Public address (PA) systems are an integral part of every building. Their function as a safety and security system could benefit from adding recording capabilities. With such capabilities, people could be located during evacuation or announcements could be adjusted to room acoustics for better intelligibility. However, adding microphones to a PA system is too costly and inefficient to be feasible. This thesis evaluates the feasibility of using the loudspeakers already in place as recording devices to provide information to the system. To this end, a system using a single loudspeaker as both a playback and recording device is analysed, modelled and simulated. The results show that using a current measuring set-up with an analogue-to-digital converter capable of detecting a range of roughly 120 dB, a speech signal up to three metres in a cone of 120° from a loudspeaker can be successfully estimated in an office room with an announcement playing and background noise present. As the estimated signal is unknown to the system, the solution generalises to other signal types as well. A system with a single loudspeaker can be utilised for the use cases presented, and is therefore proven feasible. To increase the practicality of the system, it is recommended to continue the research in two main areas. The first area considers improving the quality of the recording and extending the range from which the system can produce accurate recordings. The second area considers evaluating the practical implementation of the system, by extending the single loudspeaker case to a multiple loudspeaker case and generalising the system to be readily implementable in a large variety of PA systems. ... Read more

In this thesis the implementation of Field Oriented Control in the car of the NUON Solar Team will be discussed. The team decided to do research into the possibilities of a custom motor controller, and this thesis covers the beginning of that process. First a comparison between different control methods is made, and sensorless FOC is decided as the method to be used. Then the implementation of FOC is discussed. The Texas Instruments InstaSPIN™ technology has the preference for this implementation. This because it has all the elements of the control embedded in one microcontroller, along with a software estimator which eliminates the use of expensive sensors like a shaft encoder. Also the ease of use and the familiarity of TU Delft staff with this technology played a big part in this decision. With this technology, a simulation set-up was made as a proof of concept, which can also be used to teach the NUON Solar Team members the basics of motor control. After that the connections from the controller to the inverter are discussed, so it can be connected to other inverters in the future. In the controller, a CAN-interface is also implemented, which is essential for using it in the Nuna car. With the information presented in this thesis, the NUON Solar Team can continue the development of a controller. It is recommended to eventually leave the development kits used during this project, and integrate the MCU directly into an inverter. This will allow for well-tuned, efficient control of the motor with a small
footprint. ... Read more