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No description available.

In this thesis, we show that it is possible to design a battery-free light sensing system that can sense and communicate hand gestures while operating fully on harvested power from indoor light. We present two main innovations that push our system to tens of microwatts of power to enable battery-free operation. First, we introduce a novel visible light sensing system that can track variations in light intensity by using a solar cell as a sensor. Solar cells are unlike photodiodes optimized for energy yield in the visible light region and hence do not require any power hungry active components such as an operational amplifier. Furthermore, solar cells can operate under more diverse light conditions as they are not susceptible to saturation under bright light. Second, we devise two ultra-low power communication mechanisms based on radio frequency backscatter to transmit sensor readings at various resolutions without the need of any energy-expensive computational blocks.  We design two battery-free and self-powered hardware prototypes that are based on these two innovations. Our first design utilizes an on-board comparator based circuit to perform a 1-bit digitization of changes in light readings, consuming only sub-microwatt of power for digitization. For our second prototype, we design an analog backscatter mechanism that can map raw sensor readings directly to backscatter transmissions. We demonstrate the feasibility of our designs when sensing significant changes in light intensity caused by shadows from hand gestures, and reconstruct these at a receiving device. Our results demonstrate the ability to sense and communicate various hand gestures at a peak power of 20 microwatts when performing 1-bit digitization, and a mean power of 60 microwatts when performing analog backscatter. Both designs represent orders of magnitude improvement in terms of power consumption over state-of-the-art visible light sensing systems. / Battery-free Visible Light Sensing / MobiCom: G: Battery-free Visible Light Sensing

Domestic chores are one of the most tedious and time consuming tasks in a person’s life. A lot of time can be saved and put to better use if these tasks can be automated. One such chore is the routine task of vacuuming the house every day. Robotic vacuum cleaners that clean the house are thus one of the most widely used domestic robots. These robots have the ability to clean the entire house almost autonomously with little or no human intervention. However, most of these robots do not have a system to report the real-time pick up of dirt which can be useful to the user in knowing which parts of his house are dirty and maybe investigate the reason behind it. This information can be useful to the robot as well in determining efficient cleaning patterns based on the dirt localization in the house. In this thesis a prototype was developed to measure the real-time pick-up of dirt by a robotic vacuum cleaner. It uses light sensing technology to measure the amount of dirt picked up and can thus be used to glean which parts of the house are dirtier than the others. The signals can also potentially be used to understand the size of the dirt picked up by the robotic vacuum cleaner. Research was done to investigate the different sensing technologies that can be used and to select the appropriate one. The system was tested and conclusions were made regarding its performance. Additional functions that can be implemented and improvements that can be made have also been suggested as future work. / Att städa hemmet är en av de mest tråkiga och tidskrävande uppgifterna i en persons liv. Mycket tid kan sparas och användas bättre om dessa uppgifter kan automatiseras. Robotdammsugare som städar golvet i hemmet är en av de mest använda inhemska robotarna, då dessa robotar har möjlighet att rengöra hela huset nästan autonomt med liten eller ingen mänsklig intervention. De flesta av dessa robotar har dock inte ett system för att rapportera realtidsupphämtning av smuts som kan vara användbart, då användaren kan få reda på vilka delar av huset som är smutsiga och då ha möjlighet att undersöka orsaken bakom. Denna information kan också vara användbart för roboten för att bestämma effektiva rengöringsmönster baserat på lokalisering av smuts i huset. I denna avhandling utvecklades en prototyp för att mäta upptagning av smuts i realtid av en robotdammsugare. Den använder IR-teknik för att mäta mängden smuts som hämtas upp och kan därmed använda informationen för att avgöra vilka delar av huset som är smutsigare än andra. Signalerna kan också potentiellt användas för att förstå storleken på smuts som tas upp. Forskning av olika tekniker utfördes för att kunna välja den mest lämpliga. Systemet testades därefter och slutsatser gjordes avseende dess prestanda. Ytterligare utredningar och förbättringar som kan genomföras har också föreslagits som framtida arbete.

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The goal of this diploma thesis is to design a shooting sport simulation device. Output of this project should be a market competitive product therefore the design should be focused on low price. Other important aspects are safety, reliability and mutlifunctionality of the whole system. Shooting simulation is based on special technology of sensing laser beams with LED developed in author´s bachelor thesis. The system is controlled by a group of microcontrollers. Their program running and communication is a key part of this thesis.