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Two-Level Hierarchical Control of Hydraulic Elevator Speed


 The speed control of hydraulic elevators is usually carried out by PID controllers. But as the system properties slowly changes with the working situation, the control result is not satisfactory after long time operation. In this paper, a two-level hierarchical controller consist of an intelligent PI controller and a simple upper level expert controller is introduced. The expert controller is based on the expert knowledge accumulated from research experiences on the speed control of hydraulic elevators. The controller is realized on a small chip computer system, which is cheap and flexible to use.