Other than mobile hydraulics and high voltage switchgears, Bucher Hydraulics is also involved in the less-known area of hydraulic lifts. In fact, Bucher Hydraulics did invent the electronically controlled lift valve in the 1970s. Since then, Bucher Hydraulics developed a wide line of products for hydraulic elevators, such as valves and power units. In 2012, this valve family included various sizes, pressure ranges, systems with constant motor speeds, inverter-driven motors, energy-efficient solutions with hydraulic counterweight, as well as customized solutions. As the common principle, all these solutions apply an electronic closed-loop control that uses a volumetric flow sensor and a proportional actuator. Since 2012, Bucher Hydraulics is substituting this valve family with a new generation, the iValve. Every iValve uses several self-teaching algorithms to adapt to its environment. Their on-board and cabinet electronics control solenoid currents and measure flow, pressure, and temperature. These features enable the iValve to self-monitor, to adapt to operating parameters, and to analyze and log information about itself and the attached system. This report on a highly specialized product is meant to provide inspiring insights.

Hypersonic inlet unstart remains a major technical obstacle in the successful implementation of hypersonic air-breathing propulsion systems such as ramjets and scramjets. Unstart occurs when combustor-induced pressure fluctuations lead to rapid expulsion of the shock system from the isolator, and is associated with loss of thrust. The research presented here attempts to mitigate this behavior through the design and implementation of a closed-loop control scheme that regulates shock location within a Mach 1.8 wind tunnel isolator test section. To localize the position of the shock within the isolator, a set of high frequency Kulite pressure transducers are used to measure the static pressure at various points along the wind tunnel test section. A novel Kalman filter based approach is utilized, which fuses the estimates from two distinct shock localization algorithms running at 250 Hz to determine the location of the shock in real time. The primary shock localization algorithm is a geometrical shock detection scheme that can estimate the position of the shock system even when it is located between pressure transducers. The second algorithm utilizes a sum-of-pressures technique that can be calibrated by the geometrical algorithm in real time. The closed-loop controller generates commands every 100 ms to actuate a motorized flap downstream of the test section in an effort to regulate the shock to the desired location. The closed-loop control implementation utilized a simple logic-based controller as well as a Proportional-Integral (PI) and a Proportional-Derivative (PD) Controller. In addition to the implementation of control algorithms, the importance of various design criteria necessary to achieve satisfactory control performance is explored including parameters such as pressure transducer spacing, shock localization speed, flap-motor actuation speed and actuator resolution. Experimental results are presented for various test scenarios such as regulation of the shock location in the presence of stagnation pressure disturbances as well as tracking of time-varying step inputs. Performance and robustness properties of the tested control implementations are discussed. Further areas of improvement for the closed-loop control system in both hardware and software are discussed, and the need for reduced-order dynamics-based controllers is presented. / text

Analytical solutions to complex trajectory design problems are scarce, since only a few specific cases allow for closed-form solutions. The main purpose of this dissertation is to design simple algorithms for trajectory design using continuous thrust, with a focus on low-thrust applications. By “simple” here we seek to achieve algorithms that either admit an analytical solution, or require minimal input by the user and minimal computation time. The three main contributions of this dissertation are: designing Lyapunov-based closed-loop guidance laws for orbit transfers, finding semi-analytical solutions using a constant magnitude thrust, and perturbation theory for approximate solutions to low-thrust problems. The technical aspect that these problems share in common is that they all use, fully or partially, a thrusting model in which the energy of the system is kept constant. Many orbit transfer problems are shown to be solved with this thrusting protocol. / text

This thesis contributes to the general body of knowledge of research into engineering education. The main scope of the thesis is on enhancing laboratory education. There are three main types of laboratory: virtual, hands-on and remote. The hands-on lab is the oldest and most commonly used medium for experiential education in undergraduate degrees of science and engineering. The literature review of laboratory education has shown that hands-on labs suffer from many disadvantages, which can be overcome by utilizing hybrid laboratory structures that incorporate virtual and/or remote modes. The investigation into enhanced laboratory education is achieved via implementing new technical and pedagogical models of conducting laboratories. The technical model incorporates three access modes (virtual, hands-on and remote) to the laboratory experience in one software package called the TriLab. The TriLab concept has been applied to the Process Control Lab at the Chemical Engineering Department of Loughborough University and has been implemented using LabVIEW. The Joomla web content management system was used to develop an online portal for disseminating the remote component of the TriLab resulting in the first remote lab portal of Loughborough University and one of the few available in the UK. A pedagogical model of laboratory education based on Kolb's experiential learning theory and by the utilization of the TriLab concept is proposed. The model is built on a hypothesis, which states that the poor learning outcomes of hands-on laboratory sessions can be associated with poor activation of the stages of Kolb's experiential learning cycle. It has been proposed that access to a virtual lab in a preparatory session will play a role in activating the stages of Kolb's cycle. To verify this, educational experimentation procedures were designed and applied to two groups, control and experimental. Measurements via pre- and post-lab tests, marks for the laboratory report and the final exam of the module have been performed. The statistical analysis of the measurements has supported the stated hypothesis and solution proposal. The proposed pedagogical model is one of the few that provide a way of conducting laboratory education based on constructivist educational theories. (Continues...).

