Active Control Of Structural Vibration Based On Rotating Actuator

For civil engineering structures,installing active mass damper(AMD)is an effective method to reduce the dynamic responses of the structure and avoid structure damage under external excitations,which is helpful for achieving a reasonable balance between economy and safety.Recently,hydraulic cylinders and electrical servo motors with mechanical transmission devices are mostly used actuators in traditional active mass damper system.However,both devices are limited in application for their insurmountable disadvantages.The concept of rotating actuator is introduced into active structural vibration control,via drawing lessons from the translational oscillator with rotating actuator in the field of underactuated mechanical systems,and thus a new type of AMD device,the active mass damper with rotating actuator(R-AMD)is proposed.Electrical drive system(rotational servo motor)is adopted as actuator in the novel R-AMD,which can overcome the problems of complex structure,contact force transmission,slow response and limited stroke which exist in traditional AMD usually.In order to analyze the effectiveness of R-AMD in structural vibration suppression,a single degree of freedom(SDOF)structure is adopted as the control target on which the R-AMD is installed.Taking the control-structure-interaction effect into consideration,the modeling of R-AMD/SDOF structure coupled system is accomplished,based on which the two differentcontrol modes,rotational control mode and swing control mode are proposed.The mathematical model of R-AMD/SDOF structure can be transformed into a three-order linear system with a first-order stable inner dynamic using the maximal feedback linearization technique.Then,linear pole assignment control scheme is designed and its constraints on system parameters are proposed.To break the limitation of linear control scheme based on maximal feedback linearization and improve the performance of R-AMD control system,the nonlinear optimal controller is designed using the θ-D approximation technique to investigate the optimal performance of R-AMD in vibration mitigation,during which the important role of diffeomorphism transformation of coordinates in making θ-D approximation technique applicable to underactuated systems is addressed.Considering civil structures usually bear uncertainties in mass and stiffness(e.g.caused by equipment installation or decoration),and external loads,the hierarchical sliding mode control method based robust controller is designed to enhance the robustness of the R-AMD control system to structural modeling errors and external disturbances.Experiments are carried out on experimental setup to verify the effectiveness of proposed control schemes.To avoid the difficulties of designing high order controller,information transmission in the centralized control scheme for vibration control of multiple degree of freedom(MDOF)structure,decentralized control is designed by placing multiple R-AMDs on different parts of MDOF structure.The R-AMD/MDOF structure coupled system are divided into multiple subsystems with uncertain interconnected terms,of which controllers are designed independently.Sliding mode control based robust decentralized control scheme and dynamic neural network based adaptive decentralized control scheme are proposed,via dealing the uncertain interconnected terms of decentralized subsystems with robust suppressing and adaptive identification respectively.Experiment results show that decentralized control schemes have superior performance in suppressing high-order vibration than centralized control.To simultaneously suppress wind-induced vibration of high-rise buildings in two orthogonal directions,the single actuator type R-AMD is designed and installed on the top floor of high-rise building.A decoupled sliding mode controller is designed based on the reduced-order model of R-AMD/structure coupled system.To test the effectiveness of the proposed control scheme,the 76-story benchmark building is adopted as target structure.In order to reduce the difficulty of controller design,the original 76-story benchmark building is simplified as a SDOF model in X and Y direction respectively.Simulation results show that bidirectional wind responses(displacement and acceleration)of 76-story benchmark building can be simultaneously suppressed using R-AMD.To overcome the problems of complex structure,slow response,contact force transmission,and limited stroke which exist in traditional AMD,an innovative AMD system with rotating actuator is proposed,and its applications in vibration mitigation of different structures such as SDOF structure,MDOF structure and high-rise building(wind-induced vibration)are investigated,during which,approaches of system modeling,parameter identification and control system design are presented.Besides,numerical analyses and experiments are conducted to verify the effectiveness of the control schemes and the active control device.The novel R-AMD is featured with small occupying space and ease of integration,which make the R-AMD more potential in engineering applications,especially in decentralized control of large-scale structure and occasion where space is limited.The R-AMD device,and the proposed nonlinear control schemes and decentralized control schemes are of some value in theory and engineering application.