Effective construction management involves real-time decisions regarding the progress of specific activities, the location of materials and equipment, and the construction site safety. The decision making process can be improved using real-time positioning technologies such as Radio Frequency Identification Device (RFID) systems, Global Positioning System (GPS), and Ultra Wide Band (UWB) sensors. While the GPS is not applicable to indoor positioning and RFID tags cannot provide a fully automated system for position location, the characteristics of UWB systems make this technology a strong candidate for a fully automated positioning system in an indoor construction environment. This thesis presents a comprehensive study of the performance of UWB systems in a controlled laboratory environment and in an institutional construction site in Waterloo, Canada as well as for a particular safety application. A primary objective of the research was to establish the accuracy of real-time position location under various conditions, including the effect of different construction materials (e.g., wood and metal), and to analyze changes in the accuracy of position location as construction progresses and the indoor environment physically evolves. Different challenges faced in implementing such a system in an active construction environment are addressed. Based on a statistical analysis of laboratory data, and considering the construction site experience, the reliability of the UWB positioning system for the aforementioned environments is discussed. Furthermore, an automated safety system is proposed using the real-time UWB positioning technology. Based on the error modeling of the UWB position location, an optimum alarming algorithm is designed for the proposed safety system and the reliability of such system is evaluated through a statistical analysis.

Effective construction management involves real-time decisions regarding the progress of specific activities, the location of materials and equipment, and the construction site safety. The decision making process can be improved using real-time positioning technologies such as Radio Frequency Identification Device (RFID) systems, Global Positioning System (GPS), and Ultra Wide Band (UWB) sensors. While the GPS is not applicable to indoor positioning and RFID tags cannot provide a fully automated system for position location, the characteristics of UWB systems make this technology a strong candidate for a fully automated positioning system in an indoor construction environment. This thesis presents a comprehensive study of the performance of UWB systems in a controlled laboratory environment and in an institutional construction site in Waterloo, Canada as well as for a particular safety application. A primary objective of the research was to establish the accuracy of real-time position location under various conditions, including the effect of different construction materials (e.g., wood and metal), and to analyze changes in the accuracy of position location as construction progresses and the indoor environment physically evolves. Different challenges faced in implementing such a system in an active construction environment are addressed. Based on a statistical analysis of laboratory data, and considering the construction site experience, the reliability of the UWB positioning system for the aforementioned environments is discussed. Furthermore, an automated safety system is proposed using the real-time UWB positioning technology. Based on the error modeling of the UWB position location, an optimum alarming algorithm is designed for the proposed safety system and the reliability of such system is evaluated through a statistical analysis.

