Events: Signaler och system, Electrical Engineering events at Chalmers University of TechnologyFri, 14 Dec 2018 13:59:28 +0100öhle.aspx Fröhle, Electrical Engineering<p>EA lecture hall</p><p>Title of thesis: Channel Prediction and Target Tracking for Multi-Agent Systems</p><div>Markus Fröhle is a PhD student in the Communication systems research group​</div> <div>Opponent is Dr. Paolo Braca, Senior Scientist at NATO Science and Technology Organization<br />Examiner is Professor Henk Wymeersch</div> <h2 class="chalmersElement-H2">Abstract​</h2> <div><div>Mobile moving agents as part of a multi-agent system (MAS) utilize the wireless communication</div> <div>channel to disseminate information and to coordinate between each other. This channel is error-prone and the transmission quality depends on the environment as well as on the configuration of the transmitter and the receiver. For resource allocation and task planning of the agents, it is important to have accurate, yet computationally efficient, methods for learning and predicting the wireless channel. Furthermore, agents</div> <div>utilize on-board sensors to determine both their own state and the states of surrounding objects. To track the states over time, the objects’ dynamical models are combined with the sensors’ measurement models using a Bayesian filter. Through fusion of posterior information output by the agents’ filters, the awareness of the agents is increased. This thesis studies the uncertainties involved in the communication and the positioning of</div> <div>MASs and proposes methods to properly handle them. </div> <div><br /></div> <div>A framework to learn and predict the wireless channel is proposed, based on a Gaussian process model. It incorporates deterministic path loss and stochastic large scale fading, allowing the estimation of model parameters from measurements and an accurate prediction of the channel quality. Furthermore, the proposed framework considers the present location uncertainty of the transmitting and the receiving agent in both the learning and the prediction procedures. Simulations demonstrate the improved channel learning and prediction performance and show that by taking location uncertainty into account a better communication performance is achieved. </div> <div><br /></div> <div>The agents’ location uncertainties need to be considered when surrounding objects (targets) are estimated in the global frame of reference. Sensor impairments, such as an imperfect detector or unknown target identity, are incorporated in the Bayesian filtering framework. A Bayesian multitarget tracking filter to jointly estimate the agents’ and the targets’ states is proposed. It is a variant of the Poisson multi-Bernoulli filter and its performance is demonstrated in simulations and experiments. Results for MASs show that the agents’ state uncertainties are reduced by joint agent-target state tracking compared to tracking only the agents’ states, especially with high-resolution sensors. </div> <div><br /></div> <div>While target tracking allows for a reduction of the agents’ state uncertainties, high-resolution sensors require special care due to multiple detections per target. In this case, the tracking filter needs to explicitly model the dimensions of the target, leading to extended target tracking (ETT). An ETT filter is combined with a Gaussian process shape model, which results in accurate target state and shape estimates. Furthermore, a method to fuse posterior information from multiple ETT filters is proposed, by means of minimizing the Kullback-Leibler average. Simulation results show that the adopted ETT filter accurately tracks the targets’ kinematic states and shapes, and posterior fusion provides a holistic view of the targets provided by multiple ETT filters.</div></div> Elling<p>EDIT conference room (room 3364), Hörsalsvägen 11, 3rd floor</p><p>Bringing a H&amp;N microwave hyperthermia applicator from laboratory to clinics</p><p>Examiner: Andras Fhager, Dept of Electrical Engineering</p> <h2 class="chalmersElement-H2">​<span>Abstrac​t</span></h2> <div>Hyperthermia is a promising cancer treatment modality that has been used in combination with chemo- and radiotherapy. By increasing the temperature in the tumour to 40 - 44 °C, delivery of the chemotherapy drugs and radiosensitivity of the tumorous cells is significantly improved. The main challenge is to adequately heat deep-seated tumours while keeping the temperature of the surrounding healthy tissues at normal levels.<br /><br />In this thesis, a prototype hyperthermia applicator for Head &amp; Neck cancers developed at Chalmers was brought closer to a clinical version. The applicator consists of a circular array of 10 self-grounded Bow-Tie antennas arranged on two rings. The antennas are enclosed in a housing with circulating deionized water used both for cooling and impedance matching. Between the antennas and the body a matching medium, a so-called water bolus, is placed. This bolus is also used for cooling of the patient's skin. <br /><br />The first objective was to improve the cooling of the antennas which was found to be insufficient. The housing was redesigned to allow for better heat transfer. Turbulent flow is created next to the antenna's pins where most the heat is generated. The impact of this redesign is investigated in a EM solver and a parameter analysis of the antenna is performed. A solution is found, manufactured and tested in the laboratory.<br /><br />In the second part a novel solution for the bolus, a hydrogel, has been explored. The hydrogel greatly improves the EM coupling and reproducibility of positioning but further endeavor is made to investigate its cooling capabilities and its ease-of-use.<br /></div> <div> </div> <div><br /></div> <div> </div> <div>A patient-specific hydrogel bolus is developed and an active cooling is incorporated. The influences on the EM waves are investigated numerically and in laboratory experiments. A structure is assembled to make its usage simple and to allow its incorporation in the current neck applicator from Chalmers.​</div> <div> </div>  ​ Brown, MPIDE<p>Lunnerummet (room 3311), Hörsalsvägen 11, 3rd floor</p><p>​Usability of an at home therapy system for phantom limb pain applying user-centered design techniques to the development of a medical device</p><div>​Examiner: Max Ortiz Catalan</div> <div><br /></div> <h2 class="chalmersElement-H2">Abstract</h2> <div><br /></div> <div>A new therapeutic device for amputees aims to increase phantom motor execution through virtual reality and gaming applications in order to increase engagement in exercises prescribed for treating phantom limb pain. This therapy is currently being used by clinicians around the world and the next step to make the therapy more accessible is to design it for the patient to use at home.  In order to move from clinical use to at-home use, both the usability and user experience of the device are investigated in a new context, and a new user interface is proposed to better motivate patients with chronic phantom limb pain to perform therapy at home. The investigation is carried out using the 62366 guideline provided by the International Electrotechnical Commission on “Usability Engineering for Medical Devices” which contains User-Centered Design methodology, the usability of a therapeutic device currently being developed for treating Phantom Limb Pain was studied, and a new interface is proposed for at-home use. The development process was done in three stages, the first being the user research phase, which aimed to collect ethnographic data about current expert users (therapists) and end users at home (patients) to inform the design of the interface. In the Ideation phase, the second phase of the design process, this ethnographic data is synthesized and used to define the needed functionalities of the device. In the third phase, the Implementation phase, three iterations of a new user interface are proposed and tested for therapy at home and a final design proposal is presented to be validated by end users.<br /></div> Seminar on AI<p>Lindholmen Conference Centre, conference hall,</p><p>​Save the dates 4-5 March 2019 for the upcoming initiative seminar on AI. ​Programme and registration will be available in January.</p>