Starting from arbitrary initial conditions, the quadrotors flock towards the source (minimum) of a scalar field. The idea is to estimate a local gradient and hessian and track continuous versions of steepest descent and newton method with momentum. Stability analysis and other details could be found in this paper:

Datar, A., Paulsen, P. and Werner, H., 2019, July. Flocking Towards the Source: Indoor Experiments with Quadrotors


Links to videos:

[1] Source-seeking for a strictly convex quadratic scalar field 

[2] Source-seeking for a strictly log-convex scalar field

[3] Source-seeking for a non-convex quadratic scalar field with 2 minima 

[4] Data from all experiments visualized in an animation