This article proposes a disturbance observer (DOB)-based compliance control strategy for electrohydrostatic actuators (EHAs), particularly those with high gear reductions and long hydraulic pipelines, which could lead to a high performance interactive robot system. EHAs suffer significantly from internal leakage and friction, which hampers the application of existing compliance control methods to EHAs. Therefore, a two-degree-of-freedom (DoF) DOB is introduced to compensate for both undesirable effects separately; one degree of freedom handles friction observations and the other monitors internal leakage. Then, a compliance controller is designed without affecting the closed-loop stability. To this end, the state of the nominal plant, not the real plant, is used in the designs of the internal leakage observer and the compliance controller as it guarantees closed-loop stability. The asymptotic convergence of the closed-loop system is evaluated via simulations and experiments.

中文翻译：

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基于渐近稳定扰动观测者的电动静液压执行器顺从控制

本文提出了一种针对静电静液压执行器（EHA）的，基于扰动观察器（DOB）的顺从控制策略，尤其是那些齿轮减速较大且液压管路较长的静液压执行器，这可能会导致高性能的交互式机器人系统。EHA遭受内部泄漏和摩擦的严重困扰，这阻碍了将现有的法规遵从控制方法应用于EHA。因此，引入了两自由度（DoF）DOB，以分别补偿这两种不良影响。一个自由度处理摩擦观察，另一个自由度监视内部泄漏。然后，在不影响闭环稳定性的情况下设计一致性控制器。为此，名义工厂而不是实际工厂的状态，用于内部泄漏观测器和一致性控制器的设计中，因为它可确保闭环稳定性。通过仿真和实验评估了闭环系统的渐近收敛性。