The restoration of arm-free standing in paraplegic individuals can be accomplished with the help of functional electrical stimulation (FES). The key component of such a system is a controller that can modulate FES induced muscle contractions in real-time, such that artificially produced forces in the legs and abdominal muscles are able to generate stable standing posture. A 57 year-old individual with chronic ASIA-A (American Spinal Injury Association), T3/4 level spinal cord injury (SCI) participated in this study. The objective was to determine if a proportional-derivative (PD) or proportional-integral-derivative (PID) controller could be used to regulate FES induced muscle contractions in the ankle joint to allow it to maintain balance of the entire body during quiet standing, while exhibiting physiological dynamics seen in able-bodied individuals while doing so.

The actualization of real-time economically optimal process operation requires proper integration of real-time optimization (RTO) and dynamic control. This dissertation addresses the integration problem and provides a formal design technique that properly integrates RTO and model predictive control (MPC) under parametric uncertainties. The task is posed as an adaptive extremum-seeking control (ESC) problem in which the controller is required to steer the system to an unknown setpoint that optimizes a user-specified objective function. The integration task is first solved for linear uncertain systems. Then a method of determining appropriate excitation conditions for nonlinear systems with uncertain reference setpoint is provided. Since the identification of the true cost surface is paramount to the success of the integration scheme, novel parameter estimation techniques with better convergence properties are developed. The estimation routine allows exact reconstruction of the system's unknown parameters in finite-time. The applicability of the identifier to improve upon the performance of existing adaptive controllers is demonstrated. Adaptive nonlinear model predictive controllers are developed for a class of constrained uncertain nonlinear systems. Rather than relying on the inherent robustness of nominal MPC, robustness features are incorporated in the MPC framework to account for the effect of the model uncertainty. The numerical complexity and/or the conservatism of the resulting adaptive controller reduces as more information becomes available and a better uncertainty description is obtained. Finally, the finite-time identification procedure and the adaptive MPC are combined to achieve the integration task. The proposed design solves the economic optimization and control problem at the same frequency. This eliminates the ensuing interval of "no-feedback" that occurs between economic optimization interval, thereby improving disturbance attenuation. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2008-08-08 12:30:47.969

We consider two transceivers equipped with multiple antennas that intend to communicate i.e. both of which transmit and receive data in a TDD fashion. Assuming that the responses of the physical communication channels between these two nodes are linear and reciprocal (time invariant or with very slow time variations), and by exploiting the closed loop conversation between these nodes, we have proposed efficient algorithms allowing to adaptively identify the Best Singular Mode (BSM) of the channel (those algorithms are for training, blind, and semi-blind channel identification). Unlike other proposed algorithms, our proposed adaptive algorithms are robust to noise as the involved step-size allows a trade-off to reduce the impact of the additive noise at the expense of some estimation delay. In practice, however, the reciprocity of the equivalent channels is lost because of the mismatch between the transmit and the receive filters of the communicating nodes. This mismatch causes significant degradation in the performance of the BSM estimation. Therefore, we have also proposed adaptive self-calibrating algorithms (which do not require any additional RF circuitry) that account for such a mismatch. In addition, we have conducted a convergence analysis of the BSM algorithm and extended it to estimate multiple modes simultaneously. Finally, we have also proposed an adaptive, iterative algorithm that is capable of allocating power in such a way that maximizes the capacity of a SISO OFDM communication system. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2010-07-21 16:53:33.077

