Research On The Velocity Control Of Hydraulic Elevators

Hydraulic elevators, as one type of vertical transport tools, are widely applied in low and middle height buildings. Hydraulic elevators possess excellent features which traction elevators do not have. They are developing rapidly overseas and have a huge market room in the near future in domestic.Energy saving, stability and robustness of the system controlling are tough problems of hydraulic elevators. Energy saving, velocity feedback control and non-leveling displacement control of the load-feedback hydraulic elevator are the contents in this research. Modeling and Simulation are both important for the system design. The up and down models of the load-feedback hydraulic elevator are set up by theory analyzing. The dynamic and static state characteristics of the system are studied by computer simulations and experiments. The results of simulations coincide with the experiments. Also a new type capacitive transducer is developed in this paper. This transducer has a lot advantages such as in waterproof, dustproof and electromagnetic disturbance resistance because of its special mechanical structure and electrical circuits. The resolution of the product reaches 0.0015 degrees (linear value is 0.067mm) with the maximum velocity to 3m/s, and the displacement range tends to 386m. Hence a velocity detecting and controlling system of the hydraulic elevator based on this capacitive transducer and microcomputer is designed. Simulations and experiments research indicate that the algorithms as parameters self-tuning optimizing PID, single neural element adapting PID, and compound controlling of CMAC and PID, applying to the real time velocity control system yield quickly responsibility and great stability of the system.In general, targets of this project have been completed successfully. The load-feedback hydraulic elevator energy saving, new type of capacitive transducer, no-leveling displacement control and the algorithms of neural networks real-time adaptive control method are inventive researches. All researches and conclusions drawn in this paper are significant for the domestic hydraulic elevator developing.