The paper addresses the problem of reconciling the modern control paradigm developed by R. Kalman in the sixties of the past century, and the centenary error-based design of the proportional, integrative and derivati...The paper addresses the problem of reconciling the modern control paradigm developed by R. Kalman in the sixties of the past century, and the centenary error-based design of the proportional, integrative and derivative （PID） controllers. This is done with the help of the error loop whose stability is proved to be necessary and sufficient for the close-loop plant stability. The error loop is built by cascading the uncertain plant-to-model discrepancies （causal, parametric, initial state, neglected dynamics）, which are driven by the design model output and by arbitrary bounded signals, with the control unit transfer functions. The embedded model control takes advantage of the error loop and its equations to design appropriate algorithms of the modern control theory （state predictor, control law, reference generator）, which guarantee the error loop stability and performance. A simulated multivariate case study shows modeling and control design steps and the coherence of the predicted and simulated performance.展开更多
The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times i...The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modi fied controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms,(reference value step increase of 50 mg·L-1) and 0.01 days for the concentration of oxygen(reference value step increase of 0.1 mg·L-1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of5 × 103m3·d-1are small. Changes in the reference values of oxygen and microorganisms(increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance(increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.展开更多
There exists an increasing need for precision measurement&pointing control and extreme motion stability for current and future space systems,e.g.,Ultra-Performance Spacecraft(UPS).Some notable technologies of real...There exists an increasing need for precision measurement&pointing control and extreme motion stability for current and future space systems,e.g.,Ultra-Performance Spacecraft(UPS).Some notable technologies of realizing Ultra-Pointing(UP)ability have been developed particularly for Ultra-accuracy Ultra-stability Ultra-agility(3 U)spacecraft over recent decades.Usually,Multilevel Compound Pointing Control Techniques(MCPCTs)are deployed in aerospace engineering,especially in astronomical observation satellites and Earth observation satellites.Modern controllers and/or algorithms,which are a key factor of MCPCTs for 3 U spacecraft,especially the jitter phenomena that commonly exist in a UPS Pointing Control System(PCS),have also been effectively used in some UP spacecraft for a number of years.Micro-vibration suppression approaches,however,are often proposed to deal with low-level mechanical vibration or disturbance in the microgravity environment that is common for UPS.This latter approach potentially is one of the most practical UP techniques for 3 U tasks.Some emerging advanced Disturbance-Free Payload(DFP)satellites that exploit the benefits of non-contact actuators have also been reported in the literature.This represents an interesting and highly promising approach for solving some challenging problems in the area.This paper serves as a state-of-the-art review of UP technologies and/or methods which have been developed,mainly over the last decade,specifically for or potentially could be used for 3 U spacecraft pointing control.The problems discussed in this paper are of reference significance to UPS and millisecond optical sensors,which are involved in Gaofeng Project,deep space exploration,manned space flight,and gravitational wave detection.展开更多
文摘The paper addresses the problem of reconciling the modern control paradigm developed by R. Kalman in the sixties of the past century, and the centenary error-based design of the proportional, integrative and derivative （PID） controllers. This is done with the help of the error loop whose stability is proved to be necessary and sufficient for the close-loop plant stability. The error loop is built by cascading the uncertain plant-to-model discrepancies （causal, parametric, initial state, neglected dynamics）, which are driven by the design model output and by arbitrary bounded signals, with the control unit transfer functions. The embedded model control takes advantage of the error loop and its equations to design appropriate algorithms of the modern control theory （state predictor, control law, reference generator）, which guarantee the error loop stability and performance. A simulated multivariate case study shows modeling and control design steps and the coherence of the predicted and simulated performance.
文摘The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modi fied controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms,(reference value step increase of 50 mg·L-1) and 0.01 days for the concentration of oxygen(reference value step increase of 0.1 mg·L-1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of5 × 103m3·d-1are small. Changes in the reference values of oxygen and microorganisms(increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance(increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.
基金support from the National Natural Science Foundation of China(No.51905034)。
文摘There exists an increasing need for precision measurement&pointing control and extreme motion stability for current and future space systems,e.g.,Ultra-Performance Spacecraft(UPS).Some notable technologies of realizing Ultra-Pointing(UP)ability have been developed particularly for Ultra-accuracy Ultra-stability Ultra-agility(3 U)spacecraft over recent decades.Usually,Multilevel Compound Pointing Control Techniques(MCPCTs)are deployed in aerospace engineering,especially in astronomical observation satellites and Earth observation satellites.Modern controllers and/or algorithms,which are a key factor of MCPCTs for 3 U spacecraft,especially the jitter phenomena that commonly exist in a UPS Pointing Control System(PCS),have also been effectively used in some UP spacecraft for a number of years.Micro-vibration suppression approaches,however,are often proposed to deal with low-level mechanical vibration or disturbance in the microgravity environment that is common for UPS.This latter approach potentially is one of the most practical UP techniques for 3 U tasks.Some emerging advanced Disturbance-Free Payload(DFP)satellites that exploit the benefits of non-contact actuators have also been reported in the literature.This represents an interesting and highly promising approach for solving some challenging problems in the area.This paper serves as a state-of-the-art review of UP technologies and/or methods which have been developed,mainly over the last decade,specifically for or potentially could be used for 3 U spacecraft pointing control.The problems discussed in this paper are of reference significance to UPS and millisecond optical sensors,which are involved in Gaofeng Project,deep space exploration,manned space flight,and gravitational wave detection.
