Electrical-static discharge in single point diamond turning machining of contact lens polymers
- Authors: Kadermani, Mohamed Munir
- Date: 2015
- Subjects: Electric discharges , Electrostatics , Contact lenses , Polymers
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: http://hdl.handle.net/10948/4055 , vital:20508
- Description: Single Point Diamond Turning (SPDT) is a technology widely applied for the fabrication of contact lenses. One of the limiting factors in polymer machining is wear of the diamond tool due to electrostatic discharge resulting in poor surface quality of the machined products. The research work presented in this dissertation highlights the electrostatic properties of contact lenses during machining operations and the effects these properties have on the surface quality of the work piece materials. Two contact lens samples were experimented on, Definitive 74 (Silicone Hydrogel) and Tyro 97 (Rigid Gas Permeable). The electrostatic surface potentials (ESPs) were measured during turning operations using an electrostatic voltmeter and the surface roughness measurements were taken using a surface profilometer. Response Surface Methodology (RSM) techniques were employed to create predictive models for both surface roughness and ESPs with respect to the cutting speed, feed rate and depth of cut. Predictive surface roughness models were successfully generated for both materials and the cutting speed and feed rate were identified as the parameters with most effect on surface roughness. In addition, an electrostatic model was successfully generated for the Definitive 74 contact lens material which cited the cutting speed and feed rate as the most effective parameters on the material’s electrostatic behaviour. However, no relationship was evident between the machining parameters and electrostatic behaviour of Tyro 97.
- Full Text:
- Date Issued: 2015
- Authors: Kadermani, Mohamed Munir
- Date: 2015
- Subjects: Electric discharges , Electrostatics , Contact lenses , Polymers
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: http://hdl.handle.net/10948/4055 , vital:20508
- Description: Single Point Diamond Turning (SPDT) is a technology widely applied for the fabrication of contact lenses. One of the limiting factors in polymer machining is wear of the diamond tool due to electrostatic discharge resulting in poor surface quality of the machined products. The research work presented in this dissertation highlights the electrostatic properties of contact lenses during machining operations and the effects these properties have on the surface quality of the work piece materials. Two contact lens samples were experimented on, Definitive 74 (Silicone Hydrogel) and Tyro 97 (Rigid Gas Permeable). The electrostatic surface potentials (ESPs) were measured during turning operations using an electrostatic voltmeter and the surface roughness measurements were taken using a surface profilometer. Response Surface Methodology (RSM) techniques were employed to create predictive models for both surface roughness and ESPs with respect to the cutting speed, feed rate and depth of cut. Predictive surface roughness models were successfully generated for both materials and the cutting speed and feed rate were identified as the parameters with most effect on surface roughness. In addition, an electrostatic model was successfully generated for the Definitive 74 contact lens material which cited the cutting speed and feed rate as the most effective parameters on the material’s electrostatic behaviour. However, no relationship was evident between the machining parameters and electrostatic behaviour of Tyro 97.
- Full Text:
- Date Issued: 2015
Wireless industrial intelligent controller for a non-linear system
- Authors: Fernandes, John Manuel
- Date: 2015
- Subjects: Neural networks (Computer science) , Linear systems
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: http://hdl.handle.net/10948/9021 , vital:26457
- Description: Modern neural network (NN) based control schemes have surmounted many of the limitations found in the traditional control approaches. Nevertheless, these modern control techniques have only recently been introduced for use on high-specification Programmable Logic Controllers (PLCs) and usually at a very high cost in terms of the required software and hardware. This ‗intelligent‘ control in the sector of industrial automation, specifically on standard PLCs thus remains an area of study that is open to further research and development. The research documented in this thesis examined the effectiveness of linear traditional control schemes such as Proportional Integral Derivative (PID), Lead and Lead-Lag control, in comparison to non-linear NN based control schemes when applied on a strongly non-linear platform. To this end, a mechatronic-type balancing system, namely, the Ball-on-Wheel (BOW) system was designed, constructed and modelled. Thereafter various traditional and intelligent controllers were implemented in order to control the system. The BOW platform may be taken to represent any single-input, single-output (SISO) non-linear system in use in the real world. The system makes use of current industrial technology including a standard PLC as the digital computational platform, a servo drive and wireless access for remote control. The results gathered from the research revealed that NN based control schemes (i.e. Pure NN and NN-PID), although comparatively slower in response, have greater advantages over traditional controllers in that they are able to adapt to external system changes as well as system non-linearity through a process of learning. These controllers also reduce the guess work that is usually involved with the traditional control approaches where cumbersome modelling, linearization or manual tuning is required. Furthermore, the research showed that online-learning adaptive traditional controllers such as the NN-PID controller which maintains the best of both the intelligent and traditional controllers may be implemented easily and with minimum expense on standard PLCs.
