A port-arbitrated mechanism for behavior selection in humanoid robotics

Software engineering and best practices promote modularity and composability to reduce debugging and development time of software applications in robotics. This approach, however, increases the complexity of the system and the effort needed to properly coordinate interactions between modules. On the other hand programming robots to cope with an unstructured environment requires the implementation of highly reactive systems. Behavior-based architectures have been proposed as a programming paradigm to build complex, yet, reactive systems by integrating simpler modules. They require however that modules establish special connections dedicated to carry coordination signals. In a distributed architecture these signals must be properly synchronized with the ones that carry data. This article proposes a novel method for developing reactive systems by coordinating concurrent, distributed behaviors. In our approach arbitration exploits the connections that deliver data messages between modules and, for this reason, i) it intrinsically reduces the number of links required for coordination and ii) it can be built without changing existing modules. The proposed architecture is discussed in detail and tested on a real scenario on the iCub humanoid robot.