<p>Deep brain stimulation (DBS) is an established surgical therapy for movement disorders. The mechanisms of action of DBS remain unclear, and selection of stimulation parameters is a clinical challenge and can result in sub-optimal outcomes. Closed-loop DBS systems would use a feedback control signal for automatic adjustment of DBS parameters and improved therapeutic effectiveness. We hypothesized that evoked compound action potentials (ECAPs), generated by activated neurons in the vicinity of the stimulating electrode, would reveal the type and spatial extent of neural activation, as well as provide signatures of clinical effectiveness. The objective of this dissertation was to record and characterize the ECAP during DBS to determine its suitability as a feedback signal in closed-loop systems. The ECAP was investigated using computer simulation and <italic>in vivo</italic> experiments, including the first preclinical and clinical ECAP recordings made from the same DBS electrode implanted for stimulation. </p><p>First, we developed DBS-ECAP recording instrumentation to reduce the stimulus artifact and enable high fidelity measurements of the ECAP at short latency. <italic>In vitro</italic> and <italic>in vivo</italic> validation experiments demonstrated the capability of the instrumentation to suppress the stimulus artifact, increase amplifier gain, and reduce distortion of short latency ECAP signals.</p><p>Second, we characterized ECAPs measured during thalamic DBS across stimulation parameters in anesthetized cats, and determined the neural origin of the ECAP using pharmacological interventions and a computer-based biophysical model of a thalamic network. This model simulated the ECAP response generated by a population of thalamic neurons, calculated ECAPs similar to experimental recordings, and indicated the relative contribution from different types of neural elements to the composite ECAP. Signal energy of the ECAP increased with DBS amplitude or pulse width, reflecting an increased extent of activation. Shorter latency, primary ECAP phases were generated by direct excitation of neural elements, whereas longer latency, secondary phases were generated by post-synaptic activation.</p><p>Third, intraoperative studies were conducted in human subjects with thalamic DBS for tremor, and the ECAP and tremor responses were measured across stimulation parameters. ECAP recording was technically challenging due to the presence of a wide range of stimulus artifact magnitudes across subjects, and an electrical circuit equivalent model and finite element method model both suggested that glial encapsulation around the DBS electrode increased the artifact size. Nevertheless, high fidelity ECAPs were recorded from acutely and chronically implanted DBS electrodes, and the energy of ECAP phases was correlated with changes in tremor. </p><p>Fourth, we used a computational model to understand how electrode design parameters influenced neural recording. Reducing the diameter or length of recording contacts increased the magnitude of single-unit responses, led to greater spatial sensitivity, and changed the relative contribution from local cells or passing axons. The effect of diameter or contact length varied across phases of population ECAPs, but ECAP signal energy increased with greater contact spacing, due to changes in the spatial sensitivity of the contacts. In addition, the signal increased with glial encapsulation in the peri-electrode space, decreased with local edema, and was unaffected by the physical presence of the highly conductive recording contacts.</p><p>It is feasible to record ECAP signals during DBS, and the correlation between ECAP characteristics and tremor suggests that this signal could be used in closed-loop DBS. This was demonstrated by implementation in simulation of a closed-loop system, in which a proportional-integral-derivative (PID) controller automatically adjusted DBS parameters to obtain a target ECAP energy value, and modified parameters in response to disturbances. The ECAP also provided insight into neural activation during DBS, with the dominant contribution to clinical ECAPs derived from excited cerebellothalamic fibers, suggesting that activation of these fibers is critical for DBS therapy.</p> / Dissertation

This dissertation presents the system architecture and implementation of two wireless systems-on-chip (SoCs) for diagnostics and treatment of neurological disorders. It also validates the SoCs as an electronic implant for preoperative monitoring and treatment of intractable epilepsy. The first prototype SoC is a neural recording interface intended for wireless monitoring of intractable epilepsy. The 0.13um CMOS SoC has 64 recording channels, 64 programmable FIR filters and an integrated 915MHz FSK PLL-based wireless transmitter. Each channel contains a low-noise amplifier and a modified 8-bit SAR ADC that and can provide analog-digital multiplication by modifying the ADC sampling phase. It is used in conjunction with 12-bit digital adders and registers to implement 64 16-tap FIR filters with a minimal area and power overhead. In vivo measurement results from freely moving rodents demonstrate its utility in preoperative monitoring epileptic seizures. Treatment of intractable epilepsy by responsive neurostimulation requires seizure detection capabilities. Next, a low-power VLSI processor architecture for early seizure detection is described. It the magnitude, phase and phase synchronization of two neural signals - all precursors of a seizure. The processor is utilized in an implantable responsive neural stimulator application. The architecture uses three CORDIC processing cores that require shift-and-add operations but no multiplication. The efficacy of the processor in epileptic seizure detection is validated on human EEG data and yields comparable performance to software-based algorithms. The second prototype SoC is a closed-loop 64-channel neural stimulator that includes the aforementioned seizure detector processor and is used for preventive seizure abortion. It constitutes a neural vector analyzer that monitors the magnitude, phase and phase synchronization of neural signals to enable seizure detection. In a closed loop, abnormal phase synchrony triggers the programmable-waveform biphasic neural stimulator. To implement these functionalities, the 0.13um CMOS SoC integrates 64 amplifiers with switched-capacitor (SC) bandpass filters, 64 MADCs, 64 16-tap FIR filters, a processor, 64 biphasic stimulators and a wireless transmitter. The SoC is validated in the detection and abortion of seizures in freely moving rodents on-line and in early seizure detection in humans off-line. The results demonstrate its utility in treatment of intractable epilepsy.