- Full Text:
- Date Issued: 2015
- Authors: Fernandes, John Manuel
- Date: 2015
- Subjects: Neural networks (Computer science) , Linear systems
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: http://hdl.handle.net/10948/9021 , vital:26457
- Description: Modern neural network (NN) based control schemes have surmounted many of the limitations found in the traditional control approaches. Nevertheless, these modern control techniques have only recently been introduced for use on high-specification Programmable Logic Controllers (PLCs) and usually at a very high cost in terms of the required software and hardware. This ‗intelligent‘ control in the sector of industrial automation, specifically on standard PLCs thus remains an area of study that is open to further research and development. The research documented in this thesis examined the effectiveness of linear traditional control schemes such as Proportional Integral Derivative (PID), Lead and Lead-Lag control, in comparison to non-linear NN based control schemes when applied on a strongly non-linear platform. To this end, a mechatronic-type balancing system, namely, the Ball-on-Wheel (BOW) system was designed, constructed and modelled. Thereafter various traditional and intelligent controllers were implemented in order to control the system. The BOW platform may be taken to represent any single-input, single-output (SISO) non-linear system in use in the real world. The system makes use of current industrial technology including a standard PLC as the digital computational platform, a servo drive and wireless access for remote control. The results gathered from the research revealed that NN based control schemes (i.e. Pure NN and NN-PID), although comparatively slower in response, have greater advantages over traditional controllers in that they are able to adapt to external system changes as well as system non-linearity through a process of learning. These controllers also reduce the guess work that is usually involved with the traditional control approaches where cumbersome modelling, linearization or manual tuning is required. Furthermore, the research showed that online-learning adaptive traditional controllers such as the NN-PID controller which maintains the best of both the intelligent and traditional controllers may be implemented easily and with minimum expense on standard PLCs.
- Full Text:
- Date Issued: 2015
Autonomous guided vehicle for agricultural application
- Authors: Chikosi, Gerald
- Date: 2014
- Subjects: Autonomous vehicles , Farm equipment
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9652 , http://hdl.handle.net/10948/d1016164
- Description: With the world's population expected to reach nine billion by 2050, agricultural production will have to double to meet this growing demand. Hence, a need for better infrastructure to enhance farming efficiency becomes apparent. There are a number of solutions that have been developed to date that are commercially available. They range from genetically modified seeds and bio/green fertilizers to advanced farming machinery amongst others. However most of the farming equipment developed has drawbacks such as: heavy weight – this leads to reduced yields due to soil compacting; human dependency – constant monitoring and controlling is needed; light dependency – excludes usage during the night or when visibility is poor. Therefore, a possible solution will be researched to enhance the evolution of farming equipment. Furthermore, a model will be developed for testing and verifying the research.
- Full Text:
- Date Issued: 2014
- Authors: Chikosi, Gerald
- Date: 2014
- Subjects: Autonomous vehicles , Farm equipment
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9652 , http://hdl.handle.net/10948/d1016164
- Description: With the world's population expected to reach nine billion by 2050, agricultural production will have to double to meet this growing demand. Hence, a need for better infrastructure to enhance farming efficiency becomes apparent. There are a number of solutions that have been developed to date that are commercially available. They range from genetically modified seeds and bio/green fertilizers to advanced farming machinery amongst others. However most of the farming equipment developed has drawbacks such as: heavy weight – this leads to reduced yields due to soil compacting; human dependency – constant monitoring and controlling is needed; light dependency – excludes usage during the night or when visibility is poor. Therefore, a possible solution will be researched to enhance the evolution of farming equipment. Furthermore, a model will be developed for testing and verifying the research.
