Output feedback control for energy-saving asymmetric hydraulic servo system based on desired compensation approach

Eliminating substantial energy dissipation and achieve precise tracking accuracy are both vital for the hydraulic actuated servo system, especially in the face of the global energy crisis and energy exhaustion. When an asymmetric hydraulic cylinder moves symmetrically back and forth, the pressure and flow in the two chambers differ a lot, resulting in huge energy loss. To reduce the throttle loss and overflow loss of the system simultaneously, a hydraulic servo system structure based on dual hydraulic accumulators is proposed in this paper. On the one hand, two hydraulic accumulators with different pressure levels can switch the supply pressure based on the motion direction of the hydraulic cylinder to reduce the throttle loss. On the other hand, the hydraulic accumulators can absorb the excess flow to reduce the overflow loss. In addition, an output feedback controller based on the desired compensation approach is proposed to guarantee the control performance. First, the pressure and velocity signals are replaced by their desired values to reformulate the state equation. Subsequently, the state variables and lumped disturbance are estimated by the low-pass filter-based observer. Compared with the conventional method, this method has the advantages of low noise interference, fewer control parameters and intuitive form. To validate the feasibility of the proposed strategy, the stability of the controller and the energy efficiency of the system are analyzed. The results indicate that the proposed method can significantly improve the system efficiency and ensure tracking accuracy simultaneously. (c) 2021 Elsevier Inc. All rights reserved.

Automated summary

The paper proposes a hydraulic servo system structure based on dual hydraulic accumulators to reduce throttle loss and overflow loss simultaneously, and an output feedback controller based on the desired compensation approach. By analyzing the stability of the controller and the energy efficiency of the system, the results indicate that this method can significantly improve the system efficiency and ensure tracking accuracy.