Let us go very small, cell size level for medical applications. This size currently is out of reach for swarm robotics (a fundamental problem is that energy capacity decreases faster than e.g. the resistance). A different approach is to use passive agents that are propelled by external forces as such as controlled magnetic fields of an MRI scanner. This introduces a significant difference to classical swarm robotics since now all agents move uniformly and the only individual control is by collisions that stop a part of the agents from moving.
We now consider some possible problems, starting with the following: You are given a set of agents in an unknown environment and want to explore it with as few commands as possible. You always now the positions of the agents and can sense collisions with obstacles (by a failed movement). Such a scenario can be in medial imaging with too low contrasts for classical techniques and an application of a contrast medium is contraindicated. Try it yourself!
A related problem is the question, how to get as many agents inside as possible.
Another problem can be to collect all agents onto a single pixel (contrary to the previous problems, there can be arbitrary agents on a single pixel).
In this context one can also consider assembly. Agents stick together and we have some technique to insert them from outside. Not all shapes can be assembled because we always need to have a clear and straight path to the next part. For shapes we can assemble, the correct order can be critical.
- A.T. Becker, S.P. Fekete, P. Keldenich, D. Krupke, C. Rieck, C. Scheffer, and A. Schmidt. Tilt Assembly: Algorithms for Micro-Factories that Build Objects with Uniform External Forces. To appear in: 28th International Symposium on Algorithms and Computation (ISAAC).
- A.V. Mahadev, D. Krupke, S.P. Fekete, A.T. Becker Mapping, Foraging, and Coverage with a Particle Swarm Controlled by Uniform Inputs To appear in IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2017).
- A.V. Mahadev, D. Krupke, J.-M. Reinhardt, S.P. Fekete, A.T. Becker Collecting a Swarm in a 2D Environment Using Shared, Global Inputs. In: 13th Conference on Automation Science and Engineering (CASE 2016), 1231-1236.