Horizontal Insertion of a Ring Onto a Shaft Using a Gantry Crane With Minimal Sensors

While manufacturing heavy and large machinery, the insertion of crane-hung heavy parts into horizontal holes is often required. This paper presents a method outlining the horizontal insertion of a ring onto a shaft using a gantry crane with a single cable attachment. We exploit the underactuated nature of the single-cable crane system to prevent the hung object from being over-constrained, and allow it to gently interact with the shaft. Simply measuring the tilt angle of the ring with an IMU as it interacts with the shaft face allows a robotic crane to estimate the direction of misalignment of the ring relative to the shaft. A 3D kinematic analysis of this tilting process is performed to obtain the conditions under which the tilting angle can be measured stably. Based on the analysis, a recursive procedure for reducing the misalignment is obtained, and its convergence conditions are discussed. Furthermore, the conditions for jamming-free horizontal insertion are obtained. The autonomous horizontal insertion method is implemented on an overhead crane robot to verify the algorithm and demonstrate the feasibility.