6533b834fe1ef96bd129e254

RESEARCH PRODUCT

Minimal-model for robust control design of large-scale hydraulic machines

subject

description

Hydraulic machines are in use where the large forces, at relatively low velocities, are required by varying loads and often hazardous and hard-to-reach environments, like e.g. offshore, mining, forestry, cargo logistics, and others industries. Cranes and excavators equipped with multiple hydraulic cylinders are typical examples for that. For design of the robust feedback controls of hydraulic cylinders, already installed into large-scale machines, there is a general lack of reliable dynamic models. Also the suitable and feasible identification techniques, especially in frequency domain, yield limited. This paper pro­poses a minimal-modeling approach for determining the most relevant open-loop characteristics of hydraulic cylinders installed on a bulk loader crane. The resulted model allows for robust control design without knowledge of the overall complex system behavior. The total system gain, non-negligible input dead-zone, and aggregated phase lag are identified from the simple open- loop experiments. An aggregated phase lag is captured for the assumed bandwidth of the system, and that without knowledge of the higher-order residual system dynamics. Based thereupon, the robust feedback position regulator is designed and extended by the velocity feed-forwarding. The proposed modeling approach, together with the designed control system, are evaluated on the third axis of a hydraulic loader crane.