This paper proposes a second-order sliding mode controller for a three-dimensional overhead crane in an extremely complicated operation with uncertain system parameters. Three actuators composed of trolley-moving, bridge-traveling, and cargo-hoisting forces simultaneously drive fine outputs comprising bridge motion, trolley translation, cable length, and two payload swing angles. Simulation and experiment are performed to investigate the controller qualities.

A 3D overhead crane is an underactuated system consisting of five outputs: trolley position, bridge translation, cable length, and two cargo swings. These outputs are controlled by three actuators for cargo hoisting, trolley motion, and bridge traveling. This study proposes the use of a nonlinear controller that performs five tasks concurrently: cargo hoisting, trolley tracking, bridge motion, payload vibration suppression during transport, and cargo swing elimination at the destination.

An overhead crane transfers the payloads of various volumes and weights depending on the each operation case. The friction factors characterized by damped coefficients can be changed in connection with operating environment. This study develops an adaptive version of sliding mode controller for the overhead cranes without priori information of system parameters composed of cargo mass and damped aspects.