A Multi-mode Switching-based Command Tracking in Network Controlled Systems with Pointwise-in-Time Constraints and Disturbance Inputs

An approach to controlling networked systems with constraints is proposed. In this approach, a remote system located at a remote site switches between two feedback control laws, rejects unmeasured disturbances and responds to reference commands transmitted over a communication network from a server site. The network is unreliable in that unbounded latencies in message transmission and message losses may occur. Latencies can also occur due to time it takes to compute the new reference command on the server site (e.g., due to unknown time for numerical optimization to converge). It is furthermore desirable to minimize the amount of information communicated over the network. The adjustment of the reference command is performed by a reference governor located on the server site. It determines a virtual reference command which is as close as possible to the desired reference command and ensures that constraints will not be violated by the remote system even for the worst action by the disturbance. The reference adjustments are coordinated with controller switchings by the remote system to assure the desired behavior. A simulation example is reported to illustrate the basic approach.