Direct synthesis decoupling control for TITO processes with time delays

In this paper, a direct synthesis approach is proposed to design ETF based multivariable decoupling controllers. This new scheme is different from two existing ETF based decoupling schemes which involves the following steps: (1) by uniquely determine the ETFs for every transfer function element, the inverse matrix of transfer function matrix is approximated; (2) selecting the desired closed-loop system transfer function such that the resulted controllers are stable, causal and proper; (3) deriving the achievable full-matrix decoupling controller by specifying the tuning parameters. The effectiveness of the proposed design approach is verified by two multivariable industrial processes, which shows that it results in better overall system performance than other two ETF based schemes.