Este documento não tem página de rosto / Tese de mestrado. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 2009

This thesis investigates the principle of co-ordination of chassis subsystems by proposing a new control structure for co-ordinating active steering technologies and a brake based directional stability controller. A non-linear vehicle handling model was developed for this study using the Mattab and Simulink tools. This consists of a 4 degree of freedom (d. o. f) lumped-parameter model that includes longitudinal, lateral, yaw and roll motions with quasi-static longitudinal load transfer effects including non-linear suspension and tyre descriptions. The non-linear vehicle dynamics are discussed for the whole operating regime and two specific driving tasks are identified, steerability and stability. In the context of the vehicle states these are yaw rate control and side slip angle bounding respectively. Linear active steering controllers for front, rear and four wheel steering are designed and evaluated in the context of the vehicle handling problem throughout the non-linear operating regime to assist the driver in the two driving tasks previously defined. It is shown through the analysis of the vehicle dynamics in the Chapter 3 that linear controllers can be used to significantly improve the handling behaviour of a non-linear vehicle when only one active input is considered, however when controlling two active inputs, non-linear multivariable approach is required to deal with the strongly coupled nature of the vehicle handling with respect to front and rear steering inputs. A brake based stability system that reflects the state of the art is implemented. The work then proposes a novel co-ordination controller structure for coordination of an active steering controllers and a brake based stability controller for improving to vehicle handling control. The controller was assessed both in steady state and transient tests selected to simulate real world driving manoeuvres over the whole non-linear vehicle handling regime. The co-ordination controller is found to lead to a trade-off between stability and limit cornering performance. The proposed structure improves vehicle stability and reduces interactions in the longitudinal vehicle motion. A detailed discussion of the implications of a coordinated control approach showing it to be a powerful tool providing, the interactions can be conveniently related vehicle handling task and that an appropriate measure of vehicle performance is available. The limitations of the approach are discussed. The most significant limitations being a) the difficulty in proving the optimalty of a heuristic control structure, b) the difficult in assessing the controller behaviour and its interaction with a real driver and c) the likely complexity of the rule base for coordinating more than 2 or 3 systems or describing more complex interactions than were observed here.

Tese de mestrado integrado. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 2012

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A lightweight chassis for a battery electric vehicle being developed at the University of Waikato was required. The chassis was designed around a predetermined body shape and suspension setup. A chassis, built from 20mm thick aluminium honeycomb sandwich panel, was designed and built to LVVTA standards allowing the car to be driven on public roads. The chassis weighs a little over a third the mass of a mass production car chassis. The car has been driven over 1800km with only one minor problem, indicating the chassis is reliable and well suited to its purpose. Titanium aluminide properties were researched to identify where titanium aluminides could be used in an automobile. Titanium aluminides have a specific strength and stiffness near to steel yet only half the density making it an ideal replacement for steel components. Automotive applications identified that could benefit from the use of TiAl include valves, brake rotors and inside 'in-wheel' electric motors.

The highly competitive nature of the transportation industry has produced significant demand for increased equipment efficiency. This has been manifested in attempts to increase carrying capacity whilst lowering running costs. While these factors remain at the forefront of trailer design, the dependence on steel as the primary material has limited the extent to which these goals are realised. The advantages associated with the use of fibre composite materials in automotive applications have been well documented, demonstrating that the substitution of steel with fibre composite materials greatly increases the scope for tare mass reduction. However, to fully utilise the advantages produced through the use of fibre composites, it is necessary to formulate a design philosophy that incorporates the selection of materials and the definition of acceptable performance of both the material and the trailer. This dissertation addresses this broad subject. Within this greater context, this study addresses the incorporation of fibre composite materials into semi-trailers, with the significant issues being divided into two areas: - The development of a design philosophy, intended specifically to address the application of fibre composites to semi-trailers. - The design, analysis and experimental validation of a new type of fibre composite trailer chassis, utilising the aforementioned design philosophy. This PhD project is a foundational study on the suitability of fibre composite materials in the heavy transportation industry, primarily focusing on a practical assessment of the potential for tare mass reduction. The work presented in this dissertation is seen to provide a basis for fibre composite trailer design, in addition to a foundation upon which further investigation into this field can be made. The major outcomes of this project include, amongst others: - The definition of significant load cases and trailer classifications · The development of a design philosophy suited specifically to FRP semi-trailers - The establishment of selection criteria which identifies appropriate FRP materials for use in this application - The development of a new type of FRP chassis for a flatbed semi-trailer - Validation of the design philosophy through experimental testing - Affirmation of the potential of FRPs in application to flatbed semi-trailers