- Full Text:
- Date Issued: 2014
Characterisation of Young's modulus and loss factor of damping materials
- Authors: Nortemann, Markus
- Date: 2014
- Subjects: Elasticity , Simulation methods , Damping (Mechanics)
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9662 , http://hdl.handle.net/10948/d1021036
- Description: Given the importance of simulation techniques in automotive engineering, there is a lack of implementation regarding these techniques in the acoustics of damping materials for air-borne sound. Biot’s calculations have proven its abilities to simulate the acoustic characteristics of these damping materials. However, the characterisation of essential structural parameters, such as Young’s modulus and loss factor, in order to conduct Biot’s calculations have been inconclusive. Thus, the primary research objective of this study is to propose a new measurement system for the structural Biot parameters. After a comprehensive literature review has been undertaken on damping materials, as well as measurement apparatuses for Young’s modulus and loss factor of damping materials, two causes of measurement errors have been identified. Unknown stresses in measurement apparatuses and inhomogeneous, polytrophic and viscoelastic behaviour of specimens. A new measurement system that does not affect the specimens with unknown stresses and accounts for their complex behaviour required investigation. Non-contact ultrasound had been selected as a solution to determine the aforementioned parameters, since these methods do not necessarily touch or compress the specimen, which led to unknown stresses and neglection of the complex specimen behaviour with the aforementioned techniques. Although ultrasound had been used to determine structural parameters on various types of materials, it has never been used to measure soft porous damping materials. In order to find possible solutions, various sources using ultrasonics to investigate struc- tural parameters had been reviewed. In order to calculate structural parameters, the longitudinal and transversal wave velocity inside the specimen had to be determined. The main findings showed that non-contact ultrasound will be able to evaluate the Young’s modulus, loss factor as well as Poisson’s ratio. Consequently, it was shown that longitudinal velocity measurements could be conducted using well known transmission measurements. However, well known approaches would not be sufficient measuring the transversal wave velocity in soft damping materials. This problem was addressed with a special gas to be used, with lower sound speed velocity in the fluid than in the solid. Moreso, a new method determining the transversal wave velocity had been found, as it would enable the use of an even larger range of damping materials, especially ones with heavy frames and lower porosity. It will use refracted waves inside the specimen and the determination of the convertion position of the transversal to the longitudinal wave at the rear specimen surface. At the end of the study, hardware components were selected and a test rig was constructed, which should be able to prove that a determination of structural Biot parameters with non-contact ultrasound is possible with less errors instead of using mechanical transfer function systems. The development of measurement software as well as the testing of the measurement system and its validation was not under investigation in this dissertation. This study has expanded on the body of literature knowledge regarding non-contact ultrasound. Furthermore, a significant contribution has been made towards a new measurement system measuring Young’s modulus and loss factor which circumvents errors in mechanical transfer function systems. This will contribute to more precise simulations of damping materials and damped enclosures, which may ultimately result in enhanced efficiency of damping materials as well as the acoustic packaging of cars.
- Full Text:
- Date Issued: 2014
- Authors: Nortemann, Markus
- Date: 2014
- Subjects: Elasticity , Simulation methods , Damping (Mechanics)
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9662 , http://hdl.handle.net/10948/d1021036
- Description: Given the importance of simulation techniques in automotive engineering, there is a lack of implementation regarding these techniques in the acoustics of damping materials for air-borne sound. Biot’s calculations have proven its abilities to simulate the acoustic characteristics of these damping materials. However, the characterisation of essential structural parameters, such as Young’s modulus and loss factor, in order to conduct Biot’s calculations have been inconclusive. Thus, the primary research objective of this study is to propose a new measurement system for the structural Biot parameters. After a comprehensive literature review has been undertaken on damping materials, as well as measurement apparatuses for Young’s modulus and loss factor of damping materials, two causes of measurement errors have been identified. Unknown stresses in measurement apparatuses and inhomogeneous, polytrophic and viscoelastic behaviour of specimens. A new measurement system that does not affect the specimens with unknown stresses and accounts for their complex behaviour required investigation. Non-contact ultrasound had been selected as a solution to determine the aforementioned parameters, since these methods do not necessarily touch or compress the specimen, which led to unknown stresses and neglection of the complex specimen behaviour with the aforementioned techniques. Although ultrasound had been used to determine structural parameters on various types of materials, it has never been used to measure soft porous damping materials. In order to find possible solutions, various sources using ultrasonics to investigate struc- tural parameters had been reviewed. In order to calculate structural parameters, the longitudinal and transversal wave velocity inside the specimen had to be determined. The main findings showed that non-contact ultrasound will be able to evaluate the Young’s modulus, loss factor as well as Poisson’s ratio. Consequently, it was shown that longitudinal velocity measurements could be conducted using well known transmission measurements. However, well known approaches would not be sufficient measuring the transversal wave velocity in soft damping materials. This problem was addressed with a special gas to be used, with lower sound speed velocity in the fluid than in the solid. Moreso, a new method determining the transversal wave velocity had been found, as it would enable the use of an even larger range of damping materials, especially ones with heavy frames and lower porosity. It will use refracted waves inside the specimen and the determination of the convertion position of the transversal to the longitudinal wave at the rear specimen surface. At the end of the study, hardware components were selected and a test rig was constructed, which should be able to prove that a determination of structural Biot parameters with non-contact ultrasound is possible with less errors instead of using mechanical transfer function systems. The development of measurement software as well as the testing of the measurement system and its validation was not under investigation in this dissertation. This study has expanded on the body of literature knowledge regarding non-contact ultrasound. Furthermore, a significant contribution has been made towards a new measurement system measuring Young’s modulus and loss factor which circumvents errors in mechanical transfer function systems. This will contribute to more precise simulations of damping materials and damped enclosures, which may ultimately result in enhanced efficiency of damping materials as well as the acoustic packaging of cars.
