A High-Accuracy Car Level Compensation Device for Hydraulic Elevators (Stabilization with Estimated Acceleration Feedback)

Improved response and stability of a high-accuracy car level compensation device for hydraulic elevators is examined. The device adjusts the car position error caused by passengers getting on or off. The previous compensation device is used an electro-hydraulic position servo system. It is improved by introducing an observer to estimate the car acceleration and applying a pseudo-acceleration feedback control. The performance of the modified compensation device is examined by a stability analysis and experiments, and it is shown that the proposed control method halves the car position overshoot in comparison to the conventional device and the settling time is 0.7 s.