Development of a Standalone Pedestrian Navigation System Utilizing Sensor Fusion Strategies

Pedestrian inertial navigation systems yield the foundational information required for many possible indoor navigation and positioning services and applications, but current systems have difficulty providing accurate locational information due to system instability. Through the implementation of a low-cost ultrasonic ranging device added to a foot-mounted inertial navigation system, the ability to detect surrounding obstacles, such as walls, is granted. Using these detected walls as a basis of correction, an intuitive algorithm that can be added to already established systems was developed that allows for the demonstrable reduction of final location errors. After a 160 m walk, final location errors were reduced from 8.9 m to 0.53 m, a reduction of 5.5% of the total distance walked. Furthermore, during a 400 m walk the peak error was reduced from 10.3 m to 1.43 m. With long term system accuracy and stability being largely dependent on the ability of gyroscopes to accurately estimate changes in yaw angle, the purposed system helps correct these inaccuracies, providing strong plausible implementation in obstacle rich environments such as those found indoors

Energy efficient control of electrostatically actuated MEMS

Plenty of Micro-electro-mechanical Systems (MEMS) devices are actuated using electrostatic forces, and specially, parallel-plate actuators are extensively used, due to the simplicity of their design. Nevertheless, parallel-plate actuators have some limitations due to the nonlinearity of the generated force. The dissertation analyzes the dynamics of the lumped electrostatically actuated nonlinear system, in order to obtain insight on its characteristics, define desired performance goals and implement a controller for energy efficient robustly stable actuation of MEMS resonators. In the first part of the dissertation, the modeling of the electromechanical lumped system is developed. From a complete distributed parameters model for MEMS devices which rely on electrostatic actuation, a concentrated parameters simplification is derived to be used for analysis and control design. Based on the model, energy analysis of the pull-in instability is performed. The classic approach is revisited to extend the results to models with a nonlinear springs. Analysis of the effect of dynamics is studied as an important factor for the stability of the system. From this study, the Resonant Pull-in Condition for parallel-plate electrostatically actuated MEMS resonators is defined and experimentally validated. Given the importance of the nonlinear dynamics and its richness in behaviors, Harmonic Balance is chosen as a tool to characterize the steady-state oscillation of the resonators. This characterization leads to the understanding of the key factors for large and stable oscillation of resonators. An important conclusion is reached, Harmonic Balance predicts that any oscillation amplitude is possible for any desired frequency if the appropriate voltage is applied to the resonator. And the energy consumption is dependent on this chosen oscillation frequency. Based on Harmonic Balance results, four main goals are defined for the control strategy: Stable oscillation with large amplitudes of motion; Robust oscillation independently of MEMS imperfections; Pure sinus-like oscillation for high-grade sensing; and Low energy consumption. The second part of the dissertation deals with the controller selection, design and verification. A survey of prior work on MEMS control confirms that existing control approaches cannot provide the desired performance. Consequently, a new three-stage controller is proposed to obtain the desired oscillation with the expected stability and energy efficiency. The controller has three different control loops. The first control loop includes a Robust controller designed using on µ-synthesis, to deal with MEMS resonators uncertainties. The second control loop includes an Internal-Model-Principle Resonant controller, to generate the desired control action to obtain the desired oscillation. And the third control loop handles the energy consumption minimization through an Extremum Seeking Controller, which selects the most efficient working frequency for the desired oscillation. The proposed controller is able to automatically generate the needed control voltage, as predicted by the Harmonic Balance analysis, to operate the parallel-plate electrostatically actuated MEMS resonator at the desired oscillation. Performance verification of