From Composable Models to Correct-by-Construction Software for Contact-Rich Robotic Mobile-Manipulation Tasks

Software frameworks like the Stack of Tasks (SoT), the Stanford Whole-Body Control (WBC) library, or the instantaneous Task Specification using Constraints (iTaSC) have enabled robots to perform advanced, contact-oriented manipulation tasks. jgeom_constr and eTaSL are among the few formal, computer-interpretable languages that allow users to specify such tasks independent of these frameworks. We analyse these languages for their limitations with respect to composability , the design for extensibility without having to change existing models, and compositionality , meaning that the semantics of compositions unambiguously follows from the semantics of the components and of the composition relations. To overcome these limitations we design a graph-structured and well-defined interchange format for such tasks. The associated tooling enables us to generate correct-by-construction code that adheres to predefined rules and constraints. We showcase our models and toolchain by incrementally constructing a workspace-alignment application for a highly-redundant mobile platform that is equipped with two 7-DoF, torque-controlled manipulators.