Decentralized Nonlinear Feedback Design with Separable Control   Contraction Metrics
  The problem under consideration is the synthesis of a distributed controller for a nonlinear network composed of input affine systems. The objective is to achieve exponential convergence of the solutions. To design such a feedback law, methods based on contraction theory are employed to render the controller-synthesis problem scalable and suitable to use distributed optimization. The nature of the proposed approach is constructive, because the computation of the desired feedback law is obtained by solving a convex optimization problem. An example illustrates the proposed methodology. 
Humberto Stein Shiromoto and Ian R. Manchester
math.OC cs.SY