Practice the ROS2 Emergency Stop with a Hole in It coding problem in Safety-Critical. Browser-based execution with automated grading — no local ROS install required. 0% of engineers pass this challenge.
An e-stop system is installed and certified for same-machine operation. During cross-network safety testing, the e-stop fails completely.
The bug: the motor driver's e-stop subscriber uses BEST_EFFORT QoS, but the safety console publishes with RELIABLE QoS. These policies are incompatible — DDS silently drops all messages. On the same machine (loopback) it appears to work by coincidence. Over any real network, commands are lost.
Fix the e-stop subscriber's QoS profile so it uses RELIABLE reliability. All other logic should remain unchanged.
It is a hands-on Safety-Critical challenge on SimuCode where you implement and run ROS2 code in the browser with runtime-verified tests.
Open this page, sign in, and solve the problem in the built-in IDE. Your solution is graded against real ROS2 execution checks.
This Medium problem focuses on qos, reliability, best-effort skills used in robotics interviews and production systems.