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

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Novel nonlinear sliding mode observers for state and parameter estimation

Author: 
Date created: 
2018-04-16
Abstract: 

Interest in the area of state and parameter estimation in nonlinear systems has grown significantly in recent years. The use of sliding mode observers promises superior robustness characteristics that make them very attractive for noisy uncertain systems. In this thesis, a novel Time-Averaged Lypunov functional (TAL) is proposed that examines the effect of Gaussian noise on the stability of a sliding mode observer. The TAL averages the Lyapunov analysis over a small finite time interval, allowing for intuitive analysis of noises and disturbances affecting the system. Initially, a sliding mode observer for a linear system is analysed using the proposed functional. Later, the results are extended to various classes of nonlinear systems. The necessary and sufficient conditions for the existence of the observer are presented in the form of Linear Matrix Inequality (LMI), which can be explicitly solved offline using commercial LMI solvers. The types of nonlinearity examined are fairly general and embodies Lipschitz, bounded Jacobian, Sector bounded and Dissipative nonlinearities. All the system models considered are highly nonlinear and consist of system disturbances and sensor noise. The proposed sliding mode observer provides less conservative conditions to verify the existence and stability of the observer. The observer can also be effectively used for unknown parameter estimation as outlined in the final chapter of this report. Various examples are provided throughout the premise to support the proposed observer design and demonstrate its effectiveness.

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

Differentiating Common Workplace Postures through Plantar Pressure: Laying the Groundwork for a Low-Cost Instrumented Insole

Author: 
Date created: 
2017-12-05
Abstract: 

Prolonged weight bearing (WBR) at work is a suspected risk factor for the development of musculoskeletal disorders that commonly occur in the feet. No objective measure to quantify time spent in different WBR postures currently exists, creating a barrier in investigating the connection between WBR and foot pain. This study aimed to develop a prototype design for a low-cost instrumented insole system capable of differentiating workplace postures (sitting, standing and walking). Three objectives were defined: 1) quantify and differentiate the pedobarographic characteristics associated with each posture, 2) classify the postures from plantar pressure characteristics and 3) develop an insole system with off-the-shelf sensors capable of classifying workplace postures. Pressure measures near the hindfoot and central/lateral forefoot were found to simultaneously differentiate the postures, and machine learning algorithms accurately classified the postures using plantar pressure metrics. This foundational work facilitates the deployment of a low-cost instrumented insole for workplace studies where it will provide the objective evidence needed to resolve the link between WBR and foot pain.

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

Multi-Modality Breast Cancer Assessment Tools Using Diffuse Optical and Electrical Impedance Spectroscopy

Author: 
Date created: 
2016-11-23
Abstract: 

Diffuse optical spectroscopy (DOS) and electrical impedance spectroscopy (EIS) are promising non-invasive and non-ionizing techniques for breast anomaly detection. This research aims at development of low-cost and novel hand-held devices that are able to differentiate between malignant and benign lesions in human subjects. Three probes have been designed and developed in this research, including a diffuse optical spectroscopy probe for measuring the optical properties of breast tissue, a combined diffuse optical spectroscopy probe with electrical impedance spectroscopy probe for measuring the optical and electrical properties of the breast tissue simultaneously, and a diffuse optical breast-scanning (DOB-Scan) probe for creating cross-sectional optical images of the breast.In addition to a detailed description of the developed instruments, two studies are presented: a phantom study detecting inhomogeneity in the homogeneous phantom using DOS and DOB-Scan probe, and a clinical study to diagnosis malignant lesions in the patients who have breast cancer.The DOS-EIS probe was successfully used in an initial clinical study on cancer patients, and the results conclusively demonstrated its ability to differentiate between cancerous breast tissue and healthy tissue using diffuse optical spectroscopy combined with electrical impedance spectroscopy. The results of DOB-Scan imaging probe in the clinical study reflect that the probe can capture malignant tissues underneath of the probe. These studies demonstrate that diffuse optical spectroscopy and electrical impedance spectroscopy are valuable modalities that can play an important role in breast tumor detection and monitoring.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Farid Golnaraghi
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

An extremum seeking control system for control of RF cavity resonators

Author: 
Date created: 
2016-09-15
Abstract: 

