Internal model control with feedback compensation for uncertain non-linear systems

Control of non-linear systems by model-based strategies is often affected by model uncertainties. For these systems, internal model control with feedback compensation (IMC-FC), which consists of a non-linear model control and an error feedback loop, to achieve disturbance attenuation and offset-free performance, is proposed in this study. The matching conditions for the uncertainties of non-linear systems are not necessary, and adjustable parameters can easily be tuned to satisfy the particular specification. The underlying theoretical approach for the feedback compensation is the Lyapunov stability theory. The effectiveness of the proposed approach is illustrated by a simulation example on the composition control of a continuous stirred tank reactor. The theoretical analysis and simulation results show that the proposed IMC-FC can reduce the effect of modelling uncertainties such that the performance of the control system is greatly improved.