Abstract: Hydraulic valve-controlled servo system is an important part of high-end equipment, and the power mechanism (such as valve-controlled hydraulic cylinder) as its essential component, responsible for driving the load movement. In order for the power mechanism to fully meet the demand of driving loads, load matching method is used to calculate the parameters of the power mechanism, so that the output characteristic curves of the power mechanism can fully envelope the load trajectory. However, the load trajectory and the output characteristic curves of the power mechanism are usually four-quadrant in the actual system. It is difficult to take this characteristic into account in the matching process, which leads to a cumbersome four-quadrant load matching process and low matching efficiency. Based on this, in order to achieve a four-quadrant matching task in the first and second quadrants, a four-quadrant load equivalence method is proposed to equate a third and fourth quadrants load trajectory to a first and second quadrants. At the same time, the parameters of the equivalence formula are analyzed to grasp the influence of the key parameters on the equivalence trajectory and to further refine the four-quadrant load equivalence method. Finally, the simulation and experimental results show that the output characteristic curves of the power mechanism have the same envelope effect on the equivalent load trajectory and the four-quadrant load trajectory. The power mechanism calculated by the load matching method based on the four-quadrant load equivalence can track the load trajectory, which verifies the correctness of the four-quadrant load equivalence method.

Key words: four-quadrant load equivalence, load matching method, hydraulic valve-controlled servo system, power mechanism