Smart Servohydraulic Robot Actuation

电液伺服系统利用电子控制下的伺服阀来调节流向致动器的流体。通过包括传感器和闭环控制器来实现精确的运动/力控制。这种设置在许多行业中很常见，由于高动态性能和功率重量比，对机器人特别有用。穆格开发了一种集成智能执行器（伊萨），将伺服阀，线性执行器，传感器和控制电子设备全部结合到增材制造的钛合金主体中。这种设置是移动的机器人的理想选择，因为它的质量很低，而且其组件集成带来了鲁棒性。它也提供了一个机会，开发一个负载不可知的控制器。控制器的设计和调整需要的液压系统的动态知识，以及驱动器驱动的负载。对于给定的设置，显著改变任一组件的性质将改变控制器的行为，可能导致性能差或不稳定。ISA还采取措施处理液压系统中固有的非线性。伊萨使液压和传感器动态特性“固定”并预先已知，只留下未知的负载特性。该项目的目的是利用伊萨硬件开发一种力/运动控制算法，该算法可以处理负载不确定性，只需最少的调整，创建第一个“即插即用”伺服液压执行器。该项目的初始阶段将集中在执行器的建模，控制算法的研究以及硬件的初始设置和测试。将在Simulink中进行建模，然后在一系列操作条件下与真实的系统进行比较和验证。研究将集中在电液伺服系统中使用的不同控制算法，处理非线性的方法，特别是处理未知负载的方法。实验装置将使致动器能够驱动可变质量的负载，弹簧和阻尼率以及通过驱动另一个高性能致动器在回路中使用硬件的可能性。该试验台的大部分已经就位，包括驱动执行器的动力单元。一些组件将需要设计，以集成伊萨到钻机。后期阶段将涉及控制算法的实施和测试，并选择现实世界的比较，以验证控制器。可用的传感器数据还可以实现系统“健康监测”，以检查液压系统的状态和性能。另一个潜在的途径是研究机器人与人交互的安全要求，这对移动的机器人至关重要，以及如何将这些安全要求直接集成到执行器控制器中。

An electro-hydraulic servo system utilises a servo-valve under electronic control to regulate the flow of fluid to an actuator. Precise motion/force control is achieved by including sensors and a closed loop controller. This setup is common in many industries and is particularly useful for robotics due to high dynamic performance and power to weight ratio.Moog have developed an Integrated Smart Actuator (ISA), combining the servo-valve, linear actuator, sensors and control electronics all into an additively manufactured titanium body. This setup is ideal for mobile robotics, due to its low mass and the robustness created by its component integration. It also presents an opportunity to develop a load agnostic controller.The design and tuning of a controller requires knowledge of the dynamics of the hydraulic system, as well as the load that the actuator is to drive. For a given setup, changing the nature of either of components significantly, will alter the behaviour of the controller, potentially leading to poor performance or instability. Steps are also taken to deal with the non-linearities that are inherently present in a hydraulic system.With the ISA, the hydraulic and sensor dynamics are 'fixed' and known in advance leaving only the load characteristics as unknown. The aim of the project is to utilise the ISA hardware to develop a force/motion control algorithm that can deal with load uncertainty with minimal tuning required, creating the first 'plug and play' servo-hydraulic actuator.The initial stage of the project will focus on the modelling of the actuator, research into control algorithms and an initial set-up and testing of the hardware. Modelling will be done in Simulink and then compared and validated to the real system over a range of operating conditions.The research will focus on different control algorithms that have been used on electro-hydraulic servo systems, methods of dealing with non-linearities and particularly methods for dealing with unknown loading.The experimental setup will enable the actuator to drive a load with variable mass, spring and damping rate as well as the possibility of using hardware in the loop by driving against another high-performance actuator. The majority of this test rig is in place, including a powerpack to drive the actuator. Some components will need designing to integrate the ISA into the rig.Later stages will involve the implementation and testing of control algorithms and selection of a real-world comparison to validate the controller against. The sensor data available also yields the possibility of system 'health monitoring', to check the status and performance of the hydraulic system. Another potential avenue is to investigate the safety requirements for robotic human interaction, vital for mobile robotics, and how these can be directly integrated within the actuator controller.