stability, robustness, sinus-like oscillation and energy efficiency is carried out through simulation. Finally, the needed steps for a real implementation are analyzed. Independent two-sided actuation for full-range amplitude oscillation is introduced to overcome the limitations of one-sided actuation. And a modification of standard Electromechanical Amplitude Modulation is analyzed and validated for position feedback implementation. With these improvements, a MEMS resonator with the desired specifications for testing the proposed control is designed for fabrication. Based on this design, testing procedure is discussed as future work.Molts microsistemes (MEMS) són actuats amb forces electrostàtiques, i especialment, els actuadors electrostàtics de plaques paral.leles són molt usats, degut a la simplicitat del seu disseny. Tot i això, aquests actuadors tenen limitacions degut a la no-linealitat de les forces generades. La tesi analitza el sistema mecànic no-lineal actuat electrostàticament que forma el MEMS, per tal d'entendre'n les característiques, definir objectius de control de l'oscil.lació, i implementar un controlador robust, estable i eficient energèticament. A la primera part de la tesi es desenvolupa el modelat del sistema electromecànic complert. A partir de la formulació de paràmetres distribuïts aplicada a dispositius MEMS amb actuació electrostàtica, es deriva una formulació de paràmetres concentrats per a l'anàlisi i el disseny del control. Basat en aquest model, s'analitza energèticament la inestabilitat anomenada Pull-in, ampliant els resultats de l'enfocament clàssic al model amb motlles no-lineals. Dins de l'anàlisi, l'evolució dinàmica s'estudia per ser un factor important per a l'estabilitat. D'aquest estudi, la Resonant Pull-in Condition per a actuadors electrostàtics de plaques paral.leles es defineix i es valida experimentalment. Donada la importància de la dinàmica no-lineal del sistema i la seva riquesa de comportaments, s'utilitza Balanç d'Harmònics per tal de caracteritzar les oscil.lacions en estacionari. Aquesta caracterització permet entendre els factors claus per a obtenir oscil.lacions estables i d'amplitud elevada. El Balanç d'Harmònics dóna una conclusió important: qualsevol amplitud d'oscil.lació és possible per a qualsevol freqüència desitjada si s'aplica el voltatge adequat al ressonador. I el consum energètic associat a aquesta oscil.lació depèn de la freqüència triada. Llavors, basat en aquests resultats, quatre objectius es plantegen per a l'estratègia de control: oscil.lació estable amb amplituds elevades; robustesa de l'oscil.lació independentment de les imperfeccions dels MEMS; oscil.lació sinusoïdal sense harmònics per a aplicacions d'alta precisió; i baix consum energètic. La segona part de la tesi tracta la selecció, disseny i verificació dun controlador adequat per a aquests objectius. La revisió dels treballs existents en control de MEMS confirma que cap dels enfocaments actuals permet obtenir els objectius desitjats. En conseqüència, es proposa el disseny d'un nou controlador amb tres etapes per tal d'obtenir l'oscil.lació desitjada amb estabilitat i eficiència energètica. El controlador té tres llaços de control. Al primer llaç, un controlador robust dissenyat amb µ-síntesis gestiona les incertes es dels MEMS. El segon llaç inclou un controlador Ressonant, basat en el Principi del Model Intern, per a generar l'acció de control necessària per a obtenir l'oscil.lació desitjada. I el tercer llaç de control gestiona la minimització de l'energia consumida mitjançant un controlador basat en Extremum Seeking, el qual selecciona la freqüència de treball més eficient energèticament per a l'oscil.lació triada. El controlador proposat és capaç de generar automàticament el voltatge necessari, igual al previst pel Balanç d'Harmònics, per tal d'operar electrostàticament amb plaques paral.leles els ressonadors MEMS. Mitjançant simulació se'n verifica l'estabilitat, robustesa, inexistència d'harmònics i eficiència energètica de l'oscil.lació. Finalment, la implementació real és analitzada. En primer lloc, un nou esquema d'actuació per dos costats amb voltatges independents es proposa per aconseguir l'oscil.lació del ressonador en tot el rang d'amplituds. I en segon lloc, una modificació del sensat amb Modulació d'Amplitud Electromecànica s'utilitza per tancar el llaç de control de posició. Amb aquestes millores, un ressonador MEMS es dissenya per a ser fabricat i validar el control. Basat en aquest disseny, es proposa un procediment de test plantejat com a treball futur.Postprint (published version