RF cavity resonators are one of the key structures in particle accelerators. They provide accelerating field for a beam of charged particles passing through them. An RF source transmits required power for acceleration to cavity through waveguides. Due to impedance mismatch, some amount of available power generated by the RF source reflects back from the cavity. To save power and provide the maximum accelerating field, it is desirable to minimize this reflected power by equalizing the frequencies of the cavity and source. A mechanical tuner mounted on top of the cavity moves a tuner plate in or out of the cavity, thereby changing cavity’s resonance frequency. In this thesis, first a mathematical dynamic model of the cavity in terms of its transient and steady state signals is provided. Then based on the dynamic model, an extremum seeking (ES) algorithm is developed to automatically reach the minimum value of the reflected power and maintain this condition by keeping the resonance frequency of the cavity equal to the source frequency. The ES algorithm is derived through a Lyapunov-based analysis and uses only reflected power as feedback signal. A gradient estimation is performed to determine the direction of movement. The proposed ES controller is further compared with classical perturbation-based ES methods. Simulation and experimental results are presented to evaluate stability and the response behavior of the algorithms in reaching the minimum condition. While both algorithms successfully minimize reflected power in finite time, the results obtained from the Lyapunov-based algorithm are faster and smoother. However, if the cavity is not perfectly coupled and the minimum reflected power is greater than zero, the performance of the proposed controller degrades due to appearance of steady state oscillation. This problem can be solved by adding an initialization phase to the controller, to track the minimum value of reflected power and update the control law with the new value of the minimum.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Mehrdad Moallem
Ken Fong
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Robust human motion tracking using wireless and inertial sensors

Author: 
Date created: 
2015-12-07
Abstract: 

Recently, miniature inertial measurement units (IMUs) have been deployed as wearable devices to monitor human motion in an ambulatory fashion. This thesis presents a robust human motion tracking algorithm using the IMU and radio-based wireless sensors, such as the Bluetooth Low Energy (BLE) and ultra-wideband (UWB). First, a novel indoor localization method using the BLE and IMU is proposed. The BLE trilateration residue is deployed to adaptively weight the estimates from these sensor modalities. Second, a robust sensor fusion algorithm is developed to accurately track the location and capture the lower body motion by integrating the estimates from the UWB system and IMUs, but also taking advantage of the estimated height and velocity obtained from an aiding lower body biomechanical model. The experimental results show that the proposed algorithms can maintain high accuracy for tracking the location of a sensor/subject in the presence of the BLE/UWB outliers and signal outages.

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

Empirical Modeling of Fuel Cell Durability: Cathode Catalyst Layer Degradation

Author: 
Date created: 
2017-12-06
Abstract: 

Fuel cells for automotive applications do not yet match the durability and cost of conventional engines. Durability can be improved by better understanding degradation mechanisms of fuel cell components. A critical component is the cathode electrode, which facilitates the slow oxygen reduction reaction. In this work, fuel cells with state of the art electrodes are manufactured and subjected to degradation tests simulating two drive cycle conditions: load cycling, and start-up/shutdown cycling. The degradation data is used to empirically model the voltage loss due to cathode electrode degradation, to predict voltage loss throughout fuel cell lifetime, and compare to findings in literature. The model may be used as a starting point to better understand electrode degradation, and to develop fundamental models. Based on degradation results it is recommended to investigate coupling effects between the different drive cycle conditions, impact of mitigation factors, and effect of different catalyst loadings on the electrode durability.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Erik Kjeang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Thermal performance of aerogel blanket insulation

Author: 
Date created: 
2017-09-08
Abstract: 