- Full Text:
- Date Issued: 2014
Development of a mechatronic transmission control system for the drivetrain of the K71 project
- Authors: Nortemann, Alexander
- Date: 2014
- Subjects: Motor vehicles -- Transmission devices , Automobiles -- Power trains , Automobile driving -- Shifting gear
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9659
- Description: The tractive force has to be interrupted during a gear-shifting operation in a manual vehicle transmission, leading into a decrease of speed while changing gears during the acceleration process. Therefore in a racing application, the shifting time has to be as short as possible so that the required performance of a racing car can be achieved. The following dissertation describes the development of a transmission control system to enable gear changes within a manual gearbox, which was designed for the Formula Student racing series. Various solutions were developed on the basis of reviewed literature, technical data of components and experiences of Formula Student teams. Following this, a comparison of the concepts by means of a utility analysis identified the pneumatic actuation of selector forks to be the most suitable concept. This was mainly due to the expected shifting time, the weight, and its advantageous energy supply requirement. After the selection of the actuators and the position sensors, the system was implemented into the drivetrain to check the tment and the technical feasibility. To draw conclusions regarding the shifting time and to prove the functionality of the system, an open test bench was constructed. Additionally, the hardware and software had to be developed to enable the test run. After the manufacturing and assembling of the test bench, the optimal settings for the test run were determined. By comparing the achieved shifting time of alternative solutions, an improvement in the driving performance of a Formula Student race car is probable.
- Full Text:
- Date Issued: 2014
- Authors: Nortemann, Alexander
- Date: 2014
- Subjects: Motor vehicles -- Transmission devices , Automobiles -- Power trains , Automobile driving -- Shifting gear
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9659
- Description: The tractive force has to be interrupted during a gear-shifting operation in a manual vehicle transmission, leading into a decrease of speed while changing gears during the acceleration process. Therefore in a racing application, the shifting time has to be as short as possible so that the required performance of a racing car can be achieved. The following dissertation describes the development of a transmission control system to enable gear changes within a manual gearbox, which was designed for the Formula Student racing series. Various solutions were developed on the basis of reviewed literature, technical data of components and experiences of Formula Student teams. Following this, a comparison of the concepts by means of a utility analysis identified the pneumatic actuation of selector forks to be the most suitable concept. This was mainly due to the expected shifting time, the weight, and its advantageous energy supply requirement. After the selection of the actuators and the position sensors, the system was implemented into the drivetrain to check the tment and the technical feasibility. To draw conclusions regarding the shifting time and to prove the functionality of the system, an open test bench was constructed. Additionally, the hardware and software had to be developed to enable the test run. After the manufacturing and assembling of the test bench, the optimal settings for the test run were determined. By comparing the achieved shifting time of alternative solutions, an improvement in the driving performance of a Formula Student race car is probable.
- Full Text:
- Date Issued: 2014
Integration of an electrical discharge machining module onto a reconfigurable machine tool
- Authors: Roberts, Bryndan
- Date: 2014
- Subjects: Machine-tools -- Numerical control , Electric discharges , Manufacturing processes
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: http://hdl.handle.net/10948/6182 , vital:21047
- Description: Electrical Discharge Machining (EDM) is a non-contact manufacturing process in which material is removed from a metal workpiece by high frequency electrical pulses produced between an electrode and the workpiece. EDM machines are usually stand-alone devices, and are quite expensive. The objective of this research was to integrate an EDM machine and an existing reconfigurable CNC machine tool, using a modular approach, to enable conventional milling and EDM to be conducted in a co-ordinated fashion on the same machine tool.
- Full Text:
- Date Issued: 2014
- Authors: Roberts, Bryndan
- Date: 2014
- Subjects: Machine-tools -- Numerical control , Electric discharges , Manufacturing processes
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: http://hdl.handle.net/10948/6182 , vital:21047
- Description: Electrical Discharge Machining (EDM) is a non-contact manufacturing process in which material is removed from a metal workpiece by high frequency electrical pulses produced between an electrode and the workpiece. EDM machines are usually stand-alone devices, and are quite expensive. The objective of this research was to integrate an EDM machine and an existing reconfigurable CNC machine tool, using a modular approach, to enable conventional milling and EDM to be conducted in a co-ordinated fashion on the same machine tool.
