Title:
INVESTIGATION INTO SPEED VS ACCURACY FOR AN AUTOMATED VEHICLE CHARGING SYSTEM
INVESTIGATION INTO SPEED VS ACCURACY FOR AN AUTOMATED VEHICLE CHARGING SYSTEM
Author(s)
Cochran, Bryan Freeman
Advisor(s)
Bras, Berdinus A.
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Abstract
Recent advances in energy storage technology have finally allowed Electric Vehicles to enter the mainstream market. The suite of electronics used on these vehicles for power management and driving assistance opens the possibility of these vehicles operating autonomously. An autonomous vehicle must be recharged for it to drive to a destination beyond the range of battery system or for it to operate continuously. To extend autonomous operation, an autonomous charging system was developed. A design requirement was that the system be made using consumer grade components that are common to the DIY IOT movement to decrease system cost. The design and manufacture of the autonomous charging system will be briefly discussed but is not the focus of this thesis.
The focus of this thesis is the investigation into the relationship between the operating speed and the accuracy of the automation algorithm. Initial development focused on delivering the best performance, but the run time of the automation algorithm was more than ten minutes, which was too lengthy. The only portions of the code that could be improved were the hunt cycles for the port cover and the port detent. During the hunt cycles, the algorithm uses closed loop feedback between a vision system and the kinematics of the robot. The feedback loop compares the BB centroid to the center of the camera’s FOV. The hunt is completed when the comparison drops below a defined threshold. For the hunts, the accuracy was decreased by increasing the threshold. Three thresholds were chosen for the Port hunt and the Detent hunt and those thresholds represented high, medium, and low accuracy. An experiment was conducted using different combinations of accuracy for each hunt. The hypothesis was that it was possible for the cycle time to be reduced by decreasing accuracy without sacrificing system performance.
Test results validated the hypothesis and the cycle time was reduced by 16% without impacting system performance. This was done by using the lowest accuracy parameter for the charging Port hunt and using the medium accuracy for the Detent hunt. During the process of conducting the DOE, additional areas of improvement were identified for both the software and the mechanical systems. The proposed improvements were developed and implemented prior to outdoor, full-cycle testing. Outdoor tests were then completed and verified that the implemented improvements along with the accuracy parameters that were the outputs from the test results decreased the full cycle time by 16%.
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Date Issued
2020-09-16
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Thesis