Mechatronics Systems Engineering - Theses, Dissertations, and other Required Graduate Degree Essays

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Self-tuning electromagnetic vibration systems

Date created: 
2019-05-06
Abstract: 

This thesis presents the efforts made toward making industrial mechanical vibration systems smarter. This objective is accomplished in two steps. The first step is realization of mechanical vibration actuators that can mimic the behavior of mechanical dampers and springs with variable and controllable damping and stiffness. The second step includes the design and implementation of algorithms that can find the optimum damping and stiffness in different operating conditions. First, electromagnetic actuators are selected for force generation. It is shown that creating a parallel RL circuit with variable parameters in the shunt of an electromagnetic actuator results in variable damping and stiffness behavior by the actuator. It is shown that this circuit configuration can be realized using a power electronics converter connected to a power source. Next, automatic control methods are developed for adding a self-tuning loop to the system including an electromagnetic actuator. To this end, the sliding mode extremum seeking controller was utilized to make the system self-tuning in a model-free control architecture. The concept is applied to two major problems in vibration systems: vibration energy harvesting and vibration absorption, which is also known as tuned mass damping. In the former application, single variable and multi-variable sliding mode extremum seeking controllers are used for controlling the damping and stiffness of the actuator to maximize the harvested power. In the latter case, the same controller is used with the objective of minimizing the unwanted oscillations in a host structure. Analytical methods, computer simulations, and experimental results are provided to support the proposed concept and verify the theoretical findings. The results show that it is possible to achieve efficient, variable, and controllable damping and stiffness with an electromagnetic actuator comprised of a brushless DC motor and a mechanical motion conversion mechanism. It was also shown that the proposed extremum seeking controllers successfully tune the variables toward the optimum points.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Mehrdad Moallem
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Detection of sleep and wake states based on the combined use of actigraphy and ballistocardiography

Author: 
Date created: 
2019-04-30
Abstract: 

Sleep is a vital part of every humans daily circadian rhythm. People can rest and recover their body and mind and live a more active and alert life with an appropriate amount of sleep. The current gold standard method for sleep analysis is polysomnography, but due to the complexity, it is not convenient to perform it regularly and it disrupts the normal sleep environment of the patient. This thesis presents a method of integrating two alternative measurements of sleep analysis for an improved analysis. Combining the motion detection of actigraphy and the cardiac parameters of ballistocardiography, a novel algorithm was developed to analyze sleep and wake states without interfering with the natural sleep cycle of the participant. Without interfering with the natural sleep environment, this system can be implemented for continuous monitoring and be used to evaluate daily sleep patterns to assess overall sleep quality and health over time. The experimental results demonstrate the effectiveness of the novel proposed algorithm in comparison with each device used separately in improving the sleep classification.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Edward J. Park
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Fall detection algorithms using accelerometers, gyroscopes and a barometric pressure sensor

Date created: 
2018-04-19
Abstract: 

Falls commonly occur in older adults and could result in long-lies when no one is around to assist, which could result to additional emotional and physical consequences. The use of inertial sensors allows a portable and unobtrusive way to detect motion, enabling the automatic detection of falls when used with a fall detection algorithm. The wrist and trunk are two locations that are favorable for fall detection as the former provides a convenient location for the user, while the latter provides a good location for capturing the body’s general motion. The objective of this thesis is to further improve the performance of a wrist-mounted and a trunk-mounted threshold-based fall detection algorithm using inertial sensors comprised of tri-axial accelerometer, tri-axial gyroscope, and a barometric pressure sensor. The algorithms were tested using a comprehensive set of laboratory-simulated falls, activities of daily living (ADL), and near-falls. In the first study, a wrist-based fall detection algorithm for a commercially available smartwatch was proposed. The algorithm used forearm angle to filter the forearm’s downward vertical orientation that could be associated to a non-fall event’s post-activity position. Additionally, to deal with disturbance in barometric pressure data during dynamic motion, barometric pressure was used selectively in a Kalman filter. The algorithm gave 100% sensitivity, 97.2% ADL specificity, and 97.1% non-fall (i.e. including both ADLs and near-falls) specificity. In the second study, the addition of either difference in altitude or average vertical velocity to a trunk-based algorithm that uses vertical velocity + vertical acceleration + trunk-angle (base algorithm) was investigated. The experimental results show that adding either difference in altitude or average vertical velocity was able to increase the algorithm’s non-fall specificity from 91.8% to 98.0% and 99.6%, respectively.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Edward J. Park
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Towards wearable platform for accurate unconstrained trunk motion tracking using inertial and strain sensors data fusion

Author: 
Date created: 
2019-10-29
Abstract: 

