Robots are used in ethology and behavioural experiments to study the modes of interactions and communications between animals. These robots are usually teleoperated by the human experimenters, in order to trigger a response from the studied animals. However, an increasing number of ethological studies uses autonomous robots, capable of social integration with the animals without human intervention. We apply the same idea in the ASSISIbf project to create mixed-societies of animals and robots.
For instance, here is a video of a robot that socially integrates into a group of four zebrafish, in a closed two-patches set-up:
To be accepted by the group of fish, several aspects of robotic design must be considered. First, the fish lure must be biomimetic (i.e. “look” like a real zebrafish). Our lure was created by 3D printing a 3D scan of a real zebrafish. The lure is also covered with a decal to have the same type of color as a zebrafish.
Second, the robot must behave like a fish (biomimetic behaviour). Fish have a tendency to be attracted to each other, and to move from one room to the other. They can have complex group dynamics, with fish joining or leaving short-lived sub-groups. The robot must be able to mimic these behaviour to be accepted by the group of fish. The robot must also appear to move like a fish, with biomimetic movement patterns composed of repeated series of high acceleration (tail beat) followed by a relaxation period.
Lastly, fish move very fast in the experimental set-up (in average 9cm/s, but they can reach up to 30 cm/s). As such, the robot hardware and software must also be designed to reach comparable speeds.
With a robot socially integrated in the group of fish, it is possible to use it to influence their behaviour, and control the collective behaviours of the entire biohybrid population of fish and robots. This can be accomplished by using the robot to initiate the collective departures from one room to the other, as shown in this video:
During transitions, we observe that the fish which initiates collective departures is not always the same: the leadership is shared. However, some fish can be the leader more often than others. The leader position is linked to the number of times a fish tries to exit the room. As such, to influence the behaviour of a group of fish, our integrated robot must attempt to exit the room more often than fish. In this video, the robot integrates into the group of the fish and then initiates a transition.