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A Real-Time Database (RTDB) middleware for cooperative robotics

This project aims at providing an open source middleware to ease the design of cooperative behaviors within teams of autonomous mobile units. It includes two parts, the upper layer that is the RTDB itself, which is replicated in all units and includes the interfaces for local application processes and for the communication layer, and a wireless communication protocol that keeps the several RTDB replicas synchronized.

This project was initially supported by the CAMBADA project (partially funded by the Portuguese Government and also the University of Aveiro), by the ArtistDesign European FP7 NoE and more recently by CodeStream. Currently it is not funded but it is still maintained by its promoters.

This middleware has been successfully used in the Middle-Size League robotic soccer competition of RoboCup by the teams CAMBADA, TechUnited and NuBots.

Main features:

  • The RTDB is a distributed shared memory that allows local processes to share variables across mobile units, that are accessed as if they were local. Thus, the communication delays are removed from the computational activities and building cooperative behaviors is as easy as building a local behavior.

  • The wireless communication protocol follows a TDMA style in which each mobile unit broadcasts its variables to the remaining RTDB replicas within a dedicated slot. The nodes synchronize together by listening to each other without needing a global clock. Moreover, the number of slots is dynamic and follows the current number of active units in the team at each instant in time.

  • The only configuration needed are the duration of the TDMA round and a unique unit ID and the units can initiate, recover from a crash or leave at any time.

  • This version uses infra-structured mode and the access point plays a major role in enforcing membership consistency (i.e., membership reduces to being connected to the AP).

For more information read the following papers:

  • Luis Almeida, Frederico Santos, Luis Oliveira. Structuring Communications for Mobile Cyber-Physical Systems. In Management of Cyber Physical Objects in the Future Internet of Things: Methods, Architectures and Applications, Antonio Guerrieri, Valeria Loscri, Anna Rovella, Giancarlo Fortino (Eds.), Springer, Lecture Notes in Computer Science, 2016. ISBN 978-3-319-26869-9
  • Luis Almeida, Frederico Santos, Luis Oliveira. Comparing Adaptive TDMA against a Clock Synchronization Approach. Invited paper at ASCoMS 2014 - 3rd Workshop on Architecting Safety in Collaborative Mobile Systems, Satellite of SafeComp 2014, Firenze, Italy, 2014.

(the following are slightly outdated in some technical aspects)

For further information contact:

  • Frederico Santos -
  • Luis Almeida -