Date of Award
Master of Science (MS)
The scaling laws used to build and analyze a model of a high speed, high-rise elevator were formulated, and the effect of each parameter on the model scaling was investigated. The model was used to investigate the active control of the cable vibration during upward elevator movement and decreasing cable length. A Hat band was used to model the cable and to constrain transverse vibrations to a single plane. The motion profile of the elevator was successfully scaled, but it was found that bending stiffness of the cable, tension changes due to gravity and tension changes due to acceleration can not be fully scaled with a reasonably sized model.
Practical considerations in the design fabrication and use of the scale model were addressed. The problem of band slip, structure vibration, accelerometer bias-voltage drift, boundary condition and band warp were investigated and possible solutions explored. Band slip was reduced by coating the motor pulley with a plastic substance and can be further reduced by increasing the wrap angle of the band around the motor pulley. Structure vibration can be improved with a more rigid structure, but the structural vibrations that were encountered had a minimal effect on the results. Accelerometer bias- voltage drift was minimized by insulating the accelerometer and by judicious combinations of signal conditioners and measurement devices. Boundary conditions of the band were met by creating a band guide to provide position and slope constraints. Band warp had t'ttle effect on the act ■ »e control and v us -..mimi/ed by using the band guide.
Active control of the band vibration was investigated using an accelerometer to sense band motion and a voice coil actuator to apply a force at the control point. The force required for vibration control is proportional to the velocity at the control point, which was obtained by integrating the accelerometer data numerically or using an analog integrator. The additional mass at the control point from the actuator and accelerometer counteract the damping effect of the active control on the band, and limit the damping to only the control point. A mass compensation force was added to the actuator output to counteract the effect of the mass. The best vibration reduction at the control point was obtained using the analog integrator, and the best vibration reduction of the entire band for the stationary case was obtained using the mass compensation force. Vibration control of the entire moving band was not seen, and more experiments combining the analog integrator with th> mass compensation force are required.
Teppo, Lars J., "Experiments on Active Control of Vibration of an Elevator Vable with Varying Length" (1999). Theses and Dissertations. 805.