- Full Text:
- Date Issued: 2014
An Android and Visual C-based controller for a Delta Parallel Robot for use as a classroom training tool
- Authors: Bezuidenhout, Sarel
- Date: 2013
- Subjects: Robotics -- Human factors , Human-robot interaction , Wireless communication systems
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9656 , http://hdl.handle.net/10948/d1020284
- Description: This report will show the development of a Delta Parallel robot, to aid in teaching the basics of robotic motion programming. The platform developed will be created at a fraction of the cost of conventional commercial training systems. This report will therefore show the development procedure as well as the development of some of the example training material. The system will use wireless serial data communication in the form of a Bluetooth connection. This connection will allow an Android tablet, functioning as the human-machine interface (HMI) for the system, to communicate with the motion controller. The motion controller is based in the C environment. This will allow future development of the machine, and allow the system to be used on an integral level, should the trainers require an in depth approach. The motion control software will be implemented on a RoBoard, a development board specifically designed for low- to mid-range robotics. The conclusion of this report will show an example task being completed on the training platform. This will demonstrate some of the basic robotic motion programming aspects which include point to point, linear, and circular motion types but will also include setting and resetting outputs. Performance parameters such as repeatability and reproducibility are important, as it will indirectly show the level of ease with which the system can be manipulated from the software. Finally, the results will be briefly discussed and some recommendations for improvements on the training system and suggestions for future development will be given.
- Full Text:
- Date Issued: 2013
- Authors: Bezuidenhout, Sarel
- Date: 2013
- Subjects: Robotics -- Human factors , Human-robot interaction , Wireless communication systems
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9656 , http://hdl.handle.net/10948/d1020284
- Description: This report will show the development of a Delta Parallel robot, to aid in teaching the basics of robotic motion programming. The platform developed will be created at a fraction of the cost of conventional commercial training systems. This report will therefore show the development procedure as well as the development of some of the example training material. The system will use wireless serial data communication in the form of a Bluetooth connection. This connection will allow an Android tablet, functioning as the human-machine interface (HMI) for the system, to communicate with the motion controller. The motion controller is based in the C environment. This will allow future development of the machine, and allow the system to be used on an integral level, should the trainers require an in depth approach. The motion control software will be implemented on a RoBoard, a development board specifically designed for low- to mid-range robotics. The conclusion of this report will show an example task being completed on the training platform. This will demonstrate some of the basic robotic motion programming aspects which include point to point, linear, and circular motion types but will also include setting and resetting outputs. Performance parameters such as repeatability and reproducibility are important, as it will indirectly show the level of ease with which the system can be manipulated from the software. Finally, the results will be briefly discussed and some recommendations for improvements on the training system and suggestions for future development will be given.
- Full Text:
- Date Issued: 2013
Construction and integration of a battery pack and management system into a solar car
- Authors: Kloeblen, Arne
- Date: 2013
- Subjects: Solar cars -- Batteries , Solar cars -- Design and construction
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9653 , http://hdl.handle.net/10948/d1018654
- Description: In today’s world, we have reached the point where conventional energy forms are inevitably running out. At the same time, the technology for alternative energy harnessing is improving with big steps, especially with society rethinking their high consumption of finite energy and material. This opens the opportunity und increases acceptance for projects and research to prove its actual implementation and to push the boundaries of current technology further.One particular area of application is the automotive sector showcasing raise of costs due to depleting fuel. Solar powered cars are raising interest as it could be a way to complete independence of any resource that has to be produced, mined or in any way transported to the place of consumption. Involvement with the view to enhance their research in this field has become interesting for universities.With solar powered cars, new problems emerge, amongst others the amount of harnessed sun power and the storage to have it available at the point of use. Due to the low energy available, energy storage as light and as efficient as possible is needed. A system is required that allows to be operated independently of its surrounding in a way it is controllable.Lithium-ion based batteries were seen as the most applicable way to execute this, as they give the highest energy density with lower losses than stable, commercially available energy storage mediums.It was decided to design, build and integrate a battery system with its safety circuit into a solar car. After material selection suppliers were searched and contacted. With the successful manufacturing of this system combining different processing methods, partially at university and partially in the industry, the project included a monitoring and management system and protective measures. It was implemented so that neither the limitations of the chemistry and the physical cells nor the vibration occurring while driving the car prevents its proper use. Besides this, communication and dimensions to operate within the car followed, allowing the driver and convoy to access information and control the system.This battery system proved to be practical in street use comparable with that of regular cars and posed as a safe and effective energy supply for an electrically driven car, meeting the given demands.
