Jim Hewit

Tactile sensing technology for minimal access surgery-a review

Abstract Minimal access surgery (MAS), also known as keyhole surgery, offers many advantages over the more traditional open surgery. However, it possesses one very significant drawback––the loss, by the surgeon, of the “sense of feel” that is used routinely in open surgery to explore tissue and organs within the operative site. Because of this, important properties such as tissue compliance, viscosity and surface texture, which give indications regarding the health of the tissue, cannot easily be assessed. Restoring this tactile capability to MAS surgeons by artificial means would bring immense benefits in patient welfare and safety. Artificial tactile sensing systems for MAS are reviewed. The technology is addressed from different viewpoints including those of the basic transduction of tactile data (tactile sensing), the computer processing of the transduced data to obtain useful information (tactile data processing) and the display to the surgeon of this information (tactile display). Applications of tactile sensing in MAS, both to mediate the manipulation of organs and to assess the condition of tissue, are reviewed. Some attempts to add tactile feedback to laparoscopic surgery simulation systems for MAS surgeon training are also described.

Robot-assisted invasive orthopaedic surgery

Changes in orthopaedic practice have led to an increased reliance upon fluoroscopic image guidance during internal fracture fixation (osteosynthesis) procedures. The resulting complexity of surgical techniques, and concerns over X-ray radiation exposure levels to orthopaedic surgeons, has prompted the introduction of new technologies into the operating room with the aim of improving the precision, repeatability and radiation safety of existing surgical procedures. The generic vision-guided robotic system for orthopaedic applications described in this paper is typical of this trend. In order to satisfy the stringent safety requirements of robotic-assisted surgery, the mechatronics design philosophy has been applied to the system. A purpose built manipulator has therefore been manufactured, which when interfaced to an existing C-arm unit allows a drill-bit guide to be automatically aligned with an intra-operatively planned drilling trajectory. Manual completion of the drilling stage can then be performed by the surgeon. The preliminary findings of an ongoing study into the potential for an invasive application of such a system, through the use of an actuated drilling unit incorporating a novel use of force feedback, are also presented. Initial results indicate that force feedback could play a major role in the safety protocol of such an invasive system.

Mechatronics design — The key to performance enhancement

The mechatronics design concept is introduced and its implications discussed. Some comments on Mechatronics from Japanese workers are given to explain its significance and likely future trends. Some examples of Mechatronic systems are described with particular reference to the performance enhancement obtained via integrated design. The present state of Mechatronics worldwide is described.

Robotic sorting of paper items from a random pile

Abstract A random stack of documents is physically sorted into ordered stacks according to type and condition. This is done by first locating the topmost item using a machine vision system with algorithms based upon the Hough Transform. The edges of the items are identified from the shadows created by illuminating the pile from different directions. Having located the position and orientation of the topmost item, a robot arm is programmed to pick the item from the pile using an end-effector with vacuum picking mechanisms. The robot arm offers the picked item “on-the-fly” to devices which ascertain its physical fitness and classification. Finally, the item is placed on the appropriate one of a number of piles of similar category.

ACE: a bond graph modelling and development tool for control system design and implementation

Abstract A software tool based on bond graphs is presented together with a hardware-in-the-loop experimental rig. These are designed to be used as aids in the planning, simulation, implementation and testing of control systems containing multiple actuators with sensory feedback. The windows-based, object-orientated (OO) development tool ACE (Adaptive Control Environment) enables the user to build up a graphical representation of the system by selecting objects from a library of system elements and/or mini systems. Each of these objects, although viewed as a graphical drawing of the selected element on this level, contains data representing an acausal bond graph. As the model is built up containing several of these objects, ACE has a view of the overall interconnecting acausal bond graph of the system. For hardware-in-the-loop simulation, ACE divides the core system model into three parts, representing: • the hardware-in-the-loop objects — that is the hardware under test (e.g. an electrical motor and sensors); • the controller — whose function it is to control the afore mentioned hardware; • an applied loading. It is from the last two of these sub-systems that control code may be generated for operation and testing on a specially developed DAP (Data Acquisition Processor) controlled test-rig.

