Research On Car Lateral Vibration Suspensions For Super High-Speed Elevators

The car lateral vibration caused by the unevenness of the guide-rails and air disturbance has become more considerations, as the running speed of elevators becomes faster. It has been reported that the car lateral vibration of super high-speed elevators can't satisfy the general requirements of the riding comfort when their running speed is lager than a certain value. The passive and active control methods and their corresponding actuators have been developed to suppress the car lateral vibration, including active roller guides (ARG) and cabin actuators (CA). However, seldom researches have been done on the characteristics of these two different actuators. At the same time, because there are couplings between the passive and active controls,"they often compete with each other, rather than help". In order to obtain the optimal system performance and the minimum control cost, the systematic integrated passive and active control design method should be used to optimize the car lateral vibration suspension systems instead of the sequential counterpart, which designs the passive control first and then optimizes the active one conventionally.Integrated design of elevator car lateral vibration suspensions is a multi-objective optimization problem, which is satisfied by a series of solutions called Pareto optimal sets. When the weight-based single objective optimization method is used to solve the multi-objective integrated optimization problem, the Pareto optimal solutions are obtained by iteratively running the weight-based method with a set of precisely selected weights, which greatly increases the computation intensities and complexities.In this paper, the car lateral vibration model based state equations is established with the guide-rail unevenness as the explicit disturbances firstly, and then the integrated design problem of car lateral vibration suspension is formulated to optimize the system performance (car vibration) and the control cost, which are expressed by H2 norms. In this problem, the stiffness and damping coefficients of the roller guides and supporting rubbers and the active controller are simultaneously considered as the design variables. The integrated design approaches of car lateral vibration suspensions are classified into two categories: integrated design with structure-specified controllers and integrated design with optimal controllers. The integrated design problem with structure-specified controllers is solved directly by Multi-objective Genetic Algorithm (MOGA) based on constrained non-dominating sorting without providing any objective weights. And the combined strategies of improved Evolutionary Dynamic Weighting Algorithm (EDWA) and Linear Matrix Inequalities (LMI) are proposed to solve the second one, where the objective weights are varying with the evolutionary generation. Both of approaches can obtain all the uniformly-distributed Pareto fronts in a single run, which greatly reduces the computation intensities and complexities.The optimization results show that the close-loop system obtained by the integrated design methods can suppress the car lateral vibration of super high-speed elevators over a wide range of velocities. What's more, based on these two methods, the characteristics of the different actuators have been studied in details. The influence of the controller strategies and orders on the close-loop system performance is also discussed. The following four aspects are described:1) Considering the characteristics of the elevator industry, the integrated design problem of car lateral vibration suspensions with structure-specified controllers and ARG is established. This optimization problem is solved by MOGA based on constrained non-dominated sorting strategies. The optimization results show that the integrated design method can find the better combination of passive and active controls, so it can obtain superior performance compared with the initial design. ARG with the sky-hook damper strategy get almost the same vibration suspension efficiency as those with a higher-order controller, but they can't suppress the car anit-phase model caused by the air disturbance. It also can be found that ARG equipped at the four corners of the car can get better system performance than those equipped only on its lower parts.2) The integrated design problem of car lateral vibration suspensions with H2 optimal controllers and ARG is established, which is solved by the combination strategies of improved EDWA and LMI. In this problem, the cabin's accelerations are regarded as the feedback states. The optimization results verify the effectiveness of this method. And the integrated close-loop system with H2 optimal controllers can suppress both the guide rail and the air disturbances effectively.3) The integrated design problem of car lateral vibration suspensions with structure-specified controllers and CA is established, which is solved by MOGA to get the uniformly-distributed Pareto fronts. The optimization results show that only the floor CA is needed to satisfy the requirement of the system performance. The suspension efficiency obtained by integrated design with the 1-order controller is better than that with the controller adopted the sky-hook damper strategy (0-order controller), but it cannot get better when the controller's order become higher than 1 order. CA with the sky-hook damper strategy can get superior suspension performance compared to ARG with the same control strategies because of the different actuator and sensor positions.4) Design of car lateral vibration test-bed and experimental study on ARG. The simulation test-bed is designed according to the characteristics of the car lateral vibration. The simulation and experimental results verify that the integrated design can obtain better system performance compared with the initial design, and that ARG only installed in the lower parts of the car can suppress the cabin and frame's in-phase modes when the sky-hook damper strategy is applied, but can't suppress their anti-phase modes effectively.Above all, this paper puts emphases on the following aspects: the integrated design methods of car lateral vibration suspensions based on the structure-specified controllers and the optimal ones; comparisons on the characteristics of the two actuators (ARG and CA) based on Pareto fronts; design of car lateral vibration test-bed and experimental study on ARG.