Flatness-based feedforward and modal model-predictive state-feedback control of a double pendulum bridge crane

Abstract

In some industrial crane applications the payload is fixed at a hook by lifting slings such as belts or chains. The payload mass is typically much larger than the hook mass yielding small but high-frequent double pendulum oscillations. The main control goal for such cranes is to actively damp the single pendulum motion. Such double pendulum cranes are often approximated by single pendulum models. However, this may yield control or observation spillover effects. The influence of neglecting the double pendulum motion on feedforward control is analyzed in this paper by simulations. Therefore, a flat parametrization is derived which can be applied to both single and double pendulum cranes by simply adjusting two parameters. Besides, a modal state-feedback controller (in combination with modal state estimation) is suggested to avoid observation spillover effects without the need of damping high-frequent double pendulum oscillations at the same time. The feedback control performance is validated experimentally on a laboratory bridge crane.