DEVELOPMENT OF A SIMPLIFIED, MASS PRODUCIBLE HYBRIDIZED AMBIENT, LOW FREQUENCY, LOW INTENSITY VIBRATION ENERGY SCAVENGER (HALF-LIVES)

Scavenging energy from environmental sources is an active area of research to enable remote sensing and microsystems applications. Furthermore, as energy demands soar, there is a significant need to explore new sources and curb waste. Vibration energy scavenging is one environmental source for remote applications and a candidate for recouping energy wasted by mechanical sources that can be harnessed to monitor and optimize operation of critical infrastructure (e.g. Smart Grid). Current vibration scavengers are limited by volume and ancillary requirements for operation such as control circuitry overhead and battery sources. This dissertation, for the first time, reports a mass producible hybrid energy scavenger system that employs both piezoelectric and electrostatic transduction on a common MEMS device. The piezoelectric component provides an inherent feedback signal and pre-charge source that enables electrostatic scavenging operation while the electrostatic device provides the proof mass that enables low frequency operation. The piezoelectric beam forms the spring of the resonant mass-spring transducer for converting vibration excitation into an AC electrical output. A serially poled, composite shim, piezoelectric bimorph produces the highest output rectified voltage of over 3.3V and power output of 145uW using ¼ g vibration acceleration at 120Hz. Considering solely the volume of the piezoelectric beam and tungsten proof mass, the volume is 0.054cm3, resulting in a power density of 2.68mW/cm3. Incorporation of a simple parallel plate structure that provides the proof mass for low frequency resonant operation in addition to cogeneration via electrostatic energy scavenging provides a 19.82 to 35.29 percent increase in voltage beyond the piezoelectric generated DC rails. This corresponds to approximately 2.1nW additional power from the electrostatic scavenger component and demonstrates the first instance of hybrid energy scavenging using both piezoelectric and synchronous electrostatic transduction. Furthermore, it provides a complete system architecture and development platform for additional enhancements that will enable in excess of 100uW additional power from the electrostatic scavenger

A Real-Time Positioning System of Manufacturing Carriers Deploying Wireless MEMS Accelerometers and Gyroscopes

Modern manufacturing systems face ever-increasing pressure to maximize efficiency of production processes, minimize downtime due to unexpected deviations from normal operation, and maintain agility in dynamic market conditions. Detailed, real-time asset tracking is essential for achieving these goals. Pallets are widely-used for transporting raw materials, intermediate products, and final products in automated assembly and manufacturing lines. A sophisticated pallet monitoring system can provide possibilities for optimizing pallet routing in real time, enable dynamic scheduling changes, and historical traceability required for error diagnosis and repair. Traditionally, pallets are monitored by networks of sensors, such as RFID readers or proximity sensors to collect location data. These sensor networks are rarely dense enough to provide precise continuous data about pallet location. Real-time pallet tracking data is thus limited to recording timestamps at static checkpoints. This thesis presents an asset-aware management tool for continuous pallet location monitoring based on event logs obtained from intelligent wireless devices embedded in each pallet. Each wireless device, equipped with a 3-axis accelerometer and a 3-axis gyroscope, provides accurate information about pallet movement. The raw sensor data is pre-processed into an event stream, which is sent to a server over a 6LoWPAN network. The software developed in this research implements an algorithm for processing event logs to determine exact pallet location using artificial intelligence techniques. Calculated pallet position can be provided to high-level enterprise systems, and to manufacturing execution systems for use in scheduling, routing, and visualization of the production line. Designing the SCADA system was also part of this thesis. The solution was successfully deployed in the FASTory, a 12-cell light assembly line in the Factory Automation Systems and Technologies Laboratory (FAST-lab.) at Tampere University of Technology, as part of eSONIA, a European Commission-cofunded research project on using service-enabled embedded devices for realizing an asset-aware, self-recovering plant. The proposed solution demonstrates a novel approach for continuous, real-time pallet location tracking based on wireless sensors

