This article focuses the denitrification processes control of selective catalytic reduction, which faces great challenges caused by high-order dynamics, strong nonlinearity, wide-range load variations, and multisource disturbances. A modified active disturbance rejection control based on gain scheduling (MADRC-gs) is proposed. A parameter-switching methodology with the selected scheduling parameter is provided and the visual analyses of performance guarantees are analyzed. MADRC-gs is applied to a practical denitrification process of an in-service 660MW power plant. Actual operational data illustrate that MADRC-gs can reduce hourly average integral absolute error by about 22.61% and 43.18% in high-load and low-load ranges, respectively. Even though the power plant experiences lifting and lowering powers frequently, MADRCgs can still obtain better control performance compared to the original controller and MADRC, and show a promising application potential in energy and chemical industries.

This paper presents a new design methodology for robust fractional-order controllers with more than three parameters for first-order plus dead time systems using the synthesis scheme of the ‘more flat phase’ idea for a fractional-order controller with [proportional integral derivative] (FO[PID]) structure. The stability region of the FO[PID] controller and the synthesis scheme with the ‘more flat phase’ idea are illustrated through a simulation example. The corresponding pseudo-codes of the synthesis scheme are also summarised. The implementation and approximation error of the FO[PID] controller are also discussed. Likewise, the superiority of the FO[PID] controller designed with the ‘more flat phase’ idea is verified by additional simulations and experimental results where the closed-loop system with FO[PID] controller is not sensitive to the variations of the loop gain, ensuring satisfactory control performance. Obtained results show high potential in practical industrial applications.

High precision motion control is the key to complete the refined operation tasks for cable-driven continuum robots. However, the existence of model inaccuracy and actuator saturation pose great challenges to the high precision motion control of cable-driven continuum robots. This article proposes an extended state observer (ESO)-based antisaturation control scheme for cable-driven continuum robots with consideration of unmodeled dynamics and actuator saturation. First, the dynamic model of the cable-driven continuum robot is derived. To facilitate the design of the overall control scheme, the driving input dimension of the dynamic model is reduced from three to two based on the principle of space rotational symmetry. Taking the actuator saturation into consideration, the saturated dynamic model of the cable-driven continuum robot is further developed. Then, an ESO is designed for the saturated cable-driven continuum robots to estimate the unmodeled dynamics, and an auxiliary system is proposed to handle the actuator saturation. Hereby, a novel control law based on the ESO and auxiliary system is put forward to compensate for estimated unmodeled dynamics and actuator saturation. Moreover, the stability of the closed loop system is analyzed by Lyapunov method, and a practical and effective tuning method is provided to optimize the parameters of the proposed control scheme. Finally, comparative simulations and experiments are conducted to verify the effectiveness of the proposed control scheme.