Passivity-Based Trajectory Control of an Overhead Crane by Interconnection and Damping Assignment

This paper presents a passivity-based control scheme for the two main axes of a 5 t-overhead crane, which guarantees both tracking of desired trajectories for the crane load and an active damping of crane load oscillations. The passivity-based control is performed by interconnection and damping assignment according to the IDA-PBC approach for underactuated systems. The tracking capabilities concerning desired trajectories for the crane load can be significantly improved by introducing feedforward control based on an inverse system model. Furthermore, a reduced-order disturbance observer is utilised for the compensation of nonlinear friction forces. In this paper, feedforward and feedback control as well as observer based disturbance compensation are adapted to the varying system parameters rope length as well as load mass by gain-scheduling techniques. Thereby, desired trajectories for the crane load position in the 3-dimensional workspace can be tracked independently with high accuracy. Experimental results of an implementation on a 5 t-crane show both excellent tracking performance with maximum tracking errors of 2 cm and a high steady-state accuracy.