A Control Approach to Bandwidth Management in Networked Control Systems

Bandwidth allocation techniques for control loops closed over communication networks are based on static strategies that ensure average control performance at the expense or permanently occupying the available bandwidth. We present a dynamic approach to bandwidth management in networked control systems that allows control loops to consume bandwidth according to the dynamics of the controlled process while attempting to optimize overall control performance. By augmenting the original state-space representation of each controlled process with a new state variable that describes the network dynamics, 1) the allocation of bandwidth to control loops can be done locally at run-time according to the state of each controlled process without causing overload situations and 2) control laws can be designed to account for the variations in the assigned bandwidth preventing the unexpected control performance degradation and even destabilization that would otherwise occur. Experimental data shows that this approach improves control performance with respect to the static strategy and uses less bandwidth.