Multimodal Wearable Sensors for Human-Machine Interfaces

Certain areas of the body, such as the hands, eyes and organs of speech production, provide high-bandwidth information channels from the conscious mind to the outside world. The objective of this research was to develop an innovative wearable sensor device that records signals from these areas more conveniently than has previously been possible, so that they can be harnessed for communication. A novel bioelectrical and biomechanical sensing device, the wearable endogenous biosignal sensor (WEBS), was developed and tested in various communication and clinical measurement applications. One ground-breaking feature of the WEBS system is that it digitises biopotentials almost at the point of measurement. Its electrode connects directly to a high-resolution analog-to-digital converter. A second major advance is that, unlike previous active biopotential electrodes, the WEBS electrode connects to a shared data bus, allowing a large or small number of them to work together with relatively few physical interconnections. Another unique feature is its ability to switch dynamically between recording and signal source modes. An accelerometer within the device captures real-time information about its physical movement, not only facilitating the measurement of biomechanical signals of interest, but also allowing motion artefacts in the bioelectrical signal to be detected. Each of these innovative features has potentially far-reaching implications in biopotential measurement, both in clinical recording and in other applications. Weighing under 0.45 g and being remarkably low-cost, the WEBS is ideally suited for integration into disposable electrodes. Several such devices can be combined to form an inexpensive digital body sensor network, with shorter set-up time than conventional equipment, more flexible topology, and fewer physical interconnections. One phase of this study evaluated areas of the body as communication channels. The throat was selected for detailed study since it yields a range of voluntarily controllable signals, including laryngeal vibrations and gross movements associated with vocal tract articulation. A WEBS device recorded these signals and several novel methods of human-to-machine communication were demonstrated. To evaluate the performance of the WEBS system, recordings were validated against a high-end biopotential recording system for a number of biopotential signal types. To demonstrate an application for use by a clinician, the WEBS system was used to record 12‑lead electrocardiogram with augmented mechanical movement information