- Full Text:
- Date Issued: 2013
- Authors: Kloeblen, Arne
- Date: 2013
- Subjects: Solar cars -- Batteries , Solar cars -- Design and construction
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9653 , http://hdl.handle.net/10948/d1018654
- Description: In today’s world, we have reached the point where conventional energy forms are inevitably running out. At the same time, the technology for alternative energy harnessing is improving with big steps, especially with society rethinking their high consumption of finite energy and material. This opens the opportunity und increases acceptance for projects and research to prove its actual implementation and to push the boundaries of current technology further.One particular area of application is the automotive sector showcasing raise of costs due to depleting fuel. Solar powered cars are raising interest as it could be a way to complete independence of any resource that has to be produced, mined or in any way transported to the place of consumption. Involvement with the view to enhance their research in this field has become interesting for universities.With solar powered cars, new problems emerge, amongst others the amount of harnessed sun power and the storage to have it available at the point of use. Due to the low energy available, energy storage as light and as efficient as possible is needed. A system is required that allows to be operated independently of its surrounding in a way it is controllable.Lithium-ion based batteries were seen as the most applicable way to execute this, as they give the highest energy density with lower losses than stable, commercially available energy storage mediums.It was decided to design, build and integrate a battery system with its safety circuit into a solar car. After material selection suppliers were searched and contacted. With the successful manufacturing of this system combining different processing methods, partially at university and partially in the industry, the project included a monitoring and management system and protective measures. It was implemented so that neither the limitations of the chemistry and the physical cells nor the vibration occurring while driving the car prevents its proper use. Besides this, communication and dimensions to operate within the car followed, allowing the driver and convoy to access information and control the system.This battery system proved to be practical in street use comparable with that of regular cars and posed as a safe and effective energy supply for an electrically driven car, meeting the given demands.
- Full Text:
- Date Issued: 2013
Hardware evolution of a digital circuit using a custom VLSI architecture
- Authors: Van den Berg, Allan Edward
- Date: 2013
- Subjects: Digital electronics , Field programmable gate arrays , Sequential machine theory
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9661 , http://hdl.handle.net/10948/d1020984
- Description: This research investigates three solutions to overcoming portability and scalability concerns in the Evolutionary Hardware (EHW) field. Firstly, the study explores if the V-FPGA—a new, portable Virtual-Reconfigurable-Circuit architecture—is a practical and viable evolution platform. Secondly, the research looks into two possible ways of making EHW systems more scalable: by optimising the system’s genetic algorithm; and by decomposing the solution circuit into smaller, evolvable sub-circuits or modules. GA optimisation is done is by: omitting a canonical GA’s crossover operator (i.e. by using an algorithm); applying evolution constraints; and optimising the fitness function. The circuit decomposition is done in order to demonstrate modular evolution. Three two-bit multiplier circuits and two sub-circuits of a simple, but real-world control circuit are evolved. The results show that the evolved multiplier circuits, when compared to a conventional multiplier, are either equal or more efficient. All the evolved circuits improve two of the four critical paths, and all are unique. Thus, it is experimentally shown that the V-FPGA is a viable hardware-platform on which hardware evolution can be implemented; and how hardware evolution is able to synthesise novel, optimised versions of conventional circuits. By comparing the and canonical GAs, the results verify that optimised GAs can find solutions quicker, and with fewer attempts. Part of the optimisation also includes a comprehensive critical-path analysis, where the findings show that the identification of dependent critical paths is vital in enhancing a GA’s efficiency. Finally, by demonstrating the modular evolution of a finite-state machine’s control circuit, it is found that although the control circuit as a whole makes use of more than double the available hardware resources on the V-FPGA and is therefore not evolvable, the evolution of each state’s sub-circuit is possible. Thus, modular evolution is shown to be a successful tool when dealing with scalability.
- Full Text:
- Date Issued: 2013
- Authors: Van den Berg, Allan Edward
- Date: 2013
- Subjects: Digital electronics , Field programmable gate arrays , Sequential machine theory
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9661 , http://hdl.handle.net/10948/d1020984
- Description: This research investigates three solutions to overcoming portability and scalability concerns in the Evolutionary Hardware (EHW) field. Firstly, the study explores if the V-FPGA—a new, portable Virtual-Reconfigurable-Circuit architecture—is a practical and viable evolution platform. Secondly, the research looks into two possible ways of making EHW systems more scalable: by optimising the system’s genetic algorithm; and by decomposing the solution circuit into smaller, evolvable sub-circuits or modules. GA optimisation is done is by: omitting a canonical GA’s crossover operator (i.e. by using an algorithm); applying evolution constraints; and optimising the fitness function. The circuit decomposition is done in order to demonstrate modular evolution. Three two-bit multiplier circuits and two sub-circuits of a simple, but real-world control circuit are evolved. The results show that the evolved multiplier circuits, when compared to a conventional multiplier, are either equal or more efficient. All the evolved circuits improve two of the four critical paths, and all are unique. Thus, it is experimentally shown that the V-FPGA is a viable hardware-platform on which hardware evolution can be implemented; and how hardware evolution is able to synthesise novel, optimised versions of conventional circuits. By comparing the and canonical GAs, the results verify that optimised GAs can find solutions quicker, and with fewer attempts. Part of the optimisation also includes a comprehensive critical-path analysis, where the findings show that the identification of dependent critical paths is vital in enhancing a GA’s efficiency. Finally, by demonstrating the modular evolution of a finite-state machine’s control circuit, it is found that although the control circuit as a whole makes use of more than double the available hardware resources on the V-FPGA and is therefore not evolvable, the evolution of each state’s sub-circuit is possible. Thus, modular evolution is shown to be a successful tool when dealing with scalability.
