Compensation-Signal-Based Dual-Rate Operational Feedback Decoupling Control for Flotation Processes

The flotation industrial process is a strong nonlinear and coupling multivariable cascade process with a structure of device and operational layers. To address its operational control problem, this article describes nonlinear dynamic characteristics and disturbances in both device and operational layers as the previous sample unmodeled dynamics and its change rate and proposes a compensation-signal-based dual-rate operational feedback adaptive decoupling control approach. First, a device layer controller consisting of a controller-driven model, a proportional–integral controller, an unmodeled dynamics compensator (UDC), and an unmodeled dynamics change rate compensator (UDCRC) is designed. Then, the device layer closed-loop system and the operational layer system are unified in the same time scale, and hence, a controlled plant model is obtained. A system identification algorithm is proposed to obtain the parameters of this model. With these parameters, an operational layer controller consisting of a controller-driven model, a proportional–integral–derivative controller, a feedback decoupling controller, an UDC, and an UDCRC is designed. Finally, convergence proofs of the proposed identification algorithm and the closed-loop system stability analysis are given, and emulation experiments in a hardware-in-the-loop system are used to verify the effectiveness of the proposed approach.