which require different strategies to be selected for control. As a result of the design of the final system, the break-out process of the drill can either controlled to the required level of protrusion through the flexible interface or can be avoided altogether, with the drill bit at the medial surface. This enables, for the first time, the control of fine penetration with such great precision.

Fibre Bragg grating sensors for distributive tactile sensing

Distributive tactile sensing is a method of tactile sensing in which a small number of sensors monitors the behaviour of a flexible substrate which is in contact with the object being sensed. This paper describes the first use of fibre Bragg grating sensors in such a system. Two systems are presented: the first is a one-dimensional metal strip with an array of four sensors, which is capable of detecting the magnitude and position of a contacting load. This system is favourably compared experimentally with a similar system using resistive strain gauges. The second system is a two-dimensional steel plate with nine sensors which is able to distinguish the position and shape of a contacting load, or the positions of two loads simultaneously. This system is compared with a similar system using 16 infrared displacement sensors. Each system uses neural networks to process the sensor data to give information concerning the type of contact. Issues and limitations of the systems are discussed, along with proposed solutions to some of the difficulties.

Distributive Tactile Sensing using Fibre Bragg Grating Sensors for Biomedical Applications

Artificial tactile sensing systems using the distributive tactile sensing technique and fibre Bragg grating sensors are presented. A one-dimensional arrangement, with possible applications in an endoscope, is compared with a similar arrangement using conventional electronic sensors. A two-dimensional sensing surface is described, with potential applications in human balance and gait analysis, capable of detecting simultaneously the position and shape of an object placed upon it. It is believed that this work represents the first use of fibre Bragg grating sensors in a distributive sensing regime

Vibration analysis of submerged rectangular microplates with distributed mass loading

This paper investigates the vibration characteristics of the coupling system of a microscale fluid-loaded rectangular isotropic plate attached to a uniformly distributed mass. Previous literature has, respectively, studied the changes in the plate vibration induced by an acoustic field or by the attached mass loading. This paper investigates the issue of involving these two types of loading simultaneously. Based on Lambs assumption of the fluid-loaded structure and the Rayleigh–Ritz energy method, this paper presents an analytical solution for the natural frequencies and mode shapes of the coupling system. Numerical results for microplates with different types of boundary conditions have also been obtained and compared with experimental and numerical results from previous literature. The theoretical model and novel analytical solution are of particular interest in the design of microplate-based biosensing devices.

Controlling the penetration of flexible bone tissue using the stapedotomy microdrill

Abstract In this paper a surgical robotic system is described for microdrilling a stapedotomy. The stapedotomy procedure is a delicate operation that is challenging to achieve successfully owing to the fact that, under manual control, the surgeon is working at the thresholds of human perception and dexterity. The automated drilling system described in this paper is sensory guided along a single tool axis. Information on the state of the drilling process is derived from feed force and torque sensory data with respect to time and displacement. The information on the state of the process is used to select the strategy to move the drill bit along its trajectory in order to achieve a minimum level of protrusion of the drill bit beyond the far surface of the stapes footplate. The drilling system is able automatically to determine the unknowns of tissue thickness, hardness and flexibility. Detection of the onset of breakthrough, key to establishing the thickness, is by identification of features in the multiple sensory data that signify this condition. The system demonstrates acceptable performance in the laboratory with positional errors with respect to flexible target positions of approximately 20 μm.

Distributive tactile sensing using fibre bragg grating sensors

We describe experiments aimed at assessing the applicability of fibre Bragg grating sensors to distributive tactile sensing. Strain signals from flexible surfaces instrumented with Bragg grating sensors are processed using neural networks so as to obtain the location, shape and orientation of objects placed on the surfaces.

An Autonomous Surgical Robot Applied in Practice

Over the last 20 years, robotic surgery has made its mark as a precise means of tool deployment in surgical procedures. The majority of applications have focused on the control of tools on trajectories defined using pre-operative scan data. These pre-determined trajectories are appropriate where tissue movement between scanning and surgical therapy processes can be considered insignificant, or within acceptable limits. This level of assistance has its value in many procedures, however more complex tool paths and variations in strategy are required in many other procedures that will benefit from the precise nature of robotic manipulation technology. (Dario et al. 2000), (Davies 2000) are different example systems. To an extent this has been achieved by introducing the surgeon operator into the control loop, where master-slave systems have attempted to harness the decisions on interpretation of the state of tissue tool interaction, the formulation of strategy by the surgeon and the response and accuracy of the robotic device. Unfortunately there is always a dilemma associated with the perception of interaction with the tissue at the tool point. This is particularly true in minimal access procedures or in procedures requiring microscopic tool interaction, where information based on visual perception is compromised and the sense of tactile information is lost.

Discriminating contact in lumen with a moving flexible digit using fibre Bragg grating sensing elements

Abstract Minimal access procedures in surgery offer benefits of reduced patient recovery time and less pain, yet for the surgeon the task is more complex, as both tactile and visual perception of the working site is reduced. In this paper, experimental evidence of the performance of a novel sensing system embedded in an actuated flexible digit element is presented. The digit represents a steerable tip element of devices such as endoscopes and laparoscopes. This solution is able to discriminate types of contact and tissue interaction, and to feed back this information with the shape of the flexible digit. As an alternative to this information, force level, force distribution, and other quantifiable descriptors can also be evaluated. These can be used to aid perception in processes such as navigation and investigation of tissues through palpation. The solution is pragmatic, and by virtue of its efficient mechanical construction and a polymer construction, it offers opportunities for a disposable element with suitability for magnetic resonance imaging (MRI) and other scanning environments. By using only four photonics sensing elements, full perception of tissue contact and the shape of the actuated digit can be described in the feedback of this information. The distributive sensory method applied to the sensory signals relies on the coupled values of the sensory data transients of the four deployed sensing elements to discriminate tissue interaction directly in near real time.