- Full Text:
- Date Issued: 2013
Acoustic monitoring and control system to determine the properties of damping materials
- Authors: Stahlberg, Martin
- Date: 2012
- Subjects: Vibration (Aeronautics) -- Damping , Acoustic emission testing
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9658
- Description: Experience shows that the noise and sound quality in vehicles are often a recurring criticism. The bodies of modern vehicles consist predominantly of thin sheets of metal. It is hard to prevent the excitation of bending vibrations and the subsequent emission of disturbing noise while driving. The noise spectrum in a car that can be heard by the driver is from ”latent roar” to ”chattering” noise of the body and engine. In automotive vehicles damped materials, especially plastics or materials made from sheet metal and surface damping treatments, are used. Those have high internal energy losses and damp sound oscillatory systems found in the body or interior of cars. A further advantage of such treated components is that they are applied to existing components working over wide temperature and frequency ranges. Many companies provide such ”sound-absorbing compounds”. The requirements for these damping materials are high temperature-resistance, water repellence, fuel and oil-resistance and good adhesion to the base material [17]. The acoustic properties, especially the damping of the plate vibrations through rubber are of interest. the question arises how can the damping coeficient of coated metal sheets can be measured and secondly, by how much the road noise is reduced when built-in sheets are coated with a known damped material. With the Oberst Bar Test Method (named after Dr. H. Oberst) the properties are determined of the internal damping materials that can be used to simulate mechanical constructions to determine damping of larger surfaces. This method describes a laboratory test procedure for measuring the mechanical properties of damped materials. A block diagram of the test system consisting of a damped material bonded to a vibrating cantilever steel bar is shown in figure 2.1. This method is useful for testing materials such as metals, enamels, ceramics, rubbers, plastics, reinforced epoxy matrices and wood. In addition to damping measurement, the test allows for the determination of the Young’s modulus E of the material. E is calculated from the resonance frequency of a given mode and from the physical constants of the bar. By associating the damping factor with the Young’s modulus, a complex quantity is defined which is called the Complex Modulus of Elasticity. Measurements of dynamic mechanical properties are also useful in the research on the molecular structure of materials.
- Full Text:
- Date Issued: 2012
- Authors: Stahlberg, Martin
- Date: 2012
- Subjects: Vibration (Aeronautics) -- Damping , Acoustic emission testing
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9658
- Description: Experience shows that the noise and sound quality in vehicles are often a recurring criticism. The bodies of modern vehicles consist predominantly of thin sheets of metal. It is hard to prevent the excitation of bending vibrations and the subsequent emission of disturbing noise while driving. The noise spectrum in a car that can be heard by the driver is from ”latent roar” to ”chattering” noise of the body and engine. In automotive vehicles damped materials, especially plastics or materials made from sheet metal and surface damping treatments, are used. Those have high internal energy losses and damp sound oscillatory systems found in the body or interior of cars. A further advantage of such treated components is that they are applied to existing components working over wide temperature and frequency ranges. Many companies provide such ”sound-absorbing compounds”. The requirements for these damping materials are high temperature-resistance, water repellence, fuel and oil-resistance and good adhesion to the base material [17]. The acoustic properties, especially the damping of the plate vibrations through rubber are of interest. the question arises how can the damping coeficient of coated metal sheets can be measured and secondly, by how much the road noise is reduced when built-in sheets are coated with a known damped material. With the Oberst Bar Test Method (named after Dr. H. Oberst) the properties are determined of the internal damping materials that can be used to simulate mechanical constructions to determine damping of larger surfaces. This method describes a laboratory test procedure for measuring the mechanical properties of damped materials. A block diagram of the test system consisting of a damped material bonded to a vibrating cantilever steel bar is shown in figure 2.1. This method is useful for testing materials such as metals, enamels, ceramics, rubbers, plastics, reinforced epoxy matrices and wood. In addition to damping measurement, the test allows for the determination of the Young’s modulus E of the material. E is calculated from the resonance frequency of a given mode and from the physical constants of the bar. By associating the damping factor with the Young’s modulus, a complex quantity is defined which is called the Complex Modulus of Elasticity. Measurements of dynamic mechanical properties are also useful in the research on the molecular structure of materials.
