Analysis and synthesis of combined cooperative control and topology control over wireless network models

PIs: Hannes Frey (U Koblenz-Landau), Herbert Werner (TU Hamburg-Harburg)

In this project we consider cooperative control of mobile agents or nodes that interact over a wireless network. The network is set up by the nodes, i.e. no external communication infrastructure is assumed. Due to hardware constraints, in many cases only distributed approaches can be implemented. In such distributed cooperative control schemes, where each agent is equipped with a local control unit, the overall system performance is achieved by information exchange over a wireless communication network. Due to the broadcast property of the wireless network, agents can send samples in one transmission to their immediate neighbors. The subset of neighbors which further process the received samples in their local control is described by the interaction topology. This is a subgraph on top of the wireless communication graph. It is evident that a change in the topology as well as non-ideal communication will affect the performance and robustness of the interconnected system.

Cooperative control of multi-agent systems, as well as topology control in communication networks, have been studied extensively, but separately. Research on cooperative control of multi-agent systems usually assumes the interaction topology to be given (possibly uncertain). Research on topology control usually aims at improving the network in the sense of communication properties. However, as the interaction topology in a network of mobile agents has a considerable effect on the achievable cooperative control performance, a control scheme that combines dynamic control of the agents’ motion with adapting the interaction structure to the time-varying conditions of the communication network is expected to significantly improve the achievable performance. To the best of the applicants’ knowledge, to date such a combined control scheme has not been reported in the literature.

Objectives

  1. Local topology control will maintain the highest level of algebraic connectivity (aiming at high performance and robustness) while taking into account SINR constraints. This will be achieved by control of the wireless network graph and the interaction graph. Methods of investigation are graph spanners, backbones, and node relocation.
  2. A distributed cooperative control scheme will be developed for LPV agent models and gain- scheduled local feedback controllers; this will allow to consider mobile robots and vehicles subject to nonholonomic constraints. Analysis and synthesis conditions will be derived that guarantee stability and performance in the sense of the L2 -norm, with a complexity independent of the number of agents while taking constraints on communication resources into account.
  3. Local information about network properties will be gathered and used for topology control as well as for cooperative control to adapt interconnection weights. Our focus is on distributed and local solutions with the goal to support any system scale.
  4. Proof of concept will be given by simulation studies based on source-seeking scenarios, which will be selected to highlight the various features of the proposed integrated collaborative control and topology control scheme.

Involved PhD candidates

  • Adwait Datar (TU HH)
  • Daniel Schneider (U Koblenz-Landau): (2012-2015) Working student/intern at Nuance Communications, site Ulm, (2016) Diploma (M.Sc.) in Mathematics, Ulm University, (2017) Research fellow at University of Koblenz within the project analysis and synthesis of combined cooperative control and topology control over wireless network models.

Publications

  1. Furugh Mirali and Herbert Werner: Distributed weighting strategies for improved convergence speed of first-order consensus, American Control Conference (ACC), IEEE, 2017.
  2. Furugh Mirali, Antonio Mendez Gonzalez, and Herbert Werner: First-Order Average Consensus for Cooperative Control Problems Using Novel Weighting Strategies, IFAC-PapersOnLine 50.1 (2017): 14302-14307.
  3. Adwait Datar, Daniel Schneider, Furugh Mirali, Herbert Werner, Hannes Frey: A Memory Weighted Protocol for Sampled-Data Systems Subjected to Packet Dropouts, American Control Conference (ACC), IEEE, 2018.
  4. Shashank Jadhav, Adwait Datar, Herbert Werner: Distributed Approach to Dynamic Quantization for Multi-Agent Systems, American Control Conference (ACC), IEEE, 2018.