This dissertation presents the system architecture and implementation of two wireless systems-on-chip (SoCs) for diagnostics and treatment of neurological disorders. It also validates the SoCs as an electronic implant for preoperative monitoring and treatment of intractable epilepsy. The first prototype SoC is a neural recording interface intended for wireless monitoring of intractable epilepsy. The 0.13um CMOS SoC has 64 recording channels, 64 programmable FIR filters and an integrated 915MHz FSK PLL-based wireless transmitter. Each channel contains a low-noise amplifier and a modified 8-bit SAR ADC that and can provide analog-digital multiplication by modifying the ADC sampling phase. It is used in conjunction with 12-bit digital adders and registers to implement 64 16-tap FIR filters with a minimal area and power overhead. In vivo measurement results from freely moving rodents demonstrate its utility in preoperative monitoring epileptic seizures. Treatment of intractable epilepsy by responsive neurostimulation requires seizure detection capabilities. Next, a low-power VLSI processor architecture for early seizure detection is described. It the magnitude, phase and phase synchronization of two neural signals - all precursors of a seizure. The processor is utilized in an implantable responsive neural stimulator application. The architecture uses three CORDIC processing cores that require shift-and-add operations but no multiplication. The efficacy of the processor in epileptic seizure detection is validated on human EEG data and yields comparable performance to software-based algorithms. The second prototype SoC is a closed-loop 64-channel neural stimulator that includes the aforementioned seizure detector processor and is used for preventive seizure abortion. It constitutes a neural vector analyzer that monitors the magnitude, phase and phase synchronization of neural signals to enable seizure detection. In a closed loop, abnormal phase synchrony triggers the programmable-waveform biphasic neural stimulator. To implement these functionalities, the 0.13um CMOS SoC integrates 64 amplifiers with switched-capacitor (SC) bandpass filters, 64 MADCs, 64 16-tap FIR filters, a processor, 64 biphasic stimulators and a wireless transmitter. The SoC is validated in the detection and abortion of seizures in freely moving rodents on-line and in early seizure detection in humans off-line. The results demonstrate its utility in treatment of intractable epilepsy.

The restoration of arm-free standing in paraplegic individuals can be accomplished with the help of functional electrical stimulation (FES). The key component of such a system is a controller that can modulate FES induced muscle contractions in real-time, such that artificially produced forces in the legs and abdominal muscles are able to generate stable standing posture. A 57 year-old individual with chronic ASIA-A (American Spinal Injury Association), T3/4 level spinal cord injury (SCI) participated in this study. The objective was to determine if a proportional-derivative (PD) or proportional-integral-derivative (PID) controller could be used to regulate FES induced muscle contractions in the ankle joint to allow it to maintain balance of the entire body during quiet standing, while exhibiting physiological dynamics seen in able-bodied individuals while doing so.

Finding non-linearity is a common application of modal testing but in this way, there is a need to control the input signal. Nowadays, commercial data acquisition software is not enough flexible in controlling the applied signals, whereas MATLAB as general software which supports National Instrument makes it possible to run modal test and control input signal via closed-loop controlling. In this work, using MATLAB commands, a modal test is run with a stepped-sine excitation and the input is controlled to achieve desired pure sinusoidal excitation which commonly is used in finding the non-linearity.

In this thesis a quadrotor is studied and a linear model is derived using grey-box estimation, a discipline in system identification where a model structure based on physical relations is used and the parameters are estimated using input-output measurements. From IMU measurements and measured PWM signals to the four motors, a direct approach using the prediction-error method is applied. To investigate the impact of the unknown controller the two-stage method, a closed-loop approach in system identification,  is applied as well. The direct approach was enough for estimating the model parameters. The resulting model manages to simulate the major dynamics for the vertical acceleration and the angular rates well enough  for future control design.

