Lower limb amputation has significant effects on a person’s quality of life and ability to perform activities of daily living. Prescription of prosthetic device post amputation aims to help restore some degrees of mobility function, however studies have shown evidence of low balance confidence and higher risk of falling among amputee community, especially those suffering from above knee amputation. While advanced prostheses offer better control, they often lack a form of feedback that delivers the awareness of the limb position to the prosthetic user while walking. This research presents the development and evaluation of a wearable skinstretch haptic feedback system intended to deliver cues of two crucial gait events, namely the Initial Contact (IC) and Toe-off (TO) to its wearer. The system comprises a haptic module that applies lateral skin-stretch on the upper leg or the trunk, corresponding to the gait event detection module based on Inertial Measurement Unit (IMU) attached at the shank. The design and development iterations of the haptic module is presented, and characterization of the feedback parameters is discussed. The validation of the gait event detection module is carried out and finally the integration of the haptic feedback system is described. Experimental work with healthy subjects and an amputee indicated good perceptibility of the feedback during static and dynamic (walking) condition, although higher magnitude of stretch was required to perceive the feedback during dynamic condition. User response time during dynamic activity showed that the haptic feedback system is suitable for delivering cues of IC and TO within the duration of the stance phase. In addition, feedback delivered in discernible patterns can be learned and adapted by the subjects. Finally, a case study was carried out with an above-knee amputee to assess the effects of the haptic feedback on spatio-temporal gait parameters and on the vertical ground reaction force during treadmill and overground walking. The research presented in this report introduces a novel design of a haptic feedback device. As such, the outcome includes a well-controlled skin-stretch effect which contributes to the research by investigating skin-stretch feedback for conveying discrete event information rather than conveying direction information as presented in other studies. In addition, it is found that stretch magnitude as small as 3 mm could be perceived in short duration of 150 ms during dynamic condition, making it a suitable alternative to other widely investigated haptic modality such as vibration for ambulatory feedback application. With continuous training, the haptic feedback system could possibly benefit lower limb amputees by creating awareness of the limb placement during ambulation, potentially reducing visual dependency and increasing walking confidence.

A microwave interference cancellation system is presented in this thesis. The technique achieves high Tx/Rx isolation with relatively low degree filters. A four-port diplexer consists of two back-to-back three-port diplexers combined with a 180° phase shift in one branch. High signal isolation between Tx and Rx module is achievable by only using second-order filter topology and the design technique is based on amplitude and phase cancellation between two diplexer branches of the four-port diplexer. Three and four-port networks are intensively analysed and synthesised for solving S-parameter equations. The four-port diplexer exploits the microstrip open-loop structure. A four-port microstrip diplexer for RF interference rejection is presented in IMT-2000 applications whereas device miniaturisation and low infrastructure cost are required. The microstrip-open loop structure with coupled-feed and tapped-feed are designed for alternative techniques and cost reduction. A 180° phase shift in one branch can be achieved by delayed transmission line. The simulated microstrip four-port network is designed at the centre frequency of Tx/Rx at 1.95 GHz and 2.14 GHz, respectively. An alternative technology to reduce overall signal losses and increase power handling with the same or better isolation compared to the four-port microstrip technology is four-port combline coaxial resonator structures. To achieve filter design with a 180° different phase shift, the positive (90° inverter) and negative (-90° inverter) coupled filters are required. The design frequencies of the four-port combline diplexer are 1.73 GHz and 2.13 GHz for Rx and Tx modules, respectively. Two different designs of four-port diplexer prototypes, based on filter designs with similar and dissimilar Q-factors, are fabricated and measured to verify the new design technique. Finally, microwave interference cancellation techniques can be used in wireless communication systems where small size, low losses and low complexity are required.

