Internal Model Control: Efficient Disturbance Rejection for Dead-Time Process Models with Validation on an Active Suspension System

Internal Model Control algorithms have numerous advantages, linked to the simplicity of the tuning procedure, the intrinsic dead-time compensation, reasonable robustness. In this paper, a novel idea for tuning an optimized IMC filter for input or load disturbance rejection is used and validated experimentally on a poorly damped process, an active suspension system. The core principle of the design is that the disturbance filter compensates for the process dead-times, provided that the disturbances have a stochastic nature with the spectral energy centered in a narrow frequency band (such as quasi-periodic disturbances). Diophantine equations are used to compute the disturbance filter coefficients. The experimental results show that the novel IMC controller improves the rejection capabilities of the standard default IMC algorithm. Validation is performed considering variations in the disturbance frequency. An adaptive suspension control situation is also tested, with an adapted IMC controller improving even further the disturbance attenuation properties of the proposed optimized IMC.