Independent-of-delay stability of nonlinear networked control systems by scattering transformation

In this paper a novel stability condition is derived for nonlinear networked control systems (NCS) with arbitrarily large constant time delay. The proposed approach is based on input-output models of the subsystems and the scattering transformation, well-known from teleoperation systems analysis with time delay. Passivity of the subsystems has been a prerequisite for guaranteed stability in systems using the scattering transformation. In this paper, the approach is extended to non-passive, non-linear subsystems. The main idea is the compensation of the non-passivity of the plant by excess of passivity of the controller and vice-versa. A numerical example demonstrates that even unstable plants can independently of the constant delay be stabilized over the network.