Robot swarms neutralize harmful Byzantine robots using a blockchain-based token economy

Through cooperation, robot swarms can perform tasks or solve problems that
a single robot from the swarm could not perform/solve by itself. However,
it has been shown that a single Byzantine robot (e.g., a malfunctioning or
malicious robot) can disrupt the coordination strategy of the entire
swarm. Therefore, a versatile swarm robotics framework that addresses
security issues in inter-robot communication and coordination is urgently
needed. In this paper, we show that security issues can be addressed by
setting up a token economy between the robots. To create and maintain the
token economy, we use blockchain technology, originally developed for the
digital currency Bitcoin. The robots are given crypto tokens that allow
them to participate in the swarm's security-critical activities. The
token economy is regulated via a smart contract that decides how to
distribute crypto tokens among the robots depending on their
contributions. We design the smart contract so that Byzantine robots soon
run out of crypto tokens and can therefore no longer influence the rest of
the swarm. In experiments with up to 24 physical robots, we demonstrate
that our smart contract approach indeed works: the robots can maintain
blockchain networks and a blockchain-based token economy can be used to
neutralize the destructive actions of Byzantine robots in a
collective-sensing scenario. In experiments with more than 100 simulated
robots, we study the scalability and long-term behavior of our approach.
The obtained results demonstrate the feasibility and viability of
blockchain-based swarm robotics.