Mechatronics Systems Engineering, School of

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Controlling a Motorized Orthosis to Follow Elbow Volitional Movement: Tests with Individuals with Pathological Tremor

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2019-02-01
Abstract: 

Background:  There is a need for alternative treatment options for tremor patients who do not respond well to medications or surgery, either due to side effects or poor efficacy, or that are excluded from surgery. The study aims to evaluate feasibility of a voluntary-driven, speed-controlled tremor rejection approach with individuals with pathological tremor. The suppression approach was investigated using a robotic orthosis for suppression of elbow tremor. Importantly, the study emphasizes the performance in relation to the voluntary motion.

Methods:  Nine participants with either Essential Tremor (ET) or Parkinson’s disease (PD) were recruited and tested off medication. The participants performed computerized pursuit tracking tasks following a sinusoid and a random target, both with and without the suppressive orthosis. The impact of the Tremor Suppression Orthosis (TSO) at the tremor and voluntary frequencies was determined by the relative power change calculated from the Power Spectral Density (PSD). Voluntary motion was, in addition, assessed by position and velocity tracking errors.

Results:  The suppressive orthosis resulted in a 94.4% mean power reduction of the tremor (p < 0.001) – a substantial improvement over reports in the literature. As for the impact to the voluntary motion, paired difference tests revealed no statistical effect of the TSO on the relative power change (p = 0.346) and velocity tracking error (p = 0.283). A marginal effect was observed for the position tracking error (p = 0.05). The interaction torque with the robotic orthosis was small (0.62 Nm) when compared to the maximum voluntary torque that can be exerted by adult individuals at the elbow joint.

Conclusions:  Two key contributions of this work are first, a recently proposed approach is evaluated with individuals with tremor demonstrating high levels of tremor suppression; second, the impact of the approach to the voluntary motion is analyzed comprehensively, showing limited inhibition. This study also seeks to address a gap in studies with individuals with tremor where the impact of engineering solutions on voluntary motion is unreported. This study demonstrates feasibility of the wearable technology as an effective treatment that removes tremor with limited impediment to intentional motion. The goal for such wearable technology is to help individuals with pathological tremor regain independence in activities affected by the tremor condition. Further investigations are needed to validate the technology.

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Article
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An Adaptive Augmented Vision-based Ellipsoidal SLAM for Indoor Environments

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2019-06-21
Abstract: 

In this paper, the problem of Simultaneous Localization And Mapping (SLAM) is addressed via a novel augmented landmark vision-based ellipsoidal SLAM. The algorithm is implemented on a NAO humanoid robot and is tested in an indoor environment. The main feature of the system is the implementation of SLAM with a monocular vision system. Distinguished landmarks referred to as NAOmarks are employed to localize the robot via its monocular vision system. We henceforth introduce the notion of robotic augmented reality (RAR) and present a monocular Extended Kalman Filter (EKF)/ellipsoidal SLAM in order to improve the performance and alleviate the computational effort, to provide landmark identification, and to simplify the data association problem. The proposed SLAM algorithm is implemented in real-time to further calibrate the ellipsoidal SLAM parameters, noise bounding, and to improve its overall accuracy. The augmented EKF/ellipsoidal SLAM algorithms are compared with the regular EKF/ellipsoidal SLAM methods and the merits of each algorithm is also discussed in the paper. The real-time experimental and simulation studies suggest that the adaptive augmented ellipsoidal SLAM is more accurate than the conventional EKF/ellipsoidal SLAMs.

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Article
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Assessing Anxiety Disorders Using Wearable Devices: Challenges and Future Directions

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2019-03-01
Abstract: 

Wearable devices (WD) are starting to increasingly be used for interventions to promote well-being by reducing anxiety disorders (AD). Electrocardiogram (ECG) signal is one of the most commonly used biosignals for assessing the cardiovascular system as it significantly reflects the activity of the autonomic nervous system during emotional changes. Little is known about the accuracy of using ECG features for detecting ADs. Moreover, during our literature review, a limited number of studies were found that involve ECG collection usingWDfor promoting mental well-being. Thus, for the sake of validating the reliability of ECG features for detecting anxiety in WD, we screened 1040 articles, and only 22 were considered for our study; specifically 6 on panic, 4 on post-traumatic stress, 4 on generalized anxiety, 3 on social, 3 on mixed, and 2 on obsessive-compulsive anxiety disorder articles. Most experimental studies had controversial results. Upon reviewing each of these papers, it became apparent that the use of ECG features for detecting different types of anxiety is controversial, and the use of ECG-WD is an emerging area of research, with limited evidence suggesting its reliability. Due to the clinical nature of most studies, it is difficult to determine the specific impact of ECG features on detecting ADs, suggesting the need for more robust studies following our proposed recommendations.

