In existing methods, full-state feedback is required for the position tracking of single-rod Electro Hydrostatic Actuators (EHAs). Measuring a full state is not always possible because of cost and space limitations. Furthermore, measurement noise from pressure sensors may degrade the control performance. We propose an observer-based nonlinear position control with nonlinear coordinate transformation while only using position measurement to improve the position tracking of single-rod EHAs. The proposed method comprises a position controller and an observer. We propose a nonlinear coordinate transform for the controller design. The desired force is designed for the position tracking and boundedness of the internal state. The position controller is designed to track the desired state variables for the EHAs. Meanwhile, a nonlinear observer is proposed in order to estimate a full state using only the position measurement. The stability of the closed-loop system is investigated via an input-to-state stability property. The performance of the proposed method is validated via both simulations and experiments.

中文翻译：

---

单杆静液压执行机构仅位置测量的非线性坐标变换非线性位置控制

在现有方法中，单杆电动静液压执行器（EHA）的位置跟踪需要全状态反馈。由于成本和空间的限制，并非总是可以测量满状态。此外，来自压力传感器的测量噪声可能会降低控制性能。我们提出了一种基于观察者的具有非线性坐标变换的非线性位置控制，同时仅使用位置测量来改善单杆EHA的位置跟踪。所提出的方法包括位置控制器和观察者。我们提出用于控制器设计的非线性坐标变换。设计所需的力用于内部状态的位置跟踪和边界。位置控制器旨在跟踪EHA的所需状态变量。与此同时，为了仅使用位置测量来估计整个状态，提出了一种非线性观测器。闭环系统的稳定性通过输入到状态的稳定性属性进行研究。通过仿真和实验验证了所提方法的性能。