The thesis focused on the development of a wearable motion tracking platform employing fiber strain sensors and inertial measurement units through a data fusion algorithm. The development of a smart sleeveless shirt for measuring the kinematic angles of the trunk in complicated 3-dimensional movements was demonstrated. Fiber strain sensors were integrated into the fabric as the sensing element of the system. Furthermore, a novel method for obtaining the kinematic data of joints based on the data from wearable sensors was proposed. More specifically, the proposed method uses the data from two gyroscopes and the smart shirt strain sensors in a combined machine learning-unscented Kalman filter (UKF) data fusion approach to track the three-dimensional movements of a joint accurately. The suggested technique thus avoids the common problems associated with extracting the movement information from accelerometer and magnetometer readings in the presence of disturbances. A study with 12 participants performing an exhaustive set of simple to complex trunk movements was conducted to investigate the performance of the developed algorithm. The results of this study demonstrated that the data fusion algorithm could significantly improve the accuracy of motion tracking in complicated 3-dimensional movements. Future work requires coherently combining both types of sensors in a wearable platform for full-body motion tracking so that the proposed algorithm can be tested in a variety of daily living activities.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Carlo Menon
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Categorization methodology for skin color images into pre-defined color scales

Date created: 
2019-09-09
Abstract: 

The ability to classify skin color based on images from bare skin is highly sought after in various industries and professions, including dermatology, cosmetics, skincare products, laser-based therapies, etc. The focus of the present research work is on designing an algorithm capable of classifying images of various skin colors utilizing the Fitzpatrick and cosmetic brand skin color scales. The images are taken from a skin area by any camera, including a smartphone camera. In this study, two different methods are employed to classify a query image into a set of reference images. Both methods introduced here are among the most commonly used approaches for comparing two image histograms and defining a Difference Index (DI). The application of the proposed algorithms is not limited to the classification of skin colors. These algorithms can be applied in painting industry for building interiors, developing apps for assisting people who are color-blind, etc.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Farid Golnaraghi
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Metamodel based optimization for dynamic blade pitch control on a vertical axis wind turbine using analytical and CFD methods

Date created: 
2019-08-19
Abstract: 

In this study, the blade pitching motion on a representative (12 kW) vertical axis wind turbine (VAWT) is optimized over a wide range of operating conditions. The pitching is referred to as active blade pitching (ABP) when it is not constrained by a predetermined motion, while the operating condition is referred to as the tip speed ratio (TSR). Computational fluid dynamics (CFD) simulations are used to estimate the instantaneous torque produced by the VAWT blades. The torque is considered the system output and is dependent on the ABP which serves as the system input. This work initially used a preliminary ABP derived using an analytic model; the VAWT was then simulated at a TSR of 2.3 with fixed blades using an analytic-ABP strategy. The simulation with the analytic-ABP generated a 33.4% increase in torque output compared to the fixed pitch strategy simulation. The analytic-ABP curve was then approximated by a function of two variables, via parameterization of the ABP. The parameters of this ABP are the optimization variables of a response surface methodology (RSM) optimization, the objective function being the CFD “black-box” simulation and the output variable being the average torque of a blade. The optimization used a three-level full factorial design (FFD) as the design of experiment (DOE) strategy in order to sample the function with an initial set of points, generate a metamodel, and search for the optimum. The ABP derived from this method, termed the FFD-ABP, was simulated; the results show that it increased the torque output by 15.5% relative to the previous analytic-ABP. A new optimization procedure is proposed in this work. It starts from the simulation results of the analytic-ABP as well as +2° and −2° offset perturbations. The optimization procedure generates an optimal ABP using a modified quadratic regression metamodel over a discretized domain; the metamodel is updated with the response of the first optimal-ABP to generate a second optimal-ABP. The procedure is repeated until the ABP converges into a narrow band. The optimal-ABP simulations resulted in a 6.5% increase in torque output with fewer function calls compared to the previous FFD-ABP. The optimization procedure was extended to several TSRs and the data used to develop a governing function and power performance charts. The governing function was based on a novel nonlinear curve fit model and it estimated the pitch based on the TSR and azimuthal angle. The maximum power operation point is increased by 13% and the torque performance at low TSR is improved.

Document type: 
Thesis
Supervisor(s): 
Krishna Vijayaraghavan
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Investigating cathode catalyst layer degradation in polymer electrolyte fuel cells by lab-based x-ray computed tomography

Author: 
Date created: 
2019-09-20
Abstract: 