FPGA stands for Field Programmable Gate Array and it is a technology that has been on the rise the last decades. With a decrease in size of the logic elements commercially available products have started to have more built-in functionality in one package and by being reprogrammable makes the system a powerful competitor among its neighbors. FPGA technology in comparison with Digital Signal Processing technology is generally interesting because of the parallelism of the programming that can be made. This allows for more operations in less time. In this thesis a system is developed to control power converters with control signals in high frequency. A previous project is used as a base and a toolchain of new components are implemented to create a new, more generic system. The previous system is evaluated and a new protocol for communication is developed. The toolchain with the necessary control blocks is implemented in Quartus II that includes a timer block, a pulse width modulation block, a PID controller block and a FIR-filter block. The system is used to control a power converter and the result is evaluated.

Stochastic system identification is of great interest in the areas of control and communication. In stochastic system identification, a model of a dynamic system is determined based on given inputs and received outputs from the system, where stochastic uncertainties are also involved. The scope of the report is to consider continuous-time models used within control and communication and to estimate the model parameters from sampled data with high accuracy in a computational efficient way. Continuous-time models of systems controlled in a networked environment, stochastic closed-loop systems, and wireless channels are considered. The parameters of a transfer function based model for the process in a networked control system are first estimated by a covariance function based approach, relying upon the second order statistical properties of the output signal. Some other approaches for estimating the parameters of continuous-time models for processes in networked environments are also considered. Further, the parameters of continuous-time autoregressive exogenous models are estimated from closed-loop filtered data, where the controllers in the closed-loop are of proportional and proportional integral type, and where the closed-loop also contains a time-delay. Moreover, a stochastic differential equation is derived for Jakes's wireless channel model, describing the dynamics of a scattered electric field with the moving receiver incorporating a Doppler shift. / <p>Article I was still in manuscript form at the time of the defense.</p>

This project investigates how remanufacturing of robotic lawn mowers can be incorporated into an existent forward supply chain. The project is conducted as a single case study on Husqvarna where an interview study and a literature study provide the empirical data and theory, respectively. Alternatives are proposed for potential remanufacturing cases at various locations, where different parties ranging from original equipment manufacturers to independent manufacturers perform the remanufacturing process. SWOT analyses are conducted to identify the most promising alternatives for a further economic analysis. The economic evaluation is based on net present values and a sensitivity analysis which together determines the feasibility of the alternatives. The results of the project answer three research questions. The first concludes that out of seven defined production systems there are only two that are not suitable for remanufacturing in a general case mainly due to the low flexibility of these systems. The results of the second identifies labor, logistics, and operational prerequisite factors that must be considered when implementing remanufacturing for case specific alternatives. The conclusion of the third research question lists the feasibility of the alternatives from which the recommendations for Husqvarna are presented. This project recommends Husqvarna to implement a remanufacturing process for their robotic lawn mowers either by enlisting their current dealers or by themselves at a location nearby the spare parts warehouse in Torsvik. Which alternative is the most profitable depends mainly on the expected quantity of the acquired cores, i.e. Husqvarna as a centralized remanufacturer benefits more from higher quantities while the decentralized dealer alternative would comparably be more profitable if the quantities were lower. As it is perceived that initial collected quantities will be low, and possibly even somewhat higher for the dealers, a decentralized remanufacturing process could be the most profitable alternative to start with. Using a third-party remanufacturer is also feasible but considered risky and therefore not recommended as they could have the same core acquisition problem as Husqvarna while having lower profitability.

