Structure Research And Applications Of Observer-based PID Control

Proportional-Integral-Derivative(PID)controller is the most common feedback control mechanism in industrial processes.Owing to the fixed structure of the PID control,its three parameters maintain a clear relationship with system performance,thus facilitating straightforward online tuning.Ninety percent of the control loops in the industry adopt the PID control structure.However,with the escalating complexity of industrial processes and increased uncertainty in controlled systems,traditional PID control exposes its structural deficiencies,encompassing the following pressing issues:1)the sensitivity of differential part to noise;2)design and implementation of high-order PID;3)representation and design of PID in state space;4)ambiguous correlation between the structure of PID and parameters with advanced control methodologies.To address these concerns,this dissertation proposes an Observer-based PID control structure,leveraging a state space depiction of PID control to bridge classical and modern control methods.This framework is subject to comprehensive analysis,design,and parameter tuning.The main research results are as follows:1.The state space form of traditional PID is analyzed,and the observerbased PID controller structure is proposed.The controller also has a fixed control structure,independent of the plant model.Then it is extended to the higher order case.Through the mathematical analysis of the transfer function of the controller,the generality of the Observer-based PID is proved.Any controller that can be written as a strictly proper controller can be converted to the Observer-based PID.Thus eliminating the structural limitations of traditional PID.2.Delving into the Observer-based PID architecture,analysis based on state space structure unveils its duality with linear active disturbance rejection control(LADRC).The feedback loop transfer functions of both exhibit transposition relations.Under specific conditions,identical disturbance rejection effects can be achieved.By harnessing this duality,the transformation relationship between LADRC and Observer-based PID parameters is derived..3.An observer-based PID parameter tuning formula is proposed for the firstorder plus time-delay plant.And for the benchmark system commonly used in the industry,the simulation results verifies the good control performance of the controller tuning formula proposed in this dissertation.This tuning formula’s efficacy is corroborated in an experiment involving temperature control susceptible to environmental interference within the Temperature Control Lab(TCLab),affirming the superior disturbance rejection capability of Observerbased PID obtained through the proposed tuning formula.4.A state feedback method based on pole placement is proposed to design PID control.This method requires the adjustment of two parameters,simplifying the design process and making it easy to understand and grasp.Addressing commonly encountered second-order systems with delay,higher-order PID controllers are designed and subsequently implemented through the Observerbased PID structure.Simulation results show that the proposed method can achieve better control performance.5.Focusing on the Automatic Voltage Regulator(AVR),an Observer-based PID controller is designed.Through a comparative analysis with PID control based on teaching-learning optimization and the LADRC control methods,the simulation results reveal that the Observer-based PID proposed in this dissertation exhibits stronger robustness and disturbance resistance.This control method is suitable for engineering practices and possesses significant application value.