You are invited to the
AE Brown Bag Lunch
featuring talks by
Steven Haviland & Michelle Ku
Highlights from the Recent Robotics Grand Challenge
The Mohamed Bin Zayed International Robotic Challenge (MBZIRC) is an international robotics competition held every two years with a total prize of 5 million USD. MBZIRC aims to provide an ambitious technological demanding set of challenges in robotics with the intent to demonstrate the current state of the art and inspire the future of robotics. Twenty-five teams consisting of top universities from across the globe competed in the four challenges. Aerial and ground-based vehicles were required to complete the challenges. The Georgia Tech Aerial Robotics (GTAR) team aimed to complete all the tasks presented by MBZIRC. This presentation will outline the team's work for each challenge and go over lessons learned from the robotics competition.
Advisor: Dr. Eric Johnson
Electric Propulsion Reliability:
Statistical Analysis of On-orbit Anomalies and Failure Rates
With a few hundred spacecraft launched to date with electric propulsion (EP), it is possible to conduct an epidemiological study of EP’s on orbit reliability. The first objective of the present work was to undertake such a study and analyze EP’s track record of on orbit anomalies and failures by different covariates. The second objective was to provide a comparative analysis of EP’s failure rates with those of chemical propulsion. Satellite operators, manufacturers, and insurers will make reliability¬¬- and risk-informed decisions regarding the adoption and promotion of EP on board spacecraft. This work provides evidence-based support for such decisions. After a thorough data collection, 162 EP-equipped satellites launched between 1997 and 2015 were included in our dataset for analysis. Several statistical analyses were conducted, at the aggregate level and then with the data stratified by severity of the anomaly, by orbit type, and by EP technology. Mean Time To Anomaly (MTTA) and the distribution of the time to (minor/major) anomaly were investigated, as well as anomaly rates.
The important findings in this work include the following: (1) Post-2005, EP’s reliability has outperformed that of chemical propulsion; (2) Hall thrusters have robustly outperformed chemical propulsion, and they maintain a small but shrinking reliability advantage over gridded ion engines. Other results were also provided, for example the differentials in MTTA of minor and major anomalies for gridded ion engines and Hall thrusters. It was shown that: (3) Hall thrusters exhibit minor anomalies very early on orbit, which might be indicative of infant anomalies, and thus would benefit from better ground testing and acceptance procedures; (4) Strong evidence exists that EP anomalies (onset and likelihood) and orbit type are dependent, a dependence likely mediated by either the space environment or differences in thrusters duty cycles; (5) Gridded ion thrusters exhibit both infant and wear-out failures, and thus would benefit from a reliability growth program that addresses both these types of problems.
Advisor: Dr. Joseph Homer Saleh