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Article
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Measurement of Mechanical Strain based on Piezo-Avalanche Effect

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2019-05-13
Abstract: 

We are reporting on the use of the breakdown voltage of a pn junction to measure mechanical strain in micro-structures. The working principle relies on the dependence of silicon band gap to the mechanical stress which affects the current-voltage characteristics of the pn junction. An analytic model is developed and verified experimentally for the phenomenon. A micromechanical device with integrated junctions was designed and fabricated. Mechanical stress was applied onto the structure by subjecting it to mechanical vibrations. It is shown that the breakdown voltage of the device exhibited a high stress sensitivity of about 240ߤ/ܸܯ .ܽܲ.  The mechanical stress can also be measured by monitoring the device current while biased at a constant current. In this mode, the steep changes of the junction current in breakdown region led to nearly a tenfold higher stress sensitivity compared to a piezoresistive sensor. The high sensitivity, simple measurement, and potential for miniaturization for piezo-avalanche sensing make it a promising technique for measurement of stress in micro- and nano-mechanical devices.

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Article
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A New Approach to Compute the Porosity and Surface Roughness of Porous Coated Capillary-Assisted Low Pressure Evaporators

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2018-08-03
Abstract: 

The fundamental characteristics of metal coatings that influence heat transfer are porosity and surface roughness. It is a challenge to analyze the porosity and surface roughness due to the inadequate amount of copper per coated area. In this study, a new approach to non-invasively determine the porosity of metal films utilizing a helium pycnometer and computed micro-tomography (CMT) is presented. Furthermore, a telescope-goniometer is used to measure the surface roughness. Experiments are conducted on four varieties of thin film samples coated with copper powder using wire flame and plasma thermal spray coating methods. The porosities of the thin films were determined to be between 39 and 43%. The thermal spray coating increased the hydrophobicity of the surface and the plasma coating created super-hydrophobic surfaces. The new approach establishes that the porosity of thin films can be non-invasively determined and may also be applied to a wide variety of coated surfaces.

Document type: 
Article

An Indoor Room Classification System for Social Robots via Integration of CNN and ECOC

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2019-01-30
Abstract: 

The ability to classify rooms in a home is one of many attributes that are desired for social robots. In this paper, we address the problem of indoor room classification via several convolutional neural network (CNN) architectures, i.e., VGG16, VGG19, & Inception V3. The main objective is to recognize five indoor classes (bathroom, bedroom, dining room, kitchen, and living room) from a Places dataset. We considered 11600 images per class and subsequently fine-tuned the networks. The simulation studies suggest that cleaning the disparate data produced much better results in all the examined CNN architectures. We report that VGG16 & VGG19 fine-tuned models with training on all layers produced the best validation accuracy, with 93.29% and 93.61% on clean data, respectively. We also propose and examine a combination model of CNN and a multi-binary classifier referred to as error correcting output code (ECOC) with the clean data. The highest validation accuracy of 15 binary classifiers reached up to 98.5%, where the average of all classifiers was 95.37%. CNN and CNN-ECOC, and an alternative form called CNN-ECOC Regression, were evaluated in real-time implementation on a NAO humanoid robot. The results show the superiority of the combination model of CNN and ECOC over the conventional CNN. The implications and the challenges of real-time experiments are also discussed in the paper.

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Article
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Project-Based Approach in a First-Year Engineering Course to Promote Project Management and Sustainability

Author: 
Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2018-05-31
Abstract: 

To safeguard the environment and satisfy the energy needs of the present, without compromising the ability of future generations to do the same, sustainable energy development is urgently needed. This complex task is riddled with social, political, scientific, technical, and environmental challenges. Education is essential if we are to meet the energy demands of the world in the most sustainable manner available to us. Langara College offers a first-year engineering course that is meant to introduce students to engineering design and case studies, in addition to providing a brief glance on the history, ethics, and the different disciplines of engineering (APSC 1010). Using a project-based learning approach that promotes teamwork and research, this course uses a variety of instructional methods including lectures, class discussions, and guest appearances by experts in their fields. Introductions to technical concepts, such as soldering, 3D printing, and microcontrollers, are also addressed in this course. This paper demonstrates how this, or similar courses, are optimized to raise awareness of the sustainability issues this planet is facing. Learning outcomes are evaluated using an anonymous student survey which demonstrates how the students’ project-management and presentation skills have improved.

