Decoupled actuator structures
Task/objective
The aim of the transfer project is to develop robust control systems with an independent metering valve system for efficient use in mobile machinery. In particular, the high complexity of the control and regulation of these drives has so far hindered broad industrial acceptance. However, current development trends, such as automation and assistance, are creating completely new, higher demands on the accuracy, controllability and operating characteristics of hydraulic drives. Therefore, the focus of the investigations is on the optimal design of powerful components and their computationally efficient characterization, the sensors to be used and correspondingly highly developed, yet industrially usable, control strategies.
Solution approach
The development of a detailed multi-domain simulation model allows a profound system analysis and model-based control design using software in the loop (SiL).
With the gradual increase in model complexity, control approaches were initially developed and compared at the individual actuator level. With regard to the transfer of knowledge to industrial applications, particular attention was paid to the complexity of the hardware available for calculation and measurement data acquisition.
In addition to various non-linear control structures, the control concepts include feedforward control paths. These consist, for example, of inverse characteristics of the hydraulic components. Therefore, the project also investigated computationally efficient identification and approximation methods for the multidimensional mapping of these components, e.g. for the pressure and temperature-dependent valve flow.
As the project also involved the implementation of both operator-controlled and (partially) automated functions, holistic control concepts, some of which are known from electro-mechanical robotics, were transferred to hydraulic actuation in addition to the individual actuator controls in order to execute trajectories in the work area following a position and force controlled regime.
The associated project partners actively supported the implementation of the theoretical preliminary considerations on the demonstrator machine by providing the machine, the control technology and especially in the production of the decentralized valve technology arranged directly on the cylinders.
The research work presented was carried out within the DFG transfer project "Development and testing of load- and motion-decoupled actuator structures using non-linear, model-based control algorithms" (funding code WE4828/8-1). The authors would like to thank the German Research Foundation (DFG) for funding.