- Full Text:
- Date Issued: 2012
Vision-guided tracking of complex tree-dimensional seams for robotic gas metal arc welding
- Authors: Hamed, Maien
- Date: 2011
- Subjects: Robot vision , Robotics , Gas metal arc welding
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9646 , http://hdl.handle.net/10948/1428 , Robot vision , Robotics , Gas metal arc welding
- Description: Automation of welding systems is often restricted by the requirements of spatial information of the seams to be welded. When this cannot be obtained from the design of the welded parts and maintained using accurate xturing, the use of a seam teaching or tracking system becomes necessary. Optical seam teaching and tracking systems have many advantages compared to systems implemented with other sensor families. Direct vision promises to be a viable strategy for implementing optical seam tracking, which has been mainly done with laser vision. The current work investigated direct vision as a strategy for optical seam teaching and tracking. A robotic vision system has been implemented, consisting of an articulated robot, a hand mounted camera and a control computer. A description of the calibration methods and the seam and feature detection and three-dimensional scene reconstruction is given. The results showed that direct vision is a suitable strategy for seam detection and learning. A discussion of generalizing the method used as an architecture for simultanious system calibration and measurement estimation is provided.
- Full Text:
- Date Issued: 2011
- Authors: Hamed, Maien
- Date: 2011
- Subjects: Robot vision , Robotics , Gas metal arc welding
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9646 , http://hdl.handle.net/10948/1428 , Robot vision , Robotics , Gas metal arc welding
- Description: Automation of welding systems is often restricted by the requirements of spatial information of the seams to be welded. When this cannot be obtained from the design of the welded parts and maintained using accurate xturing, the use of a seam teaching or tracking system becomes necessary. Optical seam teaching and tracking systems have many advantages compared to systems implemented with other sensor families. Direct vision promises to be a viable strategy for implementing optical seam tracking, which has been mainly done with laser vision. The current work investigated direct vision as a strategy for optical seam teaching and tracking. A robotic vision system has been implemented, consisting of an articulated robot, a hand mounted camera and a control computer. A description of the calibration methods and the seam and feature detection and three-dimensional scene reconstruction is given. The results showed that direct vision is a suitable strategy for seam detection and learning. A discussion of generalizing the method used as an architecture for simultanious system calibration and measurement estimation is provided.
- Full Text:
- Date Issued: 2011
Develoment of a navigation system for an autonomous guided vehicle using android technology
- Authors: Snyman, Christo Johannes
- Subjects: Automated guided vehicle systems , Global Positioning System
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9660 , http://hdl.handle.net/10948/d1020917
- Description: Modern cell phone hardware, due to its integrated peripherals, provides a low cost intelligent controller for use in the navigation of an Automated Guided Vehicle (AGV). Most commercial AGV’s use proprietary hardware which is expensive to replace and also difficult to maintain. Using industrial hardware components combined with Android mobile platforms could provide a low-cost alternative. This would be easier to maintain, using existing in-house factory maintenance knowledge. A prototype AGV was designed and developed based on an integrated system between an industrial Programmable Logic Controller (PLC) and an Android operating system mobile platform. This system utilises the mobile platforms integrated Global Position System (GPS) or video camera as tools for navigation. Experimental tests were performed to determine whether the prototype can navigate a predefined course by making use of GPS and camera line following algorithms. The accuracy of the line following algorithm was influenced by the speed at which the research AGV moved. Mounting the Android camera higher above the ground improved the vision and therefore accuracy of the algorithm. The GPS algorithm successfully navigated to various waypoints. The accuracy of the implemented GPS unit on the Android device is its limitation. The research unit was only capable of reaching a waypoint consistently within a three-metre radius.
- Full Text:
- Authors: Snyman, Christo Johannes
- Subjects: Automated guided vehicle systems , Global Positioning System
- Language: English
- Type: Thesis , Masters , MEngineering (Mechatronics)
- Identifier: vital:9660 , http://hdl.handle.net/10948/d1020917
- Description: Modern cell phone hardware, due to its integrated peripherals, provides a low cost intelligent controller for use in the navigation of an Automated Guided Vehicle (AGV). Most commercial AGV’s use proprietary hardware which is expensive to replace and also difficult to maintain. Using industrial hardware components combined with Android mobile platforms could provide a low-cost alternative. This would be easier to maintain, using existing in-house factory maintenance knowledge. A prototype AGV was designed and developed based on an integrated system between an industrial Programmable Logic Controller (PLC) and an Android operating system mobile platform. This system utilises the mobile platforms integrated Global Position System (GPS) or video camera as tools for navigation. Experimental tests were performed to determine whether the prototype can navigate a predefined course by making use of GPS and camera line following algorithms. The accuracy of the line following algorithm was influenced by the speed at which the research AGV moved. Mounting the Android camera higher above the ground improved the vision and therefore accuracy of the algorithm. The GPS algorithm successfully navigated to various waypoints. The accuracy of the implemented GPS unit on the Android device is its limitation. The research unit was only capable of reaching a waypoint consistently within a three-metre radius.
- Full Text:
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