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Article
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Sol-Gel Deposition and Characterization of 1 Vanadium Pentoxide Thin Films with High TCR

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2018-07-09
Abstract: 

Vanadium pentoxide thin films have been deposited on quartz substrates via sol-gel synthesis and dip coating. The process was developed to establish a reliable and inexpensive method to produce thin films with a high temperature coefficient of resistance (TCR)for sensing applications. Sol-gel precursor concentration and post-deposition annealing conditions were varied to address their effects on film composition, morphology, structure, resistivity, and TCR response. The resulting thin films were structurally characterized by thin film profilometry, x-ray diffraction, scanning electron microscopy, and Raman spectroscopy. Resistivity and TCR measurements were carried out to determine their efficacy as sensor materials. Both low and high concentration alkoxide sol-gel precursors led to films of pure -V2O5 composition but with characteristically different structural and electrical properties. Low concentration films showed a modest decrease in resistivity and TCR with increasing annealing temperature, consistent with the formation of increasing grain size and the coalescence of largely planar grains with common crystalline orientation. In contrast, films fabricated from higher alkoxide precursor concentration are characterized by a higher density of grains with a larger dispersion in orientation and better-developed grain boundaries, leading to a general increase in resistivity and TCR with annealing temperature. The TCR of the films lied in the range of -3%◦C−1 to -4%◦C−1, comparing favorably with films produced through conventional techniques such as DC magnetron sputtering, chemical vapor deposition, or pulsed laser deposition. Further, their TCR and resistivity characteristics can be controlled through sol gel precursor concentration and post-deposition annealing temperature, indicating that sol-gel deposited vanadium pentoxide films are promising candidates for infrared sensor applications.

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Article
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Tri-Mode Capacitive Proximity Detection Towards Improved Safety in Industrial Robotics

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2018-06-15
Abstract: 

This paper presents a multi-functional capacitive sensor that is developed to improve the worker safety during the industrial human-robot interactions. The sensor is to be mounted on the worker and used to maintain a safe distance between the workers and robots or automotive parts moved by the robots. The response of a capacitive proximity sensor is a function of the distance to an object as well as the dielectric/conductance and geometry properties of the object. This uncertainty can lead to a wrong distance estimation or possibly a missed detection. The presented approach alleviates this issue by implementing three sensing capabilities including distance measurement, motion tracking, and profile recognition in a single platform. The presented sensor employs a capacitive sensing element coupled to reprogrammable interface electronics. The sensing element features a matrix of electrodes that can be reconfigured to various arrangements at run-time by controlling the interface electronics to obtain a more detailed perception of the ambient environment. Quantitative regression models are built to seek out distances while an adaptive classification tool based on support vector machines is employed to recognize the surface profiles. The performance of the sensing modalities has been experimentally assessed. Experimental results are provided to demonstrate that the system is able to detect a metallic object at distances of up to 18 cm with high resolutions, track its motion, and provide an estimate for its shape.

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Article
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A Wideband, Low-noise Accelerometer Sonar Wave Detection

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2018-01
Abstract: 

This paper presents the development of a highperformance micromachined capacitive accelerometer for detection of sonar waves. The device is intended to replace existing hydrophones in towed array sonar systems, and thus, needs to meet stringent performance requirements on noise, bandwidth, and dynamic range, among others. The in-plane, single-axis accelerometer is designed based on a mode-tuning structural platform. A frame was used instead of a solid plate for the proof-mass of the device, allowing us to push undesired vibration modes beyond the operating bandwidth of the device while enabling us to employ a portion of the area for capacitive sensing elements. The designed accelerometer was fabricated on a silicon-on-insulator wafer with 100µm device layer with capacitive gaps of ~2.2µm. The sensitivity of the accelerometer is 4.0V/g with a noise spectral density of better than

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