Angle tracking control of integrated hydraulic transformer inner loop servo system.

Integrated hydraulic transformer based on hydraulic common pressure rail system has significant energy saving effect. The control of the inner loop (i.e. valve-controlled hydraulic swing motor system) is closely bound up with the performance of the integrated hydraulic transformer. Considering the input delay, output constraints, and actual working conditions in the inner loop system, an extended state observer-based finite-time backstepping filter control strategy is designed to guarantee energy-saving performance. Firstly, an extended state observer is constructed to observe the state variables and acquire the estimated value of the unknown term. Secondly, the state equation of the system is transformed by the Pade approximation, and the robust controller is designed based on finite-time stability theory and backstepping algorithm to ensure the output of the system in the constraint set. Finally, the proposed control algorithm is compared with the traditional control algorithm through experiments, and the effectiveness is verified.