Robotic devices represent a promising solution to the space limitations of cylindrical MRI scanners, potentially allowing more accurate and faster intervention for the benefit of patients and clinicians. This thesis presents the design, control, and experimental evaluation of a robotic assistant for MRI-guided percutaneous intervention of the liver. The robot provides remotely controlled alignment of a needle guide inside the MRI scanner bore and employs manual needle insertion outside the bore. A graphical user interface allows planning the procedure based on the MR images. A systems engineering process for requirements analysis and concept generation for medical devices is employed in order to provide a solid basis for the design. This approach involves multiple methods and defines a specific workflow with the aim of generating a comprehensive set of requirements and corresponding solutions in order to address the clinical needs. The main features and functionalities of the robot are analysed and verified with a first prototype. Particular attention is paid to the design of a suitable pneumatic actuation and to the position control of the robot. In this respect, different control algorithms are designed and compared with simulations and experiments, achieving a higher positioning accuracy than previously reported for similar systems. A fully functional prototype is then presented and evaluated with extensive experiments. The effects of the system on the quality of the MR images and the robot targeting accuracy are assessed in high-field closed-bore MRI scanners. The advantages of robot-assisted needle insertion over the conventional manual procedure in terms of accuracy and time saving are highlighted with a comparative phantom study. The functionality of the system is verified with an exploratory clinical trial on one patient. Finally, the use of pneumatic actuation for teleoperated needle insertion is investigated and suitable control strategies are presented, in view of a further enhancement of the robot functionalities in following design iterations.

Embankment dams consisting of broadly graded materials have been found to be susceptible to internal erosion. The need to minimise both the cost and risk requires an accurate characterisation of a range of materials, in terms of their susceptibility. Despite significant theoretical and experimental developments, there is a lack of consensus as to how to determine the susceptibility of a material to internal erosion, and what force conditions are required to initiate erosion in susceptible materials. A significant weakness in current geotechnical modelling is the limitation to the use of a large-scale averaged representation of the flow. The immersed-boundary method alternative is a small-scale resolving method capable of elucidating the flow at arbitrarily small scales, rectifying this limitation. In this research the Immersed-Boundary Method (IBM) is used to accurately model the interaction of the particle surface and the fluid flow. The method is adapted and applied to modelling internal erosion, with the intention of understanding the micro-scale mechanisms involved. In particular, the fluid-particle coupling in the IBM model is adapted to be suitable to the case of densely packed particles, characteristic of embankment structures. In this thesis significant improvements are made to the immersed-boundary method’s ability to model fluid particle flows. Improvements to the momentum exchange between the particles surface both when the particle is removed from others, and when two particles are within each others range of influence, are made. Additionally the dependence on mesh resolution of the flow field in proximity of the particle’s surface is reduced, allowing more tractable simulation of the large scale problems characteristic of geotechnical problems. The removal of sporadic pressure fluctuations improves the accuracy of predictions. The resulting tool will provide insight into the science under-pinning internal erosion, guiding best practice with regards to predicting and preventing the onset and propagation of internal erosion.

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This thesis sets out to evaluate six novel arrangements of internal combustion engine air path designed to improve the degree of exhaust energy recovery from a practical passenger car engine system. The study was conducted using 1D engine simulation based on two experimentally validated models of modern turbocharged spark ignition engines. Improvements of up to 5% in fuel efficiency are presented, along with reductions of up to 30% in the torque rise time are presented. For at least 7 decades, efforts have been made to recover waste energy from the internal combustion engine. Heat engines, governed by the second law of thermodynamics, inevitably reject a significant proportion of the fuel energy as heat to the environment. Technologies, such as turbo-compounding, (organic) Rankine cycle and thermoelectric generators have been proven effective for waste energy recovery in high load applications. Inverted Brayton cycle is also under investigation currently due to the high exergy availability in exhaust stream and the potential to enhance the overall performance of vehicle engines. However, none of these technologies has been given extensive application in the field of automobiles, especially passenger cars, despite their effectiveness in reducing fuel consumption and CO2 emission. This thesis reviews current and previous studies to summarise the advantages and disadvantages of these technologies as well as the factors that constrain them from wide application. Transient performance, which is rarely considered in the literature, is considered here to allow a more realistic assessment of the technologies merits. Among these approaches, turbo-compounding has the advantage of compact volume, lower complexity and application cost, and is now employed to recover waste heat in heavy duty vehicles, such as mining equipment and road haulage. This thesis reviews the most recent research on turbo-compounding to identify the variables that make the greatest difference to the engine performance. The potential for the augmentation of the fuel economy and power output by a novel implementation of turbo-compounding in light duty vehicles has been demonstrated. The concept of a variable ratio supercharger drive has been studied as part of a novel boosting system to improve the low-speed torque output by up to 55% and overall fuel economy by 3%. After a careful optimisation of the specifications of the variable ratio unit, it is combined with a turbo-compounding system to fully overcome the inherent drawbacks of turboii compounding, namely the tendency to reduce the power output and engine efficiency at low speed. Finally, the concept of divided exhaust period has been introduced in a novel turbocompounded arrangement to regulate the exhaust flow for a better gas exchange process and improve fuel consumption by up to 5% while improving transient response times by 30%.