Wheelchairs are the most important mobility-aided device for those who cannot walk independently with moderate or severe physical disabilities, the elder, and the person with chronic diseases in their daily activities. Six-wheel Power Wheelchair has great functions, such as large sphere of actions, has the good capability of traversing step obstacles, great stability, and small radius of gyration. A good chassis mechanism should provide the following characteristics including good support, high stability, easy steering, high comfort for rider, and has the capability of traversing step obstacles. Therefore, the purpose of this paper is to develop the basic theories of analysis and design of six-link chassis mechanism of power wheelchairs, and produce the prototype of some novel chassis mechanisms. First, the kinematic analysis of six-link chassis mechanisms will be derived, and then a computer program will be developed. Next, the structures of six-link chassis mechanisms will be synthesized according to the creative design methodology of mechanism proposed by C. H. Hsu. Then, the structural and kinematic characteristics of chassis mechanisms proposed in patent documentation will be investigated and clarify. The optimization theory will be used to develop a feasible designing program such that the dimensions of the chassis mechanism can be determined. Finally, The results of this designs presents the three-dimension graph. The results of this paper will provide a complete theory for the systematic design of six-link chassis mechanisms for power wheelchairs, and will promote the design competency of the domestic industrial circle.

The purpose of this thesis is to establish the basis for a presentation study, whose goal is to approximate the problems and dilemas of special semi-trailer with extensible sidewalls construction to the future consumer. The thesis explains which parts the semitrailer is made of as well as which essentials should be considered when designing the construction itself. The paper partly shows one particular semi-trailer project. On this project the calculation of stabilisation system, solidity analysis of the extensible part frame and the complete visualization of the trailer unit have been completed.

The recent surge in biodiesel production has resulted in a huge surplus of crude glycerol, a by-product of the process to the level of 10% by weight. This is turn has caused the price of glycerol to fall dramatically, and there are now few economically viable channels for using this resource: waste glycerol is usually combusted. Therefore, much interest has arisen in the possibility of making use of glycerol with biotechnology, as this would not only be a more efficient use of resources but also make biodiesel itself more commercially viable. The purple bacterium Rhodopseudomonas palustris is able to metabolize glycerol through photofermentation and thereby produce hydrogen, a commercially useful commodity. R. palustris is of particular interest for this purpose as, in contrast to many other species which have been investigated with a view to fermenting glycerol, it is highly tolerant of crude glycerol. The feedstock requires little purification or dilution to be made suitable for cultivation of R. palustris. Furthermore, the hydrogen gas produced by R. palustris when grown on glycerol is of high purity, and the organism's great metabolic diversity suggests it may be a useful strain for remediation of other waste materials. However, much groundwork is needed to establish R. palustris as a viable chassis organism for biotechnological purposes. This work sets out to establish optimal conditions for cultivating R. palustris in the laboratory, including the design of a suitable batch photobioreactor system. It also determines optimal conditions for electroporation of R. palustris for the purpose of knocking out endogenous genes or introducing heterologous genes. Furthermore, the introduction of heterologous genes is attempted in order to demonstrate the possibility of producing other high-value compounds with R. palustris, and several deletion strains with potential benefits for hydrogen production are created. Finally, several existing deletion strains are investigated to establish their suitability as chassis strains for further genetic manipulation.

Wheelchair is for those who cannot walk independently and need assistances in moving around. Six-wheel Power Wheelchair has great functions, such as large sphere of actions, no movement injuries, great stability, and small radius of gyration. The purpose of this paper is to apply the idea of engineering design method and offer a design theory for chassis mechanism for Six-Wheel Power Wheelchair. Firstly, the evolution of chassis mechanism for wheelchair is discussed and the existing chassis mechanism for wheelchair is analyzed. Based on the knowledge, this paper concludes the fundamental functions and structural characteristics of chassis mechanism for power wheelchair and lists the design requirements. Secondly, applying the creative mechanism design procedures, a new design for chassis mechanism and the Kinematic design for six-wheel power wheelchair are proposed and computerized Finally, using CAE software stimulating the designs, the paper presents the three-dimension graph and prototype of the designs.