On active disturbance rejection control: Some improvements and extensions

In this paper, we summarize some of the improvements and extensions we have done to the active disturbance rejection control (ADRC) in recent years. Firstly, the improvement to ADRC is the proposition of a new separation principle (NSP) such that disturbance rejection and high precision output regulation can be implemented separately. Based on NSP, without using any observer or estimator, we can still reject disturbances and carry out the regulation effectively even for higher-order systems or multi-input-multi-output interconnected systems. Secondly, in order to meet the needs for the control of uncertain networked systems or complex systems, we extend the NSP and propose the stripping principle (SP). The method based on SP can remove all the interconnected parts, uncertainties and disturbances from the related subsystems, and make the synthesis of complex systems easier and effective. Thirdly, we sum up the methods on the stability analysis of the provided methods. Finally, we provide some applications related to the above methods, for example, the safety and comfort control of vehicles, the active control of noise suppression, and the synchronization control of complex systems which are with chaotic dynamics, etc.