The Active Disturbance Rejection Control with a Square-Root Amplifier for Non-minimum Phase System
This paper adopts the active disturbance rejection control (ADRC) technology to control the non-minimum phase system (NMP). A new amplifier called square-root amplifier (SQF) is added in the ADRC to reduce the undershoot and the settling times of the step
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Abstract This paper adopts the active disturbance rejection control (ADRC) technology to control the non-minimum phase system (NMP). A new amplifier called square-root amplifier (SQF) is added in the ADRC to reduce the undershoot and the settling times of the step response. Simulation results are given to verify the effectiveness of the proposed scheme. Keywords Non-minimum phase system Square-root amplifier
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Active disturbance rejection control
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1 Introduction Non-minimum phase system is a kind of system with poles or zeros in the right-half plane (RHP). It is well known that the terrible characteristic is caused by the unstable zeros or the zeros in the right-half plane (RHP) [1]. For NMP system, the undershoot in the step response is always a headache, which means the high-frequency gain and low-frequency gain of the system have opposite signs [2]. To deal with the NMP system, the undershoot is to be reduced along with the system to be stabilized and the overshoot as well as the settling time to be reduced. Active Disturbance Rejection Control (ADRC) technique as an emerging technique has been widely used in solving various types of control problems [3]. And the applications of this technology are mostly confined to minimum phase system [2], while there are lots of non-minimum phase (NMP) system in the real world, such as flexible manipulators, vessels, aircrafts [4], and hydraulic turbines. T. Wu ⋅ W. Zhang (✉) School of Automation and Electrical Engineering, University of Science and Technology, Beijing, China e-mail: [email protected] W. Li Southwest Institute of Clean Energy and Electric Power System, Dali University, Dali 671003, Yunnan, China © Springer Science+Business Media Singapore 2016 Y. Jia et al. (eds.), Proceedings of 2016 Chinese Intelligent Systems Conference, Lecture Notes in Electrical Engineering 405, DOI 10.1007/978-981-10-2335-4_17
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The non-minimum phase behavior is generally determined by the system’s dynamic characteristics. In the real world we cannot just neglect the NMP phenomenon. The new control strategy, Active Disturbance Rejection Control, will be used to control the NMP system in the following parts. To achieve a better performance of NMP control systems, a new kind of amplifier called square-root amplifier (SQF) is added in the ADRC technique. The past researches have shown that the SQF can be used to improve the system’s rapidity without leading to a big overshoot [5], which means the rapidity of a system can be improved by SQF without strengthening the control force. Also the NMP system is wanted a smooth control signal which is usually coupled with a longer settling time. Maybe the SQF will bring us some good luck.
2 Active Disturbance Rejection Control Technique ADRC technique is a new control technique using extended state observer (ESO) to estimate the total disturbance and cancel it with a feedback compensation strategy. It makes the controller design much easier, as the plant is approximately reduced to a double integrator using ESO [6].
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