  In this paper, we consider the optimisation of time varying functions by a
network of agents with no gradient information. The proposed a novel method to
estimate the gradient at each agent's position using only neighbour
information. The gradient estimation is coupled with a formation controller, to
minimise gradient estimation error and prevent agent collisions. Convergence
results for the algorithm are provided for functions which satisfy the
Polyak-Lojasiewicz inequality. Simulations and numerical results are provided
to support the theoretical results.
