  The World Robotics Challenge (2018 & 2020) was designed to challenge teams to
design systems that are easy to adapt to new tasks and to ensure robust
operation in a semi-structured environment. We present a layered strategy to
transform missions into tasks and actions and provide a set of strategies to
address simple and complex failures. We propose a model for characterizing
failures using this model and discuss repairs. Simple failures are by far the
most common in our WRC system and we also present how we repaired them.
