Embedded systems and robot prototypes

RoboFetz is a combat robot competition, and almost every entry is driver-controlled. Perceptron was one of the first fully autonomous robots to fight in it.

I led the project: five people, a fixed competition date, and work spanning mechanics, electronics, firmware and autonomy. I set the system architecture: what runs on the microcontroller, what runs off-board, what has to meet timing. Then I split it into tasks people could take on independently. The CAD and the firmware are mine. I started the custom SMD board and handed it to a teammate who took it the rest of the way.

Three omni wheels give it a holonomic drive, each motor closed-loop from the inverse kinematics of the wheel layout. micro-ROS has no Bluetooth LE transport, so I wrote one, firmware side and agent side. PID gains and motor direction are adjustable live through ros2 param calls and survive a reboot. Autonomy runs on behaviour trees and an artificial potential field, with ArUco markers on the lid for pose.

A vehicle can’t follow a trajectory if the control commands arrive late. On a stock ROS 2 computer without a real-time extension, sometimes they do.

I moved the Ackermann steering kinematics onto an ESP32-C6 running an RTOS, so the timing-critical part no longer depends on the host. Parameters live on the microcontroller in a persistent parameter server, and the motor controllers are ODrive units commanded over CAN.

Published with Markus Bader at the Austrian Robotics Workshop 2025. The firmware is public.

A Unitree Go2 Pro built up into a development platform. Unitree makes the base hardware, everything above it is my work. Out of the box the robot answers to a phone app, so I rooted it and now ROS 2 runs on the robot itself, with an added onboard computer for the work the stock hardware will not carry.

The back is a mounting point rather than a fixed configuration. It currently carries an SO-101 arm for teleoperation, and that comes off for a 3D scanner, a different sensor, or whatever else a job calls for.

Nav2 for autonomous navigation, and the operational layer that makes a robot usable away from the workbench: a VPN so it can be reached from anywhere, remote access for deployment and debugging, and introspection so you can watch what it is doing while it does it.

Ongoing work. It has been out on site several times.

A mobile robot platform I built to stop rewriting the same code for every chassis. Kinematics, motor control and utilities are separate C++ libraries, so the same firmware drives a mecanum base, a differential drive, a swerve base or an Ackermann vehicle.

Mechanics in SolidWorks, a Gazebo simulation with slam_toolbox for navigation work, and sensor firmware feeding LiDAR and IMU data into ROS 2. Its two carrier boards, one for four motors and encoders and one for the sensors, were the first PCBs I designed. Mostly connectors and level shifting, but they taught me the process.

A three-phase power stage for brushless motors: schematic, board layout and the control firmware.

6–30 V input, three half-bridges with separate input and inhibit lines per phase, an on-board 5 V buck converter, and phase sensing on an I²C bus. A Teensy sits on top and does the commutation.

Distance to Sound: an ATmega board that reads four ultrasonic sensors and turns what they measure into audio, so a wheelchair user can hear how much room is left around them.

Four sensor ports, a switch to run from USB-C or an external supply, and an ISP header for reflashing in place.