Efficient feedforward sloshing suppression strategy for liquid transport

Abstract

This paper introduces an advanced feedforward control method to suppress sloshing in high-speed liquid container transfers in robotic systems. Three key concepts are combined: (1.) A virtual pendulum tray is envisaged to suspend the liquid container. By moving only the virtual pivot, the resulting container motion robustly reduces sloshing. (2.) A geometric condition is found for the virtual tray/container assembly to fully suppress one specific sloshing mode, allowing rapid transfers in a way that the dominant sloshing dynamics is fully suppressed. (3.) An analytic feedforward trajectory control based on differential flatness is formulated to design fast and efficient rest-to-rest transport manoeuvres. Any sloshing of modelled higher modes which is excited during the manoeuvre is accurately stopped at the end of such a manoeuvre. The resulting control law is computationally simple and achieves excellent sloshing-suppression performance. The concept is validated via simulations, finite-element analyses, and experimental tests, proving excellent theoretical and real-world performance and showing high robustness even with variations in the liquid filling level.