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Waterpolo First Team Captain

Waterpolo is a challenging sport. A sport that I was not every particularly talented at. Never the less after trying Waterpolo, I loved it. In my first two years of playing it, our team won a combined total of 1 game. Waterpolo taught me that through hard work, you can achieve anything. In my final year, I was nominated as our team captain, and as a team, we were winning close to 50% of our games. The lessons it taught me, and the leadership skills it gave me are still ones I use today.


National u18B Hockey Side

Field hockey is a popular sport in South Africa. I started playing it in grade 6 when I was only 12 years old. I have made many friends through hockey and played for many teams. My proudest moment in hockey was being nominated to be part of the South African u18B nation team.



My dad used to take me into South Africa Drakensburg mountains. Although we never completed one of our extremely ambitious week-long hikes (generally due to getting lost). It distilled a love for hiking and mountains I have to this day.


Southern Africa Road Trip

After graduating, my friend and I decided to take a month off, rent a 4x4, and with a set of paper maps as our only companion set off on the trip of a lifetime. We drove many 1000’s of kilometers through 4 different countries and made more memories than I can recall. More importantly, I got a small taste of the beauty, kindness, and heart of Southern Africa.


Comrades Marathon

The Comrades marathon is an 89km (55 mi) race run annually in South Africa. Not only is the course long, but it also includes 2km (7000ft) of elevation gain and 1.5km (4700ft) of descent. Completing this race was a childhood dream, and before leaving South Africa, I had to complete it. On that day, I learned that prize is not finishing it, or the medal, but rather being part of this truly epic event. We are all Comrades.


Half Iron Man

After finishing Comrades, I felt unstoppable. I decided to take on a half Ironman. It was my first triathlon, and I loved it. I was planning on doing a new half Ironman in Florida in 2020, but unfortunately, it was postponed due to COVID.


Spring National Field Hockey League Champions

I am part of UVA’s field hockey club. We won the 2019 spring National Field Hockey tournament. We also placed second in the 2019 fall National Field Hockey tournament. I have since been included in the 2019 National Field Hockey All-Stars Team.



I was part of a multidisciplinary team that has developed software for ensuring patient safety. We have patented our software, have started getting IRB approval for two studies in UVA’s nursing department, and formed a startup company which is currently a finalist in the Entrepreneurship World Cup. Unfortunately, due to my visa restrictions, I had to step away once the company was formed.



Fire-Aware Planning of Aerial Trajectories and Ignitions

Evan Beachly, Carrick Detweiler, Sebastian Elbaum, Brittany Duncan, Carl Hildebrandt, Dirac Twidwell, Craig Allen

Prescribed fires can lessen wildfire severity and control invasive species, but they can also be risky and costly. Unmanned aerial systems can reduce those drawbacks by, for example, dropping ignition spheres to ignite the most hazardous areas. Existing systems, however, lack awareness of the fire vectors to operate autonomously, safely, and efficiently. In this work we address that limitation, introducing an approach that integrates a lightweight fire simulator and a planner for trajectories and ignition sphere drop waypoints. Both components are unique in that they are amenable to input from the system’s sensors and the fire crew to increase fire awareness. We conducted a preliminary study that confirms that such inputs improve the accuracy of the fire simulation to counter the unpredictability of the target environment. The field study of the system showed that the fire-aware planner generated safe trajectories with effective ignitions leveraging the fire simulator predictions.

Published in 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2018 - IROS Best Paper Award on Safety, Security, and Recue Robotics

Blending Kinematic and Software Models for Tighter Reachability Analysis

Carl Hildebrandt, Sebastian Elbaum, Nicola Bezzo

Reachable sets are critical for path planning and navigation of mobile autonomous systems. Traditionally, these sets are computed using system models instantiated with their physical bounds. This exclusive focus on the physical bounds belies the fact that these systems are increasingly driven by sophisticated software components that can also bound the variables in the system models. This work explores the degree to which bounds manifested in the software can affect the computation of reachable sets, introduces an analysis approach to discover such bounds in code, and illustrates the potential of that approach on two systems. The preliminary results reveal that taking into consideration software bounds can reduce traditionally computed reachable sets by up to 91%.

Published in 2020 IEEE/ACM 42nd International Conference on Software Engineering: New Ideas and Emerging Results (ICSE-NIER), 2020

Feasible and Stressful Trajectory Generation for Mobile Robots

Carl Hildebrandt, Sebastian Elbaum, Matthew B. Dwyer, Nicola Bezzo

While executing nominal tests on mobile robots is required for their validation, such tests may overlook faults that arise under trajectories that accentuate certain aspects of the robots behavior. Uncovering such stressful trajectories is challenging as the input space for these systems, as they move, is extremely large, and the relation between a planned trajectory and its potential to induce stress can be subtle. To address this challenge we propose a framework that 1) integrates kinematic and dynamic physical models of the robot into the automated trajectory generation in order to generate valid trajectories, and 2) incorporates a parameterizable scoring model to efficiently generate physically valid yet stressful trajectories for a broad range of mobile robots. We evaluate our approach on four variants of a state-of-the-art quadrotor in a racing simulator. We find that, for non-trivial length trajectories, the incorporation of the kinematic and dynamic model is crucial to generate any valid trajectory, and that the approach with the best hand-crafted scoring model and with a trained scoring model can cause on average a 55.9% and 41.3% more stress than a random selection among valid trajectories. A follow-up study shows that the approach was able to induce similar stress on a deployed commercial quadrotor, with trajectories that deviated up to 6m from the intended ones.

Published in ISSTA 20: 29th ACM SIGSOFT International Symposium on Software Testing and Analysis Proceedings (ISSTA), 2020 - Distinguished Artifact Award

World-in-the-Loop Simulation for Autonomous Systems Validation

Carl Hildebrandt, Sebastian Elbaum

Simulation is at the core of validating autonomous systems (AS), enabling the detection of faults at a lower cost and earlier in the development life cycle. However, simulation can only produce an approximation of the real world, leading to a gap between simulation and reality where undesirable system behaviors can go unnoticed. To address that gap, we present a novel approach, world-in-the-loop (WIL) simulation, which integrates sensing data from simulation and the real world to provide the AS with a mixed-reality. The approach executes multiple instances of the AS in parallel, one in the real world and at least one in simulation, performs configurable transformations, filtering, and merging operations on the body of sensed data in order to integrate it, and provides the pipelines to distribute the original sensor data and the integrated sensor data back to the executing AS. We present a study on multiple scenarios and two simulators that demonstrates how WIL reduces the simulation-reality gap and increases the chances of exposing failures before deployment.

Published in 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021

Preparing Software Engineers to Develop Robot Systems

Carl Hildebrandt, Meriel von Stein, Trey Woodlief, Sebastian Elbaum

Robotics is a rapidly expanding field that needs software engineers. Most of our undergraduates, however, are not equipped to manage the unique challenges associated with the development of software for modern robots. In this work we introduce a course we have designed and delivered to better prepare students to develop software for robot systems. The course is unique in that: it emphasizes the distinctive challenges of software development for robots paired with the software engineering techniques that may help manage those challenges, it provides many opportunities for experiential learning across the robotics and software engineering interface, and it lowers the barriers for learning how to build such systems. In this work we describe the principles and innovations of the course, its content and delivery, and finish with the lessons we have learned.

Published in 2022 IEEE/ACM International Conference on Software Engineering (ICSE), 2021