Many people suffer from diabetes and as a result of the disease, circulatory issues in feet are common. To find such issues at an early stage, Vistafeet were developing a product that measures the temperature in feet. This product needed to be calibrated and for that purpose, this master thesis was evaluating a proposed calibration rig and the possibility of using a digital twin in order to predict the temperature of the rig. The concept of a digital twin includes a physical product, a virtual model of the same product, and information flow between them. By receiving information from the physical product, the digital model should be able to estimate or predict information about the physical product, information that is then used to improve the physical product. In order to be a true digital twin, it should be automatic and in real time. If the data flow is delayed, a better description is digital shadow or digital model, depending on the level of connection. Due to time limitations during this master thesis, the real time connection required for a proper digital twin was not achieved. The scope was then limited from a digital twin to a digital model. The evaluation of the rig was conducted through a case study of the rig including a number of tests, with the purpose of replicating and verifying the result from a previous study by Xiao and Fan [23]. The digital model was made by logging data from the physical product to later use within the simulated environment. First the digital model was compared and adjusted to the information from several thermal points of the physical model. The thermal points were spread out to give as much information as possible the de simulation, but only placed on sides of the rig that would have easy access if the rig were to be used for calibration. Once the digital model was adjusted, the final simulation was made, and temperature data was compared in verification points to see how well the digital model fit the physical model. The verification points were chosen on the calibrating side of the rig and spread out to see if the model managed to predict potentially tricky places. To finalize the investigation of the rig, errors within the model and the rig itself were evaluated. The result showed that it was possible to fulfill the conclusions from a previously made study. The digital model turned out to be accurate and managed to predict the temperature down to ± 0,1 degrees for most verification points. However, one verification point close to a heater element had much less accuracy than the rest. The result was still acceptable, but this indicates that it is not possible to assume that the model can predict entirely correct temperature within the whole rig only because some points are correct. Especially if trying to predict temperature in more difficult places such as close to a heater. The investigation of errors within the digital model showed that the digital model simulated well within the limits as the temperature range and the controller changed. The sensor close to the heater remained in the same error range as in the first simulation. The errors in hardware were evaluated and the variation between sensors was measured to about 0,1 degrees. However, there might also be a slight offset from the true temperature due to errors affecting all thermistors equally. Even though a 0,1 resolution between sensors is quite good, it is insufficient resolution for this test since the errors in the tests were about ± 0,1 degrees. Despite that, the error of the simulation was still in an acceptable range for a digital model setup. For further improvement, a proper real time digital twin could be implemented, but also higher resolution sensors are required. / Många människor lider av diabetes och som ett resultat av denna sjukdom är cirkulations problem i fötter vanligt. För att på ett tidigt stadie upptäcka sådan problem utvecklade Vista feet en produkt som mäter temperaturen i fötterna för att upptäcka cirkulationsproblem. För att produkten ska fungera måste sensorerna i den kalibreras. I detta examensarbete görs en utvärdering av ett förslag på en kalibreringsrigg. Även möjligheten att använda en digital tvilling för att förutspå temperaturen kommer utvärderas. En digital tvilling inkluderar en fysisk produkt, and virtuell modell av samma produkt samt informationsflöde mellen dem. Genom att få information från den fysiska produkten ska den digitala modellen kunna uppskatta eller förutse information om den fysiska produkten, information som används för att förbättra den fysiska produkten. För att vara en äkta digital tvilling ska informationsflödet ske automatiskt och i realtid. Om informationsflödet sker i efterhand, är en bättre beskrivning en digital skugga eller en digital modell, beroende på nivån av automation och fördröjning. På grund av tidsbegränsning i examensarbetet var det inte möjligt att göra en realtidsuppkopplad digital tvilling, och omfattningen av arbetet begränsades till en digital modell. Utvärderingen av riggen gjordes i form av en fallstudie innehållande ett antal test och genom en replikering av en tidigare gjord studie av Xiao och Fan [23]. Den digital modellen gjordes genom att data från den fysiska produkten sparades och sedan användes för att genomföra den digitala simuleringen. Den digital modellen and passades sedan efter informationen i ett antal ”termiska” punkter (thermal points). Dessa punkter var utspridda för att ge så mycket information som möjligt, men enbart placerade på sidor som lätt kan nås om riggen skulle användas för kalibrering. När modellen var anpassad gjordes en sista simulering. Då jämfördes temperaturen i ett antal verifieringspunkter (verification points) för att se om modellen lyckades förutspå temperaturen i dess punkter. Verifieringspunkterna var på kalibreringssidan av riggen, utspridda för att se om modellen klarade att förutspå även potentiellt svåra platser. Slutligen undersöktes även felkällor i modellen och i riggen. Resultatet av studien visade att det var möjligt att uppfylla slutsatserna från den replikerade rapporten. Den digitala modellen blev mycket noggrann och lyckades förutse temperaturen med en noggrannhet på ± 0,1 grad för de flesta punkterna. Det var dock tydligt att det simulerade värdet i en punkt nära ett element hade betydligt sämre noggrannhet än resten av punkterna. Det var fortfarande en godkänd noggrannhet, men den stora variationen från övriga punkter tyder på att bara för att resultatet stämmer bra i vissa punkter så stämmer det nödvändigtvis inte lika bra i alla punkter. Speciellt om det är en punkt som avviker från övriga och därmed är svårare att uppskatta, som i detta fall, nära ett element. Undersökningen av fel i den digitala modellen visade att den stämde fortsatt bra även när temperaturen och kontrollsystemet ändrades, även om noggrannheten på sensorn nära värmaren var fortsatt låg, var det på ungefär samma nivå. I hårdvaran uppmättes skillnaden i temperatur som termistorerna mätte till 0,1 grad. Dock är det sannolikt ett lite större konstant fel då hårdvaru felen ofta påverkar alla termistorer lika. En noggrannhet mellan sensorerna på 0,1 grad är bra, men inte tillräckligt när felet mellan den simulerade modellen och mätta temperaturen är ± 0,1. Trots det är felet inom gränsen för vad som är acceptabelt för en digital modell. För att förbättra arbetet skulle in riktig realtidsuppkopplad tvilling kunna implementeras, men det krävs också att sensorerna har högre upplösning.

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