James Robert Hewit

Robotic-Assisted Internal Fixation of Femoral Fractures

Closed surgical techniques for the internal fixation of femoral fractures require orthopaedic surgeons to work in close proximity to X-rays. In addition to the occupational health risk this imposes, inexperienced surgeons often encounter great difficulty in achieving optimal positioning of fracture repair fixtures. A vision-guided robotic system has been proposed as a possible solution to these problems and an initial investigation involving two exemplar orthopaedic procedures has been undertaken Robotic surgery assistance imposes rigorous safety-related design constraints, since the orthopaedic robot must operate in close proximity to the patient and operating staff. The design and implementation of a purpose-built robotic system for orthopaedic surgery assistance is described in this paper.

Practical control enhancement via mechatronics design

Mechatronics is concerned with designing machines with enhanced capabilities using advanced control methods. Here we describe how some of these advanced control methods have evolved and how they can be applied effectively. The resulting performance enhancement is explained by the use of a number of example case studies. It is shown that using these methods greatly improves the operational capabilities of mechatronics products and can, in many cases, lead to considerable increases in performance specifications. The paper represents a survey of research work undertaken into mechatronics control methods by the authors and their colleagues. The following control issues are discussed: kinematics control; dynamic control; deadbeat robotics control; active force control; adaptive control; and an active suspension system.

Approximating large-input space functions with fine localised detail using hybrid neuro-fuzzy systems and multi-layer perceptrons

Automated currency condition screening requires an approximate model of the way human experts classify bank notes in terms of their fitness to be loaded into Automatic Teller Machines (ATMs). Part of this model must encapsulate the relationship between features describing aberrations on a bank note and a damage level dictated by the human expert. One general type of relationship is of particular interest. This function has eight inputs, is non-linear but has a generally smooth topography. However, it does contain specific points of localised detail, which Multi-Layer Perceptron (MLP) models tend to smooth out. A new architecture, called Apprentice, is described which uses both MLP and hybrid neuro-fuzzy architectures to overcome this problem and provide the required approximation. The sub-division of work within the new architecture is such that each model carries out the tasks to which it is most suited. Simple fusion algorithms combine the outputs of the two models so that the desired function is approximated with an appropriate accuracy. Results show how well the Apprentice architecture approximates the function in comparison with stand-alone MLPs.

Robotic System Based on X-Ray Navigation for Assistance in Orthopaedic Surgery

Abstract The treatment of femoral shaft fractures typically involves the surgical insertion of a metallic fixation device (intramedullary nail) into the marrow cavity of the femur. Depending upon the severity of the fracture, interlocking screws may then be inserted through the lower (distal) end of the nail/femur. Unfortunately, the pilot holes for these distal interlocking screws can only be drilled under fluoroscopic guidance. As a consequence, distal interlocking is a technically demanding process, which inevitably leads to irradiation of the surgeon. A custom-built robotic-assisted surgery system has therefore been developed with a view to providing a “remote” surgical drilling capability. This paper describes the digital X-ray photogrammetry based registration and trajectory planning techniques employed by the robotic system.