Abstract Axial piston motors and pumps are core components in many hydromechanical systems as for instance the powertrain of wheel loader vehicles. The optimal performance of the individual components as well as the entire powertrain requires a fast and exact control of both the motor’s swivel angle as well as the pressure difference over the pump by means of the currently available information and despite their respective a-priori unknown reference signal generated by the driver with a joystick or gas pedal operation. Therefore, it is essential that the swivel angle and pressure controllers fully exploit the possible dynamics and the constrained resources of the nonlinear swivel angle displacement and the pressure adjustment system, respectively. In this work, a flatness-based feedforward control strategy for the motor’s swivel angle as well as a flatness-based tracking two-degree-of-freedom controller for the pump pressure are proposed. For the realization of the flat feedforward and the tracking controller, a constrained online trajectory generation by means of a nonlinear (switched) state variable filter is designed for each. Therefore, both controllers are capable of considering the relevant state and input constraints in real-time and without relying on an online optimization. The proposed control algorithms are both discussed and their performance is illustrated with measurement data from a wheel loader vehicle.

中文翻译：

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流体力学动力系统的约束实时控制——方法论和实际应用

摘要 轴向柱塞马达和泵是许多液压机械系统的核心部件，例如轮式装载机车辆的动力系统。各个部件以及整个动力系统的最佳性能需要通过当前可用的信息快速准确地控制电机的旋转角度以及泵上的压差，尽管它们各自的先验未知参考驾驶员通过操纵杆或油门操作产生的信号。因此，摆角控制器和压力控制器必须分别充分利用非线性摆角位移和压力调节系统的可能动力学和受限资源。在这项工作中，提出了基于平面度的电机回转角前馈控制策略和基于平面度的泵压力跟踪二自由度控制器。为了实现平坦前馈和跟踪控制器，通过非线性（切换）状态变量滤波器为每个设计了约束在线轨迹生成。因此，两个控制器都能够实时考虑相关的状态和输入约束，而无需依赖在线优化。讨论了所提出的控制算法，并用轮式装载机车辆的测量数据说明了它们的性能。通过非线性（切换）状态变量滤波器为每个设计了约束在线轨迹生成。因此，两个控制器都能够实时考虑相关的状态和输入约束，而无需依赖在线优化。讨论了所提出的控制算法，并用轮式装载机车辆的测量数据说明了它们的性能。通过非线性（切换）状态变量滤波器为每个设计了约束在线轨迹生成。因此，两个控制器都能够实时考虑相关的状态和输入约束，而无需依赖在线优化。讨论了所提出的控制算法，并用轮式装载机车辆的测量数据说明了它们的性能。