Minimal Inputs/Outputs for a Networked System
Provides a fundamental theoretical result for control theory, offering a simple criterion for minimal actuation/sensing in networked systems.
This paper determines that the minimal number of inputs/outputs needed to guarantee controllability/observability of a system with a prescribed state transition matrix equals the maximum geometric multiplicity of that matrix, contrasting with NP-hard sparsest input/output problems.
This paper investigates the minimal number of inputs/outputs required to guarantees the controllability/observability of a system, under the condition that its state transition matrix (STM) is prescribed. It has been proved that this minimal number is equal to the maximum geometric multiplicity of the system STM. The obtained conclusions are in sharp contrast to those established for the problems of finding the sparest input/output matrix under the restriction of system controllability/observabilty, which have been proved to be NP-hard, and even impossible to be approximated within a multiplicative factor. Moreover, a complete parametrization is also provided for the input/output matrix of a system with this minimal input/output number.