Case context: A team trains a mobile robot to return to a charging station. The reward gives a large penalty for collisions and a bonus for stopping smoothly, with a small extra reward whenever the robot ends an episode without getting stuck. After training, the average return is high, but operators notice that the robot often stops in the wrong charging zone several meters away from the dock.

Question: What is the most likely flaw in the reward design, and how should the team update it?

Sample answer: The reward appears to emphasize avoiding collisions and stopping smoothly, but it does not give enough importance to reaching the correct docking bay. A reward function should balance all of the goals that matter for the task, and here the location of the final stop is underweighted or missing. The fix is to add an explicit term that rewards being close to the target dock, or penalizes distance from it, so the agent has incentive to end in the right place.

Key points:

• The reward must balance safety, smooth stopping, and accurate final position
• A high average reward can hide an important missing objective
• The observed behavior suggests docking location is underweighted
• A distance-based term for the target dock would address the problem

Rubric: Full credit for identifying that the final position is not sufficiently represented in the reward and for proposing a clear location-based correction; partial credit for noting that the reward is incomplete without explaining the tradeoff.