Decentralized control of multirate systems subject to arbitrary exogenous signals

This paper considers the design of decentralized digital control systems where each output is measured at an its own rate, whereas the inputs are updated all together. Specifically, a solution is given to the problem of asymptotically zeroing the system error when the exogenous signals coincide with the free motions of any unstable system. The proposed controller is constituted by a time-invariant internal model of the exogenous signals and a decentralized periodic stabilizer