The use of multiple robots - rather than a single robot - working in a coordinated way has several advantages in a diverse range of applications, and interest in such multirobot systems is rising rapidly both in academia and in industry. However, say the researchers, few studies have focused on operations in which hacked robots can behave maliciously and alter the outcome of the collective mission.
In their work, the researchers presented a set of Byzantine Follow The Leader (BFTL) problems, in which a subset of robots in the system shows unintended or inconsistent behavior (i.e., Byzantine robots). In the BFTL problems, leaders discover routes from their starting positions to specific destinations and guide the followers, while Byzantine robots try to hinder the leaders and mislead the followers.
In their research, blockchain technology was used as a communication tool within multirobot systems, for leaders to broadcast directions to the whole group. A blockchain offers a tamper-proof record of all transactions - in this case, the messages issued by robot team leaders - so follower robots can eventually identify inconsistencies in the information trail.
Leaders use tokens to signal movements and add transactions to the chain, and forfeit their tokens when they are caught in a lie, so this transaction-based communications system limits the number of lies a hacked robot could spread, say the researchers.
“The world of blockchain beyond the discourse about cryptocurrency has many things under the hood that can create new ways of understanding security protocols,” says Eduardo Castelló, a Marie Curie Fellow in the MIT Media Lab and lead author of a paper on the research.
While a blockchain is typically used as a secure ledger for cryptocurrencies, in its essence it is a list of data structures - known as blocks - that are connected in a chain. Each block contains information it is meant to store, the “hash” of the information in the block, and