Active Control Of Horizontal Vibrations For High-Speed Elevator

With the development of high and super-high buildings, elevator speed is now improving faster and faster, which results in serious horizontal vibrations. These vibrations can reduce the passengers'ride comfort and even the elevator's service life. Suppression method of horizontal vibrations is therefore required for high-speed elevators. The conventional horizontal vibration reduction techniques include improving the guide rails'quality and using passive guide roller system with stiff spring. These passive suppression methods need no power supply and have the advantages of simple structure,low price and high reliability and can work well when the elevator speed is low. But they cannot do with the increasing elevator speed. Active vibration reduction techniques can flexibly cope with the new situations and have good effects and have been used widely. Accordingly, studies on the active suppression method of horizontal vibrations for high-speed elevators have been advanced.We carry on the study of active control of horizontal vibrations for high-speed elevator in this dissertation. First the mathematical model of the horizontal vibrations for elevator is given, then a new type of active guide roller system based on hydraulic actuator is designed, and the control strategy is developed to control the hydraulic actuator. Computer simulations and experimental tests are performed to verify the effectiveness of the hydraulic device and its control strategy. Last, the robust stabilized control of the position and attitude of the elevator cage is researched.Considering the real-time simulation and the convenience of the control research about the horizontal vibrations, a dynamic model about the elevator horizontal vibrations should be presented. Precision of the model would have strong effect on the effectiveness of the response analysis and the efficiency of the controller to be developed. The space dynamic model of the elevator cage is developed based on the theory of rigid body dynamics. The motion of the elevator cage is resolved into translation and rotation round the mass center of the cage. Motion equations of the cage are given according to Newton's second law of motion and Euler equations. The guide rollers are modeled as mass-spring-damper units. Simulation model of the horizontal vibrations of elevator is developed in MATLAB/Simulink environment and simulations are executed using the measured guide rail unevenness data. Simulation results of the horizontal acceleration and the power spectral density are identified with the testing results, which verify the correctness and the accuracy of the model. This model can be used for future simulation analysis and the control research. There are many reasons contributing to the horizontal vibrations of elevators. These horizontal vibrations are mainly generated by the irregularity of the guide rails, especially for the elevators traveling at the velocity below 5 m/s. As the three rollers of the guide system can weaken the horizontal vibrations from the irregularity of the guide rails and provide good ride comfort, developing a new type of active guide roller system with good ability of vibration isolation is very important. So a new type of active guide roller system based on hydraulic actuator is proposed in this dissertation. First the structure and the working principle of the hydraulic active guide roller system are analyzed. The mathematical model of the system is given. Then the logical thresh-hold controller and the fuzzy logic controller with preview compensation are designed, respectively. Simulation software is developed utilizing the toolbox and the function of MATLAB/Simulink. Computer simulations are performed to verify the effectiveness of the hydraulic device and the superiority of the fuzzy logic controller with preview compensation. Simulation results also give the conclusion that as long as the the oil pressure of the hydraulic cylinder be kept the objective value with permitted error range, the horizontal vibrations of the elevator would be kept within the permitted range and ensure the passengers'ride comfort.Then test rig is designed based on the working principle of the hydraulic active guide roller system and the simulation results. The test rig is made up of a guide rail simulator, a hydraulic station and a single-chip-microcomputer based control system. Hydraulic dynamic characteristic examination and the active control experiments are executed using the test rig. Optimization and comparison of different control methods are also given. Experimental results show that the hydraulic system can respond rapidly and stably, and can confine the oil pressure in the permitted range. Of all the control methods, the fuzzy logic controller with preview compensation has the best performance. The experimental results are consistent with simulation results.Taking account of the characteristics of nonlinearity,parameter uncertainties and external disturbances of the elevator cage, the position and attitude stabilization of the elevator cage is performed so that the horizontal vibrations of elevator can be attenuated more effectively in any case. Input/output feedback linearization approach is used to realize the linearization of the attitude model first, and robust controller is designed using Lyapunov method. To simplify the controller design, the position controller and the attitude controller are designed based on the translation model and the rotation model, respectively. Placement,velocity and acceleration feedback and the Lyapunov method are used to design the position controller, pole placement and Lyapunov method are used to design the attitude controller. Simulation is performed in MATLAB/Simulink environment. The results demonstrate the effectiveness of the proposed controller, the position and attitude of the elevator cage are stabled successfully and the horizontal vibrations of the elevator can be reduced effectively in the presence of the parameter uncertainties and the external disturbances. This work supplies an efficient way to future research for better effect of horizontal vibrations control.The rapidly developing economy and architecture industries decide the great requirements of high-speed and super high-speed elevators in domestic market. The study on active control of horizontal vibrations for high-speed elevator in this dissertation could provide a helpful reference for the development of high-speed and super high-speed elevator and is very important for local elevator industries.