Application of wavelet transforms and neural networks to the recognition and classification of blemishes

Abstract A blemish is a stain or a damage mark on the surface of a product that is unsightly and which may thereby render the product unacceptable. Research is described which seeks to recognise the presence of blemishes and to classify them both in terms of the type of damage sustained and the extent of the damage. This will permit analysis of the cause of the blemishes and the development of ways of preventing marking in the future. It will also permit decisions to be made regarding the acceptability of the product and whether it should be withdrawn or, where appropriate, repaired. The research has led to a new approach to the derivation of shift–invariance by using an overcomplete wavelet transform. The classification performances of a complex orthogonal estimation algorithm, the Fourier transform and the wavelet transform are presented and compared.

CFD techniques and their relevance to mechatronics

Computational fluid dynamics (CFD) is a powerful technique for predicting fluid flow and heat transfer in engineering systems. Exemplars are presented to demonstrate the relevance of CFD to mechatronics. Popular CFD techniques and commercial packages are discussed. Predictions relevant to pneumatic actuators, magnetic bearings, enclosures containing electronic components, solar-concentrators and inert gas electronic insulation are presented. The exemplars chosen illustrate the prediction of: unsteady; three dimensional; turbulent; moving boundary; forced convection and free convection flows. The amount of time required to set up and run the exemplars is given and on average this is 12 min and 2.5 h, respectively.

Artificial neural networks for locating eyes in facial images

Abstract A feasibility study of artificial neural networks (ANNs) for locating eyes in digitised facial images is presented. The objective is to create a system which can be used for real-time applications at low cost. The radial basis function (RBF) feedforward network type and hybrid training algorithm were selected for this project. A resolution reduction technique minimises the amount of image data to be searched by the network. A novel cross-shaped convolution mask and geometric constraints on eye position are used to reduce execution time. The system achieved a 97.5% succes rate in identifying eyes in 20 training images and 40 test images. Success was defined as locating the eye to within two pixels of the centre of the pupil. A set of images taken under constant lighting conditions produces the best results. It is estimated that execution time would be 0.12 s if the system were implemented on a TMS320C30 DSP accelerator. This would be significantly faster than a recently developed RBF neural eye location algorithm which requires 20 s to perform the same task.

Issues Concerning the Measurement of Transformation Temperatures in NiTi Alloys

The transformation between martensite and austenite is characterized by four transformation temperatures: martensite start temperature (Ms), martensite finish temperature (Mf), austenite start temperature (As) and austenite finish temperature (Af). In actuator design that relies on the shape memory effect, it is important to obtain an accurate measure of these transformation temperatures, especially As and Af. Several methods of determining these temperatures have been reported, but their accuracy and coherence are not clear. Three methods were used to measure the transition temperatures of NiTi wire under different heat treatment conditions: differential scanning calorimetry (DSC); an electrical resistance method, which uses a sudden change in resistance as an indication of transformation; and an applied loading method, where a macroscopic change in displacement indicates the transformation. The results show that the transition temperatures measured by DSC do not correspond to those measured by the other two methods, which are similar. The applied loading method is the most effective for providing practical information about the stress-dependent transformation temperatures. The electrical resistance test gives clearly determined points for Ms and Mf in the cooling resistance-temperature curve, but As and Af are not clearly identifiable in heating process.

Teleoperation of an experimental mobile vehicle via a free-space optical laser line-of-sight communication link for use in nuclear power plant environments

The paper describes the investigations carried out to implement a line of sight control and communication link for a mobile robot vehicle for use in structured nuclear semi-hazardous environments. Line of sight free space optical laser communication links for remote teleoperation have important applications in hazardous environments. They have certain advantages over radio/microwave links and umbilical control such as greater protection against generation of and susceptance to electro-magnetic fields. The cable-less environment provides increased integrity and mechanical freedom to the mobile robot. However, to maintain the communication link, continuous point and tracking is required between the base station and the mobile vehicle. This paper presents a novel two ended optical tracking system utilizing the communication laser beams and photodetectors. The mobile robot is a six wheel drive vehicle with a manipulator arm which can operate in a variety of terrain. The operator obtains visual feedback information from cameras placed on the vehicle. From this information, the speed and direction of the vehicle can be controlled from a joystick panel. We describe the investigations carried out for the communication of analogue video and digital data signals over the laser link for speed and direction control.