Set-point tracking semi-automatic control of interconnected systems with input disturbances

This paper presents the novel concept of incrementally accumulative quadratic constraint (IAQC) and its use in the constrained stabilisation for complex interconnected systems in set-point control (set-point tracking) schemes. IAQC is an incremental and discrete-time version of the integral quadratic constraint (IQC) in the time domain. A constructive method of stabilising agents for use with decentralised model predictive controllers (MPC) in semi-automatic modes is subsequently introduced. Here, the nonzero set-point control and local disturbances are effectively dealt with by employing a quadratical dissipativity criterion w.r.t control inputs and plant outputs, and a norm bounded gain for the disturbance input and plant output pair. The procedure of IAQC-based stabilising agents accommodates the coexistence of feedback control and man-in-the-loop regulation. The multiplier matrices of the IAQC are updated on-the-fly to assure the constrained feasibility. The control application of a counter-current washing circuit in a hydrometallurgical process is simulated to illustrate the viability of the presented stabilising agent. © 2011 ENGINEERS AUSTRALIA & AUSTRALIAN OPTICAL