Bakgrund På grund av den enorma konsumtion av textilier och kläder som sker i vissa delar av världen krävs ett förändrat förhållningssätt till hur de textilier och kläder som köps hanteras både under och efter användande. En stor påverkan har även de företag som designar, tillverkar och säljer produkterna. För att minska användandet av ändliga resurser krävs en strategi som förändrar dagens linjära flöden till ett slutet kretslopp där resurser används på nytt, om och om igen, en så kallad Closed-loop supply chain. Studiens syfte är att undersöka hur fyra svenska detaljhandelsföretag inom modebranschen arbetar med just Closed-loop supply chain och dess möjligheter och utmaningar med konceptet. Syftet är även att se hur företagen arbetar med återvinning och hållbarhet som är relevanta delar i ett fungerande cirkulärt flöde. Genomförande Den teoretiska referensramen beskriver konceptet Closed-loop supply chain och de delar som innefattas, framåtriktad och omvänd försörjningskedja. Den tar även upp sju processteg som måste hanteras för att skapa en Closed-loop supply chain för kläder och textilier. För att undersöka hur de fyra svenska detaljhandelsföretagen inom modebranschen arbetar för att uppnå ett cirkulärt flöde har en grundlig genomgång av respektive företags hållbarhetsrapporter gjorts. I empiriavsnittet presenteras förutom de fyra svenska detaljhandelsföretagen även ett antal organisationer som på något vis arbetar för att möjliggöra ett cirkulärt flöde inom textil- och modebranschen. För att få en bild av konsumenternas kännedom och attityd till återvinningsmöjligheter genomfördes även en enkätundersökning. Resultat För att skapa rätt förutsättningar för att skapa en Closed-loop supply chain krävs det att både den framåtriktade och den omvända försörjningskedjan är anpassad till det. Den framåtriktade försörjningskedjan kräver att klädesplaggen är designade för att enkelt kunna återvinnas och att de av konsumenten är hanterade på ett så hållbart sätt som möjligt. Den omvända försörjningskedjan kräver först och främst att kläderna samlas in. Vidare krävs att de insamlade kläderna sedan skickas vidare för sortering och därefter ta ett beslut om ett lämpligt återanvändningsalternativ. Slutligen omdistribueras produkten för att antingen återföras in i något processteg i den framåtriktade försörjningskedjan eller säljas på en andrahandsmarknad. Av den information som framkommit ur hållbarhetsrapporter och övrig informationsinsamling har det kunnat konstaterats att detaljhandelsföretagen har en lång väg att gå till dess att en Closed-loop supply chain fungerar till 100 %. / Background Due to the enormous consumption of textiles and clothing that takes place in some parts of the world, a changed approach is needed to handle the textiles and clothing that are purchased both during and after use. The companies that design, manufacture and sell the products also have a big impact. In order to reduce the use of finite resources, a strategy that changes today's linear flows into a closed cycle, where resources are recycled, a so-called Closed-loop supply chain, is required. The purpose of the study is to investigate how four Swedish retailers in the fashion industry work with Closed-loop supply chain and the possibilities and challenges with the concept. The purpose is also to find out how companies work with recycling and sustainability that are relevant parts of a functioning circular flow Implementation The theoretical reference framework describes the Closed-loop supply chain concept and the components that are included; forward and reverse supply chain. It also takes up seven process steps that must be handled to create a Closed-loop supply chain for clothes and textiles.To investigate how the four Swedish retail companies in the fashion industry work to achieve a circular flow, a profound review of the respective company's sustainability reports has been made. In the empirical section, apart from the four Swedish retail companies, there are also a number of organizations that in one way or another work to allow circular flow in the textile and fashion industry. In order to get a reflection of consumers' awareness and attitude towards recycling opportunities, a survey was also conducted. Results In order to create the right conditions for a Closed-loop supply chain, it is necessary to adapt both the forward and the reverse supply chain. The forward supply chain requires that the garments are designed to be easily recycled and that they are handled by the consumer in a sustainable way. The reverse supply chain primarily requires that the clothes are collected. Furthermore, the collected clothes are forwarded for sorting and then a decision of the garments reuse options has to be taken. Finally, the product is redistributed either back into any process in the forward supply chain or sold in a secondary market. From the information obtained from the sustainability reports and other information gathering, it has been found that retail companies have a long way to go until a Closed-loop supply chain operates to 100%.