Getting PX4’s Simulation-In-Hardware (SIH) module running on a production flight controller — discovering the firmware doesn’t include SIH, building a custom PX4 with flash-trimming, fan-out routing serial MAVLink to both the simulator and ground station, and connecting it all to the Unity visualization pipeline.
How I replaced a proprietary terrain bundle with a fully procedural environment generated from open-source data — hundreds of buildings with window textures from OpenStreetMap, terrain-hugging roads, satellite-driven vegetation, and multiple ground and air entities — all built at runtime in a headless Unity Docker simulation.
DDS content filter parameter substitution (%0, %1) silently fails for string fields in ROS 2 with Fast DDS. The root cause is three layers deep — the DDS SQL grammar requires quoted string literals, but no ROS 2 layer adds the quotes. Here’s how I traced it and where to fix it.
A one-word review comment on my Eigen MR revealed that hand-rolling normalization with .norm() silently breaks on extreme inputs. Eigen already had the fix — I just wasn’t using it.
Four bugs in GStreamer’s shmsink/shmsrc elements — a race condition, a use-after-free, a wrong-pointer dereference, and a page alignment mismatch. What they have in common, how to find them, and what they teach about writing correct GStreamer elements.
A 2-line fix for a race condition in GStreamer’s shmsink that causes every pipeline using shared memory to exit with an error. How I found it, proved it, and verified the fix with sanitizers.
How a simple erase-remove in every add_timer() call turned entity registration into a quadratic bottleneck — and the 71x speedup from moving cleanup to the right place.
Eigen’s blocked Householder path only existed for left-side application. I added the right-side equivalent, upgrading M*Q from O(n) rank-1 updates to cache-friendly blocked matrix multiplies.
How we built a GStreamer plugin suite for zero-copy NVMM video on NVIDIA Jetson, the bugs we hit along the way, and what it takes to contribute to the GStreamer project — from filing issues to getting an MR merged.
Everything I learned submitting four pull requests to ROS 2 core repositories — from finding issues and building in Docker to passing DCO checks, handling OSRF’s AI disclosure policy, rebasing across distro branches, and running the full test suites. A warts-and-all field guide.