Reconfigurable split ring resonators using pneumatics

During the past decades, the rapid development of communication systems has extended to every aspect of modern technology. To better satisfy the need of people to interact with the world, investigations into the critical communication components mostly within the Radio-Frequency (RF) range have faced a diverse range of operational requirements and environment. The development of reconfigurable devices conforms to these demands with broader applicability. The resonant circuit, consisting of an inductance and capacitance, is fundamental to the design of passive resonant devices. The adjustment of their inherent inductance or capacitance provides a pathway for frequency reconfiguration. The split ring resonator (SRR) is first introduced to generate negative permeability in artificial materials. The physical geometry of a SRR features a gap in a broken conductive ring, and is characterised as a compact sized resonant circuit due to the effective capacitance and inductance occurring on the gap and ring respectively. The integration of SRRs to RF devices has been widely explored, not just to enhance the performance but also enable reconfiguration in some resonant devices. The concept of tuning the intrinsic capacitance or inductance of the SRR has been realised by the addition of active devices such as diodes and MEMS switches. However, interference to the electromagnetic properties due to the additional components and their bias line networks, and tolerance control on the placement of the controlling element is a serious concern. If tuning is required in array structures such as metamaterials, component count, and bias issues are significantly elevated. The aim of this research is to investigate and conceive pneumatic levitation systems as a mean of changing the structural arrangement of SRRs to reconfigure their resonant frequency or other parameters. Rotation, elevation and lateral movement of the SRRs are realised by implementing pneumatic levitation, and the resulting changes in the transmission response are characterised. The resonant frequency of a SRR is dependent on the orientation of the incident electromagnetic waves. Pneumatic levitation is firstly proposed to allow free rotation of a SRR in the azimuthal plane resulting in continuous resonant frequency variations. The inclusion of another identical SRR located below the spinning SRR forms a broad-side coupled architecture. Depending on whether the static SRR is placed parallel or perpendicular to the electric field, the coupled SRRs can achieve 10% (2.66GHz to 2.39 GHz) or 12% (2.67 GHz to 2.38 GHz) continuous frequency sweep respectively. The levitation platform which holds the SRR is demonstrated to provide different spinning speed profiles and hence frequency sweep rates for the SRR response based on various platform designs. An advanced pneumatic levitation system is devised to allow discrete on-demand resonant frequency control of broad-side coupled SRRs utilizing the rotation angle and separation of SRRs. The pneumatic structure stops the upper SRR at desired locations to achieve an associated resonant frequency response. The coupled SRRs can realise a 35% tunable frequency range (3.236 GHz to 2.11 GHz) over 180 degrees of rotation. The separation of SRRs, driven by the applied pneumatic pressure, demonstrates a tunable frequency range from 0.7% to 11.3% depending on the set rotation angle. The horizontal arrangement of SRRs introduces another dimension for structure tuning based on the lateral space between two resonators. A pneumatic levitation system which enables the manipulation of the horizontal placement of a SRR leads to a smooth conversion between edge coupled and broad-side coupled SRRs. The transition affects the mutual capacitance of the structure resulting in changes to the transmission response. A 28% frequency reduction from 3.2 GHz results during the transition from edge coupled to broad-side coupled mode if two gaps of the SRRs are initially facing each other. When the gaps are facing outwards at the start, a second resonant frequency appears in the examined band and mirrors the shift of the first resonance in the opposite direction, increasing from 3.2 GHz. The investigation of the lateral control of a SRR using pneumatic levitation is further explored with the integration of an SRR with a CPW and monopole antenna for proof of concept reconfigurable RF device functionality. The integration of pneumatic systems as an approach to tune the structure of SRRs exhibits tremendous potential for the physical modification of coupled SRRs, and possibly also any small resonant devices or components. Both simulation and experiments has demonstrated the possibilities to manipulate frequency shift between 2.1 GHz to 3.24 GHz. Furthermore its key advantages are its non-metallic structure which has minimal impact on the resonant properties and incident field, the near frictionless operation, and the control over the degrees of freedom of structural variation

Designing virtual spaces: redefining radio art through digital control

Radio Art is a composition practice that is constantly evolving. Artists share a commonality to redefine, reinvent, and repurpose analogue radio. It is an art that often bends to the will of antiqued technology, celebrating a wide pallet of found sounds. This research extends the boundaries of the art form by exploring Radio Art through sonic-centric lens and establishing a consistent and reproducible compositional framework. By shifting radio from a found object to an instrument, I have deconstructed its sonic aesthetics into two parallel materials for composition, gestural noise and broadcast signal. When tuning an analogue radio to a signal, relationships between these materials unfold. Contrast is a term found throughout my research. Contrast is embodied throughout radio and its history; radio is used as both a scientific communication device and for artistic expression. it is a symbol of democracy and oppression. Radio produces broadcast noise and signal, creating poetic reception, such as control and chaos, anxiety and ecstasy, distance and closeness. This research explores the characteristics of these forces and materials as a symbiotic relationship of unfolding radiophonic behaviours. A major focus of this research is the control of analogue radio through deconstruction and composition. I embarked on a twenty-four-month development period to build a Digital Audio Workstation called Radiophonic Environmental Designer, (RED). RED enables composers to create virtual radiophonic environments that are navigated by rotating the dial. Material is positioned along a horizon, and tuning behaviours sculpted. There is also a physical interface embedded into an analogue radio shell to control the virtual tuning, namely, Broadcast Link-up Environment, (BLUE). BLUE is an ad-on program offering an online digital platform for the diffusion of Radio Art. Using an internet connection and gyroscope technology that is built into most smart phones, a radiophonic environment is interacted through a purpose-built website. In my creative practice, analogue radio has been redesigned by adopting digital technological practices to control, edit and model it’s unique sound. In doing so, I reflect upon relationships between analogue and digital design principles through an extensive study on virtual analogue software and interfaces