• Modeling and exploring battery management strategies for use of LiCoO₂ lithium polymer cells in cold climates

      Thompson, Isaac D.; Wies, Richard; Raskovic, Dejan; Lawlor, Orion (2018-05)
      As the use of batteries to power vehicles becomes more common, a robust battery management system becomes necessary to monitor and maintain the batteries. Cold weather places a further burden on this system especially in small electric vehicles such as snowmobiles where it is desirable to use every bit of available energy from the battery cells. The problem with current battery management technology is that use of batteries in cold temperatures is often not addressed. The objective of this research was to develop an appropriate model of a lithium polymer cell with a cathode comprised of LiCoO₂ and develop an optimized charge/discharge method taking into account the effects of extreme cold weather and cell state of charge imbalance. A cell model was adapted and tuned that accurately captures the dynamics of a lithium polymer cell when discharged at temperatures below freezing. The model results were verified against cells discharged in an environmental chamber, which allowed accurate control of ambient temperature. Multiple scenarios were explored, looking at the effects of ambient temperature, cell initial temperature, internal heating, battery pack insulation, and how rapidly the cells were discharged. The results of the optimized battery management strategies showed improvements in the energy delivery capability of lithium polymer battery packs for small vehicles operating in extreme cold environments. In addition, this research extended the LiCoO₂ model down to -20 °C using validated data, showed that perceived cell capacity loss at low temperatures is primarily due to increased internal resistance, demonstrated that measured cell terminal voltage can rise under load at low temperatures, and showed that increasing the capacity of a battery pack has a better than linear gain in usable energy versus increased battery capacity. I.e., doubling battery pack capacity will more than double the useable range of the vehicle.
    • A novel low-cost autonomous 3D LIDAR system

      Dial, Ryker L.; Bogosyan, Seta; Hatfield, Michael; Lawlor, Orion (2018-05)
      To aid in humanity's efforts to colonize alien worlds, NASA's Robotic Mining Competition pits universities against one another to design autonomous mining robots that can extract the materials necessary for producing oxygen, water, fuel, and infrastructure. To mine autonomously on the uneven terrain, the robot must be able to produce a 3D map of its surroundings and navigate around obstacles. However, sensors that can be used for 3D mapping are typically expensive, have high computational requirements, and/or are designed primarily for indoor use. This thesis describes the creation of a novel low-cost 3D mapping system utilizing a pair of rotating LIDAR sensors, attached to a mobile testing platform. Also, the use of this system for 3D obstacle detection and navigation is shown. Finally, the use of deep learning to improve the scanning efficiency of the sensors is investigated.
    • Permafrost geosystem assessment at the Beaver Creek Road experimental site (Alaska Highway, Yukon, Canada)

      Stephani, Eva; Shur, Yuri; Fortier, Daniel; Kanevskiy, Mikhail; Connor, Billy (2013-05)
      An experimental site testing a range of engineering techniques for mitigating permafrost degradation along the Alaska Highway has been established in 2008 at Beaver Creek (Yukon, Canada). Based on the hypothesis that permafrost has a distinctive sensitivity to climate and terrain conditions at a local scale, a geosystem approach, which considers a set of components (e.g. permafrost, embankment, vegetation, hydrology and hydrogeology) and accounts for dynamics within a system, was applied to obtain a better understanding of local permafrost conditions and changes within the system. Therefore, this assessment, for ultimately measuring performance of the mitigation techniques, integrated the permafrost conditions, in terms of cryostratigraphic units and soil properties, with local climate, natural terrain and embankment conditions. The author, who participated in the site establishment, its baseline investigations and monitoring programs, presents here the baseline geosystem studies at the Beaver Creek Road Experimental Site with an emphasis on permafrost.