ArduPilot

Before the base could navigate, it had to know where it was. The first source was optical flow: a sensor that watches the floor slide past. I brought it up over micro-ROS and fed it into ArduPilot's EKF alongside the IMU of the Pixhawk the base ran at the time. It only read sensibly within about 10 cm of the floor, so it sits low, lit by its own LED.

To tell whether it worked, I needed ground truth. The lab's motion capture tracks the robot more precisely than anything you could measure by hand, so I wrote the package that brings it into ROS: the EKF's estimate and the mocap pose land in one bag on one clock, and every run can be compared with the truth point by point. The first runs showed why that mattered: driving 5.5 m, the estimate stayed within 0.74 m of mocap, but spinning in place sent it 155 m off. Once teammates found the sensor's mounting missing from the config, I tuned the flow gain against mocap, run by run, until the estimate stayed within 5 mm of motion capture.

OpenDubs runs on an NVIDIA Jetson Thor, so the first job was getting it ready for the whole team. I flashed JetPack onto it, got its IO talking to the rest of the robot, and set up the Docker environment we all develop in: a ROS 2 image with the build tools, Makefile and VS Code tasks to build and debug inside it, and per-person git identities so four people can commit from one shared machine.

The first version of the base drove its four mecanum wheels through a Pixhawk running ArduPilot, over MAVROS; it has since dropped the Pixhawk. With another intern, I brought up that drive code, then added what the rest of the stack needed: a URDF and an SDF with collision geometry for RViz and Gazebo, and a service that records topics to rosbags. Every test after this was a bag I could replay.

The base has since been rebuilt by others in the lab (I didn't work on it), without the Pixhawk, and carries everything else: a 51.2 V LiFePO4 battery, an emergency stop on the deck and a status display, all wired into one aluminum frame, with the arms, the Thor and the lidars riding on top.