The commercial viability of polymer electrolyte fuel cells (PEFCs) has increased rapidly over recent years with applications in public and commercial transportation, back-up power, and un-manned autonomous systems. This has come as a direct result toward increasing evidence and severity of climate change due to greenhouse gas emissions; pushing the need for government regulations to introduce stricter limits on fossil fuel combustion in new passenger cars, as well as in other light-to heavy-duty vehicles. Further cost and durability improvements in PEFCs present significant opportunities as the technology continues to be refined. PEFCs are assembled as a series of layers, each having specific functionalities to optimize the cell performance during electrochemical conversion of chemical potential energy, in the way of hydrogen and oxygen, into useable electrical power, heat, and water. These PEFC materials can undergo considerable changes during operation, and lifetime testing through critical degradation processes, which can be uniquely captured using X-ray Computed Tomography (XCT) in this complex multi-layered system. XCT provides a unique ability to delve into the innermost structures through non-destructive imaging in diverse and extensive application areas. In this thesis, a novel small-scale fuel cell fixture that mimics the performance and degradation features of a full-scale PEFC assembly is presented. By combining the 3-dimensional visualization through repeated identical location tomography using XCT scans at various temporal stages of this small-scale fixture, powerful in-situ and operando investigations of dynamic material properties are obtained. This methodology is termed as 4D CT. By means of applying accelerated stress tests focused on cathode catalyst layer degradation, unique insight into the lifetime, dynamics and interactions between the catalyst layer and surrounding components was uniquely obtained using custom developed tools and analysis methods. These new methods allow for new investigations into the temporal changes of water saturation and cathode catalyst layer morphology. It has been found that during ageing, the morphological interaction between different layers can have a considerable impact on degradation mechanisms such as crack propagation. These results uncover unique evidence around the strongly interactive nature of material degradation within a fuel cell that has previously been unobserved.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Erik Kjeang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Multivariable sliding-mode extremum seeking control in power electronic systems

Date created: 
2019-08-20
Abstract: 

This thesis investigates the design and implementation of extremum seeking control with application to power electronics. To this end, a novel multivariable sliding-mode extremum seeking (MSES) scheme is developed and applied to several control and optimization problems involving maximum power point tracking (MPPT) and motor drives. The behavior of the controller in terms of convergence characteristics and stability is studied using nonlinear systems analysis tools. The proposed MSES is utilized in three applications. First, we apply the concept to MPPT in an alternator-based energy conversion system. The objective is to achieve optimal power conversion at different speeds and output voltages of a Lundell alternator. The performance of the proposed controller is experimentally verified on a laboratory-scale setup through controlling the alternator field current and output voltage to gain fast and precise convergence and robust performance in face of disturbances and uncertainties. In the second application, the proposed MSES is used to tune a proportional-integral (PI) controller which regulates the current of a permanent magnet synchronous motor (PMSM). The performance of the proposed MSES tuning method in terms of accuracy, parametric variations, and load torque disturbances is investigated through several experimental tests on a PMSM setup. In the third application, the MSES concept is extended to a PMSM-drive system which emulates an exercise machine working at low speeds. In this case, the algorithm is modified to a multi-objective sliding-mode extremum seeking (MOES) optimization scheme for torque control of a PMSM as well as minimization of its torque ripples. To this end, the MSESC method is utilized to implement an adaptive iterative learning control (AILC) strategy for torque ripple minimization. The performance of the proposed MOES in terms of torque ripple suppression, steady state and transient performance, and load disturbance rejection is experimentally verified through synthesizing different mechanical impedances.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Mehrdad Moallem
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Passive cooling system: An integrated solution to the application in power electronics

Author: 
Date created: 
2019-09-06
Abstract: 

Passive cooling systems are commonly used in power electronic industries to dissipate the tremendous excess heat generated in semiconductors devices to maintain the efficiency, reduce the thermal stress, and prevent the thermal runaway along with component failures. This research, which has been collaborated with our industrial partner, Delta-Q Technologies, aims to enhance the overall heat rejection capacity of a commercially-available naturally cooled battery charger heat sink by focusing on the fundamental heat transfer mechanisms of thermal radiation and natural convection at the same time. In this study, the effect of anodization in various types of aluminum alloy (die-cast A380, 6061) and its thermal impact was investigated. The thermal emissivity of anodized samples was measured with Fourier Transform Infrared Reflectometer (FTIR) spectroscopy. A customized test chamber was built in our lab to carry out the steady-state thermal tests. A conjugated numerical heat transfer model was developed in Ansys Fluent in case of both natural convection and thermal radiation. Various novel fin geometries for Naturally Cooled Heat Sinks (NCHx) were also designed, prototyped, tested, and compared in terms of different surface conditions and operational orientations. A sensitivity analysis of geometrical parameters in one of the most promising fin geometries, inclined interrupted fins, was performed and analyzed. The results reveal an up to 27% overall enhancement with regard to the current IC650 design (benchmark case).

Document type: 
Thesis
File(s): 
Supervisor(s): 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Feet first: Developing instrumented insoles to prove association between weight bearing and foot pain

Author: 
Date created: 
2019-12-06
Abstract: 

It is commonly thought that more time spent weight bearing at work increases the risk of developing plantar fasciitis, a condition causing pain on the bottom of the foot. This link is not recognized by workers compensation boards because the methods used by researchers to determine workers activities lack sufficient objectivity. This work aimed to solve this problem by developing a prototype of a low-cost smart shoe insole capable of accurately recording workplace activities. This device was implemented in a variety of workplaces to collect information about 34 worker’s activities over the course of 3-5 days. An algorithm was developed to classify sitting, standing and walking with an accuracy of 99.3% and analysis showed the time spent standing throughout the workday was correlated with the presence of foot pain. This work lays the foundation for a large population study to provide the objective results needed to change workplace policies.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Carolyn Sparrey
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.