Population growth has significantly increased the energy consumption of the building sector, which is currently 32% of the total global energy demand. Energy use for residential and commercial heating and cooling is projected to strongly grow until 2050, increasing by 79% and 84%, respectively, compared to 2010 [1]. Development of high performance thermal insulation materials is crucial to saving space and energy, increasing comfort, and decreasing environmental impact, cost, and complexity. Aerogels are a promising high-performance type of thermal insulation for both stationary and mobile applications. The thermal performance of insulations is typically judged by their reported R-value (thermal resistance); however, this value may differ from the in-service R-value for reasons such as temperature and humidity variations as well as mechanical compression.In this research, the thermal performance of aerogel blanket super insulation is thoroughly studied under various operating conditions, i.e., temperature, compression, and humidity. The microstructure of commercially available aerogel blankets was characterized using microscopy, porosimetry and spectroscopy. A comprehensive set of accurate analytical models were developed and verified experimentally to predict the thermal and mechanical performance of aerogel blankets in dry and humid conditions. These models can be utilized to predict the thermal performance of the insulation for building envelopes and other large-scale applications. Furthermore, the design of such materials can be improved by performing an optimization study on the microstructural and morphological properties of aerogel blankets using the developed analytical models.The results of the aerogel blanket performance modeling and measurements indicated that mechanical load on the material, elevated temperature and high humidity decrease the R-value of aerogel blankets. These factors should be considered in the thermal insulation design and selection for an application to benefit the most from this super insulation material.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Consolidated composite adsorbent containing graphite flake for sorption cooling systems

Date created: 
2017-07-06
Abstract: 

Heat-driven sorption technology, as a sustainable and clean solution for thermal management and heat storage, has drawn a significant interest in academic and industrial research community. This interest has been intensified in the last decade as environmental and climate changes issues are becoming major global challenges. Numerous studies aim to improve materials sorption performances, as it is at the core of sorption cooling or storage systems. Due to the nature of the sorption process, heat and transport properties, e.g., thermal diffusivity and thermal conductivity of the adsorbent material play an important role in their performance. Higher thermal diffusivity can enhance the heat transfer rate and lead to faster sorption/desorption cycles and more efficient (more compact) heat-driven sorption chillers. A key part of the sorption chillers design is developing adsorbent materials (or composites) with superior hydrophilicity, high water uptake capacity, low regeneration temperature (60-150°C), and high thermal diffusivity. The focus of this research is to design tailored consolidated composite adsorbent containing graphite flakes with improved heat and mass transfer properties for sorption cooling systems. The presented Ph.D. dissertation is divided into three main parts: (i) composite adsorbent fabrication and characterization; (ii) consolidated composite characterization; and (iii) thermal properties modeling of consolidated composite adsorbent. Fabricated loose grain and consolidated composite were characterized in Dr. Bahrami’s Laboratory for Alternative Energy Conversion (LAEC) and SFU 4D LABS.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Plate Heat Exchangers Using Natural Graphite Sheets

Author: 
Date created: 
2017-07-31
Abstract: 

Graphite heat exchangers (G-HEX) are good alternatives to metallic heat exchangers due to their excellent thermal properties, low cost, light weight, and high resistivity to corrosion. In this study, the potential of fabrication of natural flake graphite-based plate heat exchanger is being investigated. A new layered G-HEX and a graphite plate heat exchanger are fabricated and their thermal and hydraulic performance are compared with an off-the-shelf chevron-type plate heat exchanger using a custom-made experimental setup. An optimization study is then conducted to further improve the graphite plate heat exchanger performance. To understand the potential of utilization of G-HEX in corrosive environments, a corrosion test is then performed on natural flake graphite sheets.

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

Electrical impedance and diffuse optical spectroscopy for early breast cancer diagnosis

Author: 
Date created: 
2017-08-16
Abstract: 

In this thesis, we apply sensor-based tools for investigating breast tissue characteristics to identify anomalies, including cancer. The non-invasive technologies utilized are based on the Electrical Impedance Spectroscopy (EIS) and Diffuse Optical Imaging (DOI). As the accuracy of Clinical Breast Examination (CBE) depends on the physician’s experience, these technologies enhance the diagnostic capabilities by providing additional information. We tested twenty patients utilizing these technologies, in a clinical trial, with around 100% success rate in identifying the location of cancerous tumors.The correlation between healthy and cancerous tissue electrical properties is defined by extracting the electrical features of tissues based on Cole-Cole model. Also, by processing the raw data of the DOI-probe, we have been able to create the cross-sectional optical images of the breast in different wavelengths from 690nm to 850nm. This study suggests that EIS and DOI are useful technologies for early detection of breast cancers.

Document type: 
Thesis
Senior supervisor: 
Dr. Farid Golnaraghi
dr. Carolyn Sparrey
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.