Vehicle drivers are exposed daily to harmful low-frequency vertical vibration over the frequency range of 1-20 Hz. This reduces ride comfort and safety as well as possibly causing long-term harmful effects on human health in the form of lower back pain and driver fatigue. Accordingly, intensive work has been undertaken in this field on active seat suspension systems that have superior performance over a wide frequency range compared with passive and semi-active systems. One of the main features of these systems is the control strategy that is used to generate the demand control force and whilst many control strategies have been investigated in this area; their practical implementation is challenging as they require unavailable or expensive system states. Hence, in this thesis, a novel and cost-effective strategy has been developed that uses measurable and inexpensive displacement and velocity preview information from the vehicle suspension. In addition to these practical advantages, employing a prior knowledge of the disturbance in the control strategy increases the ability of the active seat to react rapidly to disturbances and hence provides a supplementary improvement to the vibration attenuation performance. The potential application of this strategy for an active seat suspension is investigated through both simulation and experimental tests. Firstly, for simplicity, the control force is defined from this suspension preview information based upon a linear control approach, with optimum gains using an integrated simulation model of a linear quarter vehicle model (QvM) and one degree of freedom of seat suspension. These gains are obtained off-line by optimising ride comfort in terms of the vertical Seat Effective Amplitude Transmissibility (SEAT) factor using a genetic algorithm (GA) and considering the physical constraints on both the limited seat suspension travel and actuator force capacity. The experimental tests are performed using a prototype active seat suspension installed on a multi-axis simulation table (MAST), which has been developed to mimic the dynamic motion of the sprung mass of the (QvM) through the principle of hardware-in-loop (HIL) simulation. Moreover, the experimental test rig is used to estimate the characteristics of a passive seat suspension as well as the driver’s body model. The ‘preview’ control strategy is examined according to the ISO 2631-1 standard, in both the frequency and time domains, under a range of operating conditions, including different road profiles and vehicle speeds. Both simulation and experimental results reveal that, in comparison with a passive seat suspension, employing this strategy for the active seat system significantly improves ride comfort, especially over the HBSF range (4-8 Hz). Also, experimental tests demonstrate that combining both the preview information with the vehicle body and seat acceleration feedback states provides further improvement in the vibration attenuation level, achieving up to a 19.5 dB reduction over the HBSF range. The linear control approach cannot always satisfy the physical constraints over a range of operating conditions and thus, to overcome this fault, a fuzzy logic controller (FLC) is selected. Accordingly, two novel and cost-effective FLCs are designed and optimised using the Particle Swarming Optimisation (PSO) algorithm. The feedforward fuzzy logic controller (FF-FLC) uses similar preview information as in the linear control approach, while the feedforward/feedback controller (FFFB-FLC) utilises a combination of both the preview information with seat suspension deflection and velocity feedback states. Once again, the simulation and experimental results confirm the effectiveness of these strategies for attenuating the vertical vibration, especially over the HBSF range, in which the FFFB-FLC provides the best performance as well as the highest robustness level at a variety of different driver weights and vehicle speeds. The application of the preview enhanced controller for an active seat suspension in a full vehicle model has been investigated in the simulation. Accordingly, three FLCs strategies, namely, front-left suspension (FLS-FLC), front-axle (FA-FLC) and four wheels (4W-FLC), have been developed based upon which vehicle suspension or/ suspensions are used to acquire the preview information. The former involves utilising suspension displacement and velocity preview information from the vehicle suspension nearest to the driver’s seat. The FA-FLC uses similar preview information, but from the front-left and front-right suspensions, whilst the 4W-FLC controller employs similar preview information from all the vehicle suspensions. Numerical results show that the proposed controllers are very useful in attenuating the vertical acceleration at the driver’s seat compared with a passive alternative. The 4W-FLC provides the best vibration attenuation performance, independent of the vehicle speed. Finally, to reduce the implementation cost of this controller, a practical alternative has been developed that requires less measured preview information. In conclusion, using the preview information enhanced controller for an active seat suspension provides a practical and cost-effective system that improves ride comfort and reduces driver fatigue.