Research On Self-sensing And Self-Powered MR Damper And Its Control System

Due to the advantages of low power loss, high output force, quick response, and so on, MR(magnetorheological) dampers have been a new generation of damping device with high performance. The theoretical and experimental studies on MR dampers have made great progress, but the complex configurations for the control system, like external power supply, sensors and controllers, greatly limit its application range to some extent. To solve this problem, the self-sensing MR damper based on the optical sensor and the self-powered damper on piezoelectric or magnetoelectric energy harvesting structure were explored, and the specific contents were summarized as follows:(1) In view of the disadvantages of leakage flux, larger volume, low integration and poor linearity under high speed, the optical sensor with lower power consumption and smaller volume was designed and prepared based on the working principle of the optical mouse. The sensor can be easily integrated into the MR damper to realize the non-contact measurement of the piston rod velocity. The relative error of the sensor from the average velocity replacing the instantaneous velocity was theoretically analyzed. The effectiveness of the velocity self-sensing unit was verified by performance test of the prototype. Combining the sensing unit and damper, the velocity self-sensing MR damper based control system was experimentally investigated and the characteristics of the damping force were tested and analyzed adopting velocity feedback control strategy. According to the results, the practical force of the self-sensing damper can basically trace the theoretical force, but lightly lags behind the theoretical force in phase.(2) Only a few watts are needed for MR damper to realize considerable regulation of the damping force. Owing to that, an adaptive MR damper based control system in combination with a piezoelectric component was put forward. With the improvement of the simple Bang-Bang control strategy, the strategy for the adaptive system was proposed. Based on the principle of compatibility of deformation and the energy requirement, the design method of the piezoelectric energy harvesting device was given out. Taking the N26 cable model from the Shandong Binzhou Yellow River Highway Bridge and one five-storey building model for example, the adaptive systems were designed and simulated to validate their feasibility and effectiveness.(3) Under the force excitation with low-frequency and high-amplitude, three piezoelectric stacks with 30, 50 and 80 layers and with area 32×32mm2 were tested when the stack circuit was open or connected with external resistance. The regular properties of the piezoelectric voltage coefficient and output power were studied with different pre-stresses, the excitation frequencies and amplitudes. The output power is greatly reduced when the presstress is beyond the limit of the stack. To satisfy the power requirement of a MR damper with capacity of 1t, the feasibility of power matching and impedance matching were analyzed according to the test results. It was indicated that the required power can be provided but impedance matching cannot yet be realized.(4) On account of the drawbacks of existing self-powred MR dampers based on magnetoelectric energy harvesting unit, a novel highly integrated self-powered MR damper was proposed with the ball-screw and rotary permanent magnet DC generator incorported. Considering the core loss effect on the magnetizing current, the properties of the proposed damper were theoretically analyzed, and its mechanical model was developed. A prototype with capacity of 10 k N was fabricated and experimentally investigated. The electrical and mechanical properties of the proposed damper were studied with external excitations. On the basis of the test results, the theoretical model was identified and modified.(5) By incorporating the proposed MR damper, a new self-powered control system was built and its control strategy was compared with the existing passive control strategy and semi-active control strategy. The principle of equal maximum control force and maximum demanding power were used to the original selection of the damper paramerters of the control system. The control efficacy was used to optimaize the parameter selection. For one five-storey isolation building model, the control system was anzlyzed to validate the feasibility of system. And then the system with the optimal parameters was simulated and compared with conventional systems with different control strategies to verify the system effectiveness.