Modeling and verification of multi-winding rope winch for facade operation

Abstract

This paper presents the modeling and verification of a multi-winding rope winch for facade operation. The winch enables a robot to ascend and descend high-rise buildings using synthetic fiber ropes and can easily be installed on buildings without a gantry. To improve the positioning accuracy for facade operation, a rope-winch position model that accurately tracks the position of the winch is derived. This model comprises deformation from the rope tension and displacement from slip between the rope and winch. Owing to the nonlinearity of the synthetic-fiber-rope characteristics, the stiffness levels with and without preload are derived separately. Based on the rope stiffness, deformation from the elasticity is analytically derived. The slip length is estimated using the capstan equation, and the total slip through the differential gear mechanism is estimated. To verify the model, experiments are conducted to track the positional profile through the application of open-loop control and feedforward control on a test bench. The prediction model can maintain the root mean square error of the position tracking within 0.8%.