<p>Glaucoma is the leading cause of irreversible blindness worldwide effecting more than 2.7 million people in the U.S alone. Treatments exist in the form of both pharmaceutical and surgical options, but often do not provide the desired efficacy. For example, the failure rate of a trabeculectomy procedure is 39% within 5 years. Additionally, none of the current glaucoma treatments allow for closed loop monitoring of pressure, therefore requiring more frequent doctor visits. Glaucoma management can be improved through the use of a closed loop application of electroceutical treatment. The goal is to develop an implantable device that will be inserted into the eye to monitor intraocular pressure (IOP) and provide responsive therapeutic stimulation to the eye. I designed a discrete pressure monitoring system that interacts with a bare die piezoresistive pressure sensor. The system is based on a Wheatstone bridge design which translates the input resistances of the pressure sensor into a voltage output. This system has an average accuracy of 0.53 mmHg and draws 295 µW of power. I then combined this pressure system with data processing code and Howland current pump stimulation circuitry. This simulation system can output up to 1.05 mA of current for electroceutical intraocular stimulation to lower IOP. Future work will involve miniaturizing the circuitries in the form of an ASIC and packaging the entire system into an ocular implant. This implant can wirelessly monitor IOP and provide therapeutic stimulation to lower IOP. A reliable, closed loop method of lowering IOP would greatly benefit the ever-growing population affected by glaucoma.</p>

Image guided therapy procedures under MRI guidance has been a focused research area over past decade. Also, over the last decade, various MRI guided robotic devices have been developed and used clinically for percutaneous interventions, such as prostate biopsy, brachytherapy, and tissue ablation. Though MRI provides better soft tissue contrast compared to Computed Tomography and Ultrasound, it poses various challenges like constrained space, less ergonomic patient access and limited material choices due to its high magnetic field. Even after, advancements in MRI compatible actuation methods and robotic devices using them, most MRI guided interventions are still open-loop in nature and relies on preoperative or intraoperative images. In this thesis, an intraoperative MRI guided robotic system for prostate biopsy comprising of an MRI compatible 4-DOF robotic manipulator, robot controller and control application with Clinical User Interface (CUI) and surgical planning applications (3DSlicer and RadVision) is presented. This system utilizes intraoperative images acquired after each full or partial needle insertion for needle tip localization. Presented system was approved by Institutional Review Board at Brigham and Women's Hospital(BWH) and has been used in 30 patient trials. Successful translation of such a system utilizing intraoperative MR images motivated towards the development of a system architecture for close-loop, real-time MRI guided percutaneous interventions. Robot assisted, close-loop intervention could help in accurate positioning and localization of the therapy delivery instrument, improve physician and patient comfort and allow real-time therapy monitoring. Also, utilizing real-time MR images could allow correction of surgical instrument trajectory and controlled therapy delivery. Two of the applications validating the presented architecture; closed-loop needle steering and MRI guided brain tumor ablation are demonstrated under real-time MRI guidance.

Good quality sleep is essential for mental and physical health. Inadequate sleep impacts memory consolidation, learning and cognition, immune function, autonomic regulation, physical performance, and other vital functions. In many neurological disorders that are associated with sleep problems such as epilepsy and Alzheimer’s disease, changes in brain circuitry affect sleep-wake regulation mechanisms; this is reflected in anomalous sleep-wake architecture and usually accompanied by poor sleep depth. Thus, over many years, many approaches have been tried in humans and animal models with the goal of improving sleep quality. Unfortunately, each of those approaches comes with limitations or side effects. Thus, there is a need for a natural, safe, and low cost approach that overcomes many limitations to improve sleep and eventually the lives of individuals with sleep problems. Environmental temperature is one of the most important factors that affect sleep in humans and other animals. Studies have shown that the part of the brain governing thermoregulation is also involved in sleep-wake regulation. Even a mild change in environmental temperature can produce a significant effect on sleep. Thus, a better understanding of the sleep-thermoregulation interaction could lead to novel ways for treating many sleep disorders. As a first step on the translational pathway, experiments in animal models of disease conditions with disordered sleep are needed for investigating sleep–thermoregulation interactions and for devising and validating related approaches to enhance sleep quality before conducting them on humans. This dissertation explores and assesses the effect of changes in ambient temperature on sleep-wake architecture in control mice and epileptic mice, the latter from a model of temporal lobe epilepsy as an example of a disease model with disordered sleep. Then, based on the results of temperature effects on sleep in control and epileptic mice, different strategies are proposed and tested to modulate sleep through ambient temperature regulation in closed loop to improve sleep depth and regulate the timing of the sleep-wake cycle. The results presented in this dissertation demonstrate the feasibility of sleep enhancement and regulation of its timing and duration through manipulation of ambient temperature using closed-loop control systems. Similar approaches could foreseeably be used as more natural means for enhancing deep sleep in patients with epilepsy, Alzheimer’s, or Parkinson’s disease in which poor sleep is common and associated with adverse outcomes.