Control >> Cooperative transport

Cooperative transport

This section is devoted to present the experimental work that has been carried out in the context of cooperative transportation. This work addresses the problem of a) how to control separate s-bots to autonomously connect with an object and/or with each other, and b) how to control a swarm-bot or a collection of swarm-bots to transport an object towards a goal (e.g. along a chain of s-bots).

In general, we aim at controlling the s-bots so that they locate and approach a prey, and self-assemble into structures physically linked to the prey, in order to pull or push it towards a target location.

The design and utility of a hybrid control architecture for controlling a self-assembling group of s-bots engaged in a cooperative transport task have already been studied in simulation (Groß and Dorigo, 2004). The problem has been decomposed into the sub-problems of controlling the actions of

1. s-bots that can self-assemble,
2. assembled s-bots that are capable of locating the target during transport, and
3. assembled s-bots, that are incapable of locating the target during transport.

For each sub-problem a dedicated control module has been designed: sub-problem 2 has been addressed hand-coding a simple control policy, while sub-problem 1 and 3 have been addressed designing neural network controllers. The connection weights of both neural networks have been encoded within a single genotype. A population of 100 genotypes have been shaped by artificial evolution (Groß and Dorigo, 2004).

We have ported the most successful solutions from simulation to the real s-bot. Some adjustments have become necessary, since the simulation model used was simplified. For instance, the teeth and the elevation arm of the rigid gripper have not been modeled in all details. It is worth noting that the controllers have been developed at a time, the real s-bots were still under construction.

The following three sections are devoted to present the experimental work carried out in the context of each of the three control modules. The last section presents an experimental study on the integration of the control modules for self-assembly and cooperative transport.

Transport by a group of pre-attached s-bots This is about the transport of heavy objects by a group of pre-attached s-bots. Transport by pre-attached blind- and non-blind s-bots This is about the transport of heavy objects by a group of pre-attached s-bots of which some are not able to locate the transport target. Integration of Self-Assembly and Transport Behaviors This is an experimental study about the self-assembly and cooperative transport of a heavy prey by a group of six robots.

Control >> Cooperative transport